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Ördög B, De Coster T, Dekker SO, Bart CI, Zhang J, Boink GJJ, Bax WH, Deng S, den Ouden BL, de Vries AAF, Pijnappels DA. Opto-electronic feedback control of membrane potential for real-time control of action potentials. CELL REPORTS METHODS 2023; 3:100671. [PMID: 38086387 PMCID: PMC10753386 DOI: 10.1016/j.crmeth.2023.100671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 10/09/2023] [Accepted: 11/19/2023] [Indexed: 12/21/2023]
Abstract
To unlock new research possibilities by acquiring control of action potential (AP) morphologies in excitable cells, we developed an opto-electronic feedback loop-based system integrating cellular electrophysiology, real-time computing, and optogenetic approaches and applied it to monolayers of heart muscle cells. This allowed accurate restoration and preservation of cardiac AP morphologies in the presence of electrical perturbations of different origin in an unsupervised, self-regulatory manner, without any prior knowledge of the disturbance. Moreover, arbitrary AP waveforms could be enforced onto these cells. Collectively, these results set the stage for the refinement and application of opto-electronic control systems to enable in-depth investigation into the regulatory role of membrane potential in health and disease.
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Affiliation(s)
- Balázs Ördög
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands.
| | - Tim De Coster
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Sven O Dekker
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Cindy I Bart
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Juan Zhang
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Gerard J J Boink
- Amsterdam Cardiovascular Sciences, Department of Cardiology, Amsterdam UMC, Location AMC, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; Department of Medical Biology, Amsterdam UMC, Location AMC, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Wilhelmina H Bax
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Shanliang Deng
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands; Department of Microelectronics, Delft University of Technology, 2628 CD Delft, the Netherlands
| | - Bram L den Ouden
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands; Department of Microelectronics, Delft University of Technology, 2628 CD Delft, the Netherlands
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands.
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2
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Chakraborty P, Aggarwal AK, Nair MKK, Massé S, Riazi S, Nanthakumar K. Restoration of calcium release synchrony: A novel target for heart failure and ventricular arrhythmia. Heart Rhythm 2023; 20:1773-1781. [PMID: 37678492 DOI: 10.1016/j.hrthm.2023.08.040] [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: 06/05/2023] [Revised: 08/13/2023] [Accepted: 08/31/2023] [Indexed: 09/09/2023]
Abstract
Myocardial calcium (Ca2+) signaling plays a crucial role in contractile function and membrane electrophysiology. An abnormal myocardial Ca2+ transient is linked to heart failure and ventricular arrhythmias. At the subcellular level, the synchronous release of Ca2+ sparks from sarcoplasmic Ca2+ release units determines the configuration and amplitude of the global Ca2+ transient. This narrative review evaluates the role of aberrant Ca2+ release synchrony in the pathophysiology of cardiomyopathies and ventricular arrhythmias. The potential therapeutic benefits of restoration of Ca2+ release synchrony in heart failure and ventricular arrhythmias are also discussed.
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Affiliation(s)
- Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; Heart Rhythm Institute, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | - Arjun K Aggarwal
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Madhav Krishna Kumar Nair
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
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3
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Gómez-Viquez NL, Balderas-Villalobos J, Bello-Sánchez MD, Mayorga-Luna M, Mailloux-Salinas P, García-Castañeda M, Ríos-Pérez EB, Mártinez-Ávila MA, Camacho-Castillo LDC, Bravo G, Ávila G, Altamirano J, Carvajal K. Oxidative stress in early metabolic syndrome impairs cardiac RyR2 and SERCA2a activity and modifies the interplay of these proteins during Ca 2+ waves. Arch Physiol Biochem 2023; 129:1058-1070. [PMID: 33689540 DOI: 10.1080/13813455.2021.1895224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/19/2021] [Indexed: 10/21/2022]
Abstract
We investigated how oxidative stress (OS) alters Ca2+ handling in ventricular myocytes in early metabolic syndrome (MetS) in sucrose-fed rats. The effects of N-acetyl cysteine (NAC) or dl-Dithiothreitol (DTT) on systolic Ca2+ transients (SCaTs), diastolic Ca2+ sparks (CaS) and Ca2+ waves (CaW), recorded by confocal techniques, and L-type Ca2+ current (ICa), assessed by whole-cell patch clamp, were evaluated in MetS and Control cells. MetS myocytes exhibited decreased SCaTs and CaS frequency but unaffected CaW propagation. In Control cells, NAC/DTT reduced RyR2/SERCA2a activity blunting SCaTs, CaS frequency and CaW propagation, suggesting that basal ROS optimised Ca2+ signalling by maintaining RyR2/SERCA2a function and that these proteins facilitate CaW propagation. Conversely, NAC/DTT in MetS recovered RyR2/SERCA2a function, improving SCaTs and CaS frequency, but unexpectedly decreasing CaW propagation. We hypothesised that OS decreases RyR2/SERCA2a activity at early MetS, and while decreased SERCA2a favours CaW propagation, diminished RyR2 restrains it.
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Affiliation(s)
- Norma Leticia Gómez-Viquez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Jaime Balderas-Villalobos
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
- Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Ciudad de México, México
| | - Ma Dolores Bello-Sánchez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Maritza Mayorga-Luna
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Patrick Mailloux-Salinas
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Maricela García-Castañeda
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Erick Benjamín Ríos-Pérez
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | | | | | - Guadalupe Bravo
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Guillermo Ávila
- Departamento de Bioquímica, Centro de Investigación y de Estudios Avanzados-Instituto Politécnico Nacional, Ciudad de México, México
| | - Julio Altamirano
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, México
| | - Karla Carvajal
- Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Ciudad de México, México
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4
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Sharma AK, Singh S, Bhat M, Gill K, Zaid M, Kumar S, Shakya A, Tantray J, Jose D, Gupta R, Yangzom T, Sharma RK, Sahu SK, Rathore G, Chandolia P, Singh M, Mishra A, Raj S, Gupta A, Agarwal M, Kifayat S, Gupta A, Gupta P, Vashist A, Vaibhav P, Kathuria N, Yadav V, Singh RP, Garg A. New drug discovery of cardiac anti-arrhythmic drugs: insights in animal models. Sci Rep 2023; 13:16420. [PMID: 37775650 PMCID: PMC10541452 DOI: 10.1038/s41598-023-41942-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/04/2023] [Indexed: 10/01/2023] Open
Abstract
Cardiac rhythm regulated by micro-macroscopic structures of heart. Pacemaker abnormalities or disruptions in electrical conduction, lead to arrhythmic disorders may be benign, typical, threatening, ultimately fatal, occurs in clinical practice, patients on digitalis, anaesthesia or acute myocardial infarction. Both traditional and genetic animal models are: In-vitro: Isolated ventricular Myocytes, Guinea pig papillary muscles, Patch-Clamp Experiments, Porcine Atrial Myocytes, Guinea pig ventricular myocytes, Guinea pig papillary muscle: action potential and refractory period, Langendorff technique, Arrhythmia by acetylcholine or potassium. Acquired arrhythmia disorders: Transverse Aortic Constriction, Myocardial Ischemia, Complete Heart Block and AV Node Ablation, Chronic Tachypacing, Inflammation, Metabolic and Drug-Induced Arrhythmia. In-Vivo: Chemically induced arrhythmia: Aconitine antagonism, Digoxin-induced arrhythmia, Strophanthin/ouabain-induced arrhythmia, Adrenaline-induced arrhythmia, and Calcium-induced arrhythmia. Electrically induced arrhythmia: Ventricular fibrillation electrical threshold, Arrhythmia through programmed electrical stimulation, sudden coronary death in dogs, Exercise ventricular fibrillation. Genetic Arrhythmia: Channelopathies, Calcium Release Deficiency Syndrome, Long QT Syndrome, Short QT Syndrome, Brugada Syndrome. Genetic with Structural Heart Disease: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia, Dilated Cardiomyopathy, Hypertrophic Cardiomyopathy, Atrial Fibrillation, Sick Sinus Syndrome, Atrioventricular Block, Preexcitation Syndrome. Arrhythmia in Pluripotent Stem Cell Cardiomyocytes. Conclusion: Both traditional and genetic, experimental models of cardiac arrhythmias' characteristics and significance help in development of new antiarrhythmic drugs.
