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Shrestha N, Zorn-Pauly K, Mesirca P, Koyani CN, Wölkart G, Di Biase V, Torre E, Lang P, Gorischek A, Schreibmayer W, Arnold R, Maechler H, Mayer B, von Lewinski D, Torrente AG, Mangoni ME, Pelzmann B, Scheruebel S. Lipopolysaccharide-induced sepsis impairs M2R-GIRK signaling in the mouse sinoatrial node. Proc Natl Acad Sci U S A 2023; 120:e2210152120. [PMID: 37406102 PMCID: PMC10334783 DOI: 10.1073/pnas.2210152120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 05/15/2023] [Indexed: 07/07/2023] Open
Abstract
Sepsis has emerged as a global health burden associated with multiple organ dysfunction and 20% mortality rate in patients. Numerous clinical studies over the past two decades have correlated the disease severity and mortality in septic patients with impaired heart rate variability (HRV), as a consequence of impaired chronotropic response of sinoatrial node (SAN) pacemaker activity to vagal/parasympathetic stimulation. However, the molecular mechanism(s) downstream to parasympathetic inputs have not been investigated yet in sepsis, particularly in the SAN. Based on electrocardiography, fluorescence Ca2+ imaging, electrophysiology, and protein assays from organ to subcellular level, we report that impaired muscarinic receptor subtype 2-G protein-activated inwardly-rectifying potassium channel (M2R-GIRK) signaling in a lipopolysaccharide-induced proxy septic mouse model plays a critical role in SAN pacemaking and HRV. The parasympathetic responses to a muscarinic agonist, namely IKACh activation in SAN cells, reduction in Ca2+ mobilization of SAN tissues, lowering of heart rate and increase in HRV, were profoundly attenuated upon lipopolysaccharide-induced sepsis. These functional alterations manifested as a direct consequence of reduced expression of key ion-channel components (GIRK1, GIRK4, and M2R) in the mouse SAN tissues and cells, which was further evident in the human right atrial appendages of septic patients and likely not mediated by the common proinflammatory cytokines elevated in sepsis.
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Affiliation(s)
- Niroj Shrestha
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Klaus Zorn-Pauly
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Chintan N. Koyani
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Gerald Wölkart
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Valentina Di Biase
- Institute of Pharmacology, Medical University of Innsbruck, 6020Innsbruck, Austria
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Petra Lang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Astrid Gorischek
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Wolfgang Schreibmayer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Robert Arnold
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Heinrich Maechler
- Division of Cardiac Surgery, Medical University of Graz, 8036Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Dirk von Lewinski
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Angelo G. Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Matteo E. Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Susanne Scheruebel
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
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Ock S, Choi SW, Choi SH, Kang H, Kim SJ, Lee WS, Kim J. Insulin signaling is critical for sinoatrial node maintenance and function. Exp Mol Med 2023:10.1038/s12276-023-00988-0. [PMID: 37121973 DOI: 10.1038/s12276-023-00988-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/12/2023] [Accepted: 02/12/2023] [Indexed: 05/02/2023] Open
Abstract
Insulin and insulin-like growth factor 1 (IGF-1) signaling regulate cellular growth and glucose metabolism in the myocardium. However, their physiological role in the cells of the cardiac conduction system has never been explored. Therefore, we sought to determine the spatiotemporal function of insulin/IGF-1 receptors in the sinoatrial node (SAN). We generated cardiac conduction cell-specific inducible IGF-1 receptor (IGF-1R) knockout (KO) (CSIGF1RKO), insulin receptor (IR) KO (CSIRKO), and IR/IGF-1R double-KO (CSDIRKO) mice and evaluated their phenotypes. Telemetric electrocardiography revealed regular sinus rhythm in CSIGF1RKO mice, indicating that IGF-1R is dispensable for normal pacemaking. In contrast, CSIRKO and CSDIRKO mice exhibited profound sinus bradycardia. CSDIRKO mice showed typical sinus node dysfunction characterized by junctional rhythm and sinus pauses on electrocardiography. Interestingly, the lack of an insulin receptor in the SAN cells of CSIRKO and CSDIRKO mice caused sinus nodal fibrosis. Mechanistically, hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) protein expression significantly decreased in the CSIRKO and CSDIRKO mice relative to the controls. A patch-clamp study of the SAN cells of CSIRKO mice revealed a significant decrease in the funny current, which is responsible for spontaneous diastolic depolarization in the SAN. This result suggested that insulin receptor loss reduces the heart rate via downregulation of the HCN4 channel. Additionally, HCN1 expression was decreased in CSDIRKO mice, explaining their sinus node dysfunction. Our results reveal a previously unrecognized role of insulin/IGF-1 signaling in sinus node structural maintenance and pacemaker function.
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Affiliation(s)
- Sangmi Ock
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Seong Woo Choi
- Departments of Physiology and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
- Department of Physiology, Dongguk University College of Medicine, Gyeongju, Korea
| | - Seung Hee Choi
- Division of Endocrinology and Metabolism, Departments of Internal Medicine and Biochemistry and Cell Biology, Kyungpook National University School of Medicine, Daegu, Korea
| | - Hyun Kang
- Department of Anesthesiology, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Sung Joon Kim
- Departments of Physiology and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Wang-Soo Lee
- Division of Cardiology, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Korea.
| | - Jaetaek Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Korea.
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Lin Z. More than a key-the pathological roles of SARS-CoV-2 spike protein in COVID-19 related cardiac injury. SPORTS MEDICINE AND HEALTH SCIENCE 2023:S2666-3376(23)00024-0. [PMID: 37361919 PMCID: PMC10062797 DOI: 10.1016/j.smhs.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/13/2023] [Accepted: 03/22/2023] [Indexed: 06/28/2023] Open
Abstract
Cardiac injury is common in hospitalized coronavirus disease 2019 (COVID-19) patients and cardiac abnormalities have been observed in a significant number of recovered COVID-19 patients, portending long-term health issues for millions of infected individuals. To better understand how Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, CoV-2 for short) damages the heart, it is critical to fully comprehend the biology of CoV-2 encoded proteins, each of which may play multiple pathological roles. For example, CoV-2 spike glycoprotein (CoV-2-S) not only engages angiotensin converting enzyme II (ACE2) to mediate virus infection but also directly activates immune responses. In this work, the goal is to review the known pathological roles of CoV-2-S in the cardiovascular system, thereby shedding lights on the pathogenesis of COVID-19 related cardiac injury.
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Affiliation(s)
- Zhiqiang Lin
- Masonic Medical Research Institute, 2150 Bleecker Street, Utica, NY, 13501, USA
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Characterization of sinoatrial automaticity in Microcebus murinus to study the effect of aging on cardiac activity and the correlation with longevity. Sci Rep 2023; 13:3054. [PMID: 36810863 PMCID: PMC9944915 DOI: 10.1038/s41598-023-29723-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 02/09/2023] [Indexed: 02/24/2023] Open
Abstract
Microcebus murinus, or gray mouse lemur (GML), is one of the smallest primates known, with a size in between mice and rats. The small size, genetic proximity to humans and prolonged senescence, make this lemur an emerging model for neurodegenerative diseases. For the same reasons, it could help understand how aging affects cardiac activity. Here, we provide the first characterization of sinoatrial (SAN) pacemaker activity and of the effect of aging on GML heart rate (HR). According to GML size, its heartbeat and intrinsic pacemaker frequencies lie in between those of mice and rats. To sustain this fast automaticity the GML SAN expresses funny and Ca2+ currents (If, ICa,L and ICa,T) at densities similar to that of small rodents. SAN automaticity was also responsive to β-adrenergic and cholinergic pharmacological stimulation, showing a consequent shift in the localization of the origin of pacemaker activity. We found that aging causes decrease of basal HR and atrial remodeling in GML. We also estimated that, over 12 years of a lifetime, GML generates about 3 billion heartbeats, thus, as many as humans and three times more than rodents of equivalent size. In addition, we estimated that the high number of heartbeats per lifetime is a characteristic that distinguishes primates from rodents or other eutherian mammals, independently from body size. Thus, cardiac endurance could contribute to the exceptional longevity of GML and other primates, suggesting that GML's heart sustains a workload comparable to that of humans in a lifetime. In conclusion, despite the fast HR, GML replicates some of the cardiac deficiencies reported in old people, providing a suitable model to study heart rhythm impairment in aging. Moreover, we estimated that, along with humans and other primates, GML presents a remarkable cardiac longevity, enabling longer life span than other mammals of equivalent size.
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Landstrom AP, Yang Q, Sun B, Perelli RM, Bidzimou MT, Zhang Z, Aguilar-Sanchez Y, Alsina KM, Cao S, Reynolds JO, Word TA, van der Sangen NM, Wells Q, Kannankeril PJ, Ludwig A, Kim JJ, Wehrens XH. Reduction in Junctophilin 2 Expression in Cardiac Nodal Tissue Results in Intracellular Calcium-Driven Increase in Nodal Cell Automaticity. Circ Arrhythm Electrophysiol 2023; 16:e010858. [PMID: 36706317 PMCID: PMC9974897 DOI: 10.1161/circep.122.010858] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 01/06/2023] [Indexed: 01/29/2023]
Abstract
BACKGROUND Spontaneously depolarizing nodal cells comprise the pacemaker of the heart. Intracellular calcium (Ca2+) plays a critical role in mediating nodal cell automaticity and understanding this so-called Ca2+ clock is critical to understanding nodal arrhythmias. We previously demonstrated a role for Jph2 (junctophilin 2) in regulating Ca2+-signaling through inhibition of RyR2 (ryanodine receptor 2) Ca2+ leak in cardiac myocytes; however, its role in pacemaker function and nodal arrhythmias remains unknown. We sought to determine whether nodal Jph2 expression silencing causes increased sinoatrial and atrioventricular nodal cell automaticity due to aberrant RyR2 Ca2+ leak. METHODS A tamoxifen-inducible, nodal tissue-specific, knockdown mouse of Jph2 was achieved using a Cre-recombinase-triggered short RNA hairpin directed against Jph2 (Hcn4:shJph2). In vivo cardiac rhythm was monitored by surface ECG, implantable cardiac telemetry, and intracardiac electrophysiology studies. Intracellular Ca2+ imaging was performed using confocal-based line scans of isolated nodal cells loaded with fluorescent Ca2+ reporter Cal-520. Whole cell patch clamp was conducted on isolated nodal cells to determine action potential kinetics and sodium-calcium exchanger function. RESULTS Hcn4:shJph2 mice demonstrated a 40% reduction in nodal Jph2 expression, resting sinus tachycardia, and impaired heart rate response to pharmacologic stress. In vivo intracardiac electrophysiology studies and ex vivo optical mapping demonstrated accelerated junctional rhythm originating from the atrioventricular node. Hcn4:shJph2 nodal cells demonstrated increased and irregular Ca2+ transient generation with increased Ca2+ spark frequency and Ca2+ leak from the sarcoplasmic reticulum. This was associated with increased nodal cell AP firing rate, faster diastolic repolarization rate, and reduced sodium-calcium exchanger activity during repolarized states compared to control. Phenome-wide association studies of the JPH2 locus identified an association with sinoatrial nodal disease and atrioventricular nodal block. CONCLUSIONS Nodal-specific Jph2 knockdown causes increased nodal automaticity through increased Ca2+ leak from intracellular stores. Dysregulated intracellular Ca2+ underlies nodal arrhythmogenesis in this mouse model.
