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Chen YC, Shih CL, Wu CL, Fang YH, So EC, Wu SN. Exploring the Impact of BK Ca Channel Function in Cellular Membranes on Cardiac Electrical Activity. Int J Mol Sci 2024; 25:1537. [PMID: 38338830 PMCID: PMC10855144 DOI: 10.3390/ijms25031537] [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: 12/13/2023] [Revised: 01/14/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
This review paper delves into the current body of evidence, offering a thorough analysis of the impact of large-conductance Ca2+-activated K+ (BKCa or BK) channels on the electrical dynamics of the heart. Alterations in the activity of BKCa channels, responsible for the generation of the overall magnitude of Ca2+-activated K+ current at the whole-cell level, occur through allosteric mechanisms. The collaborative interplay between membrane depolarization and heightened intracellular Ca2+ ion concentrations collectively contribute to the activation of BKCa channels. Although fully developed mammalian cardiac cells do not exhibit functional expression of these ion channels, evidence suggests their presence in cardiac fibroblasts that surround and potentially establish close connections with neighboring cardiac cells. When cardiac cells form close associations with fibroblasts, the high single-ion conductance of these channels, approximately ranging from 150 to 250 pS, can result in the random depolarization of the adjacent cardiac cell membranes. While cardiac fibroblasts are typically electrically non-excitable, their prevalence within heart tissue increases, particularly in the context of aging myocardial infarction or atrial fibrillation. This augmented presence of BKCa channels' conductance holds the potential to amplify the excitability of cardiac cell membranes through effective electrical coupling between fibroblasts and cardiomyocytes. In this scenario, this heightened excitability may contribute to the onset of cardiac arrhythmias. Moreover, it is worth noting that the substances influencing the activity of these BKCa channels might influence cardiac electrical activity as well. Taken together, the BKCa channel activity residing in cardiac fibroblasts may contribute to cardiac electrical function occurring in vivo.
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Affiliation(s)
- Yin-Chia Chen
- Division of Cardiovascular Surgery, Department of Surgery, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Chia-Lung Shih
- Clinical Research Center, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60056, Taiwan
| | - Chao-Liang Wu
- Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Yi-Hsien Fang
- Institute of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Edmund Cheung So
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan
| | - Sheng-Nan Wu
- Department of Research and Education, An Nan Hospital, China Medical University, Tainan 70965, Taiwan
- School of Medicine, College of Medicine, National Sun Yat-sen University, Kaohsiung 80421, Taiwan
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2
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Xing C, Bao L, Li W, Fan H. Progress on role of ion channels of cardiac fibroblasts in fibrosis. Front Physiol 2023; 14:1138306. [PMID: 36969589 PMCID: PMC10033868 DOI: 10.3389/fphys.2023.1138306] [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: 01/05/2023] [Accepted: 02/27/2023] [Indexed: 03/29/2023] Open
Abstract
Cardiac fibrosis is defined as excessive deposition of extracellular matrix (ECM) in pathological conditions. Cardiac fibroblasts (CFs) activated by injury or inflammation differentiate into myofibroblasts (MFs) with secretory and contractile functions. In the fibrotic heart, MFs produce ECM which is composed mainly of collagen and is initially involved in maintaining tissue integrity. However, persistent fibrosis disrupts the coordination of excitatory contractile coupling, leading to systolic and diastolic dysfunction, and ultimately heart failure. Numerous studies have demonstrated that both voltage- and non-voltage-gated ion channels alter intracellular ion levels and cellular activity, contributing to myofibroblast proliferation, contraction, and secretory function. However, an effective treatment strategy for myocardial fibrosis has not been established. Therefore, this review describes the progress made in research related to transient receptor potential (TRP) channels, Piezo1, Ca2+ release-activated Ca2+ (CRAC) channels, voltage-gated Ca2+ channels (VGCCs), sodium channels, and potassium channels in myocardial fibroblasts with the aim of providing new ideas for treating myocardial fibrosis.
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3
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Lai MC, Wu SN, Huang CW. Rufinamide, a Triazole-Derived Antiepileptic Drug, Stimulates Ca 2+-Activated K + Currents While Inhibiting Voltage-Gated Na + Currents. Int J Mol Sci 2022; 23:ijms232213677. [PMID: 36430153 PMCID: PMC9697614 DOI: 10.3390/ijms232213677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/10/2022] Open
Abstract
Rufinamide (RFM) is a clinically utilized antiepileptic drug that, as a triazole derivative, has a unique structure. The extent to which this drug affects membrane ionic currents remains incompletely understood. With the aid of patch clamp technology, we investigated the effects of RFM on the amplitude, gating, and hysteresis of ionic currents from pituitary GH3 lactotrophs. RFM increased the amplitude of Ca2+-activated K+ currents (IK(Ca)) in pituitary GH3 lactotrophs, and the increase was attenuated by the further addition of iberiotoxin or paxilline. The addition of RFM to the cytosolic surface of the detached patch of membrane resulted in the enhanced activity of large-conductance Ca2+-activated K+ channels (BKCa channels), and paxilline reversed this activity. RFM increased the strength of the hysteresis exhibited by the BKCa channels and induced by an inverted isosceles-triangular ramp pulse. The peak and late voltage-gated Na+ current (INa) evoked by rapid step depolarizations were differentially suppressed by RFM. The molecular docking approach suggested that RFM bound to the intracellular domain of KCa1.1 channels with amino acid residues, thereby functionally affecting BKCa channels' activity. This study is the first to present evidence that, in addition to inhibiting the INa, RFM effectively modifies the IK(Ca), which suggests that it has an impact on neuronal function and excitability.
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Affiliation(s)
- Ming-Chi Lai
- Department of Pediatrics, Chi-Mei Medical Center, Tainan 71004, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (S.-N.W.); (C.-W.H.)
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (S.-N.W.); (C.-W.H.)
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Jakob D, Klesen A, Darkow E, Kari FA, Beyersdorf F, Kohl P, Ravens U, Peyronnet R. Heterogeneity and Remodeling of Ion Currents in Cultured Right Atrial Fibroblasts From Patients With Sinus Rhythm or Atrial Fibrillation. Front Physiol 2021; 12:673891. [PMID: 34149453 PMCID: PMC8209389 DOI: 10.3389/fphys.2021.673891] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/19/2021] [Indexed: 11/23/2022] Open
Abstract
Cardiac fibroblasts express multiple voltage-dependent ion channels. Even though fibroblasts do not generate action potentials, they may influence cardiac electrophysiology by electrical coupling via gap junctions with cardiomyocytes, and through fibrosis. Here, we investigate the electrophysiological phenotype of cultured fibroblasts from right atrial appendage tissue of patients with sinus rhythm (SR) or atrial fibrillation (AF). Using the patch-clamp technique in whole-cell mode, we observed steady-state outward currents exhibiting either no rectification or inward and/or outward rectification. The distributions of current patterns between fibroblasts from SR and AF patients were not significantly different. In response to depolarizing voltage pulses, we measured transient outward currents with fast and slow activation kinetics, an outward background current, and an inward current with a potential-dependence resembling that of L-type Ca2+ channels. In cell-attached patch-clamp mode, large amplitude, paxilline-sensitive single channel openings were found in ≈65% of SR and ∼38% of AF fibroblasts, suggesting the presence of “big conductance Ca2+-activated K+ (BKCa)” channels. The open probability of BKCa was significantly lower in AF than in SR fibroblasts. When cultured in the presence of paxilline, the shape of fibroblasts became wider and less spindle-like. Our data confirm previous findings on cardiac fibroblast electrophysiology and extend them by illustrating differential channel expression in human atrial fibroblasts from SR and AF tissue.
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Affiliation(s)
- Dorothee Jakob
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Alexander Klesen
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Elisa Darkow
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Fabian A Kari
- Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Cardiovascular Surgery, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany
| | - Friedhelm Beyersdorf
- Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Cardiovascular Surgery, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,CIBSS Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Freiburg, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Bae H, Kim T, Lim I. Carbon monoxide activates large-conductance calcium-activated potassium channels of human cardiac fibroblasts through various mechanisms. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2021; 25:227-237. [PMID: 33859063 PMCID: PMC8050612 DOI: 10.4196/kjpp.2021.25.3.227] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 11/21/2022]
Abstract
Carbon monoxide (CO) is a cardioprotectant and potential cardiovascular therapeutic agent. Human cardiac fibroblasts (HCFs) are important determinants of myocardial structure and function. Large-conductance Ca2+-activated K+ (BK) channel is a potential therapeutic target for cardiovascular disease. We investigated whether CO modulates BK channels and the signaling pathways in HCFs using whole-cell mode patch-clamp recordings. CO-releasing molecules (CORMs; CORM-2 and CORM-3) significantly increased the amplitudes of BK currents (IBK). The CO-induced stimulating effects on IBK were blocked by pre-treatment with specific nitric oxide synthase (NOS) blockers (L-NG-monomethyl arginine citrate and L-NG-nitroarginine methyl ester). 8-bromo-cyclic GMP increased IBK. KT5823 (inhibits PKG) or ODQ (inhibits soluble guanylate cyclase) blocked the CO-stimulating effect on IBK. Moreover, 8-bromo-cyclic AMP also increased IBK, and pre-treatment with KT5720 (inhibits PKA) or SQ22536 (inhibits adenylate cyclase) blocked the CO effect. Pre-treatment with N-ethylmaleimide (a thiol-alkylating reagent) also blocked the CO effect on IBK, and DL-dithiothreitol (a reducing agent) reversed the CO effect. These data suggest that CO activates IBK through NO via the NOS and through the PKG, PKA, and S-nitrosylation pathways.