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Affiliation(s)
- Ashish Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India.
| | - Shivam Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mehvish Bhat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Kartik Gill
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohammad Zaid
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sachin Kumar
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anjali Shakya
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Junaid Tantray
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Divyamol Jose
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rashmi Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Tsering Yangzom
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Rajesh Kumar Sharma
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | | | - Gulshan Rathore
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Priyanka Chandolia
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mithilesh Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anurag Mishra
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Shobhit Raj
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Archita Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Mohit Agarwal
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Sumaiya Kifayat
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Anamika Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Prashant Gupta
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ankit Vashist
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Parth Vaibhav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Nancy Kathuria
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Vipin Yadav
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Ravindra Pal Singh
- NIMS Institute of Pharmacy, NIMS University Rajasthan, Jaipur, Rajasthan, 303121, India
| | - Arun Garg
- MVN University, Palwal, Haryana, India
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5
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Fowler ED, Wang N, Hezzell MJ, Chanoit G, Hancox JC, Cannell MB. Improved Ca 2+ release synchrony following selective modification of I tof and phase 1 repolarization in normal and failing ventricular myocytes. J Mol Cell Cardiol 2022; 172:52-62. [PMID: 35908686 DOI: 10.1016/j.yjmcc.2022.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 12/14/2022]
Abstract
Loss of ventricular action potential (AP) early phase 1 repolarization may contribute to the impaired Ca2+ release and increased risk of sudden cardiac death in heart failure. Therefore, restoring AP phase 1 by augmenting the fast transient outward K+ current (Itof) might be beneficial, but direct experimental evidence to support this proposition in failing cardiomyocytes is limited. Dynamic clamp was used to selectively modulate the contribution of Itof to the AP and Ca2+ transient in both normal (guinea pig and rabbit) and in failing rabbit cardiac myocytes. Opposing native Itof in non-failing rabbit myocytes increased Ca2+ release heterogeneity, late Ca2+ sparks (LCS) frequency and AP duration. (APD). In contrast, increasing Itof in failing myocytes and guinea pig myocytes (the latter normally lacking Itof) increased Ca2+ transient amplitude, Ca2+ release synchrony, and shortened APD. Computer simulations also showed faster Ca2+ transient decay (mainly due to fewer LCS), decreased inward Na+/Ca2+ exchange current and APD. When the Itof conductance was increased to ~0.2 nS/pF in failing cells (a value slightly greater than seen in typical human epicardial myocytes), Ca2+ release synchrony improved and AP duration decreased slightly. Further increases in Itof can cause Ca2+ release to decrease as the peak of the bell-shaped ICa-voltage relationship is passed and premature AP repolarization develops. These results suggest that there is an optimal range for Itof enhancement that may support Ca2+ release synchrony and improve electrical stability in heart failure with the caveat that uncontrolled Itof enhancement should be avoided.
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Affiliation(s)
- Ewan D Fowler
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Nan Wang
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Melanie J Hezzell
- University of Bristol Veterinary School, Langford, Bristol BS40 5DU, UK
| | - Guillaume Chanoit
- University of Bristol Veterinary School, Langford, Bristol BS40 5DU, UK
| | - Jules C Hancox
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Mark B Cannell
- School of Physiology, Pharmacology & Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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6
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Blackwell DJ, Schmeckpeper J, Knollmann BC. Animal Models to Study Cardiac Arrhythmias. Circ Res 2022; 130:1926-1964. [PMID: 35679367 DOI: 10.1161/circresaha.122.320258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.
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Affiliation(s)
- Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Jeffrey Schmeckpeper
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
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7
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Synchronizing systolic calcium release with azumolene in an experimental model. Heart Rhythm O2 2022; 3:568-576. [PMID: 36340488 PMCID: PMC9626747 DOI: 10.1016/j.hroo.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background Post-defibrillation myocardial contractile dysfunction adversely affects the survival of patients after cardiac arrest. Attenuation of diastolic calcium (Ca2+) overload by stabilization of the cardiac ryanodine receptor (RyR2) is found to reduce refibrillation after long-duration ventricular fibrillation (LDVF). Objective In the present study, we explored the effects of RyR2 stabilization by azumolene on systolic Ca2+ release synchrony and myocardial contractility. Methods After completion of baseline optical mapping, Langendorff-perfused rabbit hearts were subjected to global ischemia followed by reperfusion with azumolene or deionized distilled water (vehicle). Following reperfusion, LDVF was induced with burst pacing. In the first series of experiments (n = 16), epicardial Ca2+ transient was analyzed for Ca2+ transient amplitude alternans and dispersion of Ca2+ transient amplitude alternans index (CAAI). In the second series of experiments following the same protocol (n = 12), ventricular contractility was assessed by measuring the left ventricular pressure. Results Ischemic LDVF led to greater CAAI (0.06 ± 0.02 at baseline vs 0.12 ± 0.02 post-LDVF, P < .01) and magnitude of dispersion of CAAI (0.04 ± 0.01 vs 0.09 ± 0.01, P < .01) in control hearts. In azumolene-treated hearts, no significant changes in CAAI (0.05 ± 0.01 vs 0.05 ± 0.01, P = .84) and dispersion of CAAI (0.04 ± 0.01 vs 0.04 ± 0.01, P = .99) were noted following ischemic LDVF. Ischemic LDVF was associated with reduction in left ventricular developed pressure (100% vs 36.8% ± 6.1%, P = .002) and dP/dtmax (100% vs 45.3% ± 6.5%, P = .003) in control hearts, but these reductions were mitigated (left ventricular developed pressure: 100% vs 74.0% ± 8.1%, P = .052, dP/dtmax: 100% vs 80.8% ± 7.9%, P = .09) in azumolene-treated hearts. Conclusion Treatment with azumolene is associated with improvement of systolic Ca2+ release synchrony and myocardial contractility following ischemic LDVF.