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Affiliation(s)
- Andrew P. Landstrom
- Dept of Pediatrics, Division of Cardiology, Duke Univ School of Medicine, Durham, NC
- Dept of Cell Biology, Duke Univ School of Medicine, Durham, NC
| | - Qixin Yang
- Dept of Pediatrics, Division of Cardiology, Duke Univ School of Medicine, Durham, NC
- Dept of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang Univ, Hangzhou, China
| | - Bo Sun
- Dept of Pediatrics, Division of Cardiology, Duke Univ School of Medicine, Durham, NC
| | | | | | - Zhushan Zhang
- Dept of Cell Biology, Duke Univ School of Medicine, Durham, NC
| | - Yuriana Aguilar-Sanchez
- Integrative Molecular & Biomedical Sciences Program, Baylor College of Medicine, Houston, TX
| | - Katherina M. Alsina
- Integrative Molecular & Biomedical Sciences Program, Baylor College of Medicine, Houston, TX
| | - Shuyi Cao
- Dept of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX
| | - Julia O. Reynolds
- Dept of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX
| | - Tarah A. Word
- Dept of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX
| | | | - Quinn Wells
- Depts of Medicine, Pharmacology, and Biomedical Informatics, Vanderbilt Univ School of Medicine, Nashville, TN
| | - Prince J. Kannankeril
- Center for Pediatric Precision Medicine, Dept of Pediatrics, Vanderbilt Univ School of Medicine, Nashville, TN
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jeffrey J. Kim
- Dept of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, TX
| | - Xander H.T. Wehrens
- Dept of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX
- Dept of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, TX
- Depts of Neuroscience & Center for Space Medicine and the Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX
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Ren L, Thai PN, Gopireddy RR, Timofeyev V, Ledford HA, Woltz RL, Park S, Puglisi JL, Moreno CM, Santana LF, Conti AC, Kotlikoff MI, Xiang YK, Yarov-Yarovoy V, Zaccolo M, Zhang XD, Yamoah EN, Navedo MF, Chiamvimonvat N. Adenylyl cyclase isoform 1 contributes to sinoatrial node automaticity via functional microdomains. JCI Insight 2022; 7:e162602. [PMID: 36509290 PMCID: PMC9746826 DOI: 10.1172/jci.insight.162602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 10/05/2022] [Indexed: 11/22/2022] Open
Abstract
Sinoatrial node (SAN) cells are the heart's primary pacemaker. Their activity is tightly regulated by β-adrenergic receptor (β-AR) signaling. Adenylyl cyclase (AC) is a key enzyme in the β-AR pathway that catalyzes the production of cAMP. There are current gaps in our knowledge regarding the dominant AC isoforms and the specific roles of Ca2+-activated ACs in the SAN. The current study tests the hypothesis that distinct AC isoforms are preferentially expressed in the SAN and compartmentalize within microdomains to orchestrate heart rate regulation during β-AR signaling. In contrast to atrial and ventricular myocytes, SAN cells express a diverse repertoire of ACs, with ACI as the predominant Ca2+-activated isoform. Although ACI-KO (ACI-/-) mice exhibit normal cardiac systolic or diastolic function, they experience SAN dysfunction. Similarly, SAN-specific CRISPR/Cas9-mediated gene silencing of ACI results in sinus node dysfunction. Mechanistically, hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) channels form functional microdomains almost exclusively with ACI, while ryanodine receptor and L-type Ca2+ channels likely compartmentalize with ACI and other AC isoforms. In contrast, there were no significant differences in T-type Ca2+ and Na+ currents at baseline or after β-AR stimulation between WT and ACI-/- SAN cells. Due to its central characteristic feature as a Ca2+-activated isoform, ACI plays a unique role in sustaining the rise of local cAMP and heart rates during β-AR stimulation. The findings provide insights into the critical roles of the Ca2+-activated isoform of AC in sustaining SAN automaticity that is distinct from contractile cardiomyocytes.
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Affiliation(s)
- Lu Ren
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, California, USA
| | - Phung N. Thai
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
- Department of Veteran Affairs, Northern California Health Care System, Sacramento, California, USA
| | | | - Valeriy Timofeyev
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
| | - Hannah A. Ledford
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
| | - Ryan L. Woltz
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
- Department of Veteran Affairs, Northern California Health Care System, Sacramento, California, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada, USA
- Prestige Biopharma Korea, Myongjigukje 7-ro, Gangseo-gu, Busan, South Korea
| | - Jose L. Puglisi
- College of Medicine. California North State University, Sacramento, California, USA
| | - Claudia M. Moreno
- Department of Physiology and Membrane Biology, UCD, Davis, California, USA
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington, USA
| | | | - Alana C. Conti
- Research & Development Service, John D. Dingell VA Medical Center, and
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | | | - Yang Kevin Xiang
- Department of Veteran Affairs, Northern California Health Care System, Sacramento, California, USA
- Department of Pharmacology, UCD, Davis, California, USA
| | | | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, United Kingdom
| | - Xiao-Dong Zhang
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
- Department of Veteran Affairs, Northern California Health Care System, Sacramento, California, USA
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada, USA
| | | | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiovascular Medicine, UCD, Davis, California, USA
- Department of Veteran Affairs, Northern California Health Care System, Sacramento, California, USA
- Department of Pharmacology, UCD, Davis, California, USA
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7
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Louradour J, Bortolotti O, Torre E, Bidaud I, Lamb N, Fernandez A, Le Guennec JY, Mangoni ME, Mesirca P. L-Type Cav1.3 Calcium Channels Are Required for Beta-Adrenergic Triggered Automaticity in Dormant Mouse Sinoatrial Pacemaker Cells. Cells 2022; 11:cells11071114. [PMID: 35406677 PMCID: PMC8997967 DOI: 10.3390/cells11071114] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/18/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Sinoatrial node cells (SANC) automaticity is generated by functional association between the activity of plasmalemmal ion channels and local diastolic intracellular Ca2+ release (LCR) from ryanodine receptors. Strikingly, most isolated SANC exhibit a “dormant” state, whereas only a fraction shows regular firing as observed in intact SAN. Recent studies showed that β-adrenergic stimulation can initiate spontaneous firing in dormant SANC, though this mechanism is not entirely understood. Methods: To investigate the role of L-type Cav1.3 Ca2+ channels in the adrenergic regulation of automaticity in dormant SANC, we used a knock-in mouse strain in which the sensitivity of L-type Cav1.2 α1 subunits to dihydropyridines (DHPs) was inactivated (Cav1.2DHP−/−), enabling the selective pharmacological inhibition of Cav1.3 by DHPs. Results: In dormant SANC, β-adrenergic stimulation with isoproterenol (ISO) induced spontaneous action potentials (AP) and Ca2+ transients, which were completely arrested with concomitant perfusion of the DHP nifedipine. In spontaneously firing SANC at baseline, Cav1.3 inhibition completely reversed the effect of β-adrenergic stimulation on AP and the frequency of Ca2+ transients. Confocal calcium imaging of SANC showed that the β-adrenergic-induced synchronization of LCRs is regulated by the activity of Cav1.3 channels. Conclusions: Our study shows a novel role of Cav1.3 channels in initiating and maintaining automaticity in dormant SANC upon β-adrenergic stimulation.
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Affiliation(s)
- Julien Louradour
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- PhyMedExp, Université de Montpellier, INSERM U1046, UMR CNRS, 34090 Montpellier, France;
| | - Olivier Bortolotti
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Ned Lamb
- Mammalian Stem Cell Biology Group, Institute of Human Genetics, Université de Montpellier, CNRS, 34090 Montpellier, France; (N.L.); (A.F.)
| | - Anne Fernandez
- Mammalian Stem Cell Biology Group, Institute of Human Genetics, Université de Montpellier, CNRS, 34090 Montpellier, France; (N.L.); (A.F.)
| | - Jean-Yves Le Guennec
- PhyMedExp, Université de Montpellier, INSERM U1046, UMR CNRS, 34090 Montpellier, France;
| | - Matteo E. Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- Correspondence: (M.E.M.); (P.M.)
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- Correspondence: (M.E.M.); (P.M.)
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Intracellular Ca2+-Mediated Mechanisms for the Pacemaker Depolarization of the Mouse and Guinea Pig Sinus Node Tissue. Biomolecules 2022; 12:biom12030377. [PMID: 35327569 PMCID: PMC8945042 DOI: 10.3390/biom12030377] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/24/2022] [Accepted: 02/11/2022] [Indexed: 11/17/2022] Open
Abstract
Intracellular Ca2+-mediated mechanisms for pacemaker depolarization were studied in sinus node tissue preparations from mice and guinea pigs. Microelectrode recordings revealed that the sinus node of the mouse, which had a higher beating rate, had a steeper slope of the pacemaker depolarization than that of the guinea pig. BAPTA and ryanodine, agents that interfere with intracellular Ca2+, significantly decreased the slope of the pacemaker depolarization in both species. In contrast, SEA0400, a specific inhibitor of the Na+-Ca2+ exchanger (NCX), as well as change to low Na+ extracellular solution, significantly decreased the slope in the mouse, but not in the guinea pig. Niflumic acid, a blocker of the Ca2+ activated Cl− channel, decreased the slope in both species. Confocal microscopy revealed the presence of spontaneous Ca2+ oscillations during the interval between Ca2+ transients; such phenomenon was more pronounced in the mouse than in the guinea pig. Thus, although intracellular Ca2+-mediated mechanisms were involved in the pacemaker depolarization of the sinus node in both species, the NCX current was involved in the mouse but not in the guinea pig.
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9
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Reddy GR, Ren L, Thai PN, Caldwell JL, Zaccolo M, Bossuyt J, Ripplinger CM, Xiang YK, Nieves-Cintrón M, Chiamvimonvat N, Navedo MF. Deciphering cellular signals in adult mouse sinoatrial node cells. iScience 2022; 25:103693. [PMID: 35036877 PMCID: PMC8749457 DOI: 10.1016/j.isci.2021.103693] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/30/2021] [Accepted: 12/22/2021] [Indexed: 01/27/2023] Open
Abstract
Sinoatrial node (SAN) cells are the pacemakers of the heart. This study describes a method for culturing and infection of adult mouse SAN cells with FRET-based biosensors that can be exploited to examine signaling events. SAN cells cultured in media with blebbistatin or (S)-nitro-blebbistatin retain their morphology, protein distribution, action potential (AP) waveform, and cAMP dynamics for at least 40 h. SAN cells expressing targeted cAMP sensors show distinct β-adrenergic-mediated cAMP pools. Cyclic GMP, protein kinase A, Ca2+/CaM kinase II, and protein kinase D in SAN cells also show unique dynamics to different stimuli. Heart failure SAN cells show a decrease in cAMP and cGMP levels. In summary, a reliable method for maintaining adult mouse SAN cells in culture is presented, which facilitates studies of signaling networks and regulatory mechanisms during physiological and pathological conditions.
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Affiliation(s)
- Gopireddy R. Reddy
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Lu Ren
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
| | - Phung N. Thai
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
| | - Jessica L. Caldwell
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Crystal M. Ripplinger
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Yang K. Xiang
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
- VA Northern California Healthcare System, 10535 Hospital Way, Mather, CA 95655, USA
| | - Madeline Nieves-Cintrón
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
- VA Northern California Healthcare System, 10535 Hospital Way, Mather, CA 95655, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
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10
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Ding Y, Lang D, Yan J, Bu H, Li H, Jiao K, Yang J, Ni H, Morotti S, Le T, Clark KJ, Port J, Ekker SC, Cao H, Zhang Y, Wang J, Grandi E, Li Z, Shi Y, Li Y, Glukhov AV, Xu X. A phenotype-based forward genetic screen identifies Dnajb6 as a sick sinus syndrome gene. eLife 2022; 11:77327. [PMID: 36255053 PMCID: PMC9642998 DOI: 10.7554/elife.77327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
Previously we showed the generation of a protein trap library made with the gene-break transposon (GBT) in zebrafish (Danio rerio) that could be used to facilitate novel functional genome annotation towards understanding molecular underpinnings of human diseases (Ichino et al, 2020). Here, we report a significant application of this library for discovering essential genes for heart rhythm disorders such as sick sinus syndrome (SSS). SSS is a group of heart rhythm disorders caused by malfunction of the sinus node, the heart's primary pacemaker. Partially owing to its aging-associated phenotypic manifestation and low expressivity, molecular mechanisms of SSS remain difficult to decipher. From 609 GBT lines screened, we generated a collection of 35 zebrafish insertional cardiac (ZIC) mutants in which each mutant traps a gene with cardiac expression. We further employed electrocardiographic measurements to screen these 35 ZIC lines and identified three GBT mutants with SSS-like phenotypes. More detailed functional studies on one of the arrhythmogenic mutants, GBT411, in both zebrafish and mouse models unveiled Dnajb6 as a novel SSS causative gene with a unique expression pattern within the subpopulation of sinus node pacemaker cells that partially overlaps with the expression of hyperpolarization activated cyclic nucleotide gated channel 4 (HCN4), supporting heterogeneity of the cardiac pacemaker cells.
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Affiliation(s)
- Yonghe Ding
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Di Lang
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States,Department of Medicine, University of California, San FranciscoSan FranciscoUnited States
| | - Jianhua Yan
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Haisong Bu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Department of Cardiothoracic Surgery, Xiangya Hospital, Central South UniversityChangshaChina
| | - Hongsong Li
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Department of Cardiovascular Medicine, Jiading District Central Hospital Affiliated Shanghai University of Medicine & Health ScienceShanghaiChina
| | - Kunli Jiao
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States,Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Jingchun Yang
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Haibo Ni
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Stefano Morotti
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Tai Le
- Department of Biomedical Engineering, University of California, IrvineIrvineUnited States
| | - Karl J Clark
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Jenna Port
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Stephen C Ekker
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
| | - Hung Cao
- Department of Biomedical Engineering, University of California, IrvineIrvineUnited States,Department of Electrical Engineering and Computer Science, University of California, IrvineIrvineUnited States
| | - Yuji Zhang
- Department of Epidemiology and Public Health, University of Maryland School of MedicineBaltimoreUnited States
| | - Jun Wang
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at HoustonHoustonUnited States
| | - Eleonora Grandi
- Department of Pharmacology, University of California, DavisDavisUnited States
| | - Zhiqiang Li
- The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Yongyong Shi
- The Affiliated Hospital of Qingdao University & The Biomedical Sciences Institute of Qingdao University (Qingdao Branch of SJTU Bio-X Institutes), Qingdao UniversityQingdaoChina
| | - Yigang Li
- Division of Cardiology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School Of MedicineShanghaiChina
| | - Alexey V Glukhov
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Department of Cardiovascular Medicine, Mayo ClinicRochesterUnited States
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11
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Dixon RE, Navedo MF, Binder MD, Santana LF. Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters. Physiol Rev 2021; 102:1159-1210. [PMID: 34927454 DOI: 10.1152/physrev.00022.2021] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Cav1.2 and Cav1.3 channels to obligatory dimeric assembly and gating of voltage-gated Nav1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP3Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.