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Affiliation(s)
- Hyemi Bae
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Taeho Kim
- Department of Internal Medicine, College of Medicine, Chung-Ang University Hospital, Seoul 06973, Korea
| | - Inja Lim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
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6
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Pineda S, Nikolova-Krstevski V, Leimena C, Atkinson AJ, Altekoester AK, Cox CD, Jacoby A, Huttner IG, Ju YK, Soka M, Ohanian M, Trivedi G, Kalvakuri S, Birker K, Johnson R, Molenaar P, Kuchar D, Allen DG, van Helden DF, Harvey RP, Hill AP, Bodmer R, Vogler G, Dobrzynski H, Ocorr K, Fatkin D. Conserved Role of the Large Conductance Calcium-Activated Potassium Channel, K Ca1.1, in Sinus Node Function and Arrhythmia Risk. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2021; 14:e003144. [PMID: 33629867 DOI: 10.1161/circgen.120.003144] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND KCNMA1 encodes the α-subunit of the large-conductance Ca2+-activated K+ channel, KCa1.1, and lies within a linkage interval for atrial fibrillation (AF). Insights into the cardiac functions of KCa1.1 are limited, and KCNMA1 has not been investigated as an AF candidate gene. METHODS The KCNMA1 gene was sequenced in 118 patients with familial AF. The role of KCa1.1 in normal cardiac structure and function was evaluated in humans, mice, zebrafish, and fly. A novel KCNMA1 variant was functionally characterized. RESULTS A complex KCNMA1 variant was identified in 1 kindred with AF. To evaluate potential disease mechanisms, we first evaluated the distribution of KCa1.1 in normal hearts using immunostaining and immunogold electron microscopy. KCa1.1 was seen throughout the atria and ventricles in humans and mice, with strong expression in the sinus node. In an ex vivo murine sinoatrial node preparation, addition of the KCa1.1 antagonist, paxilline, blunted the increase in beating rate induced by adrenergic receptor stimulation. Knockdown of the KCa1.1 ortholog, kcnma1b, in zebrafish embryos resulted in sinus bradycardia with dilatation and reduced contraction of the atrium and ventricle. Genetic inactivation of the Drosophila KCa1.1 ortholog, slo, systemically or in adult stages, also slowed the heartbeat and produced fibrillatory cardiac contractions. Electrophysiological characterization of slo-deficient flies revealed bursts of action potentials, reflecting increased events of fibrillatory arrhythmias. Flies with cardiac-specific overexpression of the human KCNMA1 mutant also showed increased heart period and bursts of action potentials, similar to the KCa1.1 loss-of-function models. CONCLUSIONS Our data point to a highly conserved role of KCa1.1 in sinus node function in humans, mice, zebrafish, and fly and suggest that KCa1.1 loss of function may predispose to AF.
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Affiliation(s)
- Santiago Pineda
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Vesna Nikolova-Krstevski
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.)
| | - Christiana Leimena
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Andrew J Atkinson
- Institute of Cardiovascular Sciences, University of Manchester, United Kingdom (A.J.A., H.D.)
| | - Ann-Kristin Altekoester
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Charles D Cox
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Arie Jacoby
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Inken G Huttner
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.)
| | - Yue-Kun Ju
- Bosch Institute, University of Sydney, Camperdown (Y.-K.J., D.G.A.)
| | - Magdalena Soka
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Monique Ohanian
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Gunjan Trivedi
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.)
| | - Sreehari Kalvakuri
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Katja Birker
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Renee Johnson
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.)
| | - Peter Molenaar
- Faculty of Health, Queensland University of Technology (P.M.).,School of Medicine, University of Queensland, Prince Charles Hospital, Brisbane, Queensland, Australia (P.M.)
| | - Dennis Kuchar
- Cardiology Department, St Vincent's Hospital, Darlinghurst (D.K., D.F.)
| | - David G Allen
- Bosch Institute, University of Sydney, Camperdown (Y.-K.J., D.G.A.)
| | - Dirk F van Helden
- University of Newcastle and Hunter Medical Research Institute, NSW, Australia (D.F.v.H.)
| | - Richard P Harvey
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.)
| | - Adam P Hill
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.)
| | - Rolf Bodmer
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Georg Vogler
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, University of Manchester, United Kingdom (A.J.A., H.D.).,Jagiellonian University Medical College, Cracow, Poland (H.D.)
| | - Karen Ocorr
- Development, Aging & Regeneration Program, Sanford-Burnham Prebys Medical Discovery Institute, La Jolla, CA (S.P., S.K., K.B., R.B., G.V., K.O.)
| | - Diane Fatkin
- Victor Chang Cardiac Research Institute, Darlinghurst (V.N.-K., C.L., A.-K.A., C.D.C., A.J., I.G.H., M.S., M.O., G.T., R.J., R.P.H., A.P.H., D.F.).,Faculty of Medicine, UNSW Sydney, Kensington (V.N.-K., I.G.H., R.J., R.P.H., A.P.H., D.F.).,Cardiology Department, St Vincent's Hospital, Darlinghurst (D.K., D.F.)
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7
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Chua SK, Wang BW, Yu YJ, Fang WJ, Lin CM, Shyu KG. Cyclic stretching boosts microRNA-499 to regulate Bcl-2 via microRNA-208a in atrial fibroblasts. J Cell Mol Med 2021; 25:3113-3123. [PMID: 33605072 PMCID: PMC7957261 DOI: 10.1111/jcmm.16373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/25/2021] [Accepted: 02/01/2021] [Indexed: 01/20/2023] Open
Abstract
MicroRNAs that modulate transcription can regulate other microRNAs and are also up-regulated under pathological stress. MicroRNA-499 (miR-499), microRNA-208a (miR-208a) and B-cell lymphoma 2 (Bcl-2) play roles in cardiovascular diseases, such as direct reprogramming of cardiac fibroblast into cardiomyocyte and cardiomyocyte apoptosis. Whether miR208a, miR499 and Bcl-2 were critical regulators in cardiac fibroblast apoptosis under mechanical stretching conditions in human cardiac fibroblasts-adult atrial (HCF-aa) was investigated. Using negative pressure, HCF-aa grown on a flexible membrane base were cyclically stretched to 20% of their maximum elongation. In adult rats, an aortocaval shunt was used to create an in vivo model of volume overload. MiR208a was up-regulated early by stretching and returned to normal levels with longer stretching cycles, whereas the expression of miR499 and Bcl-2 was up-regulated by longer stretching times. Pre-treatment with antagomir-499 reversed the miR-208a down-regulation, whereas Bcl-2 expression could be suppressed by miR-208a overexpression. In the HCF-aa under stretching for 1 h, miR-499 overexpression decreased pri-miR-208a luciferase activity; this inhibition of pri-miR-208a luciferase activity with stretching was reversed when the miR-499-5p binding site in pri-miR-208a was mutated. The addition of antagomir-208a reversed the Bcl-2-3'UTR suppression from stretching for 1 h. Flow cytometric analysis revealed that pre-treatment with miR-499 or antagomir-208a inhibited cellular apoptosis in stretched HCF-aa. In hearts with volume overload, miR-499 overexpression inhibited myocardial miR-208a expression, whereas Bcl-2 expression could be suppressed by the addition of miR-208a. In conclusion, miR-208a mediated the regulation of miR-499 on Bcl-2 expression in stretched HCF-aa and hearts with volume overload.
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Affiliation(s)
- Su-Kiat Chua
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Bao-Wei Wang
- Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Ying-Ju Yu
- Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Wei-Jen Fang
- Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Chiu-Mei Lin
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei, Taiwan.,Department of Emergency Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
| | - Kou-Gi Shyu
- Division of Cardiology, Department of Internal Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan
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8
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Bazhutina A, Balakina-Vikulova NA, Kursanov A, Solovyova O, Panfilov A, Katsnelson LB. Mathematical modelling of the mechano-electric coupling in the human cardiomyocyte electrically connected with fibroblasts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:46-57. [PMID: 32846154 DOI: 10.1016/j.pbiomolbio.2020.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 01/12/2023]
Abstract
Cardiac fibroblasts are interspersed within mammalian cardiac tissue. Fibroblasts are mechanically passive; however, they may communicate electrically with cardiomyocytes via gap junctions and thus affect the electrical and mechanical activity of myocytes. Several in-silico studies at both cellular (0D) and ventricular (3D) levels analysed the effects of fibroblasts on the myocardial electrical function. However, none of them addressed possible effects of fibroblast-myocyte electrical coupling to cardiomyocyte mechanical activity. In this paper, we propose a mathematical model for studying both electrical and mechanical responses of the human cardiomyocyte to its electrotonic interaction with cardiac fibroblasts. Our simulations have revealed that electrotonic interaction with fibroblasts affects not only the mechanical activity of the cardiomyocyte, comprising either moderate or significant reduction of contractility, but also the mechano-calcium and mechano-electric feedback loops, and all these effects are enhanced as the number of coupled fibroblasts is increased. Obtained results suggest that moderate values of the myocyte-fibroblast gap junction conductance (less than 1 nS) can be attributed to physiological conditions, contrasting to the higher values (2 nS and higher) proper rather for pathological situations (e.g. for infarct and/or border zones), since all mechanical indexes falls down dramatically in the case of such high conductance.