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8
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Louch WE, Perdreau-Dahl H, Edwards AG. Image-Driven Modeling of Nanoscopic Cardiac Function: Where Have We Come From, and Where Are We Going? Front Physiol 2022; 13:834211. [PMID: 35356084 PMCID: PMC8959215 DOI: 10.3389/fphys.2022.834211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/24/2022] Open
Abstract
Complementary developments in microscopy and mathematical modeling have been critical to our understanding of cardiac excitation–contraction coupling. Historically, limitations imposed by the spatial or temporal resolution of imaging methods have been addressed through careful mathematical interrogation. Similarly, limitations imposed by computational power have been addressed by imaging macroscopic function in large subcellular domains or in whole myocytes. As both imaging resolution and computational tractability have improved, the two approaches have nearly merged in terms of the scales that they can each be used to interrogate. With this review we will provide an overview of these advances and their contribution to understanding ventricular myocyte function, including exciting developments over the last decade. We specifically focus on experimental methods that have pushed back limits of either spatial or temporal resolution of nanoscale imaging (e.g., DNA-PAINT), or have permitted high resolution imaging on large cellular volumes (e.g., serial scanning electron microscopy). We also review the progression of computational approaches used to integrate and interrogate these new experimental data sources, and comment on near-term advances that may unify understanding of the underlying biology. Finally, we comment on several outstanding questions in cardiac physiology that stand to benefit from a concerted and complementary application of these new experimental and computational methods.
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Affiliation(s)
- William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Harmonie Perdreau-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Andrew G. Edwards
- Simula Research Laboratory, Lysaker, Norway
- *Correspondence: Andrew G. Edwards,
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9
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Jeon YK, Kwon JW, Jang J, Choi SW, Woo J, Cho SH, Yu BI, Chun YS, Youm JB, Zhang YH, Kim SJ. Lower troponin expression in the right ventricle of rats explains interventricular differences in E-C coupling. J Gen Physiol 2022; 154:212990. [PMID: 35099502 PMCID: PMC8823606 DOI: 10.1085/jgp.202112949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 01/06/2022] [Indexed: 12/12/2022] Open
Abstract
Despite distinctive functional and anatomic differences, a precise understanding of the cardiac interventricular differences in excitation–contraction (E–C) coupling mechanisms is still lacking. Here, we directly compared rat right and left cardiomyocytes (RVCM and LVCM). Whole-cell patch clamp, the IonOptix system, and fura-2 fluorimetry were used to measure electrical properties (action potential and ionic currents), single-cell contractility, and cytosolic Ca2+ ([Ca2+]i), respectively. Myofilament proteins were analyzed by immunoblotting. RVCM showed significantly shorter action potential duration (APD) and higher density of transient outward K+ current (Ito). However, the triggered [Ca2+]i change (Ca2+ transient) was not different, while the decay rate of the Ca2+ transient was slower in RVCM. Although the relaxation speed was also slower, the sarcomere shortening amplitude (ΔSL) was smaller in RVCM. SERCA activity was ∼60% lower in RVCM, which is partly responsible for the slower decay of the Ca2+ transient. Immunoblot analysis revealed lower expression of the cardiac troponin complex (cTn) in RVCM, implying a smaller Ca2+ buffering capacity (κS), which was proved by in situ analysis. The introduction of these new levels of cTn, Ito, and SERCA into a mathematical model of rat LVCM reproduced the similar Ca2+ transient, slower Ca2+ decay, shorter APD, and smaller ΔSL of RVCM. Taken together, these data show reduced expression of cTn proteins in the RVCM, which provides an explanation for the interventricular difference in the E–C coupling kinetics.
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Affiliation(s)
- Young Keul Jeon
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae Won Kwon
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jihyun Jang
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Surgery, Center for Vascular and Inflammatory Disease, University of Maryland School of Medicine, Baltimore, MD
| | - Seong Woo Choi
- Department of Physiology and Ion Channel Disease Research Center, Dongguk University College of Medicine, Seoul, Republic of Korea.,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Joohan Woo
- Department of Physiology and Ion Channel Disease Research Center, Dongguk University College of Medicine, Seoul, Republic of Korea
| | - Su Han Cho
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Byeong Il Yu
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Yang Sook Chun
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae Boum Youm
- Cardiovascular and Metabolic Disease Center, Department of Physiology, College of Medicine, Inje University, Busan, Republic of Korea
| | - Yin Hua Zhang
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.,Yanbian University Hospital, Yanji, China.,Institute of Cardiovascular Sciences, Faculty of Biology, Medicine and Health Sciences, University of Manchester, Manchester, UK
| | - Sung Joon Kim
- Department of Physiology, Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.,Wide River Institute of Immunology, Seoul National University College of Medicine, Hongcheon, Republic of Korea
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10
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Inducing I to,f and phase 1 repolarization of the cardiac action potential with a Kv4.3/KChIP2.1 bicistronic transgene. J Mol Cell Cardiol 2021; 164:29-41. [PMID: 34823101 PMCID: PMC8884339 DOI: 10.1016/j.yjmcc.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/22/2021] [Accepted: 11/11/2021] [Indexed: 11/22/2022]
Abstract
The fast transient outward potassium current (Ito,f) plays a key role in phase 1 repolarization of the human cardiac action potential (AP) and its reduction in heart failure (HF) contributes to the loss of contractility. Therefore, restoring Ito,f might be beneficial for treating HF. The coding sequence of a P2A peptide was cloned, in frame, between Kv4.3 and KChIP2.1 genes and ribosomal skipping was confirmed by Western blotting. Typical Ito,f properties with slowed inactivation and accelerated recovery from inactivation due to the association of KChIP2.1 with Kv4.3 was seen in transfected HEK293 cells. Both bicistronic components trafficked to the plasmamembrane and in adenovirus transduced rabbit cardiomyocytes both t-tubular and sarcolemmal construct labelling appeared. The resulting current was similar to Ito,f seen in human ventricular cardiomyocytes and was 50% blocked at ~0.8 mmol/l 4-aminopyridine and increased ~30% by 5 μmol/l NS5806 (an Ito,f agonist). Variation in the density of the expressed Ito,f, in rabbit cardiomyocytes recapitulated typical species-dependent variations in AP morphology. Simultaneous voltage recording and intracellular Ca2+ imaging showed that modification of phase 1 to a non-failing human phenotype improved the rate of rise and magnitude of the Ca2+ transient. Ito,f expression also reduced AP triangulation but did not affect ICa,L and INa magnitudes. This raises the possibility for a new gene-based therapeutic approach to HF based on selective phase 1 modification. Action potential phase 1 depends on fast transient outward current (Ito,f). Construction of a bicistronic transgene for Kv4.3 and KChIP2.1 with P2A separator Expressed bicistronic Kv4.3/KChIP2.1 proteins traffic to the cell surface membrane Viral transduction with Kv4.3/KChIP2.1 increases Ito,f in cardiomyocytes. Kv4.3/KChIP2.1 transgene expression increased AP phase 1 and EC coupling
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11
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Arslanova A, Shafaattalab S, Lin E, Barszczewski T, Hove-Madsen L, Tibbits GF. Investigating inherited arrhythmias using hiPSC-derived cardiomyocytes. Methods 2021; 203:542-557. [PMID: 34197925 DOI: 10.1016/j.ymeth.2021.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 10/21/2022] Open
Abstract
Fundamental to the functional behavior of cardiac muscle is that the cardiomyocytes are integrated as a functional syncytium. Disrupted electrical activity in the cardiac tissue can lead to serious complications including cardiac arrhythmias. Therefore, it is important to study electrophysiological properties of the cardiac tissue. With advancements in stem cell research, protocols for the production of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been established, providing great potential in modelling cardiac arrhythmias and drug testing. The hiPSC-CM model can be used in conjunction with electrophysiology-based platforms to examine the electrical activity of the cardiac tissue. Techniques for determining the myocardial electrical activity include multielectrode arrays (MEAs), optical mapping (OM), and patch clamping. These techniques provide critical approaches to investigate cardiac electrical abnormalities that underlie arrhythmias.