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Affiliation(s)
- Rose Ellen Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, United States
| | - Marc D Binder
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, United States
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
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12
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Ishihara M, Kojima A, Ding WG, Kitagawa H, Matsuura H. Dexmedetomidine Exerts a Negative Chronotropic Action on Sinoatrial Node Cells Through the Activation of Imidazoline Receptors. J Cardiovasc Pharmacol 2021; 78:826-838. [PMID: 34448469 DOI: 10.1097/fjc.0000000000001133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 08/05/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Dexmedetomidine (DEX), an α2-adrenoreceptor (α2-AR) and imidazoline receptor agonist, is most often used for the sedation of patients in the intensive care unit. Its administration is associated with an increased incidence of bradycardia; however, the precise mechanism of DEX-induced bradycardia has yet to be fully elucidated. This study was undertaken to examine whether DEX modifies pacemaker activity and the underlying ionic channel function through α2-AR and imidazoline receptors. The whole-cell patch-clamp techniques were used to record action potentials and related ionic currents of sinoatrial node cells in guinea pigs. DEX (≥10 nM) reduced sinoatrial node automaticity and the diastolic depolarization rate. DEX reduced the amplitude of hyperpolarization-activated cation current (If or Ih) the pacemaker current, even within the physiological pacemaker potential range. DEX slowed the If current activation kinetics and caused a significant shift in the voltage dependence of channel activation to negative potentials. In addition, efaroxan, an α2-AR and imidazoline I1 receptor antagonist, attenuated the inhibitory effects of DEX on sinoatrial node automaticity and If current activity, whereas yohimbine, an α2-AR-selective antagonist, did not. DEX did not affect the current activities of other channels, including rapidly and slowly activating delayed rectifier K+ currents (IKr and IKs), L-type Ca2+ current (ICa,L), Na+/Ca2+ exchange current (INCX), and muscarinic K+ current (IK,ACh). Our results indicate that DEX, at clinically relevant concentrations, induced a negative chronotropic effect on the sinoatrial node function through the downregulation of If current through an imidazoline I1 receptor other than the α2-AR in the clinical setting.
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Affiliation(s)
- Mariko Ishihara
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan; and
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan; and
| | - Hirotoshi Kitagawa
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan; and
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13
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Takeda Y, Matsuoka S. Impact of mitochondria on local calcium release in murine sinoatrial nodal cells. J Mol Cell Cardiol 2021; 164:42-50. [PMID: 34826768 DOI: 10.1016/j.yjmcc.2021.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 11/04/2021] [Accepted: 11/14/2021] [Indexed: 02/07/2023]
Abstract
Roles of mitochondria in sinoatrial nodal cells (SANCs) have not been fully clarified. We have previously demonstrated that mitochondrial Ca2+ efflux through the Na+-Ca2+ exchanger, NCXm, modulates sarcoplasmic reticulum (SR) Ca2+ content and automaticity of HL-1 cardiomyocytes. In this study, we extended this line of investigation to clarify the spatial and functional association between mitochondria and local calcium release (LCR) from the SR in murine SANCs. High-speed two dimensional (2D) and confocal line-scan imaging of SANCs revealed that LCRs in the early phase of the Ca2+ transient cycle length (CL) appeared with a higher probability near mitochondria. Although LCR increased toward the late phase of CL, no significant difference was noted in the occurrence of late LCRs near and distant from mitochondria. LCRs, especially in the late phase of CL, induced temporal and spatial heterogeneity of the Ca2+ transient amplitude. Attenuating mitochondrial Ca2+ efflux using an NCXm inhibitor, CGP-37157 (1 μM), reduced the amplitude, duration and size of LCR. It also attenuated early LCR occurrence, and simultaneously prolonged LCR period and CL. Additionally, CGP-37157 reduced caffeine-induced Ca2+ transient. Therefore, the inhibitory effect on LCR was attributable to the reduction of the SR Ca2+ content through NCXm inhibition. No obvious off-target effects of 1 μM CGP-37157 were found on T- and L-type voltage-gated Ca2+ currents and hyperpolarization-activated inward current. Taken together, these results suggest that mitochondria are involved in LCR generation by modulating the SR Ca2+ content through NCXm-mediated Ca2+ efflux in murine SANCs.
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Affiliation(s)
- Yukari Takeda
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan.
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14
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Jøns C, Porta-Sánchez A, Lai PFH, Wauchop M, Massé S, Azam MA, Asta J, Rose RA, Nanthakumar K. Mechanism of and strategy to mitigate liraglutide-mediated positive chronotropy. Life Sci 2021; 282:119815. [PMID: 34256040 DOI: 10.1016/j.lfs.2021.119815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/25/2021] [Accepted: 07/05/2021] [Indexed: 11/18/2022]
Abstract
AIM An adverse side-effect of Liraglutide (LG), a Glucagon-Like Peptide 1 (GLP1)-analog commonly used in treatments for diabetes, is positive chronotropy. The goal of this study is to investigate on the mechanism of this drug-induced chronotropy and explore potential means to mitigate this side-effect so as to maximize the therapeutic benefits from LG. MAIN METHODS Experiments were conducted with: 1) Isolated rabbit hearts in a Langendorff set-up to assess for direct effects of drug actions and 2) Murine cardiomyocytes isolated from the sino-atrial node (SAN) to assess the effects of LG on spontaneous action potential (AP) firing and the hyperpolarization-activated current If. KEY FINDINGS LG induced a dose-dependent increase in heart rate. Its effects on sinus node automaticity, which were not suppressed during β-blockade with Propranolol, were abolished by If blockade with Ivabradine. In isolated murine SAN myocytes, LG increased spontaneous AP firing frequency by an increase in diastolic depolarization slope without changing other electrophysiological parameters. SIGNIFICANCE LG-induced positive chronotropy is partly due to a direct effect on the SAN and is independent of the adrenergic cascade and extrinsic autonomic reflex mechanisms. The direct LG-associated increase in heart rate should be mitigated with If blockers rather than β-blockade.
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Affiliation(s)
- Christian Jøns
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada; Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen, Denmark
| | - Andreu Porta-Sánchez
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada; Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain and Hospital Universitario Quirónsalud, Madrid, Spain
| | - Patrick F H Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | | | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - John Asta
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Robert A Rose
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada; University of Toronto, Toronto, Ontario, Canada.
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15
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DiFrancesco ML, Mesirca P, Bidaud I, Isbrandt D, Mangoni ME. The funny current in genetically modified mice. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:39-50. [PMID: 34129872 DOI: 10.1016/j.pbiomolbio.2021.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/18/2021] [Accepted: 06/07/2021] [Indexed: 12/27/2022]
Abstract
Since its first description in 1979, the hyperpolarization-activated funny current (If) has been the object of intensive research aimed at understanding its role in cardiac pacemaker activity and its modulation by the sympathetic and parasympathetic branches of the autonomic nervous system. If was described in isolated tissue strips of the rabbit sinoatrial node using the double-electrode voltage-clamp technique. Since then, the rabbit has been the principal animal model for studying pacemaker activity and If for more than 20 years. In 2001, the first study describing the electrophysiological properties of mouse sinoatrial pacemaker myocytes and those of If was published. It was soon followed by the description of murine myocytes of the atrioventricular node and the Purkinje fibres. The sinoatrial node of genetically modified mice has become a very popular model for studying the mechanisms of cardiac pacemaker activity. This field of research benefits from the impressive advancement of in-vivo exploration techniques of physiological parameters, imaging, genetics, and large-scale genomic approaches. The present review discusses the influence of mouse genetic on the most recent knowledge of the funny current's role in the physiology and pathophysiology of cardiac pacemaker activity. Genetically modified mice have provided important insights into the role of If in determining intrinsic automaticity in vivo and in myocytes of the conduction system. In addition, gene targeting of f-(HCN) channel isoforms have contributed to elucidating the current's role in the regulation of heart rate by the parasympathetic nervous system. This review is dedicated to Dario DiFrancesco on his retirement.
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Affiliation(s)
- Mattia L DiFrancesco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy; Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France; LabEx Ion Channels Science and Therapeutics (ICST), France.
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France; LabEx Ion Channels Science and Therapeutics (ICST), France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France; LabEx Ion Channels Science and Therapeutics (ICST), France
| | - Dirk Isbrandt
- Deutsches Zentrum für Neurodegenerative Erktankungen (DZNE), Bonn, Germany; University of Cologne, Institute for Molecular and Behavioral Neuroscience, Cologne, Germany
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France; LabEx Ion Channels Science and Therapeutics (ICST), France.
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16
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Dual role of miR-1 in the development and function of sinoatrial cells. J Mol Cell Cardiol 2021; 157:104-112. [PMID: 33964276 DOI: 10.1016/j.yjmcc.2021.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/27/2021] [Accepted: 05/03/2021] [Indexed: 11/20/2022]
Abstract
miR-1, the most abundant miRNA in the heart, modulates expression of several transcription factors and ion channels. Conditions affecting the heart rate, such as endurance training and cardiac diseases, show a concomitant miR-1 up- or down-regulation. Here, we investigated the role of miR-1 overexpression in the development and function of sinoatrial (SAN) cells using murine embryonic stem cells (mESC). We generated mESCs either overexpressing miR-1 and EGFP (miR1OE) or EGFP only (EM). SAN-like cells were selected from differentiating mESC using the CD166 marker. Gene expression and electrophysiological analysis were carried out on both early mES-derived cardiac progenitors and SAN-like cells and on beating neonatal rat ventricular cardiomyocytes (NRVC) over-expressing miR-1. miR1OE cells increased significantly the proportion of CD166+ SAN precursors compared to EM cells (23% vs 12%) and the levels of the transcription factors TBX5 and TBX18, both involved in SAN development. miR1OE SAN-like cells were bradycardic (1,3 vs 2 Hz) compared to EM cells. In agreement with data on native SAN cells, EM SAN-like cardiomyocytes show two populations of cells expressing either slow- or fast-activating If currents; miR1OE SAN-like cells instead have only fast-activating If with a significantly reduced conductance. Western Blot and immunofluorescence analysis showed a reduced HCN4 signal in miR-1OE vs EM CD166+ precursors. Together these data point out to a specific down-regulation of the slow-activating HCN4 subunit by miR-1. Importantly, the rate and If alterations were independent of the developmental effects of miR-1, being similar in NRVC transiently overexpressing miR-1. In conclusion, we demonstrated a dual role of miR-1, during development it controls the proper development of sinoatrial-precursor, while in mature SAN-like cells it modulates the HCN4 pacemaker channel translation and thus the beating rate.
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17
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Bidaud I, D'Souza A, Forte G, Torre E, Greuet D, Thirard S, Anderson C, Chung You Chong A, Torrente AG, Roussel J, Wickman K, Boyett MR, Mangoni ME, Mesirca P. Genetic Ablation of G Protein-Gated Inwardly Rectifying K + Channels Prevents Training-Induced Sinus Bradycardia. Front Physiol 2021; 11:519382. [PMID: 33551824 PMCID: PMC7857143 DOI: 10.3389/fphys.2020.519382] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/17/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Endurance athletes are prone to bradyarrhythmias, which in the long-term may underscore the increased incidence of pacemaker implantation reported in this population. Our previous work in rodent models has shown training-induced sinus bradycardia to be due to microRNA (miR)-mediated transcriptional remodeling of the HCN4 channel, leading to a reduction of the "funny" (I f) current in the sinoatrial node (SAN). Objective: To test if genetic ablation of G-protein-gated inwardly rectifying potassium channel, also known as I KACh channels prevents sinus bradycardia induced by intensive exercise training in mice. Methods: Control wild-type (WT) and mice lacking GIRK4 (Girk4 -/-), an integral subunit of I KACh were assigned to trained or sedentary groups. Mice in the trained group underwent 1-h exercise swimming twice a day for 28 days, 7 days per week. We performed electrocardiogram recordings and echocardiography in both groups at baseline, during and after the training period. At training cessation, mice were euthanized and SAN tissues were isolated for patch clamp recordings in isolated SAN cells and molecular profiling by quantitative PCR (qPCR) and western blotting. Results: At swimming cessation trained WT mice presented with a significantly lower resting HR that was reversible by acute I KACh block whereas Girk4 -/- mice failed to develop a training-induced sinus bradycardia. In line with HR reduction, action potential rate, density of I f, as well as of T- and L-type Ca2+ currents (I CaT and I CaL ) were significantly reduced only in SAN cells obtained from WT-trained mice. I f reduction in WT mice was concomitant with downregulation of HCN4 transcript and protein, attributable to increased expression of corresponding repressor microRNAs (miRs) whereas reduced I CaL in WT mice was associated with reduced Cav1.3 protein levels. Strikingly, I KACh ablation suppressed all training-induced molecular remodeling observed in WT mice. Conclusion: Genetic ablation of cardiac I KACh in mice prevents exercise-induced sinus bradycardia by suppressing training induced remodeling of inward currents I f, I CaT and I CaL due in part to the prevention of miR-mediated transcriptional remodeling of HCN4 and likely post transcriptional remodeling of Cav1.3. Strategies targeting cardiac I KACh may therefore represent an alternative to pacemaker implantation for bradyarrhythmias seen in some veteran athletes.