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Affiliation(s)
| | - Nathalie A Balakina-Vikulova
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Alexander Kursanov
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Olga Solovyova
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Alexander Panfilov
- Ural Federal University, Ekaterinburg, Russia; Ghent University, Ghent, Belgium
| | - Leonid B Katsnelson
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia.
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9
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Szteyn K, Singh H. BK Ca Channels as Targets for Cardioprotection. Antioxidants (Basel) 2020; 9:antiox9080760. [PMID: 32824463 PMCID: PMC7463653 DOI: 10.3390/antiox9080760] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/09/2020] [Accepted: 08/13/2020] [Indexed: 12/16/2022] Open
Abstract
The large-conductance calcium- and voltage-activated K+ channel (BKCa) are encoded by the Kcnma1 gene. They are ubiquitously expressed in neuronal, smooth muscle, astrocytes, and neuroendocrine cells where they are known to play an important role in physiological and pathological processes. They are usually localized to the plasma membrane of the majority of the cells with an exception of adult cardiomyocytes, where BKCa is known to localize to mitochondria. BKCa channels couple calcium and voltage responses in the cell, which places them as unique targets for a rapid physiological response. The expression and activity of BKCa have been linked to several cardiovascular, muscular, and neurological defects, making them a key therapeutic target. Specifically in the heart muscle, pharmacological and genetic activation of BKCa channels protect the heart from ischemia-reperfusion injury and also facilitate cardioprotection rendered by ischemic preconditioning. The mechanism involved in cardioprotection is assigned to the modulation of mitochondrial functions, such as regulation of mitochondrial calcium, reactive oxygen species, and membrane potential. Here, we review the progress made on BKCa channels and cardioprotection and explore their potential roles as therapeutic targets for preventing acute myocardial infarction.
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10
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Roach KM, Bradding P. Ca 2+ signalling in fibroblasts and the therapeutic potential of K Ca3.1 channel blockers in fibrotic diseases. Br J Pharmacol 2020; 177:1003-1024. [PMID: 31758702 DOI: 10.1111/bph.14939] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022] Open
Abstract
The role of Ca2+ signalling in fibroblasts is of great interest in fibrosis-related diseases. Intracellular free Ca2+ ([Ca2+ ]i ) is a ubiquitous secondary messenger, regulating a number of cellular functions such as secretion, metabolism, differentiation, proliferation and contraction. The intermediate conductance Ca2+ -activated K+ channel KCa 3.1 is pivotal in Ca2+ signalling and plays a central role in fibroblast processes including cell activation, migration and proliferation through the regulation of cell membrane potential. Evidence from a number of approaches demonstrates that KCa 3.1 plays an important role in the development of many fibrotic diseases, including idiopathic pulmonary, renal tubulointerstitial fibrosis and cardiovascular disease. The KCa 3.1 selective blocker senicapoc was well tolerated in clinical trials for sickle cell disease, raising the possibility of rapid translation to the clinic for people suffering from pathological fibrosis. This review after analysing all the data, concludes that targeting KCa 3.1 should be a high priority for human fibrotic disease.
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Affiliation(s)
- Katy M Roach
- Institute for Lung Health, Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Peter Bradding
- Institute for Lung Health, Department of Respiratory Sciences, University of Leicester, Leicester, UK
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11
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Feng J, Armillei MK, Yu AS, Liang BT, Runnels LW, Yue L. Ca 2+ Signaling in Cardiac Fibroblasts and Fibrosis-Associated Heart Diseases. J Cardiovasc Dev Dis 2019; 6:E34. [PMID: 31547577 PMCID: PMC6956282 DOI: 10.3390/jcdd6040034] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
Cardiac fibrosis is the excessive deposition of extracellular matrix proteins by cardiac fibroblasts and myofibroblasts, and is a hallmark feature of most heart diseases, including arrhythmia, hypertrophy, and heart failure. This maladaptive process occurs in response to a variety of stimuli, including myocardial injury, inflammation, and mechanical overload. There are multiple signaling pathways and various cell types that influence the fibrogenesis cascade. Fibroblasts and myofibroblasts are central effectors. Although it is clear that Ca2+ signaling plays a vital role in this pathological process, what contributes to Ca2+ signaling in fibroblasts and myofibroblasts is still not wholly understood, chiefly because of the large and diverse number of receptors, transporters, and ion channels that influence intracellular Ca2+ signaling. Intracellular Ca2+ signals are generated by Ca2+ release from intracellular Ca2+ stores and by Ca2+ entry through a multitude of Ca2+-permeable ion channels in the plasma membrane. Over the past decade, the transient receptor potential (TRP) channels have emerged as one of the most important families of ion channels mediating Ca2+ signaling in cardiac fibroblasts. TRP channels are a superfamily of non-voltage-gated, Ca2+-permeable non-selective cation channels. Their ability to respond to various stimulating cues makes TRP channels effective sensors of the many different pathophysiological events that stimulate cardiac fibrogenesis. This review focuses on the mechanisms of Ca2+ signaling in fibroblast differentiation and fibrosis-associated heart diseases and will highlight recent advances in the understanding of the roles that TRP and other Ca2+-permeable channels play in cardiac fibrosis.
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Affiliation(s)
- Jianlin Feng
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Maria K Armillei
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Albert S Yu
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Bruce T Liang
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
| | - Loren W Runnels
- Department of Pharmacology, Rutgers, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
| | - Lixia Yue
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
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12
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Mitrokhin MV, Kalsin V, Kamkina O, Babkina I, Zotov A, Troitskiy VA, Mladenov MI, Kamkin GA. Participation of PKG and PKA-related pathways in the IFN-γ induced modulation of the BK Ca channel activity in human cardiac fibroblasts. J Pharmacol Sci 2019; 141:25-31. [PMID: 31533896 DOI: 10.1016/j.jphs.2019.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/31/2019] [Accepted: 08/20/2019] [Indexed: 01/19/2023] Open
Abstract
This study was devoted to elucidating the interferon (IFN)-γ-induced signaling pathway and the interaction between protein kinase G (PKG) and protein kinase A (PKA) through large-conductance Ca(2+)-activated K(+) channels in human cardiac fibroblasts. The IK currents were recorded using a whole-cell patch clamp method. A large depolarization (+50 mV) and a high Ca2+ concentration (pCa 6.0) were used in the internal pipette solution to activate only the KCa channels. Iberiotoxin (Ibtx), which selectively inhibits BKCa channels at a concentration of 100 nmol/l, caused a significant reduction of basal IK. Adding IFN-γ in the presence of Ibtx had no effect on IK. Application of the IFN-γ caused a significant reduction in total K+ current amplitude, recorded with a 500 ms depolarizing pulse duration, to +50 mV from a holding potential of -80 mV. We tested the involvement of the sGC/cGMP/PKG signaling pathway by using specific PKG inhibitor KT 5823, potent sGC inhibitor NS 2028, and specific sGC agonist BAY 41-8543. The obtained data confirmed that only sGC participated in the IFN-γ-mediated BKCa channel modulation, which was mediated further by PKA. This study represents first evidence about the participation of the IFN-γ in the mechanisms responsible for BKCa modulation in HCFs. We also believe that this process occurs via negative crosstalk between the PKG- and PKA-associated pathways.
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Affiliation(s)
- M V Mitrokhin
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovitjanova 1, Moscow 117997, Russia
| | - V Kalsin
- Federal Scientific Clinical Center for Specialized Types of Medical Assistance and Medical Technologies for the Federal Medical and Biological Agency, Orekhoviy Boulevard 28, Moscow 115682, Russia
| | - O Kamkina
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovitjanova 1, Moscow 117997, Russia
| | - I Babkina
- Federal Scientific Clinical Center for Specialized Types of Medical Assistance and Medical Technologies for the Federal Medical and Biological Agency, Orekhoviy Boulevard 28, Moscow 115682, Russia
| | - A Zotov
- Federal Scientific Clinical Center for Specialized Types of Medical Assistance and Medical Technologies for the Federal Medical and Biological Agency, Orekhoviy Boulevard 28, Moscow 115682, Russia
| | - V A Troitskiy
- Federal Scientific Clinical Center for Specialized Types of Medical Assistance and Medical Technologies for the Federal Medical and Biological Agency, Orekhoviy Boulevard 28, Moscow 115682, Russia
| | - M I Mladenov
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovitjanova 1, Moscow 117997, Russia; Faculty of Natural Sciences and Mathematics, Institute of Biology, "Ss. Cyril and Methodius" University, P.O. Box 162, 1000 Skopje, Macedonia.
| | - G A Kamkin
- Department of Fundamental and Applied Physiology, Russian National Research Medical University, Ostrovitjanova 1, Moscow 117997, Russia
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Liu YW, Fang YH, Su CT, Hwang SM, Liu PY, Wu SN. The biochemical and electrophysiological profiles of amniotic fluid-derived stem cells following Wnt signaling modulation cardiac differentiation. Cell Death Discov 2019; 5:59. [PMID: 30701091 PMCID: PMC6349909 DOI: 10.1038/s41420-019-0143-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/31/2018] [Accepted: 01/08/2019] [Indexed: 12/12/2022] Open
Abstract
Owing to the beneficial properties of amniotic fluid-derived stem cells (AFSCs), including pluripotency and the lack of ethical issues associated with embryonic stem cells (ESCs), they should be a promising cell source for regenerative medicine. However, how to differentiate AFSCs into contracting cardiomyocytes has not been established. In this study, a well-established, direct cardiac differentiation protocol involving the modulation of Wnt signaling was used to differentiate Oct 3/4+ AFSCs into cardiomyocytes. By day 14 of cardiomyocyte differentiation, these AFSCs expressed cardiac-specific genes (i.e., cardiac troponin T and myosin light chain 2v) and proteins but could not spontaneously contract. Using the patch-clamp technique, we further characterized the electrophysiological properties of human ESC-derived cardiomyocytes (hESC-CMs) and differentiated AFSCs. We used different configurations to investigate membrane potentials and ion currents in differentiated AFSCs and hESC-CMs. Under cell-attached voltage- or whole-cell current-clamp modes, we recorded spontaneous action currents (ACs) or action potentials (APs) in hESC-CMs but not in differentiated AFSCs. Compared to hESC-CMs, differentiated AFSCs showed significantly diminished activity of both BKCa and IKCa channels, which might lead to a lack of spontaneous ACs and APs in differentiated AFSCs. These results indicated that this well-established Wnt signaling modulating cardiac differentiation protocol was insufficient to induce the differentiation of functional cardiomyocytes from Oct 3/4+ AFSCs. Therefore, AFSC may not be an ideal candidate for cardiomyocyte differentiation.