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Affiliation(s)
- Alia Arslanova
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser, University, Burnaby, BC V5A 1S6, Canada; hiPSC-CM Research Team, British Columbia Children's Hospital Research Institute, Vancouver, BC V5Z4H4, Canada
| | - Sanam Shafaattalab
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser, University, Burnaby, BC V5A 1S6, Canada; hiPSC-CM Research Team, British Columbia Children's Hospital Research Institute, Vancouver, BC V5Z4H4, Canada
| | - Eric Lin
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser, University, Burnaby, BC V5A 1S6, Canada
| | - Tiffany Barszczewski
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser, University, Burnaby, BC V5A 1S6, Canada; hiPSC-CM Research Team, British Columbia Children's Hospital Research Institute, Vancouver, BC V5Z4H4, Canada
| | - Leif Hove-Madsen
- Cardiac Rhythm and Contraction Group, IIBB-CSIC, Hospital de la Santa Creu i Sant Pau, Barcelona 08041, Spain; CIBERCV, Hospital de la Santa Creu i Sant Pau, Barcelona 08041, Spain; IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona 08041, Spain
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser, University, Burnaby, BC V5A 1S6, Canada; hiPSC-CM Research Team, British Columbia Children's Hospital Research Institute, Vancouver, BC V5Z4H4, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
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12
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Gross P, Johnson J, Romero CM, Eaton DM, Poulet C, Sanchez-Alonso J, Lucarelli C, Ross J, Gibb AA, Garbincius JF, Lambert J, Varol E, Yang Y, Wallner M, Feldsott EA, Kubo H, Berretta RM, Yu D, Rizzo V, Elrod J, Sabri A, Gorelik J, Chen X, Houser SR. Interaction of the Joining Region in Junctophilin-2 With the L-Type Ca 2+ Channel Is Pivotal for Cardiac Dyad Assembly and Intracellular Ca 2+ Dynamics. Circ Res 2021; 128:92-114. [PMID: 33092464 PMCID: PMC7790862 DOI: 10.1161/circresaha.119.315715] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RATIONALE Ca2+-induced Ca2+ release (CICR) in normal hearts requires close approximation of L-type calcium channels (LTCCs) within the transverse tubules (T-tubules) and RyR (ryanodine receptors) within the junctional sarcoplasmic reticulum. CICR is disrupted in cardiac hypertrophy and heart failure, which is associated with loss of T-tubules and disruption of cardiac dyads. In these conditions, LTCCs are redistributed from the T-tubules to disrupt CICR. The molecular mechanism responsible for LTCCs recruitment to and from the T-tubules is not well known. JPH (junctophilin) 2 enables close association between T-tubules and the junctional sarcoplasmic reticulum to ensure efficient CICR. JPH2 has a so-called joining region that is located near domains that interact with T-tubular plasma membrane, where LTCCs are housed. The idea that this joining region directly interacts with LTCCs and contributes to LTCC recruitment to T-tubules is unknown. OBJECTIVE To determine if the joining region in JPH2 recruits LTCCs to T-tubules through direct molecular interaction in cardiomyocytes to enable efficient CICR. METHODS AND RESULTS Modified abundance of JPH2 and redistribution of LTCC were studied in left ventricular hypertrophy in vivo and in cultured adult feline and rat ventricular myocytes. Protein-protein interaction studies showed that the joining region in JPH2 interacts with LTCC-α1C subunit and causes LTCCs distribution to the dyads, where they colocalize with RyRs. A JPH2 with induced mutations in the joining region (mutPG1JPH2) caused T-tubule remodeling and dyad loss, showing that an interaction between LTCC and JPH2 is crucial for T-tubule stabilization. mutPG1JPH2 caused asynchronous Ca2+-release with impaired excitation-contraction coupling after β-adrenergic stimulation. The disturbed Ca2+ regulation in mutPG1JPH2 overexpressing myocytes caused calcium/calmodulin-dependent kinase II activation and altered myocyte bioenergetics. CONCLUSIONS The interaction between LTCC and the joining region in JPH2 facilitates dyad assembly and maintains normal CICR in cardiomyocytes.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism
- Cats
- Cells, Cultured
- Disease Models, Animal
- Excitation Contraction Coupling
- Humans
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Kinetics
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/pathology
- Muscle Proteins/genetics
- Muscle Proteins/metabolism
- Mutation
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Organelle Biogenesis
- Protein Binding
- Protein Interaction Domains and Motifs
- Rats, Sprague-Dawley
- Ryanodine Receptor Calcium Release Channel
- Rats
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Affiliation(s)
- Polina Gross
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Jaslyn Johnson
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Carlos M. Romero
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Deborah M. Eaton
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Claire Poulet
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Jose Sanchez-Alonso
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Carla Lucarelli
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Jean Ross
- Bioimaging Center Research, Delaware Biotechnology Institute, Newark
| | - Andrew A. Gibb
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Joanne F. Garbincius
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Jonathan Lambert
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Erdem Varol
- Columbia University, Center for Theoretical Neuroscience, Department of Statistics, New York, NY
| | - Yijun Yang
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Markus Wallner
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
- Medical University of Graz, Division of Cardiology, Graz, Austria
- Center for Biomarker Research in Medicine, CBmed GmbH, Graz, Austria
| | - Eric A. Feldsott
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Hajime Kubo
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Remus M. Berretta
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Daohai Yu