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Affiliation(s)
- Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Alicia D'Souza
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Gabriella Forte
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Denis Greuet
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Steeve Thirard
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cali Anderson
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Antony Chung You Chong
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Julien Roussel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Mark R Boyett
- Division of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
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18
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Baudot M, Torre E, Bidaud I, Louradour J, Torrente AG, Fossier L, Talssi L, Nargeot J, Barrère-Lemaire S, Mesirca P, Mangoni ME. Concomitant genetic ablation of L-type Ca v1.3 (α 1D) and T-type Ca v3.1 (α 1G) Ca 2+ channels disrupts heart automaticity. Sci Rep 2020; 10:18906. [PMID: 33144668 PMCID: PMC7642305 DOI: 10.1038/s41598-020-76049-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/15/2020] [Indexed: 12/02/2022] Open
Abstract
Cardiac automaticity is set by pacemaker activity of the sinus node (SAN). In addition to the ubiquitously expressed cardiac voltage-gated L-type Cav1.2 Ca2+ channel isoform, pacemaker cells within the SAN and the atrioventricular node co-express voltage-gated L-type Cav1.3 and T-type Cav3.1 Ca2+ channels (SAN-VGCCs). The role of SAN-VGCCs in automaticity is incompletely understood. We used knockout mice carrying individual genetic ablation of Cav1.3 (Cav1.3−/−) or Cav3.1 (Cav3.1−/−) channels and double mutant Cav1.3−/−/Cav3.1−/− mice expressing only Cav1.2 channels. We show that concomitant loss of SAN-VGCCs prevents physiological SAN automaticity, blocks impulse conduction and compromises ventricular rhythmicity. Coexpression of SAN-VGCCs is necessary for impulse formation in the central SAN. In mice lacking SAN-VGCCs, residual pacemaker activity is predominantly generated in peripheral nodal and extranodal sites by f-channels and TTX-sensitive Na+ channels. In beating SAN cells, ablation of SAN-VGCCs disrupted late diastolic local intracellular Ca2+ release, which demonstrates an important role for these channels in supporting the sarcoplasmic reticulum based “Ca2+clock” mechanism during normal pacemaking. These data implicate an underappreciated role for co-expression of SAN-VGCCs in heart automaticity and define an integral role for these channels in mechanisms that control the heartbeat.
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Affiliation(s)
- Matthias Baudot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France.,Department of Biotechnology and Biosciences, Università Degli Studi di Milano-Bicocca, Milan, Italy
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Julien Louradour
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Lucile Fossier
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Leïla Talssi
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Joël Nargeot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Stéphanie Barrère-Lemaire
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx ICST, Montpellier, France
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France. .,LabEx ICST, Montpellier, France.
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 141, rue de la cardonille, 34094, Montpellier, France. .,LabEx ICST, Montpellier, France.
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19
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Maurocalcin and its analog MCaE12A facilitate Ca2+ mobilization in cardiomyocytes. Biochem J 2020; 477:3985-3999. [PMID: 33034621 DOI: 10.1042/bcj20200206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 09/23/2020] [Accepted: 10/09/2020] [Indexed: 11/17/2022]
Abstract
Ryanodine receptors are responsible for the massive release of calcium from the sarcoplasmic reticulum that triggers heart muscle contraction. Maurocalcin (MCa) is a 33 amino acid peptide toxin known to target skeletal ryanodine receptor. We investigated the effect of MCa and its analog MCaE12A on isolated cardiac ryanodine receptor (RyR2), and showed that they increase RyR2 sensitivity to cytoplasmic calcium concentrations promoting channel opening and decreases its sensitivity to inhibiting calcium concentrations. By measuring intracellular Ca2+ transients, calcium sparks and contraction on cardiomyocytes isolated from adult rats or differentiated from human-induced pluripotent stem cells, we demonstrated that MCaE12A passively penetrates cardiomyocytes and promotes the abnormal opening of RyR2. We also investigated the effect of MCaE12A on the pacemaker activity of sinus node cells from different mice lines and showed that, MCaE12A improves pacemaker activity of sinus node cells obtained from mice lacking L-type Cav1.3 channel, or following selective pharmacologic inhibition of calcium influx via Cav1.3. Our results identify MCaE12A as a high-affinity modulator of RyR2 and make it an important tool for RyR2 structure-to-function studies as well as for manipulating Ca2+ homeostasis and dynamic of cardiac cells.
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20
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Wang H, Liu Y, Han S, Zi Y, Zhang Y, Kong R, Liu Z, Cai Z, Zhong C, Liu W, Li L, Jiang L. Nkx2-5 Regulates the Proliferation and Migration of H9c2 Cells. Med Sci Monit 2020; 26:e925388. [PMID: 32780729 PMCID: PMC7441744 DOI: 10.12659/msm.925388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background The protein NKX2–5 affects mammalian heart development. In mice, the disruption of Nkx2–5 has been associated with arrhythmias, abnormal myocardial contraction, abnormal cardiac morphogenesis, and death. However, the details of the mechanisms are unclear. This study was designed to investigate them. Material/Methods Rat cardiomyocytes from the H9c2 cell line were used in our study. First, we knocked down Nkx2–5 in the H9c2 cells and then validated consequent changes in cell proliferation and migration. We then used RNA sequencing to determine the changes in transcripts. Finally, we validated these results by quantitative reverse transcription-polymerase chain reaction. Results We confirmed that Nkx2–5 regulates the proliferation and migration of H9c2 cells. In our experiments, Nkx2–5 regulated the expression of genes related to proliferation, migration, heart development, and disease. Based on bioinformatics analysis, knockdown of Nkx2–5 caused differential expression of genes involved in cardiac development, calcium ion-related biological activity, the transforming growth factor (TGF)-β signaling pathway, pathways related to heart diseases, the MAPK signaling pathway, and other biological processes and signaling pathways. Conclusions Nkx2–5 may regulate proliferation and migration of the H9c2 cells through the genes Tgfb-2, Bmp10, Id2, Wt1, Hey1, and Cacna1g; rno-miR-1-3p; the TGF-β signaling pathway; the MAPK signaling pathway; as well as other genes and pathways.
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Affiliation(s)
- Hongshu Wang
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Yong Liu
- Fuwai Yunnan Cardiovascular Hospital, Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Shen Han
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Yunfeng Zi
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Yayong Zhang
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Ruize Kong
- The First People's Hospital of Yunnan Province, Kunming, Yunnan, China (mainland)
| | - Zu Liu
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Zhibin Cai
- Yan'an Hospital Affiliated to Kunming Medical University, Kunming, Yunnan, China (mainland)
| | - Chongbin Zhong
- Department of Thoracic Surgery, The People's Hospital of Chuxiong Yi Autonomous Prefecture, Chuxiong, Yunnan, China (mainland)
| | - Wei Liu
- Department II of Hepatobillary Surgery, The People's Hospital of Chuxiong Yi Autonomous Prefecture, Chuxiong, Yunnan, China (mainland)
| | - Lifeng Li
- Department of Thoracic Surgery, The People's Hospital of Chuxiong Yi Autonomous Prefecture, Chuxiong, Yunnan, China (mainland)
| | - Lihong Jiang
- The First People's Hospital of Yunnan Province, Kunming, Yunnan, China (mainland)
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21
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Torrente AG, Mesirca P, Bidaud I, Mangoni ME. Channelopathies of voltage-gated L-type Cav1.3/α 1D and T-type Cav3.1/α 1G Ca 2+ channels in dysfunction of heart automaticity. Pflugers Arch 2020; 472:817-830. [PMID: 32601767 DOI: 10.1007/s00424-020-02421-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/12/2020] [Accepted: 06/19/2020] [Indexed: 10/24/2022]
Abstract
The heart automaticity is a fundamental physiological function in vertebrates. The cardiac impulse is generated in the sinus node by a specialized population of spontaneously active myocytes known as "pacemaker cells." Failure in generating or conducting spontaneous activity induces dysfunction in cardiac automaticity. Several families of ion channels are involved in the generation and regulation of the heart automaticity. Among those, voltage-gated L-type Cav1.3 (α1D) and T-type Cav3.1 (α1G) Ca2+ channels play important roles in the spontaneous activity of pacemaker cells. Ca2+ channel channelopathies specifically affecting cardiac automaticity are considered rare. Recent research on familial disease has identified mutations in the Cav1.3-encoding CACNA1D gene that underlie congenital sinus node dysfunction and deafness (OMIM # 614896). In addition, both Cav1.3 and Cav3.1 channels have been identified as pathophysiological targets of sinus node dysfunction and heart block, caused by congenital autoimmune disease of the cardiac conduction system. The discovery of channelopathies linked to Cav1.3 and Cav3.1 channels underscores the importance of Ca2+ channels in the generation and regulation of heart's automaticity.
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Affiliation(s)
- Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France. .,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France.
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22
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Yue X, Hazan A, Lotteau S, Zhang R, Torrente AG, Philipson KD, Ottolia M, Goldhaber JI. Na/Ca exchange in the atrium: Role in sinoatrial node pacemaking and excitation-contraction coupling. Cell Calcium 2020; 87:102167. [PMID: 32028091 DOI: 10.1016/j.ceca.2020.102167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 01/21/2020] [Indexed: 01/14/2023]
Abstract
Na/Ca exchange is the dominant calcium (Ca) efflux mechanism in cardiac myocytes. Although our knowledge of exchanger function (NCX1 in the heart) was originally established using biochemical and electrophysiological tools such as cardiac sarcolemmal vesicles and the giant patch technique [1-4], many advances in our understanding of the physiological/pathophysiological roles of NCX1 in the heart have been obtained using a suite of genetically modified mice. Early mouse studies focused on modification of expression levels of NCX1 in the ventricles, with transgenic overexpressors, global NCX1 knockout (KO) mice (which were embryonic lethal if homozygous), and finally ventricular-specific NCX1 KO [5-12]. We found, to our surprise, that ventricular cardiomyocytes lacking NCX1 can survive and function by engaging a clever set of adaptations to minimize Ca entry, while maintaining contractile function through an increase in excitation-contraction (EC) coupling gain [5,6,13]. Having studied ventricular NCX1 ablation in detail, we more recently focused on elucidating the role of NCX1 in the atria through altering NCX1 expression. Using a novel atrial-specific NCX1 KO mouse, we found unexpected changes in atrial cell morphology and calcium handling, together with dramatic alterations in the function of sinoatrial node (SAN) pacemaker activity. In this review, we will discuss these findings and their implications for cardiac disease.
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Affiliation(s)
- Xin Yue
- Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Adina Hazan
- Smidt Heart Institute, Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Sabine Lotteau
- Smidt Heart Institute, Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Rui Zhang
- Smidt Heart Institute, Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Angelo G Torrente
- Institute for Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | | | - Michela Ottolia
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Department of Cardiology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
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23
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Aziz Q, Nobles M, Tinker A. Acute Isolation of Cells from Murine Sino-atrial Node. Bio Protoc 2020; 10:e3477. [PMID: 33654710 DOI: 10.21769/bioprotoc.3477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/23/2019] [Accepted: 11/28/2019] [Indexed: 11/02/2022] Open
Abstract
The cardiac conduction system allows the synchronized propagation of electrical activity through heart muscle. This is initiated by the spontaneous activity of the specialized pacemaker cells of the sino-atrial node (SAN). The SAN region underlies automaticity in mammals and therefore has a crucial role in the pathogenesis of cardiac disorders such as arrhythmia. Isolation of SAN tissue and SAN cells is critical to advance our understanding of SAN structure and function in health and disease. Initially, isolation of SAN tissue and SAN cells was carried out in the rabbit owing to its larger size and similar electrical properties to human. This protocol was optimized by Mangoni and Nargeot (2001) for use in mice to take advantage of advancements in transgenic models. Here, we provide a step-by-step guide to dissecting the SAN tissue and isolating pacemaker cardiomyocytes from mouse hearts using an enzyme digestion approach.