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Affiliation(s)
- Yen-Wen Liu
- 1Division of Cardiology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd. North District, Tainan, 70403 Taiwan.,2Institute of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Hsein Fang
- 2Institute of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chi-Ting Su
- 3Division of Nephrology, Department of Internal Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan
| | - Shiaw-Min Hwang
- 4Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan
| | - Ping-Yen Liu
- 1Division of Cardiology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd. North District, Tainan, 70403 Taiwan.,2Institute of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Sheng-Nan Wu
- 5Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Rd, East District, Tainan, Taiwan.,6Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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14
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Vagos M, van Herck IGM, Sundnes J, Arevalo HJ, Edwards AG, Koivumäki JT. Computational Modeling of Electrophysiology and Pharmacotherapy of Atrial Fibrillation: Recent Advances and Future Challenges. Front Physiol 2018; 9:1221. [PMID: 30233399 PMCID: PMC6131668 DOI: 10.3389/fphys.2018.01221] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/13/2018] [Indexed: 12/19/2022] Open
Abstract
The pathophysiology of atrial fibrillation (AF) is broad, with components related to the unique and diverse cellular electrophysiology of atrial myocytes, structural complexity, and heterogeneity of atrial tissue, and pronounced disease-associated remodeling of both cells and tissue. A major challenge for rational design of AF therapy, particularly pharmacotherapy, is integrating these multiscale characteristics to identify approaches that are both efficacious and independent of ventricular contraindications. Computational modeling has long been touted as a basis for achieving such integration in a rapid, economical, and scalable manner. However, computational pipelines for AF-specific drug screening are in their infancy, and while the field is progressing quite rapidly, major challenges remain before computational approaches can fill the role of workhorse in rational design of AF pharmacotherapies. In this review, we briefly detail the unique aspects of AF pathophysiology that determine requirements for compounds targeting AF rhythm control, with emphasis on delimiting mechanisms that promote AF triggers from those providing substrate or supporting reentry. We then describe modeling approaches that have been used to assess the outcomes of drugs acting on established AF targets, as well as on novel promising targets including the ultra-rapidly activating delayed rectifier potassium current, the acetylcholine-activated potassium current and the small conductance calcium-activated potassium channel. Finally, we describe how heterogeneity and variability are being incorporated into AF-specific models, and how these approaches are yielding novel insights into the basic physiology of disease, as well as aiding identification of the important molecular players in the complex AF etiology.
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Affiliation(s)
- Márcia Vagos
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Ilsbeth G. M. van Herck
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Department of Informatics, University of Oslo, Oslo, Norway
| | - Joakim Sundnes
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Hermenegild J. Arevalo
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Andrew G. Edwards
- Computational Physiology Department, Simula Research Laboratory, Lysaker, Norway
- Center for Cardiological Innovation, Oslo, Norway
| | - Jussi T. Koivumäki
- BioMediTech Institute and Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, Tampere, Finland
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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15
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Bae H, Choi J, Kim YW, Lee D, Kim JH, Ko JH, Bang H, Kim T, Lim I. Effects of Nitric Oxide on Voltage-Gated K⁺ Currents in Human Cardiac Fibroblasts through the Protein Kinase G and Protein Kinase A Pathways but Not through S-Nitrosylation. Int J Mol Sci 2018. [PMID: 29534509 PMCID: PMC5877675 DOI: 10.3390/ijms19030814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This study investigated the expression of voltage-gated K+ (KV) channels in human cardiac fibroblasts (HCFs), and the effect of nitric oxide (NO) on the KV currents, and the underlying phosphorylation mechanisms. In reverse transcription polymerase chain reaction, two types of KV channels were detected in HCFs: delayed rectifier K+ channel and transient outward K+ channel. In whole-cell patch-clamp technique, delayed rectifier K+ current (IK) exhibited fast activation and slow inactivation, while transient outward K+ current (Ito) showed fast activation and inactivation kinetics. Both currents were blocked by 4-aminopyridine. An NO donor, S-nitroso-N-acetylpenicillamine (SNAP), increased the amplitude of IK in a concentration-dependent manner with an EC50 value of 26.4 µM, but did not affect Ito. The stimulating effect of SNAP on IK was blocked by pretreatment with 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or by KT5823. 8-bromo-cyclic GMP stimulated the IK. The stimulating effect of SNAP on IK was also blocked by pretreatment with KT5720 or by SQ22536. Forskolin and 8-bromo-cyclic AMP each stimulated IK. On the other hand, the stimulating effect of SNAP on IK was not blocked by pretreatment of N-ethylmaleimide or by DL-dithiothreitol. Our data suggest that NO enhances IK, but not Ito, among KV currents of HCFs, and the stimulating effect of NO on IK is through the PKG and PKA pathways, not through S-nitrosylation.
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Affiliation(s)
- Hyemi Bae
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Jeongyoon Choi
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Young-Won Kim
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Donghee Lee
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Jung-Ha Kim
- Department of Family Medicine, College of Medicine, Chung-Ang University Hospital, 102 Heukseok-ro, Seoul 06973, Korea.
| | - Jae-Hong Ko
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Hyoweon Bang
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
| | - Taeho Kim
- Department of Internal Medicine, College of Medicine, Chung-Ang University Hospital, 102 Heukseok-ro, Seoul 06973, Korea.
| | - Inja Lim
- Department of Physiology, College of Medicine, Chung-Ang University, 84 Heukseok-ro, Seoul 06974, Korea.
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16
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Klesen A, Jakob D, Emig R, Kohl P, Ravens U, Peyronnet R. Cardiac fibroblasts : Active players in (atrial) electrophysiology? Herzschrittmacherther Elektrophysiol 2018; 29:62-69. [PMID: 29392412 DOI: 10.1007/s00399-018-0553-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 12/22/2017] [Accepted: 12/22/2017] [Indexed: 06/07/2023]
Abstract
Fibrotic areas in cardiac muscle-be it in ventricular or atrial tissue-are considered as obstacles for conduction of the excitatory wave and can therefore facilitate re-entry, which may contribute to the sustenance of cardiac arrhythmias. Persistence of one of the most frequent arrhythmias, atrial fibrillation (AF), is accompanied by enhanced atrial fibrosis. Any kind of myocardial perturbation, whether via mechanical stress or ischemic damage, inflammation, or irregular and high-frequency electrical activity, activates fibroblasts. This leads to the secretion of paracrine factors and extracellular matrix proteins, especially collagen, and to the differentiation of fibroblasts into myofibroblasts. Excessive collagen production is the hallmark of fibrosis and impairs regular impulse propagation. In addition, direct electrical coupling between cardiomyocytes and nonmyocytes, such as fibroblasts and macrophages, via gap junctions affects conduction. Although fibroblasts are not electrically excitable, they express functional ion channels, in particular K+ channels and mechanosensitive channels, some of which could be involved in tissue remodeling. Here, we briefly review these aspects with special reference to AF.
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Affiliation(s)
- Alexander Klesen
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Dorothee Jakob
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Ramona Emig
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany.
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany.
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17
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Bae H, Lim I. Effects of nitric oxide on large-conductance Ca 2+ -activated K + currents in human cardiac fibroblasts through PKA and PKG-related pathways. Clin Exp Pharmacol Physiol 2017; 44:1116-1124. [PMID: 28731589 DOI: 10.1111/1440-1681.12817] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/29/2017] [Accepted: 07/11/2017] [Indexed: 01/22/2023]
Abstract
The human cardiac fibroblast (HCF) is the most abundant cell type in the myocardium, and HCFs play critical roles in maintaining normal cardiac function. However, unlike cardiomyocytes, the electrophysiology of HCFs is not well established. In the cardiovascular system, Ca2+ -activated K+ (KCa) channels have distinct physiological and pathological functions, and nitric oxide (NO) plays a key role. In this study, we investigated the potential effects of NO on KCa channels in HCFs. We recorded strong oscillating, well-maintained outward K+ currents without marked inactivation throughout the test pulse period and detected outward rectification in the I-V curve; these are all characteristics that are typical of KCa currents. These currents were blocked with iberiotoxin (IBTX, a BKCa blocker) but not with TRAM-34 (an IKCa blocker). The amplitudes of the currents were increased with SNAP (an NO donor), and these increases were inhibited with IBTX. The SNAP-stimulating effect on the BKCa currents was blocked by pretreatment with KT5823 (a protein kinase G [PKG] inhibitor) or 1 H-[1,-2, -4] oxadiazolo-[4,-3-a] quinoxalin-1-one (ODQ; a soluble guanylate cyclase inhibitor). Additionally, 8-bromo-cyclic guanosine 3',5'-monophosphate (8-Br-cGMP) stimulated the BKCa currents, and pretreatment with KT5720 (a protein kinase A [PKA] inhibitor) and SQ22536 (an adenylyl cyclase inhibitor) blocked the NO-stimulating effect on the BKCa currents. Furthermore, 8-bromo-cyclic adenosine 3',5'-monophosphate (8-Br-cAMP) activated the BKCa currents. These data suggest that BKCa current is the main subtype of the KCa current in HCFs and that NO enhances these currents through the PKG and PKA pathways.