- Clinical Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia
| | - Victor Rizzo
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - John Elrod
- Lewis Katz Temple University School of Medicine, Center for Translational Medicine, Department of Pharmacology, Philadelphia
| | - Abdelkarim Sabri
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Julia Gorelik
- Imperial College London, Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, London
| | - Xiongwen Chen
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
| | - Steven R. Houser
- Lewis Katz Temple University School of Medicine, Cardiovascular Research Center, Department of Physiology, Philadelphia
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13
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Celestino-Montes A, Pérez-Treviño P, Sandoval-Herrera MD, Gómez-Víquez NL, Altamirano J. Relative role of T-tubules disruption and decreased SERCA2 on contractile dynamics of isolated rat ventricular myocytes. Life Sci 2021; 264:118700. [PMID: 33130073 DOI: 10.1016/j.lfs.2020.118700] [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: 07/13/2020] [Revised: 10/25/2020] [Accepted: 10/28/2020] [Indexed: 10/23/2022]
Abstract
AIMS Ventricular myocytes (VM) depolarization activates L-type Ca2+ channels (LCC) allowing Ca2+ influx (ICa) to synchronize sarcoplasmic reticulum (SR) Ca2+ release, via Ca2+-release channels (RyR2). The resulting whole-cell Ca2+ transient triggers contraction, while cytosolic Ca2+ removal by SR Ca2+ pump (SERCA2) and sarcolemmal Na+/Ca2+ exchanger (NCX) allows relaxation. In diseased hearts, extensive VM remodeling causes heterogeneous, blunted and slow Ca2+ transients. Among remodeling changes are: A) T-tubules disorganization. B) Diminished SERCA2 and low SR Ca2+. However, those often overlap, hindering their relative contribution to contractile dysfunction (CD). Furthermore, few studies have assessed their specific impact on the spatiotemporal Ca2+ transient properties and contractile dynamics simultaneously. Therefore, we sought to perform a quantitative comparison of how heterogeneous and slow Ca2+ transients, with different underlying determinants, affect contractile performance. METHODS We used two experimental models: A) formamide-induced acute "detubulation", where VM retain functional RyR2 and SERCA2, but lack T-tubules-associated LCC and NCX. B) Intact VM from hypothyroid rats, presenting decreased SERCA2 and SR Ca2+, but maintained T-tubules. By confocal imaging of Fluo-4-loaded VM, under field-stimulation, simultaneously acquired Ca2+ transients and shortening, allowing direct correlations. KEY FINDINGS We found near-linear correlations among key parameters of altered Ca2+ transients, caused independently by T-tubules disruption or decreased SR Ca2+, and shortening and relaxation, SIGNIFICANCE: Unrelated structural and molecular alterations converge in similarly abnormal Ca2+ transients and CD, highlighting the importance of independently reproduce disease-specific alterations, to quantitatively assess their impact on Ca2+ signaling and contractility, which would be valuable to determine potential disease-specific therapeutic targets.
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Affiliation(s)
- Antonio Celestino-Montes
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto No. 3000 Pte., Monterrey, N.L. 64710, Mexico
| | - Perla Pérez-Treviño
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto No. 3000 Pte., Monterrey, N.L. 64710, Mexico
| | - Maya D Sandoval-Herrera
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto No. 3000 Pte., Monterrey, N.L. 64710, Mexico
| | - Norma L Gómez-Víquez
- Departamento de Farmacobiologia, CINVESTAV-IPN sede Sur, Mexico, D.F. 14330, Mexico
| | - Julio Altamirano
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto No. 3000 Pte., Monterrey, N.L. 64710, Mexico.
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14
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Yang HQ, Zhou P, Wang LP, Zhao YT, Ren YJ, Guo YB, Xu M, Wang SQ. Compartmentalized β1-adrenergic signalling synchronizes excitation-contraction coupling without modulating individual Ca2+ sparks in healthy and hypertrophied cardiomyocytes. Cardiovasc Res 2020; 116:2069-2080. [PMID: 32031586 DOI: 10.1093/cvr/cvaa013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/20/2019] [Accepted: 01/30/2020] [Indexed: 12/21/2022] Open
Abstract
AIMS β-adrenergic receptors (βARs) play pivotal roles in regulating cardiac excitation-contraction (E-C) coupling. Global signalling of β1ARs up-regulates both the influx of Ca2+ through sarcolemmal L-type Ca2+ channels (LCCs) and the release of Ca2+ from the sarcoplasmic reticulum (SR) through the ryanodine receptors (RyRs). However, we recently found that β2AR stimulation meditates 'offside compartmentalization', confining β1AR signalling into subsarcolemmal nanodomains without reaching SR proteins. In the present study, we aim to investigate the new question, whether and how compartmentalized β1AR signalling regulates cardiac E-C coupling. METHODS AND RESULTS By combining confocal Ca2+ imaging and patch-clamp techniques, we investigated the effects of compartmentalized βAR signalling on E-C coupling at both cellular and molecular levels. We found that simultaneous activation of β2 and β1ARs, in contrast to global signalling of β1ARs, modulated neither the amplitude and spatiotemporal properties of Ca2+ sparks nor the kinetics of the RyR response to LCC Ca2+ sparklets. Nevertheless, by up-regulating LCC current, compartmentalized β1AR signalling synchronized RyR Ca2+ release and increased the functional reserve (stability margin) of E-C coupling. In circumstances of briefer excitation durations or lower RyR responsivity, compartmentalized βAR signalling, by increasing the intensity of Ca2+ triggers, helped stabilize the performance of E-C coupling and enhanced the Ca2+ transient amplitude in failing heart cells. CONCLUSION Given that compartmentalized βAR signalling can be induced by stress-associated levels of catecholamines, our results revealed an important, yet unappreciated, heart regulation mechanism that is autoadaptive to varied stress conditions.
