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Gelman I, Sharma N, Mckeeman O, Lee P, Campagna N, Tomei N, Baranchuk A, Zhang S, El-Diasty M. The ion channel basis of pharmacological effects of amiodarone on myocardial electrophysiological properties, a comprehensive review. Biomed Pharmacother 2024; 174:116513. [PMID: 38565056 DOI: 10.1016/j.biopha.2024.116513] [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: 01/30/2024] [Accepted: 03/28/2024] [Indexed: 04/04/2024] Open
Abstract
Amiodarone is a benzofuran-based class III antiarrhythmic agent frequently used for the treatment of atrial and ventricular arrhythmias. The primary target of class III antiarrhythmic drugs is the cardiac human ether-a-go-go-related gene (hERG) encoded channel, KCNH2, commonly known as HERG, that conducts the rapidly activating delayed rectifier potassium current (IKr). Like other class III antiarrhythmic drugs, amiodarone exerts its physiologic effects mainly through IKr blockade, delaying the repolarization phase of the action potential and extending the effective refractory period. However, while many class III antiarrhythmics, including sotalol and dofetilide, can cause long QT syndrome (LQTS) that can progress to torsade de pointes, amiodarone displays less risk of inducing this fatal arrhythmia. This review article discusses the arrhythmogenesis in LQTS from the aspects of the development of early afterdepolarizations (EADs) associated with Ca2+ current, transmural dispersion of repolarization (TDR), as well as reverse use dependence associated with class III antiarrhythmic drugs to highlight electropharmacological effects of amiodarone on the myocardium.
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Affiliation(s)
- Illia Gelman
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada
| | - Neelakshi Sharma
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada
| | - Olivia Mckeeman
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada
| | - Peter Lee
- Division of Cardiology, Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Noah Campagna
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada
| | - Nicole Tomei
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada
| | - Adrian Baranchuk
- Division of Cardiology, Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Shetuan Zhang
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada.
| | - Mohammad El-Diasty
- Department of Biomedical and Molecular Sciences, Queens's University, Kingston, ON, Canada; Harrington Heart and Vascular Institute, Department of Cardiac Surgery, University Hospitals Cleveland Medical Center, Cleveland, Ohio 44106, United States.
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2
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Gray RA, Franz MR. Amiodarone prevents wave front-tail interactions in patients with heart failure: an in silico study. Am J Physiol Heart Circ Physiol 2023; 325:H952-H964. [PMID: 37656133 PMCID: PMC10907032 DOI: 10.1152/ajpheart.00227.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/25/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023]
Abstract
Amiodarone (AM) is an antiarrhythmic drug whose chronic use has proved effective in preventing ventricular arrhythmias in a variety of patient populations, including those with heart failure (HF). AM has both class III [i.e., it prolongs the action potential duration (APD) via blocking potassium channels) and class I (i.e., it affects the rapid sodium channel) properties; however, the specific mechanism(s) by which it prevents reentry formation in patients with HF remains unknown. We tested the hypothesis that AM prevents reentry induction in HF during programmed electrical stimulation (PES) via its ability to induce postrepolarization refractoriness (PRR) via its class I effects on sodium channels. Here we extend our previous human action potential model to represent the effects of both HF and AM separately by calibrating to human tissue and clinical PES data, respectively. We then combine these models (HF + AM) to test our hypothesis. Results from simulations in cells and cables suggest that AM acts to increase PRR and decrease the elevation of takeoff potential. The ability of AM to prevent reentry was studied in silico in two-dimensional sheets in which a variety of APD gradients (ΔAPD) were imposed. Reentrant activity was induced in all HF simulations but was prevented in 23 of 24 HF + AM models. Eliminating the AM-induced slowing of the recovery of inactivation of the sodium channel restored the ability to induce reentry. In conclusion, in silico testing suggests that chronic AM treatment prevents reentry induction in patients with HF during PES via its class I effect to induce PRR.NEW & NOTEWORTHY This work presents a new model of the action potential of the human, which reproduces the complex dynamics during premature stimulation in heart failure patients with and without amiodarone. A specific mechanism of the ability of amiodarone to prevent reentrant arrhythmias is presented.
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Affiliation(s)
- Richard A Gray
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland, United States
| | - Michael R Franz
- Cardiology Division, Veteran Affairs Medical Center, Washington, District of Columbia, United States
- Department of Pharmacology, Georgetown University Medical Center, Washington, District of Columbia, United States
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3
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Bonkowski TJ, Madison CM, Dandamudi S, McNamara DA. A Treacherous Twist on ECG. Am J Med 2022; 135:331-333. [PMID: 34715063 DOI: 10.1016/j.amjmed.2021.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/06/2021] [Accepted: 10/06/2021] [Indexed: 11/17/2022]
Affiliation(s)
- Tyler J Bonkowski
- Internal Medicine, Spectrum Health/Michigan State University College of Human Medicine, Grand Rapids
| | - Christopher M Madison
- Division of Medicine, Michigan State University College of Human Medicine, Grand Rapids; Frederik Meijer Heart & Vascular Institute, Spectrum Health, Grand Rapids
| | - Sanjay Dandamudi
- Division of Medicine, Michigan State University College of Human Medicine, Grand Rapids; Frederik Meijer Heart & Vascular Institute, Spectrum Health, Grand Rapids
| | - David A McNamara
- Division of Medicine, Michigan State University College of Human Medicine, Grand Rapids; Frederik Meijer Heart & Vascular Institute, Spectrum Health, Grand Rapids.
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4
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Wang L, Wada Y, Ballan N, Schmeckpeper J, Huang J, Rau CD, Wang Y, Gepstein L, Knollmann BC. Triiodothyronine and dexamethasone alter potassium channel expression and promote electrophysiological maturation of human-induced pluripotent stem cell-derived cardiomyocytes. J Mol Cell Cardiol 2021; 161:130-138. [PMID: 34400182 PMCID: PMC9809541 DOI: 10.1016/j.yjmcc.2021.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as a promising tool for disease modeling and drug development. However, hiPSC-CMs remain functionally immature, which hinders their utility as a model of human cardiomyocytes. OBJECTIVE To improve the electrophysiological maturation of hiPSC-CMs. METHODS AND RESULTS On day 16 of cardiac differentiation, hiPSC-CMs were treated with 100 nmol/L triiodothyronine (T3) and 1 μmol/L Dexamethasone (Dex) or vehicle for 14 days. On day 30, vehicle- and T3 + Dex-treated hiPSC-CMs were dissociated and replated either as cell sheets or single cells. Optical mapping and patch-clamp technique were used to examine the electrophysiological properties of vehicle- and T3 + Dex-treated hiPSC-CMs. Compared to vehicle, T3 + Dex-treated hiPSC-CMs had a slower spontaneous beating rate, more hyperpolarized resting membrane potential, faster maximal upstroke velocity, and shorter action potential duration. Changes in spontaneous activity and action potential were mediated by decreased hyperpolarization-activated current (If) and increased inward rectifier potassium currents (IK1), sodium currents (INa), and the rapidly and slowly activating delayed rectifier potassium currents (IKr and IKs, respectively). Furthermore, T3 + Dex-treated hiPSC-CM cell sheets (hiPSC-CCSs) exhibited a faster conduction velocity and shorter action potential duration than the vehicle. Inhibition of IK1 by 100 μM BaCl2 significantly slowed conduction velocity and prolonged action potential duration in T3 + Dex-treated hiPSC-CCSs but had no effect in the vehicle group, demonstrating the importance of IK1 for conduction velocity and action potential duration. CONCLUSION T3 + Dex treatment is an effective approach to rapidly enhance electrophysiological maturation of hiPSC-CMs.
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Affiliation(s)
- Lili Wang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232, USA,Correspondence to: Lili Wang, Ph.D., Division of Clinical Pharmacology, Vanderbilt University Medical Center, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232-0575 Or Bjorn C. Knollmann, MD, Ph.D., Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Vanderbilt, University Medical Center, Medical Research Building IV, Rm. 1265, 2215B Garland Ave, Nashville, TN 37232-0575,
| | - Yuko Wada
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232, USA
| | - Nimer Ballan
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, POB 9649, Haifa 3109601, Israel
| | - Jeffrey Schmeckpeper
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232, USA
| | - Jijun Huang
- Department of Anesthesiology, Medicine and Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Christoph Daniel Rau
- Department of Anesthesiology, Medicine and Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Yibin Wang
- Department of Anesthesiology, Medicine and Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Lior Gepstein
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, POB 9649, Haifa 3109601, Israel,Cardiology Department, Rambam Health Care Campus, Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, 2 Efron St. POB 9649, Haifa, 3109601, Israel
| | - Bjorn C. Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232, USA,Correspondence to: Lili Wang, Ph.D., Division of Clinical Pharmacology, Vanderbilt University Medical Center, Medical Research Building IV, Rm.1275, 2215B Garland Ave, Nashville, TN 37232-0575 Or Bjorn C. Knollmann, MD, Ph.D., Vanderbilt Center for Arrhythmia Research and Therapeutics (VanCART), Vanderbilt, University Medical Center, Medical Research Building IV, Rm. 1265, 2215B Garland Ave, Nashville, TN 37232-0575,
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5
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Premont A, Balthes S, Marr CM, Jeevaratnam K. Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation. Equine Vet J 2021; 54:262-282. [PMID: 34564902 DOI: 10.1111/evj.13518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/26/2022]
Abstract
Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.
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Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Samantha Balthes
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Celia M Marr
- Rossdales Equine Hospital and Diagnostic Centre, Newmarket, UK
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6
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Maturation strategies and limitations of induced pluripotent stem cell-derived cardiomyocytes. Biosci Rep 2021; 41:226678. [PMID: 33057659 PMCID: PMC8209171 DOI: 10.1042/bsr20200833] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 10/06/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) have the ability to differentiate into cardiomyocytes (CMs). They are not only widely used in cardiac pharmacology screening, human heart disease modeling, and cell transplantation-based treatments, but also the most promising source of CMs for experimental and clinical applications. However, their use is largely restricted by the immature phenotype of structure and function, which is similar to embryonic or fetal CMs and has certain differences from adult CMs. In order to overcome this critical issue, many studies have explored and revealed new strategies to induce the maturity of iPSC-CMs. Therefore, this article aims to review recent induction methods of mature iPSC-CMs, related mechanisms, and limitations.