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Affiliation(s)
- Hyemi Bae
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Inja Lim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, Korea
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18
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Herum KM, Lunde IG, McCulloch AD, Christensen G. The Soft- and Hard-Heartedness of Cardiac Fibroblasts: Mechanotransduction Signaling Pathways in Fibrosis of the Heart. J Clin Med 2017; 6:jcm6050053. [PMID: 28534817 PMCID: PMC5447944 DOI: 10.3390/jcm6050053] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/04/2017] [Accepted: 05/08/2017] [Indexed: 12/27/2022] Open
Abstract
Cardiac fibrosis, the excessive accumulation of extracellular matrix (ECM), remains an unresolved problem in most forms of heart disease. In order to be successful in preventing, attenuating or reversing cardiac fibrosis, it is essential to understand the processes leading to ECM production and accumulation. Cardiac fibroblasts are the main producers of cardiac ECM, and harbor great phenotypic plasticity. They are activated by the disease-associated changes in mechanical properties of the heart, including stretch and increased tissue stiffness. Despite much remaining unknown, an interesting body of evidence exists on how mechanical forces are translated into transcriptional responses important for determination of fibroblast phenotype and production of ECM constituents. Such mechanotransduction can occur at multiple cellular locations including the plasma membrane, cytoskeleton and nucleus. Moreover, the ECM functions as a reservoir of pro-fibrotic signaling molecules that can be released upon mechanical stress. We here review the current status of knowledge of mechanotransduction signaling pathways in cardiac fibroblasts that culminate in pro-fibrotic gene expression.
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Affiliation(s)
- Kate M Herum
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0450 Oslo, Norway.
- Center for Heart Failure Research, Oslo University Hospital, 0450 Oslo, Norway.
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA.
| | - Ida G Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0450 Oslo, Norway.
- Center for Heart Failure Research, Oslo University Hospital, 0450 Oslo, Norway.
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA.
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA.
| | - Geir Christensen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0450 Oslo, Norway.
- Center for Heart Failure Research, Oslo University Hospital, 0450 Oslo, Norway.
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19
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Civitarese RA, Kapus A, McCulloch CA, Connelly KA. Role of integrins in mediating cardiac fibroblast–cardiomyocyte cross talk: a dynamic relationship in cardiac biology and pathophysiology. Basic Res Cardiol 2016; 112:6. [DOI: 10.1007/s00395-016-0598-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/14/2016] [Indexed: 12/16/2022]
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20
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Poulet C, Künzel S, Büttner E, Lindner D, Westermann D, Ravens U. Altered physiological functions and ion currents in atrial fibroblasts from patients with chronic atrial fibrillation. Physiol Rep 2016; 4:4/2/e12681. [PMID: 26811054 PMCID: PMC4760386 DOI: 10.14814/phy2.12681] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The contribution of human atrial fibroblasts to cardiac physiology and pathophysiology is poorly understood. Fibroblasts may contribute to arrhythmogenesis through fibrosis, or by directly altering electrical activity in cardiomyocytes. The objective of our study was to uncover phenotypic differences between cells from patients in sinus rhythm (SR) and chronic atrial fibrillation (AF), with special emphasis on electrophysiological properties. We isolated fibroblasts from human right atrial tissue for patch-clamp experiments, proliferation, migration, and differentiation assays, and gene expression profiling. In culture, proliferation and migration of AF fibroblasts were strongly impaired but differentiation into myofibroblasts was increased. This was associated with a higher number of AF fibroblasts expressing functional Nav1.5 channels. Strikingly Na(+) currents were considerably larger in AF cells. Blocking Na(+) channels in culture with tetrodotoxin did not affect proliferation, migration, or differentiation in neither SR nor AF cells. While freshly isolated fibroblasts showed mostly weak rectifier currents, fibroblasts in culture developed outward rectifier K(+) currents of similar amplitude between the SR and AF groups. Adding the K(+) channel blockers tetraethylammonium and 4-aminopyridin in culture reduced current amplitude and inhibited proliferation in the SR group only. Analysis of gene expression revealed significant differences between SR and AF in genes encoding for ion channels, collagen, growth factors, connexins, and cadherins. In conclusion, this study shows that under AF conditions atrial fibroblasts undergo phenotypic changes that are revealed in culture. Future experiments should be performed in situ to understand the nature of those changes and whether they affect cardiac electrical activity.
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Affiliation(s)
- Claire Poulet
- Department of Pharmacology and Toxicology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany
| | - Stephan Künzel
- Department of Pharmacology and Toxicology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany
| | - Edgar Büttner
- Department of Pharmacology and Toxicology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany
| | - Diana Lindner
- Department of General and Interventional Cardiology, University Heart Center Hamburg Eppendorf, Hamburg, Germany
| | - Dirk Westermann
- Department of General and Interventional Cardiology, University Heart Center Hamburg Eppendorf, Hamburg, Germany
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany
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Bae H, Lee D, Kim YW, Choi J, Lee HJ, Kim SW, Kim T, Noh YH, Ko JH, Bang H, Lim I. Effects of hydrogen peroxide on voltage-dependent K(+) currents in human cardiac fibroblasts through protein kinase pathways. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:315-24. [PMID: 27162486 PMCID: PMC4860374 DOI: 10.4196/kjpp.2016.20.3.315] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 01/29/2023]
Abstract
Human cardiac fibroblasts (HCFs) have various voltage-dependent K(+) channels (VDKCs) that can induce apoptosis. Hydrogen peroxide (H2O2) modulates VDKCs and induces oxidative stress, which is the main contributor to cardiac injury and cardiac remodeling. We investigated whether H2O2 could modulate VDKCs in HCFs and induce cell injury through this process. In whole-cell mode patch-clamp recordings, application of H2O2 stimulated Ca(2+)-activated K(+) (KCa) currents but not delayed rectifier K(+) or transient outward K(+) currents, all of which are VDKCs. H2O2-stimulated KCa currents were blocked by iberiotoxin (IbTX, a large conductance KCa blocker). The H2O2-stimulating effect on large-conductance KCa (BKCa) currents was also blocked by KT5823 (a protein kinase G inhibitor) and 1 H-[1, 2, 4] oxadiazolo-[4, 3-a] quinoxalin-1-one (ODQ, a soluble guanylate cyclase inhibitor). In addition, 8-bromo-cyclic guanosine 3', 5'-monophosphate (8-Br-cGMP) stimulated BKCa currents. In contrast, KT5720 and H-89 (protein kinase A inhibitors) did not block the H2O2-stimulating effect on BKCa currents. Using RT-PCR and western blot analysis, three subtypes of KCa channels were detected in HCFs: BKCa channels, small-conductance KCa (SKCa) channels, and intermediate-conductance KCa (IKCa) channels. In the annexin V/propidium iodide assay, apoptotic changes in HCFs increased in response to H2O2, but IbTX decreased H2O2-induced apoptosis. These data suggest that among the VDKCs of HCFs, H2O2 only enhances BKCa currents through the protein kinase G pathway but not the protein kinase A pathway, and is involved in cell injury through BKCa channels.
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Affiliation(s)
- Hyemi Bae
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Donghee Lee
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Young-Won Kim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Jeongyoon Choi
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Hong Jun Lee
- Biomedical Research Institute, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Sang-Wook Kim
- Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Taeho Kim
- Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Yun-Hee Noh
- Department of Biochemistry, School of Medicine, Konkuk University, Seoul 05029, Korea
| | - Jae-Hong Ko
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Hyoweon Bang
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
| | - Inja Lim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, Korea
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22
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Mahoney VM, Mezzano V, Morley GE. A review of the literature on cardiac electrical activity between fibroblasts and myocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:128-33. [PMID: 26713556 DOI: 10.1016/j.pbiomolbio.2015.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/12/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022]
Abstract
Myocardial injuries often lead to fibrotic deposition. This review presents evidence supporting the concept that fibroblasts in the heart electrically couple to myocytes.
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Affiliation(s)
- Vanessa M Mahoney
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Valeria Mezzano
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Gregory E Morley
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA.