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Affiliation(s)
- Qadeer Aziz
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Muriel Nobles
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Andrew Tinker
- Clinical Pharmacology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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24
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Yang M, Zhao Q, Zhao H, Yang A, Wang F, Wang X, Tang Y, Huang C. Adipose‑derived stem cells overexpressing SK4 calcium‑activated potassium channel generate biological pacemakers. Int J Mol Med 2019; 44:2103-2112. [PMID: 31638180 PMCID: PMC6844603 DOI: 10.3892/ijmm.2019.4374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/11/2019] [Indexed: 01/14/2023] Open
Abstract
Recent studies have suggested that calcium-activated potassium channel (KCa) agonists increase the proportion of mouse embryonic stem cell-derived cardiomyocytes and promote the differentiation of pacemaker cells. In the present study, it was hypothesized that adipose-derived stem cells (ADSCs) can differentiate into pacemaker-like cells via over-expression of the SK4 gene. ADSCs were transduced with a recombinant adenovirus vector carrying the mouse SK4 gene, whereas the control group was transduced with GFP vector. ADSCs transduced with SK4 vector were implanted into the rat left ventricular free wall. Complete atrioventricular block (AVB) was established in isolated perfused rat hearts after 2 weeks. SK4 was successfully and stably expressed in ADSCs following transduction. The mRNA levels of the pluripotent markers Oct-4 and Sox-2 declined and that of the transcription factor Shox2 was upregulated following SK4 transduction. The expression of α-actinin and hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4) increased in the SK4 group. The hyperpolarizing activated pacemaker current If (8/20 cells) was detected in ADSCs transduced with SK4, but not in the GFP group. Furthermore, SK4 transduction induced the expression of p-ERK1/2 and p-p38 MAPK. In the ex vivo experiments, the heart rate of the SK4 group following AVB establishment was significantly higher compared with that in the GFP group. Immunofluorescence revealed that the transduced ADSCs were successfully implanted and expressed HCN4 in the SK4 group. In conclusion, SK4 induced ADSCs to differentiate into cardiomyocyte-like and pacemaker-like cells via activation of the extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase pathways. Therefore, ADSCs transduced with SK4 may be used to generate biological pacemakers in ex vivo rat hearts.
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Affiliation(s)
- Mei Yang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Qingyan Zhao
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Hongyi Zhao
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Ankang Yang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Fengyuan Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Xi Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Yanhong Tang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
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25
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Kim MS, Maltsev AV, Monfredi O, Maltseva LA, Wirth A, Florio MC, Tsutsui K, Riordon DR, Parsons SP, Tagirova S, Ziman BD, Stern MD, Lakatta EG, Maltsev VA. Heterogeneity of calcium clock functions in dormant, dysrhythmically and rhythmically firing single pacemaker cells isolated from SA node. Cell Calcium 2018; 74:168-179. [PMID: 30092494 DOI: 10.1016/j.ceca.2018.07.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 05/30/2018] [Accepted: 07/09/2018] [Indexed: 11/30/2022]
Abstract
Current understanding of how cardiac pacemaker cells operate is based mainly on studies in isolated single sinoatrial node cells (SANC), specifically those that rhythmically fire action potentials similar to the in vivo behavior of the intact sinoatrial node. However, only a small fraction of SANC exhibit rhythmic firing after isolation. Other SANC behaviors have not been studied. Here, for the first time, we studied all single cells isolated from the sinoatrial node of the guinea pig, including traditionally studied rhythmically firing cells ('rhythmic SANC'), dysrhythmically firing cells ('dysrhythmic SANC') and cells without any apparent spontaneous firing activity ('dormant SANC'). Action potential-induced cytosolic Ca2+ transients and spontaneous local Ca2+ releases (LCRs) were measured with a 2D camera. LCRs were present not only in rhythmically firing SANC, but also in dormant and dysrhythmic SANC. While rhythmic SANC were characterized by large LCRs synchronized in space and time towards late diastole, dysrhythmic and dormant SANC exhibited smaller LCRs that appeared stochastically and were widely distributed in time. β-adrenergic receptor (βAR) stimulation increased LCR size and synchronized LCR occurrences in all dysrhythmic and a third of dormant cells (25 of 75 cells tested). In response to βAR stimulation, these dormant SANC developed automaticity, and LCRs became coupled to spontaneous action potential-induced cytosolic Ca2+ transients. Conversely, dormant SANC that did not develop automaticity showed no significant change in average LCR characteristics. The majority of dysrhythmic cells became rhythmic in response to βAR stimulation, with the rate of action potential-induced cytosolic Ca2+ transients substantially increasing. In summary, isolated SANC can be broadly categorized into three major populations: dormant, dysrhythmic, and rhythmic. We interpret our results based on simulations of a numerical model of SANC operating as a coupled-clock system. On this basis, the two previously unstudied dysrhythmic and dormant cell populations have intrinsically partially or completely uncoupled clocks. Such cells can be recruited to fire rhythmically in response to βAR stimulation via increased rhythmic LCR activity and ameliorated coupling between the Ca2+ and membrane clocks.
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Affiliation(s)
- Mary S Kim
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Alexander V Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Oliver Monfredi
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA; Department of Cardiovascular Electrophysiology, The Johns Hopkins Hospital, 1800 Orleans St, Baltimore, MD 21287, USA; Institute of Cardiovascular Sciences, University of Manchester, 46 Grafton St, Manchester M13 9NT, UK
| | - Larissa A Maltseva
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Ashley Wirth
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Maria Cristina Florio
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Kenta Tsutsui
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Sean P Parsons
- Farncombe Institute, McMaster University, Hamilton, ON, Canada
| | - Syevda Tagirova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Bruce D Ziman
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Michael D Stern
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Biomedical Research Center, 251 Bayview Blvd. Suite 100, Baltimore, MD 21224-6825, USA.
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26
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Aziz Q, Finlay M, Montaigne D, Ojake L, Li Y, Anderson N, Ludwig A, Tinker A. ATP-sensitive potassium channels in the sinoatrial node contribute to heart rate control and adaptation to hypoxia. J Biol Chem 2018; 293:8912-8921. [PMID: 29666184 DOI: 10.1074/jbc.ra118.002775] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/16/2018] [Indexed: 11/06/2022] Open
Abstract
ATP-sensitive potassium channels (KATP) contribute to membrane currents in many tissues, are responsive to intracellular metabolism, and open as ATP falls and ADP rises. KATP channels are widely distributed in tissues and are prominently expressed in the heart. They have generally been observed in ventricular tissue, but they are also expressed in the atria and conduction tissues. In this study, we focused on the contribution and role of the inwardly rectifying KATP channel subunit, Kir6.1, in the sinoatrial node (SAN). To develop a murine, conduction-specific Kir6.1 KO model, we selectively deleted Kir6.1 in the conduction system in adult mice (cKO). Electrophysiological data in single SAN cells indicated that Kir6.1 underlies a KATP current in a significant proportion of cells and influences early repolarization during pacemaking, resulting in prolonged cycle length. Implanted telemetry probes to measure heart rate and electrocardiographic characteristics revealed that the cKO mice have a slow heart rate, with episodes of sinus arrest in some mice. The PR interval (time between the onset of the P wave to the beginning of QRS complex) was increased, suggesting effects on the atrioventricular node. Ex vivo studies of whole heart or dissected heart regions disclosed impaired adaptive responses of the SAN to hypoxia, and this may have had long-term pathological consequences in the cKO mice. In conclusion, Kir6.1-containing KATP channels in the SAN have a role in excitability, heart rate control, and the electrophysiological adaptation of the SAN to hypoxia.
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Affiliation(s)
- Qadeer Aziz
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Malcolm Finlay
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - David Montaigne
- the Department of Clinical Physiology & Echocardiography, CHU Lille and the University of Lille, EGID, INSERM UMR1011, F-59000 Lille, France
| | - Leona Ojake
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Yiwen Li
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Naomi Anderson
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Andreas Ludwig
- the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Erlangen-Nürnberg, 91054 Erlangen, Germany, and
| | - Andrew Tinker
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom,
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Li Y, Zhang X, Zhang C, Zhang X, Li Y, Qi Z, Szeto C, Tang M, Peng Y, Molkentin JD, Houser SR, Xie M, Chen X. Increasing T-type calcium channel activity by β-adrenergic stimulation contributes to β-adrenergic regulation of heart rates. J Physiol 2018; 596:1137-1151. [PMID: 29274077 PMCID: PMC5878229 DOI: 10.1113/jp274756] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 12/13/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cav3.1 T-type Ca2+ channel current (ICa-T ) contributes to heart rate genesis but is not known to contribute to heart rate regulation by the sympathetic/β-adrenergic system (SAS). We show that the loss of Cav3.1 makes the beating rates of the heart in vivo and perfused hearts ex vivo, as well as sinoatrial node cells, less sensitive to β-adrenergic stimulation; it also renders less conduction acceleration through the atrioventricular node by β-adrenergic stimulation. Increasing Cav3.1 in cardiomyocytes has the opposite effects. ICa-T in sinoatrial nodal cells can be upregulated by β-adrenergic stimulation. The results of the present study add a new contribution to heart rate regulation by the SAS system and provide potential new mechanisms for the dysregulation of heart rate and conduction by the SAS in the heart. T-type Ca2+ channel can be a target for heart disease treatments that aim to slow down the heart rate ABSTRACT: Cav3.1 (α1G ) T-type Ca2+ channel (TTCC) is expressed in mouse sinoatrial node cells (SANCs) and atrioventricular (AV) nodal cells and contributes to heart rate (HR) genesis and AV conduction. However, its role in HR regulation and AV conduction acceleration by the β-adrenergic system (SAS) is unclear. In the present study, L- (ICa-L ) and T-type (ICa-T ) Ca2+ currents were recorded in SANCs from Cav3.1 transgenic (TG) and knockout (KO), and control mice. ICa-T was absent in KO SANCs but enhanced in TG SANCs. In anaesthetized animals, different doses of isoproterenol (ISO) were infused via the jugular vein and the HR was recorded. The EC50 of the HR response to ISO was lower in TG mice but higher in KO mice, and the maximal percentage of HR increase by ISO was greater in TG mice but less in KO mice. In Langendorff-perfused hearts, ISO increased HR and shortened PR intervals to a greater extent in TG but to a less extent in KO hearts. KO SANCs had significantly slower spontaneous beating rates than control SANCs before and after ISO; TG SANCs had similar basal beating rates as control SANCs probably as a result of decreased ICa-L but a greater response to ISO than control SANCs. ICa-T in SANCs was significantly increased by ISO. ICa-T upregulation by β-adrenergic stimulation contributes to HR and conduction regulation by the SAS. TTCC can be a target for slowing the HR.