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7
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Niimi N, Yuki K, Zaleski K. Long QT Syndrome and Perioperative Torsades de Pointes: What the Anesthesiologist Should Know. J Cardiothorac Vasc Anesth 2020; 36:286-302. [PMID: 33495078 DOI: 10.1053/j.jvca.2020.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 11/16/2020] [Accepted: 12/07/2020] [Indexed: 02/08/2023]
Affiliation(s)
- Naoko Niimi
- Department of Anesthesiology, Juntendo University, Tokyo, Japan.
| | - Koichi Yuki
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital, Boston, MA; Department of Anesthesia, Harvard Medical School, Boston, MA
| | - Katherine Zaleski
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital, Boston, MA; Department of Anesthesia, Harvard Medical School, Boston, MA
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8
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Oliván-Viguera A, Pérez-Zabalza M, García-Mendívil L, Mountris KA, Orós-Rodrigo S, Ramos-Marquès E, Vallejo-Gil JM, Fresneda-Roldán PC, Fañanás-Mastral J, Vázquez-Sancho M, Matamala-Adell M, Sorribas-Berjón F, Bellido-Morales JA, Mancebón-Sierra FJ, Vaca-Núñez AS, Ballester-Cuenca C, Marigil MÁ, Pastor C, Ordovás L, Köhler R, Diez E, Pueyo E. Minimally invasive system to reliably characterize ventricular electrophysiology from living donors. Sci Rep 2020; 10:19941. [PMID: 33203905 PMCID: PMC7673124 DOI: 10.1038/s41598-020-77076-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 11/03/2020] [Indexed: 01/03/2023] Open
Abstract
Cardiac tissue slices preserve the heterogeneous structure and multicellularity of the myocardium and allow its functional characterization. However, access to human ventricular samples is scarce. We aim to demonstrate that slices from small transmural core biopsies collected from living donors during routine cardiac surgery preserve structural and functional properties of larger myocardial specimens, allowing accurate electrophysiological characterization. In pigs, we compared left ventricular transmural core biopsies with transmural tissue blocks from the same ventricular region. In humans, we analyzed transmural biopsies and papillary muscles from living donors. All tissues were vibratome-sliced. By histological analysis of the transmural biopsies, we showed that tissue architecture and cellular organization were preserved. Enzymatic and vital staining methods verified viability. Optically mapped transmembrane potentials confirmed that action potential duration and morphology were similar in pig biopsies and tissue blocks. Action potential morphology and duration in human biopsies and papillary muscles agreed with published ranges. In both pigs and humans, responses to increasing pacing frequencies and β-adrenergic stimulation were similar in transmural biopsies and larger tissues. We show that it is possible to successfully collect and characterize tissue slices from human myocardial biopsies routinely extracted from living donors, whose behavior mimics that of larger myocardial preparations both structurally and electrophysiologically.
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Affiliation(s)
- Aida Oliván-Viguera
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain.
| | - María Pérez-Zabalza
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain
| | - Laura García-Mendívil
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain
| | - Konstantinos A Mountris
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain
| | - Sofía Orós-Rodrigo
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain
| | - Estel Ramos-Marquès
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain
| | - José María Vallejo-Gil
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, Zaragoza, Spain
| | | | - Javier Fañanás-Mastral
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, Zaragoza, Spain
| | - Manuel Vázquez-Sancho
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, Zaragoza, Spain
| | - Marta Matamala-Adell
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, Zaragoza, Spain
| | | | | | | | | | | | | | | | - Laura Ordovás
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain.,Aragón Agency for Research and Development (ARAID), Zaragoza, Spain
| | - Ralf Köhler
- Aragón Institute of Health Sciences (IACS), Zaragoza, Spain.,Aragón Agency for Research and Development (ARAID), Zaragoza, Spain
| | - Emiliano Diez
- Institute of Experimental Medicine and Biology of Cuyo (IMBECU), CONICET, Mendoza, Argentina
| | - Esther Pueyo
- Biomedical Signal Interpretation and Computational Simulation (BSICoS) Group, Aragón, Institute of Engineering Research (I3A) and Instituto de Investigación Sanitaria (IIS) Aragón, University of Zaragoza, Edificio I+D+i, C/Mariano Esquillor s/n, 50018, Zaragoza, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
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9
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Fukushima H, Yoshioka M, Kawatou M, López-Dávila V, Takeda M, Kanda Y, Sekino Y, Yoshida Y, Yamashita JK. Specific induction and long-term maintenance of high purity ventricular cardiomyocytes from human induced pluripotent stem cells. PLoS One 2020; 15:e0241287. [PMID: 33137106 PMCID: PMC7605685 DOI: 10.1371/journal.pone.0241287] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 10/13/2020] [Indexed: 12/28/2022] Open
Abstract
Currently, cardiomyocyte (CM) differentiation methods require a purification step after CM induction to ensure the high purity of the cell population. Here we show an improved human CM differentiation protocol with which high-purity ventricular-type CMs can be obtained and maintained without any CM purification process. We induced and collected a mesodermal cell population (platelet-derived growth factor receptor-α (PDGFRα)-positive cells) that can respond to CM differentiation cues, and then stimulated CM differentiation by means of Wnt inhibition. This method reproducibly generated CMs with purities above 95% in several human pluripotent stem cell lines. Furthermore, these CM populations were maintained in culture at such high purity without any further CM purification step for over 200 days. The majority of these CMs (>95%) exhibited a ventricular-like phenotype with a tendency to structural and electrophysiological maturation, including T-tubule-like structure formation and the ability to respond to QT prolongation drugs. This is a simple and valuable method to stably generate CM populations suitable for cardiac toxicology testing, disease modeling and regenerative medicine.
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Affiliation(s)
- Hiroyuki Fukushima
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Miki Yoshioka
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Masahide Kawatou
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- Department of Cardiovascular Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
- Institute for Advancement of Clinical and Translational Science (iACT), Kyoto University Hospital, Kyoto, Japan
| | - Víctor López-Dávila
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Masafumi Takeda
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- Institute for Advancement of Clinical and Translational Science (iACT), Kyoto University Hospital, Kyoto, Japan
| | - Yasunari Kanda
- Division of Pharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Yuko Sekino
- Division of Pharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Yoshinori Yoshida
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Jun K. Yamashita
- Department of Cell Growth and Differentiation, Laboratory of Stem Cell Differentiation, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- * E-mail:
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10
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Bazmi M, Escobar AL. Excitation-Contraction Coupling in the Goldfish ( Carassius auratus) Intact Heart. Front Physiol 2020; 11:1103. [PMID: 33041845 PMCID: PMC7518121 DOI: 10.3389/fphys.2020.01103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/10/2020] [Indexed: 12/17/2022] Open
Abstract
Cardiac physiology of fish models is an emerging field given the ease of genome editing and the development of transgenic models. Several studies have described the cardiac properties of zebrafish (Denio rerio). The goldfish (Carassius auratus) belongs to the same family as the zebrafish and has emerged as an alternative model with which to study cardiac function. Here, we propose to acutely study electrophysiological and systolic Ca2+ signaling in intact goldfish hearts. We assessed the Ca2+ dynamics and the electrophysiological cardiac function of goldfish, zebrafish, and mice models, using pulsed local field fluorescence microscopy, intracellular microelectrodes, and flash photolysis in perfused hearts. We observed goldfish ventricular action potentials (APs) and Ca2+ transients to be significantly longer when compared to the zebrafish. The action potential half duration at 50% (APD50) of goldfish was 370.38 ± 8.8 ms long, and in the zebrafish they were observed to be only 83.9 ± 9.4 ms. Additionally, the half duration of the Ca2+ transients was also longer for goldfish (402.1 ± 4.4 ms) compared to the zebrafish (99.1 ± 2.7 ms). Also, blocking of the L-type Ca2+ channels with nifedipine revealed this current has a major role in defining the amplitude and the duration of goldfish Ca2+ transients. Interestingly, nifedipine flash photolysis experiments in the intact heart identified whether or not the decrease in the amplitude of Ca2+ transients was due to shorter APs. Moreover, an increase in temperature and heart rate had a strong shortening effect on the AP and Ca2+ transients of goldfish hearts. Furthermore, ryanodine (Ry) and thapsigargin (Tg) significantly reduced the amplitude of the Ca2+ transients, induced a prolongation in the APs, and altogether exhibited the degree to which the Ca2+ release from the sarcoplasmic reticulum contributed to the Ca2+ transients. We conclude that the electrophysiological properties and Ca2+ signaling in intact goldfish hearts strongly resembles the endocardial layer of larger mammals.
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Affiliation(s)
- Maedeh Bazmi
- Quantitative Systems Biology Program, School of Natural Sciences, University of California, Merced, Merced, CA, United States
| | - Ariel L Escobar
- Department of Bioengineering, School of Engineering, University of California, Merced, Merced, CA, United States
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11
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Simulating Notch-Dome Morphology of Action Potential of Ventricular Cell: How the Speeds of Positive and Negative Feedbacks on Transmembrane Voltage Can Influence the Health of a Cell? BIOMED RESEARCH INTERNATIONAL 2020; 2020:5169241. [PMID: 32953882 PMCID: PMC7487097 DOI: 10.1155/2020/5169241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/23/2020] [Accepted: 07/18/2020] [Indexed: 11/24/2022]
Abstract
Ventricular action potential is well-known because of its plateau phase with a spike-notch-dome morphology. As such, the morphology of action potential is necessary for ensuring a correct heart functioning. Any distraction from normal notch-dome morphology may trigger a circus movement reentry in the form of lethal ventricular fibrillation. When the epicardial action potential dome propagates from a site where it is maintained to regions where it has been lost, it gives rise to the proposed mechanism for the Brugada syndrome. Despite the impact of notch-dome dynamics on the heart function, no independent and explicit research has been performed on the simulation of notch-dome dynamics and morphology. In this paper, using a novel mathematical approach, a three-state variable model is proposed; we show that our proposed model not only can simulate morphology of action potential of ventricular cells but also can propose a biological reasonable tool for controlling of the morphology of action potential spike-notch-dome. We show that the processes of activation and inactivation of ionic gating variables (as positive or negative feedbacks on the voltage of cell membrane) and the ratio of their speeds (time constants) can be treated as a reasonable biological tool for simulating ventricular cell notch-dome. This finding may led to a new insight to the quantification of the health of a ventricular cell and may also propose a new drug therapy strategy for cardiac diseases.