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23
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Chiang NJ, Wu SN, Chen LT. The potent activation of Ca2+-activated K+ current by NVP-AUY922 in the human pancreatic duct cell line (PANC-1) possibly independent of heat shock protein 90 inhibition. J Pharmacol Sci 2015; 127:404-13. [DOI: 10.1016/j.jphs.2015.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 02/02/2015] [Accepted: 02/12/2015] [Indexed: 12/20/2022] Open
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24
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Dostal D, Glaser S, Baudino TA. Cardiac Fibroblast Physiology and Pathology. Compr Physiol 2015; 5:887-909. [DOI: 10.1002/cphy.c140053] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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25
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Oguri G, Nakajima T, Yamamoto Y, Takano N, Tanaka T, Kikuchi H, Morita T, Nakamura F, Yamasoba T, Komuro I. Effects of methylglyoxal on human cardiac fibroblast: roles of transient receptor potential ankyrin 1 (TRPA1) channels. Am J Physiol Heart Circ Physiol 2014; 307:H1339-52. [PMID: 25172898 DOI: 10.1152/ajpheart.01021.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cardiac fibroblasts contribute to the pathogenesis of cardiac remodeling. Methylglyoxal (MG) is an endogenous carbonyl compound produced under hyperglycemic conditions, which may play a role in the development of pathophysiological conditions including diabetic cardiomyopathy. However, the mechanism by which this occurs and the molecular targets of MG are unclear. We investigated the effects of MG on Ca(2+) signals, its underlying mechanism, and cell cycle progression/cell differentiation in human cardiac fibroblasts. The conventional and quantitative real-time RT-PCR, Western blot, immunocytochemical analysis, and intracellular Ca(2+) concentration [Ca(2+)]i measurement were applied. Cell cycle progression was assessed using the fluorescence activated cell sorting. MG induced Ca(2+) entry concentration dependently. Ruthenium red (RR), a general cation channel blocker, and HC030031, a selective transient receptor potential ankyrin 1 (TRPA1) antagonist, inhibited MG-induced Ca(2+) entry. Treatment with aminoguanidine, a MG scavenger, also inhibited it. Allyl isothiocyanate, a selective TRPA1 agonist, increased Ca(2+) entry. The use of small interfering RNA to knock down TRPA1 reduced the MG-induced Ca(2+) entry as well as TRPA1 mRNA expression. The quantitative real-time RT-PCR analysis showed the prominent existence of TRPA1 mRNA. Expression of TRPA1 protein was confirmed by Western blotting and immunocytochemical analyses. MG promoted cell cycle progression from G0/G1 to S/G2/M, which was suppressed by HC030031 or RR. MG also enhanced α-smooth muscle actin expression. The present results suggest that methylglyoxal activates TRPA1 and promotes cell cycle progression and differentiation in human cardiac fibroblasts. MG might participate the development of pathophysiological conditions including diabetic cardiomyopathy via activation of TRPA1.
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Affiliation(s)
- Gaku Oguri
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Toshiaki Nakajima
- Department of Ischemic Circulatory Physiology, University of Tokyo, Tokyo, Japan;
| | - Yumiko Yamamoto
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Nami Takano
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Tomofumi Tanaka
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Hironobu Kikuchi
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Toshihiro Morita
- Department of Ischemic Circulatory Physiology, University of Tokyo, Tokyo, Japan
| | | | - Tatsuya Yamasoba
- Department of Otolaryngology, University of Tokyo, Tokyo, Japan; and
| | - Issei Komuro
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
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26
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Wrzosek A. The potassium channel opener NS1619 modulates calcium homeostasis in muscle cells by inhibiting SERCA. Cell Calcium 2014; 56:14-24. [DOI: 10.1016/j.ceca.2014.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 02/25/2014] [Accepted: 03/29/2014] [Indexed: 12/31/2022]
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27
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Heijman J, Voigt N, Nattel S, Dobrev D. Cellular and molecular electrophysiology of atrial fibrillation initiation, maintenance, and progression. Circ Res 2014; 114:1483-99. [PMID: 24763466 DOI: 10.1161/circresaha.114.302226] [Citation(s) in RCA: 459] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most common clinically relevant arrhythmia and is associated with increased morbidity and mortality. The incidence of AF is expected to continue to rise with the aging of the population. AF is generally considered to be a progressive condition, occurring first in a paroxysmal form, then in persistent, and then long-standing persistent (chronic or permanent) forms. However, not all patients go through every phase, and the time spent in each can vary widely. Research over the past decades has identified a multitude of pathophysiological processes contributing to the initiation, maintenance, and progression of AF. However, many aspects of AF pathophysiology remain incompletely understood. In this review, we discuss the cellular and molecular electrophysiology of AF initiation, maintenance, and progression, predominantly based on recent data obtained in human tissue and animal models. The central role of Ca(2+)-handling abnormalities in both focal ectopic activity and AF substrate progression is discussed, along with the underlying molecular basis. We also deal with the ionic determinants that govern AF initiation and maintenance, as well as the structural remodeling that stabilizes AF-maintaining re-entrant mechanisms and finally makes the arrhythmia refractory to therapy. In addition, we highlight important gaps in our current understanding, particularly with respect to the translation of these concepts to the clinical setting. Ultimately, a comprehensive understanding of AF pathophysiology is expected to foster the development of improved pharmacological and nonpharmacological therapeutic approaches and to greatly improve clinical management.
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Affiliation(s)
- Jordi Heijman
- From the Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (J.H., N.V., D.D.); Department of Medicine, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (S.N.); and Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada (S.N.)
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28
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Reed A, Kohl P, Peyronnet R. Molecular candidates for cardiac stretch-activated ion channels. Glob Cardiol Sci Pract 2014; 2014:9-25. [PMID: 25405172 PMCID: PMC4220428 DOI: 10.5339/gcsp.2014.19] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/08/2014] [Indexed: 01/20/2023] Open
Abstract
The heart is a mechanically-active organ that dynamically senses its own mechanical environment. This environment is constantly changing, on a beat-by-beat basis, with additional modulation by respiratory activity and changes in posture or physical activity, and further overlaid with more slowly occurring physiological (e.g. pregnancy, endurance training) or pathological challenges (e.g. pressure or volume overload). Far from being a simple pump, the heart detects changes in mechanical demand and adjusts its performance accordingly, both via heart rate and stroke volume alteration. Many of the underlying regulatory processes are encoded intracardially, and are thus maintained even in heart transplant recipients. Over the last three decades, molecular substrates of cardiac mechanosensitivity have gained increasing recognition in the scientific and clinical communities. Nonetheless, the processes underlying this phenomenon are still poorly understood. Stretch-activated ion channels (SAC) have been identified as one contributor to mechanosensitive autoregulation of the heartbeat. They also appear to play important roles in the development of cardiac pathologies – most notably stretch-induced arrhythmias. As recently discovered, some established cardiac drugs act, in part at least, via mechanotransduction pathways suggesting SAC as potential therapeutic targets. Clearly, identification of the molecular substrate of cardiac SAC is of clinical importance and a number of candidate proteins have been identified. At the same time, experimental studies have revealed variable–and at times contrasting–results regarding their function. Further complication arises from the fact that many ion channels that are not classically defined as SAC, including voltage and ligand-gated ion channels, can respond to mechanical stimulation. Here, we summarise what is known about the molecular substrate of the main candidates for cardiac SAC, before identifying potential further developments in this area of translational research.
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Affiliation(s)
- Alistair Reed
- Medical Sciences Division, University of Oxford, United Kingdom
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29
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Takahashi K, Naruse K. Stretch-activated BK channel and heart function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 110:239-44. [PMID: 23281538 DOI: 10.1016/j.pbiomolbio.2012.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The heart is an organ that is exposed to extreme dynamic mechanical stimuli. From birth till death, the heart indefinitely repeats periodic contraction and dilation, i.e., shortening and elongation of cardiomyocytes. Mechanical stretch elicits a change in heart rate and may cause arrhythmia if it is excessive. Thus, mechanosensitivity is crucial to heart function. The molecule that is substantially involved in mechanosensitivity is a stretch-activated ion channel. Among several ion channels believed to be activated by stretch in the heart, the stretch-activated KCa (SAKCA) channel, a member of the group of large conductance (Big Potassium, BK) channels, shows a mechanosensitive (MS) response to membrane stretch. As BK channels respond to voltage and intracellular calcium concentration with large conductance, they are considered to be involved in repolarization after depolarization. Some BK channels are known to be activated by stretch and are expressed in a number of cells, including human osteoblasts and guinea pig intestinal neurons. The SAKCA channel was found to be sensitive to stretch in the chick heart. Given that the cardiomyocyte is unremittingly exposed to contraction and dilation and that it generates action potential and its contractility is modulated by intracellular calcium concentration, the SAKCA channel, which is dependent voltage and calcium, may be involved in action potential generation. It was recently reported that a BK channel is involved in the modulation of heart rate in the mouse. Further studies regarding the role of MS BK channels, including SAKCA, in the modulation of heart rate and contractility are expected.