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Affiliation(s)
- Hua-Qian Yang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Peng Zhou
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Li-Peng Wang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Yan-Ting Zhao
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Yu-Jie Ren
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Yun-Bo Guo
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Ming Xu
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
| | - Shi-Qiang Wang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, 5 Yiheyuan Rd, Beijing 100871, China
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15
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Wacker C, Dams N, Schauer A, Ritzer A, Volk T, Wagner M. Region-specific mechanisms of corticosteroid-mediated inotropy in rat cardiomyocytes. Sci Rep 2020; 10:11604. [PMID: 32665640 PMCID: PMC7360564 DOI: 10.1038/s41598-020-68308-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/23/2020] [Indexed: 11/09/2022] Open
Abstract
Regional differences in ion channel activity in the heart control the sequence of repolarization and may contribute to differences in contraction. Corticosteroids such as aldosterone or corticosterone increase the L-type Ca2+ current (ICaL) in the heart via the mineralocorticoid receptor (MR). Here, we investigate the differential impact of corticosteroid-mediated increase in ICaL on action potentials (AP), ion currents, intracellular Ca2+ handling and contractility in endo- and epicardial myocytes of the rat left ventricle. Dexamethasone led to a similar increase in ICaL in endocardial and epicardial myocytes, while the K+ currents Ito and IK were unaffected. However, AP duration (APD) and AP-induced Ca2+ influx (QCa) significantly increased exclusively in epicardial myocytes, thus abrogating the normal differences between the groups. Dexamethasone increased Ca2+ transients, contractility and SERCA activity in both regions, the latter possibly due to a decrease in total phospholamban (PLB) and an increase PLBpThr17. These results suggest that corticosteroids are powerful modulators of ICaL, Ca2+ transients and contractility in both endo- and epicardial myocytes, while APD and QCa are increased in epicardial myocytes only. This indicates that increased ICaL and SERCA activity rather than QCa are the primary drivers of contractility by adrenocorticoids.
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Affiliation(s)
- Caroline Wacker
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Niklas Dams
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Alexander Schauer
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Anne Ritzer
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany
| | - Tilmann Volk
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany. .,Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
| | - Michael Wagner
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstraße 6, 91054, Erlangen, Germany. .,Abteilung für Rhythmologie, Herzzentrum Dresden, Fetscherstraße 76, 01307, Dresden, Germany.
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16
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Calloe K. Doctoral Dissertation: The transient outward potassium current in healthy and diseased hearts. Acta Physiol (Oxf) 2019; 225 Suppl 717:e13225. [PMID: 30628199 DOI: 10.1111/apha.13225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Kirstine Calloe
- Section for Anatomy; Biochemistry and Physiology; Department for Veterinary and Animal Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Frederiksberg C Denmark
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17
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Correll RN, Makarewich CA, Zhang H, Zhang C, Sargent MA, York AJ, Berretta RM, Chen X, Houser SR, Molkentin JD. Caveolae-localized L-type Ca2+ channels do not contribute to function or hypertrophic signalling in the mouse heart. Cardiovasc Res 2018; 113:749-759. [PMID: 28402392 DOI: 10.1093/cvr/cvx046] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 03/07/2017] [Indexed: 12/17/2022] Open
Abstract
Aims L-type Ca2+ channels (LTCCs) in adult cardiomyocytes are localized to t-tubules where they initiate excitation-contraction coupling. Our recent work has shown that a subpopulation of LTCCs found at the surface sarcolemma in caveolae of adult feline cardiomyocytes can also generate a Ca2+ microdomain that activates nuclear factor of activated T-cells signaling and cardiac hypertrophy, although the relevance of this paradigm to hypertrophy regulation in vivo has not been examined. Methods and results Here we generated heart-specific transgenic mice with a putative caveolae-targeted LTCC activator protein that was ineffective in initiating or enhancing cardiac hypertrophy in vivo. We also generated transgenic mice with cardiac-specific overexpression of a putative caveolae-targeted inhibitor of LTCCs, and while this protein inhibited caveolae-localized LTCCs without effects on global Ca2+ handling, it similarly had no effect on cardiac hypertrophy in vivo. Cardiac hypertrophy was elicited by pressure overload for 2 or 12 weeks or with neurohumoral agonist infusion. Caveolae-specific LTCC activator or inhibitor transgenic mice showed no greater change in nuclear factor of activated T-cells activity after 2 weeks of pressure overload stimulation compared with control mice. Conclusion Our results indicate that LTCCs in the caveolae microdomain do not affect cardiac function and are not necessary for the regulation of hypertrophic signaling in the adult mouse heart.
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Affiliation(s)
- Robert N Correll
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, 240 Albert Sabin Way, Cincinnati, OH 45229, USA
| | - Catherine A Makarewich
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Hongyu Zhang
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Chen Zhang
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Michelle A Sargent
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, 240 Albert Sabin Way, Cincinnati, OH 45229, USA
| | - Allen J York
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, 240 Albert Sabin Way, Cincinnati, OH 45229, USA
| | - Remus M Berretta
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Xiongwen Chen
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Steven R Houser
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Jeffery D Molkentin
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati, 240 Albert Sabin Way, Cincinnati, OH 45229, USA.,Department of Pediatrics, Howard Hughes Medical Institute, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, Cincinnati, OH 45229-3039, USA
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18
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Abstract
PURPOSE OF REVIEW Membrane invaginations called t-tubules play an integral role in triggering cardiomyocyte contraction, and their disruption during diseases such as heart failure critically impairs cardiac performance. In this review, we outline the growing understanding of the malleability of t-tubule structure and function, and highlight emerging t-tubule regulators which may be exploited for novel therapies. RECENT FINDINGS New technologies are revealing the nanometer scale organization of t-tubules, and their functional junctions with the sarcoplasmic reticulum called dyads, which generate Ca2+ sparks. Recent data have indicated that the dyadic anchoring protein junctophilin-2, and the membrane-bending protein BIN1 are key regulators of dyadic formation and maintenance. While the underlying signals which control expression and localization of these proteins remain unclear, accumulating data support an important role of myocardial workload. Although t-tubule alterations are believed to be a key cause of heart failure, the plasticity of these structures also creates an opportunity for therapy. Promising recent data suggest that such therapies may specifically target junctophilin-2, BIN1, and/or mechanotransduction.