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12
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Árpádffy-Lovas T, Husti Z, Baczkó I, Varró A, Virág L. Different effects of amiodarone and dofetilide on the dispersion of repolarization between well-coupled ventricular and Purkinje fibers 1. Can J Physiol Pharmacol 2020; 99:48-55. [PMID: 32692935 DOI: 10.1139/cjpp-2020-0234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increased transmural dispersion of repolarization is an established contributing factor to ventricular tachyarrhythmias. In this study, we evaluated the effect of chronic amiodarone treatment and acute administration of dofetilide in canine cardiac preparations containing electrotonically coupled Purkinje fibers (PFs) and ventricular muscle (VM) and compared the effects to those in uncoupled PF and VM preparations using the conventional microelectrode technique. Dispersion between PFs and VM was inferred from the difference in the respective action potential durations (APDs). In coupled preparations, amiodarone decreased the difference in APDs between PFs and VM, thus decreasing dispersion. In the same preparations, dofetilide increased the dispersion by causing a more pronounced prolongation in PFs. This prolongation was even more emphasized in uncoupled PF preparations, while the effect in VM was the same. In uncoupled preparations, amiodarone elicited no change on the difference in APDs. In conclusion, amiodarone decreased the dispersion between PFs and VM, while dofetilide increased it. The measured difference in APD between cardiac regions may be the affected by electrotonic coupling; thus, studying PFs and VM separately may lead to an over- or underestimation of dispersion.
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Affiliation(s)
- Tamás Árpádffy-Lovas
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Husti
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary.,MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
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13
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The role of amiodarone in contemporary management of complex cardiac arrhythmias. Pharmacol Res 2020; 151:104521. [PMID: 31756386 DOI: 10.1016/j.phrs.2019.104521] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/25/2019] [Accepted: 10/30/2019] [Indexed: 01/09/2023]
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14
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Chang SL, Chang CT, Hung WT, Chen LK. A case of congenital long QT syndrome, type 8, undergoing laparoscopic hysterectomy with general anesthesia. Taiwan J Obstet Gynecol 2019; 58:552-556. [PMID: 31307750 DOI: 10.1016/j.tjog.2019.05.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2019] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVE Patients with Long QT syndrome (LQTS) P may present with torsades de pointes, ventricular tachycardia (VT), or ventricular fibrillation (VF) and are at risk of sudden cardiac death. MATERIALS AND METHODS A 38 y/o female patient with uterus myoma developed VF during laparoscopic assisted vaginal hysterectomy surgery. Defibrillation was delivered and the electrocardiogram (ECG) returned to sinus rhythm after CPR. RESULTS Patient survived and implantable cardioverter-defibrillator was implanted and received beta-blocker therapy. ECG obtained in out-patient clinic still showed QT interval prolongation, but revealed no prolongation few months after persistent beta-blocker therapy. LQTS type 8 (CACNA1C E768del mutation) was identified by genetic DNA sequencing study. CONCLUSIONS Patients with concealed LQTS may have normal QT interval unless exposing to stress or specific stimuli. Unexpected ventricular arrhythmia may happen during any medical management. We should avoid triggers of QT prolongation, and get familiar with management of the episode.
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Affiliation(s)
- Shih-Lun Chang
- Department of Anesthesiology, Fu Jen Catholic University Hospital, No.69, Guizi Rd., Taishan Dist., New Taipei City 243, Taiwan.
| | - Ching-Tao Chang
- Department of Anesthesiology, National Taiwan University Hospital Hsin-Chu Branch, No.25, Ln. 442, Sec. 1, Jingguo Rd., East Dist., Hsinchu City 300, Taiwan.
| | - Wei-Te Hung
- Department of Anesthesiology, Chung Shan Medical University, Taichung City, Taiwan; Department of Anesthesiology, Chung Shan Medical University Hospital, Taichung City, Taiwan.
| | - Li-Kuei Chen
- Department of Anesthesiology, Chung Shan Medical University, Taichung City, Taiwan; Department of Anesthesiology, Chung Shan Medical University Hospital, Taichung City, Taiwan.
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15
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Brunetti L, Lee SM, Nahass RG, Suh D, Miao B, Bucek J, Kim D, Kim OK, Suh DC. The risk of cardiac events in patients who received concomitant levofloxacin and amiodarone. Int J Infect Dis 2018; 78:50-56. [PMID: 30385404 DOI: 10.1016/j.ijid.2018.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/22/2018] [Accepted: 10/24/2018] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVES Levofloxacin and amiodarone are both known to prolong the QT interval. This study was conducted to estimate the risk of cardiac events in patients receiving concomitant levofloxacin and amiodarone. METHODS The study included patients who were admitted to a large academic community medical center from 1/2012 to 12/2015 and received both levofloxacin and amiodarone at some point during their hospitalization. Patients received concomitant or non-concomitant levofloxacin and amiodarone during hospitalization. The primary outcome was the occurrence of cardiac events during therapy. The secondary outcome was the proportion of patients with an electrocardiogram performed before and after initiation of therapy. Odds ratios for cardiac events were calculated using a multivariable logistic regression model with and without adjusting for the study variables. The concomitant group was further evaluated for predictors of the primary outcome using multivariable logistic regression. RESULTS This study included 240 patients, 164 (68.3%) of whom received concomitant levofloxacin and amiodarone. Concomitant medication therapy was associated with a greater than six-fold increased risk of cardiac events after adjusting for the study variables (Odds Ratio=6.20; 95% Confidence Interval=1.34-28.62). CONCLUSIONS Patients receiving concomitant amiodarone and levofloxacin experienced a five-fold increase in cardiac events compared to patients given either medication alone.
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Affiliation(s)
- Luigi Brunetti
- Rutgers University School of Pharmacy, Piscataway, NJ, USA; RWJ Barnabas Health-Robert Wood Johnson University Hospital Somerset, Somerville, NJ, USA
| | - Seung-Mi Lee
- Rutgers University School of Pharmacy, Piscataway, NJ, USA; Chung-Ang University College of Pharmacy, Seoul, South Korea
| | - Ronald G Nahass
- Rutgers University School of Pharmacy, Piscataway, NJ, USA; RWJ Barnabas Health-Robert Wood Johnson University Hospital Somerset, Somerville, NJ, USA
| | - David Suh
- Columbia University School of Public Health, New York, NY, USA
| | - Benjamin Miao
- Rutgers University School of Pharmacy, Piscataway, NJ, USA
| | - John Bucek
- RWJ Barnabas Health-Robert Wood Johnson University Hospital Somerset, Somerville, NJ, USA
| | - Dongwon Kim
- Chung-Ang University College of Pharmacy, Seoul, South Korea
| | - Ok-Kyu Kim
- Chung-Ang University College of Pharmacy, Seoul, South Korea
| | - Dong-Churl Suh
- Chung-Ang University College of Pharmacy, Seoul, South Korea.
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16
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Carro J, Pueyo E, Rodríguez Matas JF. A response surface optimization approach to adjust ionic current conductances of cardiac electrophysiological models. Application to the study of potassium level changes. PLoS One 2018; 13:e0204411. [PMID: 30281636 PMCID: PMC6169915 DOI: 10.1371/journal.pone.0204411] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 09/07/2018] [Indexed: 01/23/2023] Open
Abstract
Cardiac electrophysiological computational models are often developed from previously published models. The new models may incorporate additional features to adapt the model to a different species or may upgrade a specific ionic formulation based on newly available experimental data. A relevant challenge in the development of a new model is the estimation of certain ionic current conductances that cannot be reliably identified from experiments. A common strategy to estimate those conductances is by means of constrained non-linear least-squares optimization. In this work, a novel methodology is proposed for estimation of ionic current conductances of cardiac electrophysiological models by using a response surface approximation-based constrained optimization with trust region management. Polynomial response surfaces of a number of electrophysiological markers were built using statistical sampling methods. These markers included action potential duration (APD), triangulation, diastolic and systolic intracellular calcium concentration, and time constants of APD rate adaptation. The proposed methodology was applied to update the Carro et al. human ventricular action potential model after incorporation of intracellular potassium ([K+]i) dynamics. While the Carro et al. model was well suited for investigation of arrhythmogenesis, it did not allow simulation of [K+]i changes. With the methodology proposed in this study, the updated Carro et al. human ventricular model could be used to simulate [K+]i changes in response to varying extracellular potassium ([K+]o) levels. Additionally, it rendered values of evaluated electrophysiological markers within physiologically plausible ranges. The optimal values of ionic current conductances in the updated model were found in a notably shorter time than with previously proposed methodologies. As a conclusion, the response surface optimization-based approach proposed in this study allows estimating ionic current conductances of cardiac electrophysiological computational models while guaranteeing replication of key electrophysiological features and with an important reduction in computational cost with respect to previously published approaches. The updated Carro et al. model developed in this study is thus suitable for the investigation of arrhythmic risk-related conditions, including those involving large changes in potassium concentration.