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Affiliation(s)
- Ken Takahashi
- Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
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30
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Benamer N, Vasquez C, Mahoney VM, Steinhardt MJ, Coetzee WA, Morley GE. Fibroblast KATP currents modulate myocyte electrophysiology in infarcted hearts. Am J Physiol Heart Circ Physiol 2013; 304:H1231-9. [PMID: 23436329 DOI: 10.1152/ajpheart.00878.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac metabolism remains altered for an extended period of time after myocardial infarction. Studies have shown fibroblasts from normal hearts express KATP channels in culture. It is unknown whether fibroblasts from infarcted hearts express KATP channels and whether these channels contribute to scar and border zone electrophysiology. KATP channel subunit expression levels were determined in fibroblasts isolated from normal hearts (Fb), and scar (sMI-Fb) and remote (rMI-Fb) regions of left anterior descending coronary artery (LAD) ligated rat hearts. Whole cell KATP current density was determined with patch clamp. Action potential duration (APD) was measured with optical mapping in myocyte-only cultures and heterocellular cultures with fibroblasts with and without 100 μmol/l pinacidil. Whole heart optical mapping was used to assess KATP channel activity following LAD ligation. Pinacidil activated a potassium current (35.4 ± 7.5 pA/pF at 50 mV) in sMI-Fb that was inhibited with 10 μmol/l glibenclamide. Kir6.2 and SUR2 transcript levels were elevated in sMI-Fb. Treatment with Kir6.2 short interfering RNA decreased KATP currents (87%) in sMI-Fb. Treatment with pinacidil decreased APD (26%) in co-cultures with sMI-Fb. APD values were prolonged in LAD ligated hearts after perfusion with glibenclamide. KATP channels are present in fibroblasts from the scar and border zones of infarcted hearts. Activation of fibroblast KATP channels could modulate the electrophysiological substrate beyond the acute ischemic event. Targeting fibroblast KATP channels could represent a novel therapeutic approach to modify border zone electrophysiology after cardiac injury.
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Affiliation(s)
- Najate Benamer
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016, USA
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31
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Heijman J, Voigt N, Nattel S, Dobrev D. Calcium handling and atrial fibrillation. Wien Med Wochenschr 2013; 162:287-91. [PMID: 22695810 DOI: 10.1007/s10354-012-0109-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in the clinical setting. It is associated with substantial cardiovascular morbidity and mortality. Recent research has indicated that abnormal Ca(2+) handling plays a critical role in the induction and maintenance of AF, contributing to ectopic activity, AF-maintaining reentry circuits and related prothrombotic atrial hypocontractility. The AF-specific Ca(2+)-handling abnormalities may constitute viable therapeutic approaches to treat AF. Here, we review the causes, consequences, and therapeutic implications of altered atrial Ca(2+) handling for AF pathophysiology.
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Affiliation(s)
- Jordi Heijman
- Division of Experimental Cardiology, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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Heijman J, Voigt N, Dobrev D. New directions in antiarrhythmic drug therapy for atrial fibrillation. Future Cardiol 2013; 9:71-88. [DOI: 10.2217/fca.12.78] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and has a significant impact on morbidity and mortality. Current antiarrhythmic drugs for AF suffer from limited safety and efficacy, probably because they were not designed based on specific pathological mechanisms. Recent research has provided important insights into the mechanisms contributing to AF and highlighted several potential novel antiarrhythmic strategies. In this review, we highlight the main pathological mechanisms of AF, discuss traditional and novel aspects of atrial antiarrhythmic drugs in relation to these pathological mechanisms, and present potential novel therapeutic approaches including structure-based modulation of atrial-specific cardiac ion channels, restoring abnormal Ca2+ handling in AF and targeting atrial remodeling.
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Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
- Division of Experimental Cardiology, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Dobromir Dobrev
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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33
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The clinical significance of the atrial subendocardial smooth muscle layer and cardiac myofibroblasts in human atrial tissue with valvular atrial fibrillation. Cardiovasc Pathol 2013; 22:58-64. [DOI: 10.1016/j.carpath.2012.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 04/14/2012] [Accepted: 05/03/2012] [Indexed: 11/18/2022] Open
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Wrzosek A, Tomaskova Z, Ondrias K, Łukasiak A, Szewczyk A. The potassium channel opener CGS7184 activates Ca2+ release from the endoplasmic reticulum. Eur J Pharmacol 2012; 690:60-7. [DOI: 10.1016/j.ejphar.2012.06.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Revised: 06/13/2012] [Accepted: 06/21/2012] [Indexed: 12/20/2022]
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Rosker C, Salvarani N, Schmutz S, Grand T, Rohr S. Abolishing myofibroblast arrhythmogeneicity by pharmacological ablation of α-smooth muscle actin containing stress fibers. Circ Res 2011; 109:1120-31. [PMID: 21921266 DOI: 10.1161/circresaha.111.244798] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Myofibroblasts typically appear in the myocardium after insults to the heart like mechanical overload and infarction. Apart from contributing to fibrotic remodeling, myofibroblasts induce arrhythmogenic slow conduction and ectopic activity in cardiomyocytes after establishment of heterocellular electrotonic coupling in vitro. So far, it is not known whether α-smooth muscle actin (α-SMA) containing stress fibers, the cytoskeletal components that set myofibroblasts apart from resident fibroblasts, are essential for myofibroblasts to develop arrhythmogenic interactions with cardiomyocytes. OBJECTIVE We investigated whether pharmacological ablation of α-SMA containing stress fibers by actin-targeting drugs affects arrhythmogenic myofibroblast-cardiomyocyte cross-talk. METHODS AND RESULTS Experiments were performed with patterned growth cell cultures of neonatal rat ventricular cardiomyocytes coated with cardiac myofibroblasts. The preparations exhibited slow conduction and ectopic activity under control conditions. Exposure to actin-targeting drugs (Cytochalasin D, Latrunculin B, Jasplakinolide) for 24 hours led to disruption of α-SMA containing stress fibers. In parallel, conduction velocities increased dose-dependently to values indistinguishable from cardiomyocyte-only preparations and ectopic activity measured continuously over 24 hours was completely suppressed. Mechanistically, antiarrhythmic effects were due to myofibroblast hyperpolarization (Cytochalasin D, Latrunculin B) and disruption of heterocellular gap junctional coupling (Jasplakinolide), which caused normalization of membrane polarization of adjacent cardiomyocytes. CONCLUSIONS The results suggest that α-SMA containing stress fibers importantly contribute to myofibroblast arrhythmogeneicity. After ablation of this cytoskeletal component, cells lose their arrhythmic effects on cardiomyocytes, even if heterocellular electrotonic coupling is sustained. The findings identify α-SMA containing stress fibers as a potential future target of antiarrhythmic therapy in hearts undergoing structural remodeling.
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Affiliation(s)
- Christian Rosker
- Dept. of Physiology, University of Bern, Bühlplatz 5, CH-3012 Bern, Switzerland
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36
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Abstract
The cytoarchitecture of the working myocardium is characterized by densely packed cardiomyocytes that are embedded in a three-dimensional network of numerous fibroblasts. Although the importance of cardiac fibroblasts in maintaining an orderly structured extracellular matrix is well recognized, less is known about their potential paracrine and electrotonic interactions with cardiomyocytes. This is partly the result of the complex intermingling of both cell types in vivo that tends to preclude a direct investigation of heterocellular crosstalk. It is for that reason that most of our present knowledge regarding stromal-parenchymal cell interactions is based on culture systems that permit direct access to either cell type. An often disregarded feature of such studies is that cardiac fibroblasts in standard two-dimensional cell culture have a pronounced tendency to undergo a phenotype switch to myofibroblasts. This cell type typically appears in injured hearts where it contributes importantly to fibrotic remodeling. The present review focuses on recent insights into electrical and paracrine crosstalk between myofibroblasts and cardiomyocytes while acknowledging that a comprehensive understanding of stromal-parenchymal cell interactions will depend on future methodological developments that permit retaining the fibroblast phenotype in cell culture systems and that will, most importantly, allow direct investigations of heterocellular crosstalk in intact tissue.
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The cardiac fibroblast: functional and electrophysiological considerations in healthy and diseased hearts. J Cardiovasc Pharmacol 2011; 57:380-8. [PMID: 21242811 DOI: 10.1097/fjc.0b013e31820cda19] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cardiac fibrosis occurs in a number of cardiovascular diseases associated with a high incidence of arrhythmias. A critical event in the development of fibrosis is the transformation of fibroblasts into an active phenotype or myofibroblast. This transformation results in functional changes including increased proliferation and changes in the release of signaling molecules and extracellular matrix deposition. Traditionally, fibroblasts have been considered to affect cardiac electrophysiology indirectly by physically isolating myocytes and creating conduction barriers. There is now increasing evidence that cardiac fibroblasts may play a direct role in modulating the electrophysiological substrate in diseased hearts. The purpose of this review is to summarize the functional changes associated with fibroblast activation, the membrane currents that have been identified in adult cardiac fibroblasts, and describe recent studies of fibroblast-myocyte electrical interactions with emphasis on the changes that occur with cardiac injury. Further analysis of fibroblast membrane electrophysiology and their interactions with myocytes will lead to a more complete understanding of the arrhythmic substrate. These studies have the potential to generate new therapeutic approaches for the prevention of arrhythmias associated with cardiac fibrosis.