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MESH Headings
- Adrenergic Agents/pharmacology
- Animals
- Arrhythmias, Cardiac/drug therapy
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/pathology
- Calcium Channels, T-Type/physiology
- Heart Rate/drug effects
- Heart Rate/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Receptors, Adrenergic, beta/metabolism
- Signal Transduction
- Sinoatrial Node/cytology
- Sinoatrial Node/drug effects
- Sinoatrial Node/metabolism
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Affiliation(s)
- Yingxin Li
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Xiaoxiao Zhang
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
- Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyHubei Provincial Key Laboratory of Molecular ImagineWuhanChina
| | - Chen Zhang
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Xiaoying Zhang
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Ying Li
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
- The General Hospital of The PLA Rocket ForceBeijingChina
- Institute of Burn Research, Southwest Hospital, State Key Laboratory of TraumaThird Military Medical UniversityChongqingChina
| | - Zhao Qi
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Christopher Szeto
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Mingxin Tang
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Yizhi Peng
- Institute of Burn Research, Southwest Hospital, State Key Laboratory of TraumaThird Military Medical UniversityChongqingChina
| | - Jeffery D. Molkentin
- Howard Hughes Medical Institute & Cincinnati Children's Hospital Medical CenterCincinnatiOHUSA
| | - Steven R. Houser
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
| | - Mingxing Xie
- Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyHubei Provincial Key Laboratory of Molecular ImagineWuhanChina
| | - Xiongwen Chen
- Cardiovascular Research Center and Department of PhysiologyTemple University School of Medicine3500 North Broad StreetPhiladelphiaPAUSA
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28
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Monfredi O, Tsutsui K, Ziman B, Stern MD, Lakatta EG, Maltsev VA. Electrophysiological heterogeneity of pacemaker cells in the rabbit intercaval region, including the SA node: insights from recording multiple ion currents in each cell. Am J Physiol Heart Circ Physiol 2018; 314:H403-H414. [PMID: 28916636 PMCID: PMC5899256 DOI: 10.1152/ajpheart.00253.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/13/2017] [Accepted: 09/13/2017] [Indexed: 11/22/2022]
Abstract
Cardiac pacemaker cells, including cells of the sinoatrial node, are heterogeneous in size, morphology, and electrophysiological characteristics. The exact extent to which these cells differ electrophysiologically is unclear yet is critical to understanding their functioning. We examined major ionic currents in individual intercaval pacemaker cells (IPCs) sampled from the paracristal, intercaval region (including the sinoatrial node) that were spontaneously beating after enzymatic isolation from rabbit hearts. The beating rate was measured at baseline and after inhibition of the Ca2+ pump with cyclopiazonic acid. Thereafter, in each cell, we consecutively measured the density of funny current ( If), delayed rectifier K+ current ( IK) (a surrogate of repolarization capacity), and L-type Ca2+ current ( ICa,L) using whole cell patch clamp. The ionic current densities varied to a greater extent than previously appreciated, with some IPCs demonstrating very small or zero If . The density of none of the currents was correlated with cell size, while ICa,L and If densities were related to baseline beating rates. If density was correlated with IK density but not with that of ICa,L. Inhibition of Ca2+ cycling had a greater beating rate slowing effect in IPCs with lower If densities. Our numerical model simulation indicated that 1) IPCs with small (or zero) If or small ICa,L can operate via a major contribution of Ca2+ clock, 2) If-Ca2+-clock interplay could be important for robust pacemaking function, and 3) coupled If- IK function could regulate maximum diastolic potential. Thus, we have demonstrated marked electrophysiological heterogeneity of IPCs. This heterogeneity is manifested in basal beating rate and response to interference of Ca2+ cycling, which is linked to If. NEW & NOTEWORTHY In the present study, a hitherto unrecognized range of heterogeneity of ion currents in pacemaker cells from the intercaval region is demonstrated. Relationships between basal beating rate and L-type Ca2+ current and funny current ( If) density are uncovered, along with a positive relationship between If and delayed rectifier K+ current. Links are shown between the response to Ca2+ cycling blockade and If density.
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Affiliation(s)
- Oliver Monfredi
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
- Department of Cardiovascular Electrophysiology, The Johns Hopkins Hospital , Baltimore, Maryland
- Division of Cardiovascular Sciences, University of Manchester , Manchester , United Kingdom
| | - Kenta Tsutsui
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
| | - Bruce Ziman
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
| | - Michael D Stern
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, Biomedical Research Center, National Institute on Aging, National Institutes of Health , Baltimore, Maryland
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29
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Brown K, Legros S, Ortega FA, Dai Y, Doss MX, Christini DJ, Robinson RB, Foley AC. Overexpression of Map3k7 activates sinoatrial node-like differentiation in mouse ES-derived cardiomyocytes. PLoS One 2017; 12:e0189818. [PMID: 29281682 PMCID: PMC5744947 DOI: 10.1371/journal.pone.0189818] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 12/02/2017] [Indexed: 12/12/2022] Open
Abstract
In vivo, cardiomyocytes comprise a heterogeneous population of contractile cells defined by unique electrophysiologies, molecular markers and morphologies. The mechanisms directing myocardial cells to specific sub-lineages remain poorly understood. Here we report that overexpression of TGFβ-Activated Kinase (TAK1/Map3k7) in mouse embryonic stem (ES) cells faithfully directs myocardial differentiation of embryoid body (EB)-derived cardiac cells toward the sinoatrial node (SAN) lineage. Most cardiac cells in Map3k7-overexpressing EBs adopt markers, cellular morphologies, and electrophysiological behaviors characteristic of the SAN. These data, in addition to the fact that Map3k7 is upregulated in the sinus venous—the source of cells for the SAN—suggest that Map3k7 may be an endogenous regulator of the SAN fate.
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Affiliation(s)
- Kemar Brown
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Stephanie Legros
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Francis A. Ortega
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Yunkai Dai
- Department of Bioengineering, Clemson University, Charleston, SC, United States of America
| | - Michael Xavier Doss
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - David J. Christini
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Richard B. Robinson
- Department of Pharmacology, Columbia University Medical Center, New York, NY, United States of America
| | - Ann C. Foley
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, New York, United States of America
- Department of Bioengineering, Clemson University, Charleston, SC, United States of America
- * E-mail:
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30
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Toyoda F, Ding WG, Matsuura H. Heterogeneous functional expression of the sustained inward Na + current in guinea pig sinoatrial node cells. Pflugers Arch 2017; 470:481-490. [PMID: 29197941 DOI: 10.1007/s00424-017-2091-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/08/2017] [Accepted: 11/21/2017] [Indexed: 11/26/2022]
Abstract
The sustained inward Na+ current (I st) identified in the sinoatrial node (SAN) cell has been suggested to play a pivotal role in cardiac pacemaking. However, the composition of cells in the SAN is heterogeneous and cell-to-cell variability in the magnitude of I st remains to be fully characterized. The present study investigated the current density of I st in morphologically different types of pacemaker cells dissociated from guinea pig SAN. I st was preferentially detected in spontaneously active spindle or spider-shaped cells, but was less well expressed in larger-sized elongated spindle-type cells and practically absent in clearly striated atrial-like cells, despite clear expression of the funny current (I f). The current density of I st in spindle and spider cells varied from 0.7 to 1.6 pA pF-1 and was significantly reduced in non-beating cells with similar morphologies. By linear regression analysis, we identified a positive correlation between the current densities of I st and the L-type Ca2+ current (I Ca,L), which was specifically observed in spindle and spider cells. These cells exhibited a more negative voltage for half maximal I Ca,L activation than atrial-like cells, suggesting a variable ratio between CaV1.2- and CaV1.3-mediated I Ca,L in SAN cells. Consistent single-cell transcript measurements confirmed a higher relative expression of CaV1.3, which activates at more negative potentials, in spindle cells than in atrial-like cells. Taken together, these results can be interpreted as indicating that I st plays a specific role in primary pacemaker cells and that its presence is closely correlated with functional levels of CaV1.3-mediated I Ca,L.
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Affiliation(s)
- Futoshi Toyoda
- Department of Physiology, Shiga University of Medical Science, Seta Tsukinowa, Otsu, Shiga, 520-2192, Japan.
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Seta Tsukinowa, Otsu, Shiga, 520-2192, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Seta Tsukinowa, Otsu, Shiga, 520-2192, Japan
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31
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Ca V1.3 L-type Ca 2+ channel contributes to the heartbeat by generating a dihydropyridine-sensitive persistent Na + current. Sci Rep 2017; 7:7869. [PMID: 28801600 PMCID: PMC5554211 DOI: 10.1038/s41598-017-08191-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/07/2017] [Indexed: 11/22/2022] Open
Abstract
The spontaneous activity of sinoatrial node (SAN) pacemaker cells is generated by a functional interplay between the activity of ionic currents of the plasma membrane and intracellular Ca2+ dynamics. The molecular correlate of a dihydropyridine (DHP)-sensitive sustained inward Na+ current (Ist), a key player in SAN automaticity, is still unknown. Here we show that Ist and the L-type Ca2+ current (ICa,L) share CaV1.3 as a common molecular determinant. Patch-clamp recordings of mouse SAN cells showed that Ist is activated in the diastolic depolarization range, and displays Na+ permeability and minimal inactivation and sensitivity to ICa,L activators and blockers. Both CaV1.3-mediated ICa,L and Ist were abolished in CaV1.3-deficient (CaV1.3−/−) SAN cells but the CaV1.2-mediated ICa,L current component was preserved. In SAN cells isolated from mice expressing DHP-insensitive CaV1.2 channels (CaV1.2DHP−/−), Ist and CaV1.3-mediated ICa,L displayed overlapping sensitivity and concentration–response relationships to the DHP blocker nifedipine. Consistent with the hypothesis that CaV1.3 rather than CaV1.2 underlies Ist, a considerable fraction of ICa,L was resistant to nifedipine inhibition in CaV1.2DHP−/− SAN cells. These findings identify CaV1.3 channels as essential molecular components of the voltage-dependent, DHP-sensitive Ist Na+ current in the SAN.
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32
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Phosphodiesterases 3 and 4 Differentially Regulate the Funny Current, I f, in Mouse Sinoatrial Node Myocytes. J Cardiovasc Dev Dis 2017; 4. [PMID: 28868308 PMCID: PMC5573264 DOI: 10.3390/jcdd4030010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cardiac pacemaking, at rest and during the sympathetic fight-or-flight response, depends on cAMP (3',5'-cyclic adenosine monophosphate) signaling in sinoatrial node myocytes (SAMs). The cardiac "funny current" (If) is among the cAMP-sensitive effectors that drive pacemaking in SAMs. If is produced by hyperpolarization-activated, cyclic nucleotide-sensitive (HCN) channels. Voltage-dependent gating of HCN channels is potentiated by cAMP, which acts either by binding directly to the channels or by activating the cAMP-dependent protein kinase (PKA), which phosphorylates them. PKA activity is required for signaling between β adrenergic receptors (βARs) and HCN channels in SAMs but the mechanism that constrains cAMP signaling to a PKA-dependent pathway is unknown. Phosphodiesterases (PDEs) hydrolyze cAMP and form cAMP signaling domains in other types of cardiomyocytes. Here we examine the role of PDEs in regulation of If in SAMs. If was recorded in whole-cell voltage-clamp experiments from acutely-isolated mouse SAMs in the absence or presence of PDE and PKA inhibitors, and before and after βAR stimulation. General PDE inhibition caused a PKA-independent depolarizing shift in the midpoint activation voltage (V1/2) of If at rest and removed the requirement for PKA in βAR-to-HCN signaling. PDE4 inhibition produced a similar PKA-independent depolarizing shift in the V1/2 of If at rest, but did not remove the requirement for PKA in βAR-to-HCN signaling. PDE3 inhibition produced PKA-dependent changes in If both at rest and in response to βAR stimulation. Our results suggest that PDE3 and PDE4 isoforms create distinct cAMP signaling domains that differentially constrain access of cAMP to HCN channels and establish the requirement for PKA in signaling between βARs and HCN channels in SAMs.
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33
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Wang YY, Mesirca P, Marqués-Sulé E, Zahradnikova A, Villejoubert O, D'Ocon P, Ruiz C, Domingo D, Zorio E, Mangoni ME, Benitah JP, Gómez AM. RyR2R420Q catecholaminergic polymorphic ventricular tachycardia mutation induces bradycardia by disturbing the coupled clock pacemaker mechanism. JCI Insight 2017; 2:91872. [PMID: 28422759 DOI: 10.1172/jci.insight.91872] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/09/2017] [Indexed: 01/14/2023] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal genetic arrhythmia that manifests syncope or sudden death in children and young adults under stress conditions. CPVT patients often present bradycardia and sino-atrial node (SAN) dysfunction. However, the mechanism remains unclear. We analyzed SAN function in two CPVT families and in a novel knock-in (KI) mouse model carrying the RyR2R420Q mutation. Humans and KI mice presented slower resting heart rate. Accordingly, the rate of spontaneous intracellular Ca2+ ([Ca2+]i) transients was slower in KI mouse SAN preparations than in WT, without any significant alteration in the "funny" current (If ). The L-type Ca2+ current was reduced in KI SAN cells in a [Ca2+]i-dependent way, suggesting that bradycardia was due to disrupted crosstalk between the "voltage" and "Ca2+" clock, and the mechanisms of pacemaking was induced by aberrant spontaneous RyR2- dependent Ca2+ release. This finding was consistent with a higher Ca2+ leak during diastolic periods produced by long-lasting Ca2+ sparks in KI SAN cells. Our results uncover a mechanism for the CPVT-causing RyR2 N-terminal mutation R420Q, and they highlight the fact that enhancing the Ca2+ clock may slow the heart rhythm by disturbing the coupling between Ca2+ and voltage clocks.