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Affiliation(s)
- Jesús Carro
- Universidad San Jorge, Villanueva de Gállego, Zaragoza, Spain
- Aragón Institute for Engineering Research, University of Zaragoza, IIS Aragón, Spain
- CIBER in Bioengineering, Biomaterials & Nanomedicne (CIBER-BBN), Spain
- * E-mail:
| | - Esther Pueyo
- Aragón Institute for Engineering Research, University of Zaragoza, IIS Aragón, Spain
- CIBER in Bioengineering, Biomaterials & Nanomedicne (CIBER-BBN), Spain
| | - José F. Rodríguez Matas
- Aragón Institute for Engineering Research, University of Zaragoza, IIS Aragón, Spain
- LaBS, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Italy
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17
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Mora MT, Ferrero JM, Gomez JF, Sobie EA, Trenor B. Ca 2+ Cycling Impairment in Heart Failure Is Exacerbated by Fibrosis: Insights Gained From Mechanistic Simulations. Front Physiol 2018; 9:1194. [PMID: 30190684 PMCID: PMC6116328 DOI: 10.3389/fphys.2018.01194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/08/2018] [Indexed: 12/28/2022] Open
Abstract
Heart failure (HF) is characterized by altered Ca2+ cycling, resulting in cardiac contractile dysfunction. Failing myocytes undergo electrophysiological remodeling, which is known to be the main cause of abnormal Ca2+ homeostasis. However, structural remodeling, specifically proliferating fibroblasts coupled to myocytes in the failing heart, could also contribute to Ca2+ cycling impairment. The goal of the present study was to systematically analyze the mechanisms by which myocyte–fibroblast coupling could affect Ca2+ dynamics in normal conditions and in HF. Simulations of healthy and failing human myocytes were performed using established mathematical models, and cells were either isolated or coupled to fibroblasts. Univariate and multivariate sensitivity analyses were performed to quantify effects of ion transport pathways on biomarkers computed from intracellular [Ca2+] waveforms. Variability in ion channels and pumps was imposed and populations of models were analyzed to determine effects on Ca2+ dynamics. Our results suggest that both univariate and multivariate sensitivity analyses are valuable methodologies to shed light into the ionic mechanisms underlying Ca2+ impairment in HF, although differences between the two methodologies are observed at high parameter variability. These can result from either the fact that multivariate analyses take into account ion channels or non-linear effects of ion transport pathways on Ca2+ dynamics. Coupling either healthy or failing myocytes to fibroblasts decreased Ca2+ transients due to an indirect sink effect on action potential (AP) and thus on Ca2+ related currents. Simulations that investigated restoration of normal physiology in failing myocytes showed that Ca2+ cycling can be normalized by increasing SERCA and L-type Ca2+ current activity while decreasing Na+–Ca2+ exchange and SR Ca2+ leak. Changes required to normalize APs in failing myocytes depended on whether myocytes were coupled to fibroblasts. In conclusion, univariate and multivariate sensitivity analyses are helpful tools to understand how Ca2+ cycling is impaired in HF and how this can be exacerbated by coupling of myocytes to fibroblasts. The design of pharmacological actions to restore normal activity should take into account the degree of fibrosis in the failing heart.
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Affiliation(s)
- Maria T Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Juan F Gomez
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Eric A Sobie
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
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18
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Edwards SL, Zlochiver V, Conrad DB, Vaidyanathan R, Valiquette AM, Joshi-Mukherjee R. A Multiwell Cardiac μGMEA Platform for Action Potential Recordings from Human iPSC-Derived Cardiomyocyte Constructs. Stem Cell Reports 2018; 11:522-536. [PMID: 30033088 PMCID: PMC6092761 DOI: 10.1016/j.stemcr.2018.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 01/14/2023] Open
Abstract
Multielectrode array (MEA) technology has been extensively used for field potential recordings from excitable cells. However, its application for action potential (AP) measurements has not been harnessed. Here, we report a novel platform for high-resolution intracellular AP recordings from induced pluripotent stem cell-cardiomyocyte constructs derived from human cardiac fibroblasts. To gain intracellular access, micro-gold MEAs were used to electroporate multiple constructs simultaneously. High-throughput AP measurements were obtained from 41 multicellular constructs. Repeated electroporations of the same cells did not affect the signal stability. Our model has the capability to distinguish subtle differences in AP morphology to characterize the network profile. Furthermore, we confirm the reliability of the system by recapitulating known drug-induced physiological and arrhythmogenic responses. Overall, the model provides a unique cardio-electronic interface for non-invasive measurements of AP dynamics for drug screening and disease modeling. This technology opens the door for identifying novel cardio-factors to enhance electrophysiological maturation. Electroporation-mediated action potential (AP) recordings using MEA technology Simultaneous high-throughput AP measurement from multiple cell networks Multiple electroporations of the same cells over days with stable signal Model validation for developmental, disease, and drug screening studies
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Affiliation(s)
- Stacie L Edwards
- Aurora Research Institute, Aurora Health Care, 960 N 12th Avenue, Milwaukee, WI 53233, USA
| | - Viviana Zlochiver
- Aurora Research Institute, Aurora Health Care, 960 N 12th Avenue, Milwaukee, WI 53233, USA
| | - Donald B Conrad
- Aurora Research Institute, Aurora Health Care, 960 N 12th Avenue, Milwaukee, WI 53233, USA
| | - Ravi Vaidyanathan
- Cellular and Molecular Arrhythmia Research Program, Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin, Madison, WI 53705, USA
| | | | - Rosy Joshi-Mukherjee
- Aurora Research Institute, Aurora Health Care, 960 N 12th Avenue, Milwaukee, WI 53233, USA; Department of Medicine-Cardiovascular, School of Medicine, Johns Hopkins University; Baltimore, MD 21205, USA.
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Haverinen J, Hassinen M, Korajoki H, Vornanen M. Cardiac voltage-gated sodium channel expression and electrophysiological characterization of the sodium current in the zebrafish (Danio rerio) ventricle. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 138:59-68. [PMID: 29655910 DOI: 10.1016/j.pbiomolbio.2018.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/22/2018] [Accepted: 04/11/2018] [Indexed: 12/11/2022]
Abstract
Na+ channel α-subunit composition of the zebrafish heart and electrophysiological properties of Na+ current (INa) of zebrafish ventricular myocytes were examined. Eight Na+ channel α-subunits were expressed in both atrium and ventricle of the zebrafish heart. Nav1.5Lb, an orthologue to the human Nav1.5, was clearly the predominant isoform in both chambers representing 65.2 ± 4.1% and 83.1 ± 2.1% of all Na+ channel transcripts in atrium and ventricle, respectively. Nav1.4b, an orthologue to human Nav1.4, formed 34.1 ± 4.1 and 16.2 ± 2.0% of the Na+ channel transcripts in atrium and ventricle, respectively. The density of INa and the rate of action potential upstroke in zebrafish ventricular myocytes at 28 °C were similar to those of human ventricles at the comparable temperature. Na+ channel isoforms and the main electrophysiological characteristics of the INa are largely similar in zebrafish and human hearts indicating evolutionary conservation of Na+ channel composition and function. The zebrafish INa differs from the human cardiac INa in terms of higher tetrodotoxin sensitivity (IC50-value = 5.3 ± 0.1 nM) and slower inactivation kinetics. The zebrafish INa was inhibited with tricaine (MS-222) with an IC50-value of 1.2 ± 0.18 mM (336 mg l-1), suggesting some care in the use of MS-222 as an anesthetic.
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Affiliation(s)
- Jaakko Haverinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Finland
| | - Minna Hassinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Finland
| | - Hanna Korajoki
- Department of Environmental and Biological Sciences, University of Eastern Finland, Finland
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Finland.
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20
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Perioperative management of patients with congenital or acquired disorders of the QT interval. Br J Anaesth 2018; 120:629-644. [DOI: 10.1016/j.bja.2017.12.040] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 11/16/2017] [Accepted: 01/14/2018] [Indexed: 12/19/2022] Open
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21
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Horváth A, Lemoine MD, Löser A, Mannhardt I, Flenner F, Uzun AU, Neuber C, Breckwoldt K, Hansen A, Girdauskas E, Reichenspurner H, Willems S, Jost N, Wettwer E, Eschenhagen T, Christ T. Low Resting Membrane Potential and Low Inward Rectifier Potassium Currents Are Not Inherent Features of hiPSC-Derived Cardiomyocytes. Stem Cell Reports 2018; 10:822-833. [PMID: 29429959 PMCID: PMC5918194 DOI: 10.1016/j.stemcr.2018.01.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 11/18/2022] Open
Abstract
Human induced pluripotent stem cell (hiPSC) cardiomyocytes (CMs) show less negative resting membrane potential (RMP), which is attributed to small inward rectifier currents (IK1). Here, IK1 was measured in hiPSC-CMs (proprietary and commercial cell line) cultured as monolayer (ML) or 3D engineered heart tissue (EHT) and, for direct comparison, in CMs from human right atrial (RA) and left ventricular (LV) tissue. RMP was measured in isolated cells and intact tissues. IK1 density in ML- and EHT-CMs from the proprietary line was similar to LV and RA, respectively. IK1 density in EHT-CMs from the commercial line was 2-fold smaller than in the proprietary line. RMP in EHT of both lines was similar to RA and LV. Repolarization fraction and IK,ACh response discriminated best between RA and LV and indicated predominantly ventricular phenotype in hiPSC-CMs/EHT. The data indicate that IK1 is not necessarily low in hiPSC-CMs, and technical issues may underlie low RMP in hiPSC-CMs.
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Affiliation(s)
- András Horváth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany; Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Marc D Lemoine
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Alexandra Löser
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Frederik Flenner
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ahmet Umur Uzun
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Evaldas Girdauskas
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Hermann Reichenspurner
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Stephan Willems
- Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Erich Wettwer
- Institute of Pharmacology, University Duisburg-Essen, 45122 Essen, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany.
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22
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Mora MT, Ferrero JM, Romero L, Trenor B. Sensitivity analysis revealing the effect of modulating ionic mechanisms on calcium dynamics in simulated human heart failure. PLoS One 2017; 12:e0187739. [PMID: 29117223 PMCID: PMC5678731 DOI: 10.1371/journal.pone.0187739] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Abnormal intracellular Ca2+ handling is the major contributor to the depressed cardiac contractility observed in heart failure. The electrophysiological remodeling associated with this pathology alters both the action potential and the Ca2+ dynamics, leading to a defective excitation-contraction coupling that ends in mechanical dysfunction. The importance of maintaining a correct intracellular Ca2+ concentration requires a better understanding of its regulation by ionic mechanisms. To study the electrical activity and ionic homeostasis of failing myocytes, a modified version of the O’Hara et al. human action potential model was used, including electrophysiological remodeling. The impact of the main ionic transport mechanisms was analyzed using single-parameter sensitivity analyses, the first of which explored the modulation of electrophysiological characteristics related to Ca2+ exerted by the remodeled parameters. The second sensitivity analysis compared the potential consequences of modulating individual channel conductivities, as one of the main effects of potential drugs, on Ca2+ dynamic properties under both normal conditions and in heart failure. The first analysis revealed the important contribution of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) dysfunction to the altered Ca2+ homeostasis, with the Na+/Ca2+ exchanger (NCX) and other Ca2+ cycling proteins also playing a significant role. Our results highlight the importance of improving the SR uptake function to increase Ca2+ content and restore Ca2+ homeostasis and contractility. The second sensitivity analysis highlights the different response of the failing myocyte versus the healthy myocyte to potential pharmacological actions on single channels. The result of modifying the conductances of the remodeled proteins such as SERCA and NCX in heart failure has less impact on Ca2+ modulation. These differences should be taken into account when designing drug therapies.