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19
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Troupes CD, Wallner M, Borghetti G, Zhang C, Mohsin S, von Lewinski D, Berretta RM, Kubo H, Chen X, Soboloff J, Houser S. Role of STIM1 (Stromal Interaction Molecule 1) in Hypertrophy-Related Contractile Dysfunction. Circ Res 2017; 121:125-136. [PMID: 28592415 DOI: 10.1161/circresaha.117.311094] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/02/2017] [Accepted: 06/07/2017] [Indexed: 12/20/2022]
Abstract
RATIONALE Pathological increases in cardiac afterload result in myocyte hypertrophy with changes in myocyte electrical and mechanical phenotype. Remodeling of contractile and signaling Ca2+ occurs in pathological hypertrophy and is central to myocyte remodeling. STIM1 (stromal interaction molecule 1) regulates Ca2+ signaling in many cell types by sensing low endoplasmic reticular Ca2+ levels and then coupling to plasma membrane Orai channels to induce a Ca2+ influx pathway. Previous reports suggest that STIM1 may play a role in cardiac hypertrophy, but its role in electrical and mechanical phenotypic alterations is not well understood. OBJECTIVE To define the contributions of STIM1-mediated Ca2+ influx on electrical and mechanical properties of normal and diseased myocytes, and to determine whether Orai channels are obligatory partners for STIM1 in these processes using a clinically relevant large animal model of hypertrophy. METHODS AND RESULTS Cardiac hypertrophy was induced by slow progressive pressure overload in adult cats. Hypertrophied myocytes had increased STIM1 expression and activity, which correlated with altered Ca2+-handling and action potential (AP) prolongation. Exposure of hypertrophied myocytes to the Orai channel blocker BTP2 caused a reduction of AP duration and reduced diastolic Ca2+ spark rate. BTP2 had no effect on normal myocytes. Forced expression of STIM1 in cultured adult feline ventricular myocytes increased diastolic spark rate and prolonged AP duration. STIM1 expression produced an increase in the amount of Ca2+ stored within the sarcoplasmic reticulum and activated Ca2+/calmodulin-dependent protein kinase II. STIM1 expression also increased spark rates and induced spontaneous APs. STIM1 effects were eliminated by either BTP2 or by coexpression of a dominant negative Orai construct. CONCLUSIONS STIM1 can associate with Orai in cardiac myocytes to produce a Ca2+ influx pathway that can prolong the AP duration and load the sarcoplasmic reticulum and likely contributes to the altered electromechanical properties of the hypertrophied heart.
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Affiliation(s)
- Constantine D Troupes
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Markus Wallner
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Giulia Borghetti
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Chen Zhang
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Sadia Mohsin
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Dirk von Lewinski
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Remus M Berretta
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Hajime Kubo
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Xiongwen Chen
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Jonathan Soboloff
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Steven Houser
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.).
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Abstract
Unique to striated muscle cells, transverse tubules (t-tubules) are membrane organelles that consist of sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network. Mature t-tubule networks are found in mammalian ventricular cardiomyocytes, with the transverse components of t-tubules occurring near sarcomeric z-discs. Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain. Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts.
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Affiliation(s)
- TingTing Hong
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
| | - Robin M Shaw
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California; and Department of Medicine, University of California Los Angeles, Los Angeles, California
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22
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Roe AT, Frisk M, Louch WE. Targeting cardiomyocyte Ca2+ homeostasis in heart failure. Curr Pharm Des 2015; 21:431-48. [PMID: 25483944 PMCID: PMC4475738 DOI: 10.2174/138161282104141204124129] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 08/06/2014] [Indexed: 12/19/2022]
Abstract
Improved treatments for heart failure patients will require the development of novel therapeutic strategies that target basal disease
mechanisms. Disrupted cardiomyocyte Ca2+ homeostasis is recognized as a major contributor to the heart failure phenotype, as it
plays a key role in systolic and diastolic dysfunction, arrhythmogenesis, and hypertrophy and apoptosis signaling. In this review, we outline
existing knowledge of the involvement of Ca2+ homeostasis in these deficits, and identify four promising targets for therapeutic intervention:
the sarcoplasmic reticulum Ca2+ ATPase, the Na+-Ca2+ exchanger, the ryanodine receptor, and t-tubule structure. We discuss
experimental data indicating the applicability of these targets that has led to recent and ongoing clinical trials, and suggest future therapeutic
approaches.
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Affiliation(s)
| | | | - William E Louch
- Institute for Experimental Medical Research, Kirkeveien 166, 4.etg. Bygg 7, Oslo University Hospital Ullevål, 0407 Oslo, Norway.
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23
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Zhi-Bin H, Chang F, Mao-Huan L, Gui-Yi Y, Shu-Xian Z, Wei W. Valsartan improves the electrophysiological characteristics of left ventricular hypertrophic myocardium in spontaneously hypertensive rats. Hypertens Res 2014; 37:824-9. [DOI: 10.1038/hr.2014.85] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 01/29/2014] [Accepted: 03/20/2014] [Indexed: 11/09/2022]
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24
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Huang ZB, Fang C, Lin MH, Yuan GY, Zhou SX, Wu W. Effect of fosinopril on the transient outward potassium current of hypertrophied left ventricular myocardium in the spontaneously hypertensive rat. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2014; 387:419-25. [PMID: 24441766 DOI: 10.1007/s00210-014-0956-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/02/2014] [Indexed: 11/26/2022]
Abstract
To investigate fosinopril's effect on the transient outward potassium current (Ito) of differing degrees of hypertrophied myocytes in the spontaneously hypertensive rat (SHR). Ten- and 24-week-old SHRs were used as models for cardiac hypertrophy. Hypertrophied ventricular myocytes were exposed to 1, 10, and 100 μmol/L fosinopril; the whole-cell patch-clamp technique was used to study the effects on the transient outward potassium current. Ito current density was decreased in SHR myocytes relative to controls (14.17 ± 0.31 and 11.62 ± 0.08 pA/pF in 10- and 24-week-old SHR versus 16.73 ± 0.15 pA/pF, p < 0.01). Higher concentrations of fosinopril (10 and 100 μmol/L) increased Ito peak current density in 10-week-old SHR myocytes compared with controls (14.92 ± 0.14 and 15.27 ± 0.13 pA/pF versus 14.17 ± 0.31 pA/pF, p < 0.01). Fosinopril increased Ito peak current density in 24-week-old SHR myocytes at all doses (12.70 ± 0.07, 13.74 ± 0.10, and 14.53 ± 0.13 versus 11.62 ± 0.08 pA/pF for controls, p < 0.01). Fosinopril had a greater Ito elevation potential on hypertrophied myocytes in 24-week-old compared with 10-week-old SHR for each dose (1.08 ± 0.09 versus 0.37 ± 0.26 pA/pF, p < 0.01; 2.13 ± 0.05 versus 0.75 ± 0.35 pA/pF, p < 0.01; 2.92 ± 0.07 versus 1.10 ± 0.40 pA/pF, p < 0.01). Fosinopril increased Ito current density in hypertrophied myocytes. This effect was more pronounced in myocytes with a greater degree of hypertrophy.
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Affiliation(s)
- Zhi-Bin Huang
- Department of Cardiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China
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25
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Ferrantini C, Crocini C, Coppini R, Vanzi F, Tesi C, Cerbai E, Poggesi C, Pavone FS, Sacconi L. The transverse-axial tubular system of cardiomyocytes. Cell Mol Life Sci 2013; 70:4695-710. [PMID: 23846763 PMCID: PMC11113601 DOI: 10.1007/s00018-013-1410-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/03/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
Abstract
A characteristic histological feature of striated muscle cells is the presence of deep invaginations of the plasma membrane (sarcolemma), most commonly referred to as T-tubules or the transverse-axial tubular system (TATS). TATS mediates the rapid spread of the electrical signal (action potential) to the cell core triggering Ca(2+) release from the sarcoplasmic reticulum, ultimately inducing myofilament contraction (excitation-contraction coupling). T-tubules, first described in vertebrate skeletal muscle cells, have also been recognized for a long time in mammalian cardiac ventricular myocytes, with a structure and a function that in recent years have been shown to be far more complex and pivotal for cardiac function than initially thought. Renewed interest in T-tubule function stems from the loss and disorganization of T-tubules found in a number of pathological conditions including human heart failure (HF) and dilated and hypertrophic cardiomyopathies, as well as in animal models of HF, chronic ischemia and atrial fibrillation. Disease-related remodeling of the TATS leads to asynchronous and inhomogeneous Ca(2+)-release, due to the presence of orphan ryanodine receptors that have lost their coupling with the dihydropyridine receptors and are either not activated or activated with a delay. Here, we review the physiology of the TATS, focusing first on the relationship between function and structure, and then describing T-tubular remodeling and its reversal in disease settings and following effective therapeutic approaches.