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Affiliation(s)
- Yue Yi Wang
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Pietro Mesirca
- UMR-5203, CNRS, INSERM U1191, Institut de Génomique Fonctionnelle, Département de Physiologie, Université de Montpellier, Montpellier, France
| | - Elena Marqués-Sulé
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France.,Physiotherapy Department
| | - Alexandra Zahradnikova
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Olivier Villejoubert
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Pilar D'Ocon
- ERI BIOTECMED and Department of Pharmacology School, University of Valencia, Valencia, Spain
| | | | - Diana Domingo
- Cardiology Department, Hospital Universitario y Politécnico La Fe, Valencia, Spain
| | - Esther Zorio
- Cardiology Department, Hospital Universitario y Politécnico La Fe, Valencia, Spain
| | - Matteo E Mangoni
- UMR-5203, CNRS, INSERM U1191, Institut de Génomique Fonctionnelle, Département de Physiologie, Université de Montpellier, Montpellier, France
| | - Jean-Pierre Benitah
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Ana María Gómez
- UMR-S 1180, Inserm, Université Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
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34
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Sharpe EJ, Larson ED, Proenza C. Cyclic AMP reverses the effects of aging on pacemaker activity and If in sinoatrial node myocytes. J Gen Physiol 2017; 149:237-247. [PMID: 28057842 PMCID: PMC5299620 DOI: 10.1085/jgp.201611674] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/09/2016] [Accepted: 11/22/2016] [Indexed: 12/19/2022] Open
Abstract
Aging reduces pacemaker activity and shifts the voltage dependence of activation of the funny current, If, in sinoatrial node myocytes. Sharpe et al. find that these effects of aging can be reversed by application of exogenous cAMP but not by stimulation of endogenous cAMP. Aerobic capacity decreases with age, in part because of an age-dependent decline in maximum heart rate (mHR) and a reduction in the intrinsic pacemaker activity of the sinoatrial node of the heart. Isolated sinoatrial node myocytes (SAMs) from aged mice have slower spontaneous action potential (AP) firing rates and a hyperpolarizing shift in the voltage dependence of activation of the “funny current,” If. Cyclic AMP (cAMP) is a critical modulator of both AP firing rate and If in SAMs. Here, we test the ability of endogenous and exogenous cAMP to overcome age-dependent changes in acutely isolated murine SAMs. We found that maximal stimulation of endogenous cAMP with 3-isobutyl-1-methylxanthine (IBMX) and forskolin significantly increased AP firing rate and depolarized the voltage dependence of activation of If in SAMs from both young and aged mice. However, these changes were insufficient to overcome the deficits in aged SAMs, and significant age-dependent differences in AP firing rate and If persisted in the presence of IBMX and forskolin. In contrast, the effects of aging on SAMs were completely abolished by a high concentration of exogenous cAMP, which restored AP firing rate and If activation to youthful levels in cells from aged animals. Interestingly, the age-dependent differences in AP firing rates and If were similar in whole-cell and perforated-patch recordings, and the hyperpolarizing shift in If persisted in excised inside-out patches, suggesting a limited role for cAMP in causing these changes. Collectively, the data indicate that aging does not impose an absolute limit on pacemaker activity and that it does not act by simply reducing the concentration of freely diffusible cAMP in SAMs.
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Affiliation(s)
- Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - Eric D Larson
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045 .,Department of Medicine, Division of Cardiology, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
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35
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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36
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Sharpe EJ, St Clair JR, Proenza C. Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice. J Vis Exp 2016. [PMID: 27805586 DOI: 10.3791/54555] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sinoatrial node myocytes (SAMs) act as the natural pacemakers of the heart, initiating each heart beat by generating spontaneous action potentials (APs). These pacemaker APs reflect the coordinated activity of numerous membrane currents and intracellular calcium cycling. However the precise mechanisms that drive spontaneous pacemaker activity in SAMs remain elusive. Acutely isolated SAMs are an essential preparation for experiments to dissect the molecular basis of cardiac pacemaking. However, the indistinct anatomy, complex microdissection, and finicky enzymatic digestion conditions have prevented widespread use of acutely isolated SAMs. In addition, methods were not available until recently to permit longer-term culture of SAMs for protein expression studies. Here we provide a step-by-step protocol and video demonstration for the isolation of SAMs from adult mice. A method is also demonstrated for maintaining adult mouse SAMs in vitro and for expression of exogenous proteins via adenoviral infection. Acutely isolated and cultured SAMs prepared via these methods are suitable for a variety of electrophysiological and imaging studies.
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Affiliation(s)
- Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus
| | - Joshua R St Clair
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus; Department of Bioengineering, University of Colorado Anschutz Medical Campus
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus; Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical Campus;
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37
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Liao C, Gui Y, Guo Y, Xu D. The regulatory function of microRNA-1 in arrhythmias. MOLECULAR BIOSYSTEMS 2016; 12:328-33. [PMID: 26671473 DOI: 10.1039/c5mb00806a] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Arrhythmia, the basis of which is cardiomyocyte ion channel abnormalities, poses a serious threat to human health. A large number of studies have demonstrated that miRNA-1(miR-1) is involved in the occurrence of arrhythmia in many myocardial pathological conditions by post-transcriptionally regulating a variety of ion channels and proteins related to cardiac electrical activity. We aim at emphasizing the relationship between miR-1 and ion channels and proteins involved in the process of arrhythmia. In addition, we will pay attention to its future therapeutic prospects.
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Affiliation(s)
- Caixiu Liao
- Department of Cardiology, Internal Medicine, The Second Xiangya Hospital, Central South University, 139 Middle Renmin Road, Changsha 410011, Hunan, China.
| | - Yajun Gui
- Department of Cardiology, Internal Medicine, The Second Xiangya Hospital, Central South University, 139 Middle Renmin Road, Changsha 410011, Hunan, China.
| | - Yuan Guo
- Department of Cardiology, Internal Medicine, The Second Xiangya Hospital, Central South University, 139 Middle Renmin Road, Changsha 410011, Hunan, China.
| | - Danyan Xu
- Department of Cardiology, Internal Medicine, The Second Xiangya Hospital, Central South University, 139 Middle Renmin Road, Changsha 410011, Hunan, China.
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38
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Mesirca P, Bidaud I, Mangoni ME. Rescuing cardiac automaticity in L-type Cav1.3 channelopathies and beyond. J Physiol 2016; 594:5869-5879. [PMID: 27374078 DOI: 10.1113/jp270678] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/24/2016] [Indexed: 11/08/2022] Open
Abstract
Pacemaker activity of the sino-atrial node generates the heart rate. Disease of the sinus node and impairment of atrioventricular conduction induce an excessively low ventricular rate (bradycardia), which cannot meet the needs of the organism. Bradycardia accounts for about half of the total workload of clinical cardiologists. The 'sick sinus' syndrome (SSS) is characterized by sinus bradycardia and periods of intermittent atrial fibrillation. Several genetic or acquired risk factors or pathologies can lead to SSS. Implantation of an electronic pacemaker constitutes the only available therapy for SSS. The incidence of SSS is forecast to double over the next 50 years, with ageing of the general population thus urging the development of complementary or alternative therapeutic strategies. In recent years an increasing number of mutations affecting ion channels involved in sino-atrial automaticity have been reported to underlie inheritable SSS. L-type Cav 1.3 channels play a major role in the generation and regulation of sino-atrial pacemaker activity and atrioventricular conduction. Mutation in the CACNA1D gene encoding Cav 1.3 channels induces loss-of-function in channel activity and underlies the sino-atrial node dysfunction and deafness syndrome (SANDD). Mice lacking Cav 1.3 channels (Cav 1.3-/- ) fairly recapitulate SSS and constitute a precious model to test new therapeutic approaches to handle this disease. Work in our laboratory shows that targeting G protein-gated K+ (IKACh ) channels effectively rescues SSS of Cav 1.3-/- mice. This new concept of 'compensatory' ion channel targeting shines new light on the principles underlying the pacemaker mechanism and may open the way to new therapies for SSS.
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Affiliation(s)
- Pietro Mesirca
- Département de Physiologie, Institut de Genomique Fonctionnelle, LabEx ICST, UMR-5203, Centre national de la recherche scientifique, F-34094, Montpellier, France. .,INSERM U1191, F-34094, Montpellier, France. .,Université de Montpellier, F-34094, Montpellier, France.
| | - Isabelle Bidaud
- Département de Physiologie, Institut de Genomique Fonctionnelle, LabEx ICST, UMR-5203, Centre national de la recherche scientifique, F-34094, Montpellier, France.,INSERM U1191, F-34094, Montpellier, France.,Université de Montpellier, F-34094, Montpellier, France
| | - Matteo E Mangoni
- Département de Physiologie, Institut de Genomique Fonctionnelle, LabEx ICST, UMR-5203, Centre national de la recherche scientifique, F-34094, Montpellier, France. .,INSERM U1191, F-34094, Montpellier, France. .,Université de Montpellier, F-34094, Montpellier, France.
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39
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Novella Romanelli M, Sartiani L, Masi A, Mannaioni G, Manetti D, Mugelli A, Cerbai E. HCN Channels Modulators: The Need for Selectivity. Curr Top Med Chem 2016; 16:1764-91. [PMID: 26975509 PMCID: PMC5374843 DOI: 10.2174/1568026616999160315130832] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.
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Affiliation(s)
- Maria Novella Romanelli
- University of Florence, Department of Neurosciences, Psychology, Drug Research and Child's Health, Section of Pharmaceutical and Nutraceutical Sciences, via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
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40
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Zamponi GW, Striessnig J, Koschak A, Dolphin AC. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015; 67:821-70. [PMID: 26362469 PMCID: PMC4630564 DOI: 10.1124/pr.114.009654] [Citation(s) in RCA: 684] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.
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Affiliation(s)
- Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Joerg Striessnig
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Alexandra Koschak
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
| | - Annette C Dolphin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada (G.W.Z.); Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria (J.S., A.K.); and Department of Neuroscience, Physiology, and Pharmacology, Division of Biosciences, University College London, London, United Kingdom (A.C.D.)
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41
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The effect of ivabradine on long term prevention of major adverse cardiac events in acute coronary syndrome using high-sensitivity C-reactive protein level. EGYPTIAN JOURNAL OF CRITICAL CARE MEDICINE 2015. [DOI: 10.1016/j.ejccm.2015.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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42
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St Clair JR, Sharpe EJ, Proenza C. Culture and adenoviral infection of sinoatrial node myocytes from adult mice. Am J Physiol Heart Circ Physiol 2015; 309:H490-8. [PMID: 26001410 DOI: 10.1152/ajpheart.00068.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/19/2015] [Indexed: 12/19/2022]
Abstract
Pacemaker myocytes in the sinoatrial node of the heart initiate each heartbeat by firing spontaneous action potentials. However, the molecular processes that underlie pacemaking are incompletely understood, in part because of our limited ability to manipulate protein expression within the native cellular context of sinoatrial node myocytes (SAMs). Here we describe a new method for the culture of fully differentiated SAMs from adult mice, and we demonstrate that robust expression of introduced proteins can be achieved within 24-48 h in vitro via adenoviral gene transfer. Comparison of morphological and electrophysiological characteristics of 48 h-cultured versus acutely isolated SAMs revealed only minor changes in vitro. Specifically, we found that cells tended to flatten in culture but retained an overall normal morphology, with no significant changes in cellular dimensions or membrane capacitance. Cultured cells beat spontaneously and, in patch-clamp recordings, the spontaneous action potential firing rate did not differ between cultured and acutely isolated cells, despite modest changes in a subset of action potential waveform parameters. The biophysical properties of two membrane currents that are critical for pacemaker activity in SAMs, the "funny current" (If) and voltage-gated Ca(2+) currents (ICa), were also indistinguishable between cultured and acutely isolated cells. This new method for culture and adenoviral infection of fully-differentiated SAMs from the adult mouse heart expands the range of experimental techniques that can be applied to study the molecular physiology of cardiac pacemaking because it will enable studies in which protein expression levels can be modified or genetically encoded reporter molecules expressed within SAMs.
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Affiliation(s)
- Joshua R St Clair
- Department of Physiology and Biophysics, University of Colorado - Anschutz Medical Campus, Denver, Colorado; and
| | - Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado - Anschutz Medical Campus, Denver, Colorado; and
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado - Anschutz Medical Campus, Denver, Colorado; and Department of Medicine, Division of Cardiology - Anschutz Medical Campus, Denver, Colorado
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43
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Barbuti A, Robinson RB. Stem Cell–Derived Nodal-Like Cardiomyocytes as a Novel Pharmacologic Tool: Insights from Sinoatrial Node Development and Function. Pharmacol Rev 2015; 67:368-88. [DOI: 10.1124/pr.114.009597] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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44
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Hansen PBL. Functional importance of T-type voltage-gated calcium channels in the cardiovascular and renal system: news from the world of knockout mice. Am J Physiol Regul Integr Comp Physiol 2015; 308:R227-37. [DOI: 10.1152/ajpregu.00276.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Over the years, it has been discussed whether T-type calcium channels Cav3 play a role in the cardiovascular and renal system. T-type channels have been reported to play an important role in renal hemodynamics, contractility of resistance vessels, and pacemaker activity in the heart. However, the lack of highly specific blockers cast doubt on the conclusions. As new T-type channel antagonists are being designed, the roles of T-type channels in cardiovascular and renal pathology need to be elucidated before T-type blockers can be clinically useful. Two types of T-type channels, Cav3.1 and Cav3.2, are expressed in blood vessels, the kidney, and the heart. Studies with gene-deficient mice have provided a way to investigate the Cav3.1 and Cav3.2 channels and their role in the cardiovascular system. This review discusses the results from these knockout mice. Evaluation of the literature leads to the conclusion that Cav3.1 and Cav3.2 channels have important, but different, functions in mice. T-type Cav3.1 channels affect heart rate, whereas Cav3.2 channels are involved in cardiac hypertrophy. In the vascular system, Cav3.2 activation leads to dilation of blood vessels, whereas Cav3.1 channels are mainly suggested to affect constriction. The Cav3.1 channel is also involved in neointima formation following vascular damage. In the kidney, Cav3.1 regulates plasma flow and Cav3.2 plays a role setting glomerular filtration rate. In conclusion, Cav3.1 and Cav3.2 are new therapeutic targets in several cardiovascular pathologies, but the use of T-type blockers should be specifically directed to the disease and to the channel subtype.