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Affiliation(s)
- Maria T. Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M. Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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Kane C, Terracciano CMN. Concise Review: Criteria for Chamber-Specific Categorization of Human Cardiac Myocytes Derived from Pluripotent Stem Cells. Stem Cells 2017; 35:1881-1897. [PMID: 28577296 PMCID: PMC5575566 DOI: 10.1002/stem.2649] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/25/2017] [Accepted: 05/12/2017] [Indexed: 11/30/2022]
Abstract
Human pluripotent stem cell‐derived cardiomyocytes (PSC‐CMs) have great potential application in almost all areas of cardiovascular research. A current major goal of the field is to build on the past success of differentiation strategies to produce CMs with the properties of those originating from the different chambers of the adult human heart. With no anatomical origin or developmental pathway to draw on, the question of how to judge the success of such approaches and assess the chamber specificity of PSC‐CMs has become increasingly important; commonly used methods have substantial limitations and are based on limited evidence to form such an assessment. In this article, we discuss the need for chamber‐specific PSC‐CMs in a number of areas as well as current approaches used to assess these cells on their likeness to those from different chambers of the heart. Furthermore, describing in detail the structural and functional features that distinguish the different chamber‐specific human adult cardiac myocytes, we propose an evidence‐based tool to aid investigators in the phenotypic characterization of differentiated PSC‐CMs. Stem Cells2017;35:1881–1897
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Affiliation(s)
- Christopher Kane
- Imperial College London, National Heart and Lung Institute, Hammersmith Campus, BHF Centre for Regenerative Medicine, London, United Kingdom
| | - Cesare M N Terracciano
- Imperial College London, National Heart and Lung Institute, Hammersmith Campus, BHF Centre for Regenerative Medicine, London, United Kingdom
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25
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Cai L, Wang Y, Gao H, Li Y, Luo X. A mathematical model for active contraction in healthy and failing myocytes and left ventricles. PLoS One 2017; 12:e0174834. [PMID: 28406991 PMCID: PMC5391010 DOI: 10.1371/journal.pone.0174834] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/15/2017] [Indexed: 02/07/2023] Open
Abstract
Cardiovascular disease is one of the leading causes of death worldwide, in particular myocardial dysfunction, which may lead to heart failure eventually. Understanding the electro-mechanics of the heart will help in developing more effective clinical treatments. In this paper, we present a multi-scale electro-mechanics model of the left ventricle (LV). The Holzapfel-Ogden constitutive law was used to describe the passive myocardial response in tissue level, a modified Grandi-Pasqualini-Bers model was adopted to model calcium dynamics in individual myocytes, and the active tension was described using the Niederer-Hunter-Smith myofilament model. We first studied the electro-mechanics coupling in a single myocyte in the healthy and diseased left ventricle, and then the single cell model was embedded in a dynamic LV model to investigate the compensation mechanism of LV pump function due to myocardial dysfunction caused by abnormality in cellular calcium dynamics. The multi-scale LV model was solved using an in-house developed hybrid immersed boundary method with finite element extension. The predictions of the healthy LV model agreed well with the clinical measurements and other studies, and likewise, the results in the failing states were also consistent with clinical observations. In particular, we found that a low level of intracellular Ca2+ transient in myocytes can result in LV pump function failure even with increased myocardial contractility, decreased systolic blood pressure, and increased diastolic filling pressure, even though they will increase LV stroke volume. Our work suggested that treatments targeted at increased contractility and lowering the systolic blood pressure alone are not sufficient in preventing LV pump dysfunction, restoring a balanced physiological Ca2+ handling mechanism is necessary.
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Affiliation(s)
- Li Cai
- NPU-UoG International Cooperative Lab for Computation & Application in Cardiology, Northwestern Polytechnical University, Xi’an, Shanxi Province, China
| | - Yongheng Wang
- NPU-UoG International Cooperative Lab for Computation & Application in Cardiology, Northwestern Polytechnical University, Xi’an, Shanxi Province, China
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Yiqiang Li
- NPU-UoG International Cooperative Lab for Computation & Application in Cardiology, Northwestern Polytechnical University, Xi’an, Shanxi Province, China
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow, Scotland, United Kingdom
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26
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Edwards AG, Louch WE. Species-Dependent Mechanisms of Cardiac Arrhythmia: A Cellular Focus. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2017; 11:1179546816686061. [PMID: 28469490 PMCID: PMC5392019 DOI: 10.1177/1179546816686061] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/20/2016] [Indexed: 12/17/2022]
Abstract
Although ventricular arrhythmia remains a leading cause of morbidity and mortality, available antiarrhythmic drugs have limited efficacy. Disappointing progress in the development of novel, clinically relevant antiarrhythmic agents may partly be attributed to discrepancies between humans and animal models used in preclinical testing. However, such differences are at present difficult to predict, requiring improved understanding of arrhythmia mechanisms across species. To this end, we presently review interspecies similarities and differences in fundamental cardiomyocyte electrophysiology and current understanding of the mechanisms underlying the generation of afterdepolarizations and reentry. We specifically highlight patent shortcomings in small rodents to reproduce cellular and tissue-level arrhythmia substrate believed to be critical in human ventricle. Despite greater ease of translation from larger animal models, discrepancies remain and interpretation can be complicated by incomplete knowledge of human ventricular physiology due to low availability of explanted tissue. We therefore point to the benefits of mathematical modeling as a translational bridge to understanding and treating human arrhythmia.
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Affiliation(s)
- Andrew G Edwards
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway.,Center for Cardiological Innovation, Simula Research Laboratory, Lysaker, Norway.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo, Oslo, Norway
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Singh BN, Wadhani N. Antiarrhythmic and Proarrhythmic Properties of QT-Prolonging Antianginal Drugs. J Cardiovasc Pharmacol Ther 2016; 9 Suppl 1:S85-97. [PMID: 15378133 DOI: 10.1177/107424840400900107] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In recent years there has been a major reorientation of drug therapy for cardiac arrhythmias, its changing role, and above all, a radical change in the class of arrhythmia drugs because of their impact on mortality. The decline in the use of sodium-channel blockers has led to an expanding use of β-blockers and simple or complex class III agents for controlling cardiac arrhythmias. Success with these agents in the context of their side effects has spurred the development of compounds with simpler ion-channel blocking properties that have less complex adverse reactions. The resulting so-called pure class III agents, such as dofetilide or ibutilide, were found to have antifibrillatory effects in atrial fibrillation and flutter and in ventricular tachyarrhythmias. Such agents are effective and have diversity, but they have come into therapeutics with a price: the sometimes-fatal torsades de pointes. The drug amiodarone, a complex compound that was synthesized as an antianginal agent, has been an exception in this regard. Its therapeutic use is associated with a negligibly low incidence of torsades de pointes, even though the drug produces significant bradycardia and QT lengthening to 500 to 700 msec. Recent electrophysiologic studies suggest that this paradox is likely due to the differential block of ion channels in endocardium, epicardium, midmyocardial (M) cells, and Purkinje fibers in the ventricular myocardium. There is also clinical evidence suggesting that amiodarone reduces the “torsadogenic” effects of pure class III agents. Ranolazine was also synthesized for the development of antianginal properties that stem from a partial inhibition of fatty acid oxidation; it too has been found to have electrophysioloigic properties. These are somewhat similar to those of amiodarone on ion channels in endocardium, epicardium, M cells, and Purkinje fibers in the ventricular myocardium, but the drug does not prolong the QT interval to the same extent as amiodarone does. Thus, the drug produces modest increases in repolarization as judged by its effects on the action potential duration (APD) without the potential for the development of torsades de pointes. By virtue of its suppressant action on early afterdepolarizations and triggered activity in Purkinje fibers and M cells, the drug appears to have a powerful potential for reducing the torsadogenic proclivity of conventional class III antiarrhythmic compounds. The rationale for the therapeutic niche for amiodarone, and especially in the case of ranolazine, in the prevention of drug-induced torsades de pointes is discussed.
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Affiliation(s)
- Bramah N Singh
- Division of Cardiology, Veterans Administration Greater Los Angeles Healthcare System and the David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, CA 90073, USA.
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Abstract
Gap junctions are channels which allow electrical signals to propagate through the heart from the sinoatrial node and through the atria, conduction system and onwards to the ventricles, and hence are essential for co-ordinated cardiac contraction. Twelve connexin (Cx) proteins make up one gap junction channel, of which there are three main subtypes in the heart; Cx40, Cx43 and Cx45. In the cardiac myocyte, gap junctions are present mainly at the intercalated discs between neighbouring myocytes, and assist in rapid electrical conduction throughout the ventricular myocardium. Fibroblasts provide the structural skeleton of the myocardium and fibroblast numbers significantly increase in heart disease. Fibroblasts also express connexins and this may facilitate heterocellular electrical coupling between myocytes and fibroblasts in the setting of cardiac disease. Interestingly, cardiac fibroblasts have been demonstrated to increase Cx43 expression in experimental models of myocardial infarction and functional gap junctions between myocytes and fibroblasts have been reported. Therefore, in the setting of heart disease enhanced cardiac myocyte: fibroblast coupling may influence the electrical activity of the myocyte and contribute to arrhythmias.
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Hartman ME, Dai DF, Laflamme MA. Human pluripotent stem cells: Prospects and challenges as a source of cardiomyocytes for in vitro modeling and cell-based cardiac repair. Adv Drug Deliv Rev 2016; 96:3-17. [PMID: 25980938 DOI: 10.1016/j.addr.2015.05.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/27/2015] [Accepted: 05/07/2015] [Indexed: 12/13/2022]
Abstract
Human pluripotent stem cells (PSCs) represent an attractive source of cardiomyocytes with potential applications including disease modeling, drug discovery and safety screening, and novel cell-based cardiac therapies. Insights from embryology have contributed to the development of efficient, reliable methods capable of generating large quantities of human PSC-cardiomyocytes with cardiac purities ranging up to 90%. However, for human PSCs to meet their full potential, the field must identify methods to generate cardiomyocyte populations that are uniform in subtype (e.g. homogeneous ventricular cardiomyocytes) and have more mature structural and functional properties. For in vivo applications, cardiomyocyte production must be highly scalable and clinical grade, and we will need to overcome challenges including graft cell death, immune rejection, arrhythmogenesis, and tumorigenic potential. Here we discuss the types of human PSCs, commonly used methods to guide their differentiation into cardiomyocytes, the phenotype of the resultant cardiomyocytes, and the remaining obstacles to their successful translation.