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Yue L, Xie J, Nattel S. Molecular determinants of cardiac fibroblast electrical function and therapeutic implications for atrial fibrillation. Cardiovasc Res 2010; 89:744-53. [PMID: 20962103 DOI: 10.1093/cvr/cvq329] [Citation(s) in RCA: 273] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cardiac fibroblasts account for about 75% of all cardiac cells, but because of their small size contribute only ∼10-15% of total cardiac cell volume. They play a crucial role in cardiac pathophysiology. For a long time, it has been recognized that fibroblasts and related cell types are the principal sources of extracellular matrix (ECM) proteins, which organize cardiac cellular architecture. In disease states, fibroblast production of increased quantities of ECM proteins leads to tissue fibrosis, which can impair both mechanical and electrical function of the heart, contributing to heart failure and arrhythmogenesis. Atrial fibrosis is known to play a particularly important role in atrial fibrillation (AF). This review article focuses on recent advances in understanding the molecular electrophysiology of cardiac fibroblasts. Cardiac fibroblasts express a variety of ion channels, in particular voltage-gated K(+) channels and non-selective cation channels of the transient receptor potential (TRP) family. Both K(+) and TRP channels are important determinants of fibroblast function, with TRP channels acting as Ca(2+)-entry pathways that stimulate fibroblast differentiation into secretory myofibroblast phenotypes producing ECM proteins. Fibroblasts can couple to cardiomyocytes and substantially affect their cellular electrical properties, including conduction, resting potential, repolarization, and excitability. Co-cultured preparations of cardiomyocytes and fibroblasts generate arrhythmias by a variety of mechanisms, including spontaneous impulse formation and rotor-driven reentry. In addition, the excess ECM proteins produced by fibroblasts can interrupt cardiomyocyte-bundle continuity, leading to local conduction disturbances and reentrant arrhythmias. A better understanding of the electrical properties of fibroblasts should lead to an improved comprehension of AF pathophysiology and a variety of novel targets for antiarrhythmic intervention.
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Affiliation(s)
- Lixia Yue
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
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An investigation of the occurrence and properties of the mitochondrial intermediate-conductance Ca2+-activated K+ channel mtKCa3.1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1797:1260-7. [PMID: 20036632 DOI: 10.1016/j.bbabio.2009.12.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 12/15/2009] [Accepted: 12/19/2009] [Indexed: 12/24/2022]
Abstract
The mitochondrial intermediate-conductance Ca2+-activated K+ channel mtKCa3.1 has recently been discovered in the HCT116 colon tumor-derived cell line, which expresses relatively high levels of this protein also in the plasma membrane. Electrophysiological recordings revealed that the channel can exhibit different conductance states and kinetic modes, which we tentatively ascribe to post-translational modifications. To verify whether the localization of this channel in mitochondria might be a peculiarity of these cells or a more widespread feature we have checked for the presence of mtKCa3.1 in a few other cell lines using biochemical and electrophysiological approaches. It turned out to be present at least in some of the cells investigated. Functional assays explored the possibility that mtKCa3.1 might be involved in cell proliferation or play a role similar to that of the Shaker-type KV1.3 channel in lymphocytes, which interacts with outer mitochondrial membrane-inserted Bax thereby promoting apoptosis (Szabò, I. et al., Proc. Natl. Acad Sci. USA 105 (2008) 14861-14866). A specific KCa3.1 inhibitor however did not have any detectable effect on cell proliferation or death.
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Li GR, Sun HY, Chen JB, Zhou Y, Tse HF, Lau CP. Characterization of multiple ion channels in cultured human cardiac fibroblasts. PLoS One 2009; 4:e7307. [PMID: 19806193 PMCID: PMC2751830 DOI: 10.1371/journal.pone.0007307] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 09/14/2009] [Indexed: 01/11/2023] Open
Abstract
Background Although fibroblast-to-myocyte electrical coupling is experimentally suggested, electrophysiology of cardiac fibroblasts is not as well established as contractile cardiac myocytes. The present study was therefore designed to characterize ion channels in cultured human cardiac fibroblasts. Methods and Findings A whole-cell patch voltage clamp technique and RT-PCR were employed to determine ion channels expression and their molecular identities. We found that multiple ion channels were heterogeneously expressed in human cardiac fibroblasts. These include a big conductance Ca2+-activated K+ current (BKCa) in most (88%) human cardiac fibroblasts, a delayed rectifier K+ current (IKDR) and a transient outward K+ current (Ito) in a small population (15 and 14%, respectively) of cells, an inwardly-rectifying K+ current (IKir) in 24% of cells, and a chloride current (ICl) in 7% of cells under isotonic conditions. In addition, two types of voltage-gated Na+ currents (INa) with distinct properties were present in most (61%) human cardiac fibroblasts. One was a slowly inactivated current with a persistent component, sensitive to tetrodotoxin (TTX) inhibition (INa.TTX, IC50 = 7.8 nM), the other was a rapidly inactivated current, relatively resistant to TTX (INa.TTXR, IC50 = 1.8 µM). RT-PCR revealed the molecular identities (mRNAs) of these ion channels in human cardiac fibroblasts, including KCa.1.1 (responsible for BKCa), Kv1.5, Kv1.6 (responsible for IKDR), Kv4.2, Kv4.3 (responsible for Ito), Kir2.1, Kir2.3 (for IKir), Clnc3 (for ICl), NaV1.2, NaV1.3, NaV1.6, NaV1.7 (for INa.TTX), and NaV1.5 (for INa.TTXR). Conclusions These results provide the first information that multiple ion channels are present in cultured human cardiac fibroblasts, and suggest the potential contribution of these ion channels to fibroblast-myocytes electrical coupling.
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Affiliation(s)
- Gui-Rong Li
- Department of Medicine and Research Centre of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China.
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See VY, Roberts-Thomson KC, Stevenson WG, Camp PC, Koplan BA. Atrial Arrhythmias After Lung Transplantation. Circ Arrhythm Electrophysiol 2009; 2:504-10. [DOI: 10.1161/circep.109.867978] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Vincent Y. See
- From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine (V.Y.S., K.C.R.-T., W.G.S., B.A.K.), and the Division of Thoracic Surgery, Department of Surgery (P.C.C.), Brigham and Women’s Hospital, Boston, Mass
| | - Kurt C. Roberts-Thomson
- From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine (V.Y.S., K.C.R.-T., W.G.S., B.A.K.), and the Division of Thoracic Surgery, Department of Surgery (P.C.C.), Brigham and Women’s Hospital, Boston, Mass
| | - William G. Stevenson
- From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine (V.Y.S., K.C.R.-T., W.G.S., B.A.K.), and the Division of Thoracic Surgery, Department of Surgery (P.C.C.), Brigham and Women’s Hospital, Boston, Mass
| | - Phillip C. Camp
- From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine (V.Y.S., K.C.R.-T., W.G.S., B.A.K.), and the Division of Thoracic Surgery, Department of Surgery (P.C.C.), Brigham and Women’s Hospital, Boston, Mass
| | - Bruce A. Koplan
- From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine (V.Y.S., K.C.R.-T., W.G.S., B.A.K.), and the Division of Thoracic Surgery, Department of Surgery (P.C.C.), Brigham and Women’s Hospital, Boston, Mass
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Benamer N, Moha Ou Maati H, Demolombe S, Cantereau A, Delwail A, Bois P, Bescond J, Faivre JF. Molecular and functional characterization of a new potassium conductance in mouse ventricular fibroblasts. J Mol Cell Cardiol 2009; 46:508-17. [PMID: 19166858 DOI: 10.1016/j.yjmcc.2008.12.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 12/04/2008] [Accepted: 12/21/2008] [Indexed: 01/08/2023]
Abstract
The present work is aimed at identifying and characterizing, at a molecular and functional level, new ionic conductances potentially involved in the excitation-secretion coupling and proliferation of cardiac ventricular fibroblasts. Among potassium channel transcripts which were screened by high-throughput real-time PCR, SUR2 and Kir6.1 mRNAs were found to be the most abundant in ventricular fibroblasts. The corresponding proteins were not detected by western blot following 5 days of cell culture, but had appeared at 7 days, increasing with extended cell culture duration as the fibroblasts differentiated into myofibroblasts. Using the inside-out configuration of the patch-clamp technique, single potassium channels could be recorded. These had properties similar to those reported for SUR2/Kir6.1 channels, i.e. activation by pinacidil, inhibition by glibenclamide and activation by intracellular UDP. As already reported for this molecular signature, they were insensitive to intracellular ATP. In the whole-cell configuration, these channels have been shown to be responsible for a glibenclamide-sensitive macroscopic potassium current which can be activated not only by pinacidil, but also by nanomolar concentrations of the sphingolipid sphingosine-1-phosphate (S1P). The activation of this current resulted in an increase in cell proliferation and a decrease in IL-6 secretion, suggesting it has a functional role in situations where S1P increases. Overall, this work demonstrates for the first time that SUR2/Kir6.1 channels represent a significant potassium conductance in ventricular fibroblasts which may be activated in physio-pathological conditions and which may impact on fibroblast proliferation and function.
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Affiliation(s)
- Najate Benamer
- Institut de Physiologie et Biologie Cellulaires, CNRS UMR 6187, Université de Poitiers, France
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Nouchi H, Takahara A, Nakamura H, Namekata I, Sugimoto T, Tsuneoka Y, Takeda K, Tanaka T, Shigenobu K, Sugiyama A, Tanaka H. Chronic left atrial volume overload abbreviates the action potential duration of the canine pulmonary vein myocardium via activation of IK channel. Eur J Pharmacol 2008; 597:81-5. [DOI: 10.1016/j.ejphar.2008.09.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 08/21/2008] [Accepted: 09/01/2008] [Indexed: 11/29/2022]
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Wang YJ, Chen BS, Lin MW, Lin AA, Peng H, Sung RJ, Wu SN. Time-Dependent Block of Ultrarapid-Delayed Rectifier K+ Currents by Aconitine, a Potent Cardiotoxin, in Heart-Derived H9c2 Myoblasts and in Neonatal Rat Ventricular Myocytes. Toxicol Sci 2008; 106:454-63. [DOI: 10.1093/toxsci/kfn189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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