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Affiliation(s)
- Pernille B. L. Hansen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark
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45
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Wu Y, Rasmussen TP, Koval OM, Joiner MLA, Hall DD, Chen B, Luczak ED, Wang Q, Rokita AG, Wehrens XHT, Song LS, Anderson ME. The mitochondrial uniporter controls fight or flight heart rate increases. Nat Commun 2015; 6:6081. [PMID: 25603276 PMCID: PMC4398998 DOI: 10.1038/ncomms7081] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 12/10/2014] [Indexed: 01/13/2023] Open
Abstract
Heart rate increases are a fundamental adaptation to physiological stress, while inappropriate heart rate increases are resistant to current therapies. However, the metabolic mechanisms driving heart rate acceleration in cardiac pacemaker cells remain incompletely understood. The mitochondrial calcium uniporter (MCU) facilitates calcium entry into the mitochondrial matrix to stimulate metabolism. We developed mice with myocardial MCU inhibition by transgenic expression of a dominant negative (DN) MCU. Here we show that DN-MCU mice had normal resting heart rates but were incapable of physiological fight or flight heart rate acceleration. We found MCU function was essential for rapidly increasing mitochondrial calcium in pacemaker cells and that MCU enhanced oxidative phoshorylation was required to accelerate reloading of an intracellular calcium compartment prior to each heartbeat. Our findings show the MCU is necessary for complete physiological heart rate acceleration and suggest MCU inhibition could reduce inappropriate heart rate increases without affecting resting heart rate.
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Affiliation(s)
- Yuejin Wu
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Tyler P Rasmussen
- 1] Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA [2] Department of Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Olha M Koval
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Mei-Ling A Joiner
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Duane D Hall
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Biyi Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Elizabeth D Luczak
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Qiongling Wang
- Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics and Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Adam G Rokita
- 1] Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA [2] Department of Internal Medicine II, University Hospital Regensburg, 93042 Regensburg, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics and Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Mark E Anderson
- 1] Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA [2] Department of Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
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46
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Egom EE, Vella K, Hua R, Jansen HJ, Moghtadaei M, Polina I, Bogachev O, Hurnik R, Mackasey M, Rafferty S, Ray G, Rose RA. Impaired sinoatrial node function and increased susceptibility to atrial fibrillation in mice lacking natriuretic peptide receptor C. J Physiol 2015; 593:1127-46. [PMID: 25641115 DOI: 10.1113/jphysiol.2014.283135] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 12/06/2014] [Indexed: 12/17/2022] Open
Abstract
Natriuretic peptides (NPs) are critical regulators of the cardiovascular system that are currently viewed as possible therapeutic targets for the treatment of heart disease. Recent work demonstrates potent NP effects on cardiac electrophysiology, including in the sinoatrial node (SAN) and atria. NPs elicit their effects via three NP receptors (NPR-A, NPR-B and NPR-C). Among these receptors, NPR-C is poorly understood. Accordingly, the goal of this study was to determine the effects of NPR-C ablation on cardiac structure and arrhythmogenesis. Cardiac structure and function were assessed in wild-type (NPR-C(+/+)) and NPR-C knockout (NPR-C(-/-)) mice using echocardiography, intracardiac programmed stimulation, patch clamping, high-resolution optical mapping, quantitative polymerase chain reaction and histology. These studies demonstrate that NPR-C(-/-) mice display SAN dysfunction, as indicated by a prolongation (30%) of corrected SAN recovery time, as well as an increased susceptibility to atrial fibrillation (6% in NPR-C(+/+) vs. 47% in NPR-C(-/-)). There were no differences in SAN or atrial action potential morphology in NPR-C(-/-) mice; however, increased atrial arrhythmogenesis in NPR-C(-/-) mice was associated with reductions in SAN (20%) and atrial (15%) conduction velocity, as well as increases in expression and deposition of collagen in the atrial myocardium. No differences were seen in ventricular arrhythmogenesis or fibrosis in NPR-C(-/-) mice. This study demonstrates that loss of NPR-C results in SAN dysfunction and increased susceptibility to atrial arrhythmias in association with structural remodelling and fibrosis in the atrial myocardium. These findings indicate a critical protective role for NPR-C in the heart.
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Affiliation(s)
- Emmanuel E Egom
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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47
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Sun C, Yu D, Ye W, Liu C, Gu S, Sinsheimer NR, Song Z, Li X, Chen C, Song Y, Wang S, Schrader L, Chen Y. The short stature homeobox 2 (Shox2)-bone morphogenetic protein (BMP) pathway regulates dorsal mesenchymal protrusion development and its temporary function as a pacemaker during cardiogenesis. J Biol Chem 2014; 290:2007-23. [PMID: 25488669 DOI: 10.1074/jbc.m114.619007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The atrioventricular (AV) junction plays a critical role in chamber septation and transmission of cardiac conduction pulses. It consists of structures that develop from embryonic dorsal mesenchymal protrusion (DMP) and the embryonic AV canal. Despite extensive studies on AV junction development, the genetic regulation of DMP development remains poorly understood. In this study we present evidence that Shox2 is expressed in the developing DMP. Intriguingly, this Shox2-expressing domain possesses a pacemaker-specific genetic profile including Hcn4 and Tbx3. This genetic profile leads to nodal-like electrophysiological properties, which is gradually silenced as the AV node becomes matured. Phenotypic analyses of Shox2(-/-) mice revealed a hypoplastic and defectively differentiated DMP, likely attributed to increased apoptosis, accompanied by dramatically reduced expression of Bmp4 and Hcn4, ectopic activation of Cx40, and an aberrant pattern of action potentials. Interestingly, conditional deletion of Bmp4 or inhibition of BMP signaling by overexpression of Noggin using a Shox2-Cre allele led to a similar DMP hypoplasia and down-regulation of Hcn4, whereas activation of a transgenic Bmp4 allele in Shox2(-/-) background attenuated DMP defects. Moreover, the lack of Hcn4 expression in the DMP of mice carrying Smad4 conditional deletion and direct binding of pSmad1/5/8 to the Hcn4 regulatory region further confirm the Shox2-BMP genetic cascade in the regulation of DMP development. Our results reveal that Shox2 regulates DMP fate and development by controlling BMP signaling through the Smad-dependent pathway to drive tissue growth and to induce Hcn4 expression and suggest a temporal pacemaking function for the DMP during early cardiogenesis.
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Affiliation(s)
- Cheng Sun
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Diankun Yu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Wenduo Ye
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chao Liu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shuping Gu
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Nathan R Sinsheimer
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Zhongchen Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Xihai Li
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Chun Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Yingnan Song
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Shusheng Wang
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Laura Schrader
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - YiPing Chen
- From the Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
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48
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Lai MH, Wu Y, Gao Z, Anderson ME, Dalziel JE, Meredith AL. BK channels regulate sinoatrial node firing rate and cardiac pacing in vivo. Am J Physiol Heart Circ Physiol 2014; 307:H1327-38. [PMID: 25172903 DOI: 10.1152/ajpheart.00354.2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels play prominent roles in shaping muscle and neuronal excitability. In the cardiovascular system, BK channels promote vascular relaxation and protect against ischemic injury. Recently, inhibition of BK channels has been shown to lower heart rate in intact rodents and isolated hearts, suggesting a novel role in heart function. However, the underlying mechanism is unclear. In the present study, we recorded ECGs from mice injected with paxilline (PAX), a membrane-permeable BK channel antagonist, and examined changes in cardiac conduction. ECGs revealed a 19 ± 4% PAX-induced reduction in heart rate in wild-type but not BK channel knockout (Kcnma1(-/-)) mice. The heart rate decrease was associated with slowed cardiac pacing due to elongation of the sinus interval. Action potential firing recorded from isolated sinoatrial node cells (SANCs) was reduced by 55 ± 15% and 28 ± 9% by application of PAX (3 μM) and iberiotoxin (230 nM), respectively. Furthermore, baseline firing rates from Kcnma1(-/-) SANCs were 33% lower than wild-type SANCs. The slowed firing upon BK current inhibition or genetic deletion was due to lengthening of the diastolic depolarization phase of the SANC action potential. Finally, BK channel immunoreactivity and PAX-sensitive currents were identified in SANCs with HCN4 expression and pacemaker current, respectively, and BK channels cloned from SANCs recapitulated similar activation as the PAX-sensitive current. Together, these data localize BK channels to SANCs and demonstrate that loss of BK current decreases SANC automaticity, consistent with slowed sinus pacing after PAX injection in vivo. Furthermore, these findings suggest BK channels are potential therapeutic targets for disorders of heart rate.
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Affiliation(s)
- Michael H Lai
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Yuejin Wu
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
| | - Zhan Gao
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
| | - Mark E Anderson
- Department of Internal Medicine and the François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa; Department of Physiology and Molecular Biophysics, University of Iowa, Iowa City, Iowa; and
| | - Julie E Dalziel
- AgResearch, Grasslands Research Centre, Palmerston North, New Zealand
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland; Fischell Department of Bioengineering, University of Maryland, College Park, Maryland;
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49
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Cardiac arrhythmia induced by genetic silencing of 'funny' (f) channels is rescued by GIRK4 inactivation. Nat Commun 2014; 5:4664. [PMID: 25144323 PMCID: PMC4207211 DOI: 10.1038/ncomms5664] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/14/2014] [Indexed: 01/01/2023] Open
Abstract
The mechanisms underlying cardiac automaticity are still incompletely
understood and controversial. Here we report the complete conditional and
time-controlled silencing of the "funny" current
(If) by expression of a dominant-negative,
non-conductive HCN4-channel subunit (hHCN4-AYA). Heart-specific
If silencing caused altered
[Ca2+]i release and Ca2+ handling in the
sinoatrial node, impaired pacemaker activity, and symptoms reminiscent of severe
human disease of pacemaking. The effects of If
silencing critically depended on the activity of the autonomic nervous system.
We were able to rescue the failure of impulse generation and conduction by
additional genetic deletion of cardiac muscarinic G-protein-activated (GIRK4)
channels in If-deficient mice without impairing
heartbeat regulation. Our study establishes the role of f-channels in cardiac
automaticity and indicates that arrhythmia related to HCN
loss-of-function may be managed by pharmacological or genetic inhibition of
GIRK4 channels, thus offering a new therapeutic strategy for the treatment of
heart rhythm diseases.
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Direct negative chronotropic action of desflurane on sinoatrial node pacemaker activity in the guinea pig heart. Anesthesiology 2014; 120:1400-13. [PMID: 24518231 DOI: 10.1097/aln.0000000000000165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Desflurane inhalation is associated with sympathetic activation and concomitant increase in heart rate in humans and experimental animals. There is, however, little information concerning the direct effects of desflurane on electrical activity of sinoatrial node pacemaker cells that determines the intrinsic heart rate. METHODS Whole-cell patch-clamp experiments were conducted on guinea pig sinoatrial node pacemaker cells to record spontaneous action potentials and ionic currents contributing to sinoatrial node automaticity, namely, hyperpolarization-activated cation current (If), T-type and L-type Ca currents (ICa,T and ICa,L, respectively), Na/Ca exchange current (INCX), and rapidly and slowly activating delayed rectifier K currents (IKr and IKs, respectively). Electrocardiograms were recorded from ex vivo Langendorff-perfused hearts and in vivo hearts. RESULTS Desflurane at 6 and 12% decreased spontaneous firing rate of sinoatrial node action potentials by 15.9% (n = 11) and 27.6% (n = 10), respectively, which was associated with 20.4% and 42.5% reductions in diastolic depolarization rate, respectively. Desflurane inhibited If, ICa,T, ICa,L, INCX, and IKs but had little effect on IKr. The negative chronotropic action of desflurane was reasonably well reproduced in sinoatrial node computer model. Desflurane reduced the heart rate in Langendorff-perfused hearts. High concentration (12%) of desflurane inhalation was associated with transient tachycardia, which was totally abolished by pretreatment with the β-adrenergic blocker propranolol. CONCLUSIONS Desflurane has a direct negative chronotropic action on sinoatrial node pacemaking activity, which is mediated by its inhibitory action on multiple ionic currents. This direct inhibitory action of desflurane on sinoatrial node automaticity seems to be counteracted by sympathetic activation associated with desflurane inhalation in vivo.
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