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Liu J, Laksman Z, Backx PH. The electrophysiological development of cardiomyocytes. Adv Drug Deliv Rev 2016; 96:253-73. [PMID: 26788696 DOI: 10.1016/j.addr.2015.12.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/23/2015] [Accepted: 12/31/2015] [Indexed: 02/07/2023]
Abstract
The generation of human cardiomyocytes (CMs) from human pluripotent stem cells (hPSCs) has become an important resource for modeling human cardiac disease and for drug screening, and also holds significant potential for cardiac regeneration. Many challenges remain to be overcome however, before innovation in this field can translate into a change in the morbidity and mortality associated with heart disease. Of particular importance for the future application of this technology is an improved understanding of the electrophysiologic characteristics of CMs, so that better protocols can be developed and optimized for generating hPSC-CMs. Many different cell culture protocols are currently utilized to generate CMs from hPSCs and all appear to yield relatively “developmentally” immature CMs with highly heterogeneous electrical properties. These hPSC-CMs are characterized by spontaneous beating at highly variable rates with a broad range of depolarization-repolarization patterns, suggestive of mixed populations containing atrial, ventricular and nodal cells. Many recent studies have attempted to introduce approaches to promote maturation and to create cells with specific functional properties. In this review, we summarize the studies in which the electrical properties of CMs derived from stem cells have been examined. In order to place this information in a useful context, we also review the electrical properties of CMs as they transition from the developing embryo to the adult human heart. The signal pathways involved in the regulation of ion channel expression during development are also briefly considered.
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31
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Ramakrishna H, O’Hare M, Mookadam F, Gutsche JT, Shah R, Augoustides JG. Sudden Cardiac Death and Disorders of the QT Interval: Anesthetic Implications and Focus on Perioperative Management. J Cardiothorac Vasc Anesth 2015; 29:1723-33. [DOI: 10.1053/j.jvca.2015.07.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 12/19/2022]
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32
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Veerman CC, Kosmidis G, Mummery CL, Casini S, Verkerk AO, Bellin M. Immaturity of Human Stem-Cell-Derived Cardiomyocytes in Culture: Fatal Flaw or Soluble Problem? Stem Cells Dev 2015; 24:1035-52. [DOI: 10.1089/scd.2014.0533] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Christiaan C. Veerman
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Georgios Kosmidis
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
| | - Christine L. Mummery
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
| | - Simona Casini
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
| | - Arie O. Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Milena Bellin
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
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33
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Cummins MA, Dalal PJ, Bugana M, Severi S, Sobie EA. Comprehensive analyses of ventricular myocyte models identify targets exhibiting favorable rate dependence. PLoS Comput Biol 2014; 10:e1003543. [PMID: 24675446 PMCID: PMC3967944 DOI: 10.1371/journal.pcbi.1003543] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 02/13/2014] [Indexed: 12/02/2022] Open
Abstract
Reverse rate dependence is a problematic property of antiarrhythmic drugs that prolong the cardiac action potential (AP). The prolongation caused by reverse rate dependent agents is greater at slow heart rates, resulting in both reduced arrhythmia suppression at fast rates and increased arrhythmia risk at slow rates. The opposite property, forward rate dependence, would theoretically overcome these parallel problems, yet forward rate dependent (FRD) antiarrhythmics remain elusive. Moreover, there is evidence that reverse rate dependence is an intrinsic property of perturbations to the AP. We have addressed the possibility of forward rate dependence by performing a comprehensive analysis of 13 ventricular myocyte models. By simulating populations of myocytes with varying properties and analyzing population results statistically, we simultaneously predicted the rate-dependent effects of changes in multiple model parameters. An average of 40 parameters were tested in each model, and effects on AP duration were assessed at slow (0.2 Hz) and fast (2 Hz) rates. The analysis identified a variety of FRD ionic current perturbations and generated specific predictions regarding their mechanisms. For instance, an increase in L-type calcium current is FRD when this is accompanied by indirect, rate-dependent changes in slow delayed rectifier potassium current. A comparison of predictions across models identified inward rectifier potassium current and the sodium-potassium pump as the two targets most likely to produce FRD AP prolongation. Finally, a statistical analysis of results from the 13 models demonstrated that models displaying minimal rate-dependent changes in AP shape have little capacity for FRD perturbations, whereas models with large shape changes have considerable FRD potential. This can explain differences between species and between ventricular cell types. Overall, this study provides new insights, both specific and general, into the determinants of AP duration rate dependence, and illustrates a strategy for the design of potentially beneficial antiarrhythmic drugs. Several drugs intended to treat cardiac arrhythmias have failed because of unfavorable rate-dependent properties. That is, the drugs fail to alter electrical activity at fast heart rates, where this would be beneficial, but they do affect electrical activity at slow rates, where this is unwanted. In targeted studies, several agents have been shown to exhibit these unfavorable properties, suggesting that these rate-dependent responses may be intrinsic to ventricular muscle. To determine whether drugs with desirable rate-dependent properties could be rationally designed, we performed comprehensive and systematic analyses of several heart cell models. These analyses calculated the rate-dependent properties of changes in any model parameter, thereby generating simultaneously a large number of model predictions. The analyses showed that targets with favorable rate-dependent properties could indeed be identified, and further simulations uncovered the mechanisms underlying these behaviors. Moreover, a quantitative comparison of results obtained in different models provided new insight in why a given drug applied to different species, or to different tissue types, might produce different rate-dependent behaviors. Overall this study shows how a comprehensive and systematic approach to heart cell models can both identify novel targets and produce more general insight into rate-dependent alterations to cardiac electrical activity.
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Affiliation(s)
- Megan A. Cummins
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Pavan J. Dalal
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | | | | | - Eric A. Sobie
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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34
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Keung W, Boheler KR, Li RA. Developmental cues for the maturation of metabolic, electrophysiological and calcium handling properties of human pluripotent stem cell-derived cardiomyocytes. Stem Cell Res Ther 2014; 5:17. [PMID: 24467782 PMCID: PMC4055054 DOI: 10.1186/scrt406] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human pluripotent stem cells (hPSCs), including embryonic and induced pluripotent stem cells, are abundant sources of cardiomyocytes (CMs) for cell replacement therapy and other applications such as disease modeling, drug discovery and cardiotoxicity screening. However, hPSC-derived CMs display immature structural, electrophysiological, calcium-handling and metabolic properties. Here, we review various biological as well as physical and topographical cues that are known to associate with the development of native CMs in vivo to gain insights into the development of strategies for facilitated maturation of hPSC-CMs.
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Moreno JD, Yang PC, Bankston JR, Grandi E, Bers DM, Kass RS, Clancy CE. Ranolazine for congenital and acquired late INa-linked arrhythmias: in silico pharmacological screening. Circ Res 2013; 113:e50-e61. [PMID: 23897695 DOI: 10.1161/circresaha.113.301971] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE The antianginal ranolazine blocks the human ether-a-go-go-related gene-based current IKr at therapeutic concentrations and causes QT interval prolongation. Thus, ranolazine is contraindicated for patients with preexisting long-QT and those with repolarization abnormalities. However, with its preferential targeting of late INa (INaL), patients with disease resulting from increased INaL from inherited defects (eg, long-QT syndrome type 3 or disease-induced electric remodeling (eg, ischemic heart failure) might be exactly the ones to benefit most from the presumed antiarrhythmic properties of ranolazine. OBJECTIVE We developed a computational model to predict if therapeutic effects of pharmacological targeting of INaL by ranolazine prevailed over the off-target block of IKr in the setting of inherited long-QT syndrome type 3 and heart failure. METHODS AND RESULTS We developed computational models describing the kinetics and the interaction of ranolazine with cardiac Na(+) channels in the setting of normal physiology, long-QT syndrome type 3-linked ΔKPQ mutation, and heart failure. We then simulated clinically relevant concentrations of ranolazine and predicted the combined effects of Na(+) channel and IKr blockade by both the parent compound ranolazine and its active metabolites, which have shown potent blocking effects in the therapeutically relevant range. Our simulations suggest that ranolazine is effective at normalizing arrhythmia triggers in bradycardia-dependent arrhythmias in long-QT syndrome type 3 as well tachyarrhythmogenic triggers arising from heart failure-induced remodeling. CONCLUSIONS Our model predictions suggest that acute targeting of INaL with ranolazine may be an effective therapeutic strategy in diverse arrhythmia-provoking situations that arise from a common pathway of increased pathological INaL.
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Affiliation(s)
- Jonathan D Moreno
- Tri-Institutional MD-PhD Program, Weill Cornell Medical College/The Rockefeller University/Sloan-Kettering Cancer Institute, New York, New York, USA, 10021
| | - Pei-Chi Yang
- Department of Pharmacology, University of California, Davis, Genome Building Rm 3503, Davis, CA 95616-8636
| | - John R Bankston
- Department of Pharmacology Columbia University College of Physicians and Surgeons 630 W. 168th St. New York, NY 10032, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome Building Rm 3503, Davis, CA 95616-8636
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome Building Rm 3503, Davis, CA 95616-8636
| | - Robert S Kass
- Department of Pharmacology Columbia University College of Physicians and Surgeons 630 W. 168th St. New York, NY 10032, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome Building Rm 3503, Davis, CA 95616-8636
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36
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Robertson C, Tran DD, George SC. Concise review: maturation phases of human pluripotent stem cell-derived cardiomyocytes. Stem Cells 2013; 31:829-37. [PMID: 23355363 PMCID: PMC3749929 DOI: 10.1002/stem.1331] [Citation(s) in RCA: 243] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 12/21/2012] [Indexed: 12/19/2022]
Abstract
Human pluripotent stem cell-derived cardiomyocytes (hPS-CM) may offer a number of advantages over previous cardiac models, however, questions of their immaturity complicate their adoption as a new in vitro model. hPS-CM differ from adult cardiomyocytes with respect to structure, proliferation, metabolism and electrophysiology, better approximating fetal cardiomyocytes. Time in culture appears to significantly impact phenotype, leading to what can be referred to as early and late hPS-CM. This work surveys the phenotype of hPS-CM, including structure, bioenergetics, sensitivity to damage, gene expression, and electrophysiology, including action potential, ion channels, and intracellular calcium stores, while contrasting fetal and adult CM with hPS-CM at early and late time points after onset of differentiation.
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Affiliation(s)
- Claire Robertson
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California, USA
| | - David D. Tran
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California, USA
- Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California, USA
| | - Steven C. George
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California, USA
- Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California, USA
- Department of Medicine, University of California, Irvine, Irvine, California, USA
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Kaye AD, Volpi-Abadie J, Bensler JM, Kaye AM, Diaz JH. QT interval abnormalities: risk factors and perioperative management in long QT syndromes and Torsades de Pointes. J Anesth 2013; 27:575-87. [PMID: 23412014 DOI: 10.1007/s00540-013-1564-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 01/21/2013] [Indexed: 01/08/2023]
Abstract
Electrophysiological abnormalities of the QT interval of the standard electrocardiogram are not uncommon. Congenital long QT syndrome is due to mutations of several possible genes (genotype) that result in prolongation of the corrected QT interval (phenotype). Abnormalities of the QT interval can be acquired and are often drug-induced. Torsades de Pointes (TP) is an arrhythmia that is a result of aberrant repolarization/QT abnormalities. If not recognized and corrected quickly, QT interval abnormalities may precipitate potentially fatal ventricular dysrhythmias. The main mechanism responsible for the development of QT prolongation is blockade of the rapid component of the delayed rectifier potassium current (I kr), encoded for by the human-ether-a-go-go-related gene (hERG). The objectives of this review were (1) to describe the electrical pathophysiology of QT interval abnormalities, (2) to differentiate congenital from acquired QT interval abnormalities, (3) to describe the currently known risk factors for QT interval abnormalities, (4) to identify current drug-induced causes of acquired QT interval abnormalities, and (5) to recommend immediate and effective management strategies to prevent unanticipated dysrhythmias and deaths from QT abnormalities in the perioperative period.
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Affiliation(s)
- Alan David Kaye
- Department of Anesthesiology, LSU School of Medicine, New Orleans, LA 70112, USA.
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Guns PJ, Johnson DM, Van Op den Bosch J, Weltens E, Lissens J. The electro-mechanical window in anaesthetized guinea pigs: a new marker in screening for Torsade de Pointes risk. Br J Pharmacol 2012; 166:689-701. [PMID: 22122450 DOI: 10.1111/j.1476-5381.2011.01795.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE QT prolongation is commonly used as a surrogate marker for Torsade de Pointes (TdP) risk of non-cardiovascular drugs. However, use of this indirect marker often leads to misinterpretation of the realistic TdP risk, as tested compounds may cause QT prolongation without evoking TdP in humans. A negative electro-mechanical (E-M) window has recently been proposed as an alternative risk marker for TdP in a canine LQT1 model. Here, we evaluated the E-M window in anaesthetized guinea pigs as a screening marker for TdP in humans. EXPERIMENTAL APPROACH The effects of various reference drugs and changes in body temperature on the E-M window were assessed in instrumented guinea pigs. The E-M window was defined as the delay between the duration of the electrical (QT interval) and mechanical (QLVP(end) ) systole. KEY RESULTS Drugs with known TdP liability (quinidine, haloperidol, domperidone, terfenadine, thioridazine and dofetilide), but not those with no TdP risk in humans (salbutamol and diltiazem) consistently decreased the E-M window. Interestingly, drugs with known clinical QT prolongation, but with low risk for TdP (amiodarone, moxifloxacin and ciprofloxacin) did not decrease the E-M window. Furthermore, the E-M window was minimally affected by changes in heart rate or body temperature. CONCLUSIONS AND IMPLICATIONS A decreased E-M window was consistently observed with drugs already known to have high TdP risk, but not with drugs with low or no TdP risk. These results suggest that the E-M window in anaesthetized guinea pigs is a risk marker for TdP in humans.
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Affiliation(s)
- P-J Guns
- Bio-Plus Safety Pharmacology, Bio-Plus Services, Mol, Belgium.
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Osadchii OE. Impact of Na+ channel blockers on transmural dispersion of refractoriness and arrhythmic susceptibility in guinea-pig left ventricle. Eur J Pharmacol 2012; 691:173-81. [DOI: 10.1016/j.ejphar.2012.07.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/27/2012] [Accepted: 07/02/2012] [Indexed: 02/03/2023]
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40
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Morley SR. Drug-Induced Long QT Syndrome - Clinical and Analytical Aspects for Medical Examiners. Acad Forensic Pathol 2012. [DOI: 10.23907/2012.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The long QT syndrome may occur due to genetic aberrations of cardiac transcellular ionic transporters, but also occurs secondary to a wide range of therapeutic and illicit drugs. This review will outline how the interaction of the blockade of the cardiac ion channels with drugs may lead to death from the long QT syndrome. Toxicology laboratories have a role, although somewhat limited, in supporting the investigation of sudden adult death and the contribution to the etiology of the long QT syndrome.
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Affiliation(s)
- Stephen R. Morley
- Sheffield Teaching Hospitals and an honorary senior lecturer at Sheffield University and Kings College London, all in the United Kingdom
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Hoekstra M, Mummery CL, Wilde AAM, Bezzina CR, Verkerk AO. Induced pluripotent stem cell derived cardiomyocytes as models for cardiac arrhythmias. Front Physiol 2012; 3:346. [PMID: 23015789 PMCID: PMC3449331 DOI: 10.3389/fphys.2012.00346] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/09/2012] [Indexed: 12/20/2022] Open
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality. In younger patients, the majority of sudden cardiac deaths have an underlying Mendelian genetic cause. Over the last 15 years, enormous progress has been made in identifying the distinct clinical phenotypes and in studying the basic cellular and genetic mechanisms associated with the primary Mendelian (monogenic) arrhythmia syndromes. Investigation of the electrophysiological consequences of an ion channel mutation is ideally done in the native cardiomyocyte (CM) environment. However, the majority of such studies so far have relied on heterologous expression systems in which single ion channel genes are expressed in non-cardiac cells. In some cases, transgenic mouse models have been generated, but these also have significant shortcomings, primarily related to species differences. The discovery that somatic cells can be reprogrammed to pluripotency as induced pluripotent stem cells (iPSC) has generated much interest since it presents an opportunity to generate patient- and disease-specific cell lines from which normal and diseased human CMs can be obtained These genetically diverse human model systems can be studied in vitro and used to decipher mechanisms of disease and identify strategies and reagents for new therapies. Here, we review the present state of the art with respect to cardiac disease models already generated using IPSC technology and which have been (partially) characterized. Human iPSC (hiPSC) models have been described for the cardiac arrhythmia syndromes, including LQT1, LQT2, LQT3-Brugada Syndrome, LQT8/Timothy syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT). In most cases, the hiPSC-derived cardiomyoctes recapitulate the disease phenotype and have already provided opportunities for novel insight into cardiac pathophysiology. It is expected that the lines will be useful in the development of pharmacological agents for the management of these disorders.
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Affiliation(s)
- Maaike Hoekstra
- Department of Clinical and Experimental Cardiology, Heart Failure Research Center, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
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Gauthier LD, Greenstein JL, Winslow RL. Toward an integrative computational model of the Guinea pig cardiac myocyte. Front Physiol 2012; 3:244. [PMID: 22783206 PMCID: PMC3389778 DOI: 10.3389/fphys.2012.00244] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/14/2012] [Indexed: 11/22/2022] Open
Abstract
The local control theory of excitation-contraction (EC) coupling asserts that regulation of calcium (Ca2+) release occurs at the nanodomain level, where openings of single L-type Ca2+ channels (LCCs) trigger openings of small clusters of ryanodine receptors (RyRs) co-localized within the dyad. A consequence of local control is that the whole-cell Ca2+ transient is a smooth continuous function of influx of Ca2+ through LCCs. While this so-called graded release property has been known for some time, its functional importance to the integrated behavior of the cardiac ventricular myocyte has not been fully appreciated. We previously formulated a biophysically based model, in which LCCs and RyRs interact via a coarse-grained representation of the dyadic space. The model captures key features of local control using a low-dimensional system of ordinary differential equations. Voltage-dependent gain and graded Ca2+ release are emergent properties of this model by virtue of the fact that model formulation is closely based on the sub-cellular basis of local control. In this current work, we have incorporated this graded release model into a prior model of guinea pig ventricular myocyte electrophysiology, metabolism, and isometric force production. The resulting integrative model predicts the experimentally observed causal relationship between action potential (AP) shape and timing of Ca2+ and force transients, a relationship that is not explained by models lacking the graded release property. Model results suggest that even relatively subtle changes in AP morphology that may result, for example, from remodeling of membrane transporter expression in disease or spatial variation in cell properties, may have major impact on the temporal waveform of Ca2+ transients, thus influencing tissue level electromechanical function.
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Affiliation(s)
- Laura Doyle Gauthier
- Department of Biomedical Engineering, Institute for Computational Medicine, The Johns Hopkins University School of Medicine and Whiting School of Engineering Baltimore, MD, USA
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Kallergis EM, Goudis CA, Simantirakis EN, Kochiadakis GE, Vardas PE. Mechanisms, risk factors, and management of acquired long QT syndrome: a comprehensive review. ScientificWorldJournal 2012; 2012:212178. [PMID: 22593664 PMCID: PMC3347892 DOI: 10.1100/2012/212178] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/22/2011] [Indexed: 12/19/2022] Open
Abstract
Long QT syndrome is characterized by prolongation of the corrected QT (QTc) interval on the surface electrocardiogram and is associated with precipitation of torsade de pointes (TdP), a polymorphic ventricular tachycardia that may cause sudden death. Acquired long QT syndrome describes pathologic excessive prolongation of the QT interval, upon exposure to an environmental stressor, with reversion back to normal following removal of the stressor. The most common environmental stressor in acquired long QT syndrome is drug therapy. Acquired long QT syndrome is an important issue for clinicians and a significant public health problem concerning the large number of drugs with this adverse effect with a potentially fatal outcome, the large number of patients exposed to these drugs, and our inability to predict the risk for a given individual. In this paper, we focus on mechanisms underlying QT prolongation, risk factors for torsades de pointes and describe the short- and long-term treatment of acquired long QT syndrome.
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Affiliation(s)
- Eleftherios M Kallergis
- Department of Cardiology, University Hospital of Heraklion, 711 10 Heraklion, Crete, Greece.
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Zhou SX, Fang C, Zheng SX, Zhang YL, Lei J, Wang JF. Effect of amiodarone on dispersion of ventricular repolarization in a canine congestive heart failure model. Clin Exp Pharmacol Physiol 2012; 39:241-6. [PMID: 22229329 DOI: 10.1111/j.1440-1681.2012.05667.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of amiodarone on ventricular electrophysiological parameters, especially the dispersion of ventricular repolarization, were investigated in a canine model of congestive heart failure (CHF). Dogs were randomized to either a control, amiodarone, CHF, or CHF+amiodarone group. Dogs in the CHF and CHF+amiodarone groups underwent 4-5 weeks of rapid ventricular pacing; dogs in the control and amiodarone groups underwent sham operation only. Amiodarone (20 mg/kg per day) was administered orally, beginning on postoperative Day 1, in the treatment groups; ventricular electrophysiological variables were evaluated 4-5 weeks after rapid pacing or sham operation. In CHF dogs, the transmural dispersion ventricular repolarization time (TDVRT) increased significantly. Amiodarone significantly decreased the TDVRT in CHF dogs. The ventricular fibrillation threshold (VFT) decreased in the CHF group. Amiodarone increased the VFT in CHF dogs. The TDVRT increased in CHF dogs, but amiodarone decreased TDVRT and increased VFT in these dogs. These results suggest a beneficial effect of amiodarone on malignant arrhythmias and may provide the basis for its use in CHF patients.
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Affiliation(s)
- Shu-Xian Zhou
- Division of Cardiology, Department of Internal Medicine, Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University, Guangzhou, China.
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Smetana P, Schmidt A, Zabel M, Hnatkova K, Franz M, Huber K, Malik M. Assessment of repolarization heterogeneity for prediction of mortality in cardiovascular disease: peak to the end of the T wave interval and nondipolar repolarization components. J Electrocardiol 2011; 44:301-8. [PMID: 21511064 DOI: 10.1016/j.jelectrocard.2011.03.004] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Indexed: 12/23/2022]
Abstract
BACKGROUND In the canine wedge preparation, the interval from the peak to the end of the T wave (TpTe) reflects transwedge heterogeneities. Increase of ventricular dispersion of action potential durations has been repeatedly shown to be arrhythmogenic; thus, prolonged TpTe intervals were assumed to reflect increased risk. However, despite attempted extrapolation to clinical electrocardiograms, the appropriateness of this assumption has not been investigated in a large population. In another animal model, nondipolar components of the descending T-wave limb (TWRd) have been shown to correlate with TpTe interval. Although total T-wave nondipolar components (TWRt), believed to reflect heterogeneities during total repolarization, were shown associated with worse outcome of cardiac patients, this has not been investigated for TWRd. METHODS AND RESULTS Male cardiovascular patients (n = 813) had digital 12-lead electrocardiograms recorded between 1984 and 1991 and were followed until 2000. Using commercial and previously validated technology, QT intervals, TpTe intervals, TWRd, and TWRt were calculated, heart rate corrected, and compared between survivors and nonsurvivors. Their predictive power was also compared with established markers of mortality risk. In contrast to former reports, TpTe(c) intervals were significantly shorter in nonsurvivors (98.76 ± 20.63 milliseconds vs 103.14 ± 20.87 milliseconds, P = .016) and not predictive of outcome. Although TWRd(c) was significantly higher in nonsurvivors (0.007% ± 0.02% vs 0.005% ± 0.08%, P = .03), it was also not predictive of outcome. Only increased TWRt(c), increased heart rate, and increased age were predictive of death. CONCLUSIONS The findings challenge the concept that prolongation of TpTe corresponds to higher risk of death from any cause in every population. Further investigations are needed to confirm that clinically measured TpTe reflects transmural repolarization heterogeneity in all clinical populations and indeed is a useful risk marker.
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Affiliation(s)
- Peter Smetana
- Division of Clinical Sciences, St. George's, University of London, England
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OSAKA TOSHIYUKI, YOKOYAMA ERIKO, HASEBE HIDEYUKI, KODAMA ITSUO. Effects of Chronic Amiodarone on the Electrical Restitution in the Human Ventricle With Reference to Its Antiarrhythmic Efficacy. J Cardiovasc Electrophysiol 2011; 22:669-76. [DOI: 10.1111/j.1540-8167.2010.01990.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Myles RC, Burton FL, Cobbe SM, Smith GL. Alternans of action potential duration and amplitude in rabbits with left ventricular dysfunction following myocardial infarction. J Mol Cell Cardiol 2010; 50:510-21. [PMID: 21145895 DOI: 10.1016/j.yjmcc.2010.11.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 11/21/2010] [Accepted: 11/24/2010] [Indexed: 10/18/2022]
Abstract
T-wave alternans may predict the occurrence of ventricular arrhythmias in patients with left ventricular dysfunction and experimental work has linked discordant repolarization alternans to the induction of re-entry. The aim of this study was to examine the occurrence of transmural repolarization alternans and to investigate the link between alternans and ventricular arrhythmia in rabbits with left ventricular dysfunction following myocardial infarction. Optical mapping was used to record action potentials from the transmural surface of left ventricular wedge preparations from normal and post-infarction hearts during a progressive reduction in pacing cycle length at 30 and 37°C. Data were analyzed using custom software, including spectral analysis. There were no significant differences in baseline transmural electrophysiology between the groups. Post-infarction hearts had a lower threshold for both repolarization alternans (286 vs. 333 bpm, p<0.05) and ventricular arrhythmias (79 vs. 19%, p<0.01) during rapid pacing, which was not accounted for by increased transmural discordant alternans. In VF-prone hearts, alternans in optical action potential amplitude was observed and increased until 2:1 block occurred. The degree of optical action potential amplitude alternans (12.0 ± 7.0 vs. 1.8 ± 0.3, p<0.05), but not APD(90) alternans (1.4 ± 0.6 vs. 1.1 ± 0.1, p>0.05) was associated with VF inducibility during rapid pacing. Post-infarction hearts are more vulnerable to transmural alternans and ventricular arrhythmias at rapid rates. Alternans in optical action potential amplitude was associated with conduction block and VF. The data suggest that changes in optical action potential amplitude may underlie a mechanism for alternans-associated ventricular arrhythmia in left ventricular dysfunction.
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Affiliation(s)
- Rachel C Myles
- British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
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Podrid PJ. Aggravation of Arrhythmia by Antiarrhythmic Drugs (Proarrhythmia). Card Electrophysiol Clin 2010; 2:459-470. [PMID: 28770803 DOI: 10.1016/j.ccep.2010.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arrhythmia aggravation by antiarrhythmic drugs (proarrhythmia) can be caused by worsening or a change of a preexisting arrhythmia, development of a new arrhythmia, or development of a bradyarrhythmia. Aggravation of arrhythmia usually occurs within several days of beginning an antiarrhythmic drug or increasing the dose of the drug. The time of occurrence is based on the particular drug and its pharmacokinetic properties. Although there are no ways to predict the patient at risk for developing arrhythmia aggravation with any specific agents, risk factors include QT interval prolongation, elevated serum levels of the drug, electrolyte abnormalities, presence of heart failure, a history of a sustained ventricular tachyarrhythmia, and underlying myocardial ischemia.
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Affiliation(s)
- Philip J Podrid
- Section of Cardiology, West Roxbury Veterans Administration Hospital, 1400 VFW Parkway, West Roxbury, MA 02132, USA
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Li EC, Esterly JS, Pohl S, Scott SD, McBride BF. Drug-Induced QT-Interval Prolongation: Considerations for Clinicians. Pharmacotherapy 2010; 30:684-701. [DOI: 10.1592/phco.30.7.684] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Grandi E, Pasqualini FS, Bers DM. A novel computational model of the human ventricular action potential and Ca transient. J Mol Cell Cardiol 2009; 48:112-21. [PMID: 19835882 DOI: 10.1016/j.yjmcc.2009.09.019] [Citation(s) in RCA: 296] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2009] [Revised: 08/18/2009] [Accepted: 09/30/2009] [Indexed: 11/17/2022]
Abstract
We have developed a detailed mathematical model for Ca handling and ionic currents in the human ventricular myocyte. Our aims were to: (1) simulate basic excitation-contraction coupling phenomena; (2) use realistic repolarizing K current densities; (3) reach steady-state. The model relies on the framework of the rabbit myocyte model previously developed by our group, with subsarcolemmal and junctional compartments where ion channels sense higher [Ca] vs. bulk cytosol. Ion channels and transporters have been modeled on the basis of the most recent experimental data from human ventricular myocytes. Rapidly and slowly inactivating components of I(to) have been formulated to differentiate between endocardial and epicardial myocytes. Transmural gradients of Ca handling proteins and Na pump were also simulated. The model has been validated against a wide set of experimental data including action potential duration (APD) adaptation and restitution, frequency-dependent increase in Ca transient peak and [Na](i). Interestingly, Na accumulation at fast heart rate is a major determinant of APD shortening, via outward shifts in Na pump and Na-Ca exchange currents. We investigated the effects of blocking K currents on APD and repolarization reserve: I(Ks) block does not affect the former and slightly reduces the latter; I(K1) blockade modestly increases APD and more strongly reduces repolarization reserve; I(Kr) blockers significantly prolong APD, an effect exacerbated as pacing frequency is decreased, in good agreement with experimental results in human myocytes. We conclude that this model provides a useful framework to explore excitation-contraction coupling mechanisms and repolarization abnormalities at the single myocyte level.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California, 451 Health Sciences Drive, GBSF Room 3513, Davis, CA 95616-8636, USA
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