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Affiliation(s)
- C. Ferrantini
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - C. Crocini
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
| | - R. Coppini
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - F. Vanzi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Biology, University of Florence, Florence, Italy
| | - C. Tesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - E. Cerbai
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - C. Poggesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - F. S. Pavone
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
| | - L. Sacconi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
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26
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Synchrony of cardiomyocyte Ca(2+) release is controlled by T-tubule organization, SR Ca(2+) content, and ryanodine receptor Ca(2+) sensitivity. Biophys J 2013; 104:1685-97. [PMID: 23601316 DOI: 10.1016/j.bpj.2013.03.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 02/27/2013] [Accepted: 03/13/2013] [Indexed: 02/06/2023] Open
Abstract
Recent work has demonstrated that cardiomyocyte Ca(2+)release is desynchronized in several pathological conditions. Loss of Ca(2+) release synchrony has been attributed to t-tubule disruption, but it is unknown if other factors also contribute. We investigated this issue in normal and failing myocytes by integrating experimental data with a mathematical model describing spatiotemporal dynamics of Ca(2+) in the cytosol and sarcoplasmic reticulum (SR). Heart failure development in postinfarction mice was associated with progressive t-tubule disorganization, as quantified by fast-Fourier transforms. Data from fast-Fourier transforms were then incorporated in the model as a dyadic organization index, reflecting the proportion of ryanodine receptors located in dyads. With decreasing dyadic-organization index, the model predicted greater dyssynchrony of Ca(2+) release, which exceeded that observed in experimental line-scan images. Model and experiment were reconciled by reducing the threshold for Ca(2+) release in the model, suggesting that increased RyR sensitivity partially offsets the desynchronizing effects of t-tubule disruption in heart failure. Reducing the magnitude of SR Ca(2+) content and release, whether experimentally by thapsigargin treatment, or in the model, desynchronized the Ca(2+) transient. However, in cardiomyocytes isolated from SERCA2 knockout mice, RyR sensitization offset such effects. A similar interplay between RyR sensitivity and SR content was observed during treatment of myocytes with low-dose caffeine. Initial synchronization of Ca(2+) release during caffeine was reversed as SR content declined due to enhanced RyR leak. Thus, synchrony of cardiomyocyte Ca(2+) release is not only determined by t-tubule organization but also by the interplay between RyR sensitivity and SR Ca(2+) content.
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27
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Zhang HB, Li RC, Xu M, Xu SM, Lai YS, Wu HD, Xie XJ, Gao W, Ye H, Zhang YY, Meng X, Wang SQ. Ultrastructural uncoupling between T-tubules and sarcoplasmic reticulum in human heart failure. Cardiovasc Res 2013; 98:269-76. [PMID: 23405000 DOI: 10.1093/cvr/cvt030] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Chronic heart failure is a complex clinical syndrome with impaired myocardial contractility. In failing cardiomyocytes, decreased signalling efficiency between the L-type Ca(2+) channels (LCCs) in the plasma membrane (including transverse tubules, TTs) and the ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR) underlies the defective excitation-contraction (E-C) coupling. It is therefore intriguing to know how the LCC-RyR signalling apparatus is remodelled in human heart failure. METHODS AND RESULTS Stereological analysis of transmission electron microscopic images showed that the volume densities and the surface areas of TTs and junctional SRs were both decreased in heart failure specimens of dilated cardiomyopathy (DCM) and ischaemic cardiomyopathy (ICM). The TT-SR junctions were reduced by ~60%, with the remaining displaced from the Z-line areas. Moreover, the spatial span of individual TT-SR junctions was reduced by ~17% in both DCM and ICM tissues. In accordance with these remodelling, junctophilin-2 (JP2), a structural protein anchoring SRs to TTs, was down-regulated, and miR-24, a microRNA that suppresses JP2 expression, was up-regulated in both heart failure tissues. CONCLUSION Human heart failure of distinct causes shared similar physical uncoupling between TTs and SRs, which appeared attributable to the reduced expression of JP2 and increased expression of miR-24. Therapeutic strategy against JP2 down-regulation would be expected to protect patients from cardiac E-C uncoupling.
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Affiliation(s)
- Hai-Bo Zhang
- Beijing Anzhen Hospital, Capital Medical University, Beijing 100092, China
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28
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Guo A, Zhang C, Wei S, Chen B, Song LS. Emerging mechanisms of T-tubule remodelling in heart failure. Cardiovasc Res 2013; 98:204-15. [PMID: 23393229 DOI: 10.1093/cvr/cvt020] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction coupling occurs primarily at the sites of transverse (T)-tubule/sarcoplasmic reticulum junctions. The orderly T-tubule network guarantees the instantaneous excitation and synchronous activation of nearly all Ca(2+) release sites throughout the large ventricular myocyte. Because of the critical roles played by T-tubules and the array of channels and transporters localized to the T-tubule membrane network, T-tubule architecture has recently become an area of considerable research interest in the cardiovascular field. This review will focus on the current knowledge regarding normal T-tubule structure and function in the heart, T-tubule remodelling in the transition from compensated hypertrophy to heart failure, and the impact of T-tubule remodelling on myocyte Ca(2+) handling function. In the last section, we discuss the molecular mechanisms underlying T-tubule remodelling in heart disease.
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Affiliation(s)
- Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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29
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Wu HD, Xu M, Li RC, Guo L, Lai YS, Xu SM, Li SF, Lü QL, Li LL, Zhang HB, Zhang YY, Zhang CM, Wang SQ. Ultrastructural remodelling of Ca(2+) signalling apparatus in failing heart cells. Cardiovasc Res 2012; 95:430-8. [PMID: 22707157 DOI: 10.1093/cvr/cvs195] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS The contraction of a heart cell is controlled by Ca(2+)-induced Ca(2+) release between L-type Ca(2+) channels (LCCs) in the cell membrane/T-tubules (TTs) and ryanodine receptors (RyRs) in the junctional sarcoplasmic reticulum (SR). During heart failure, LCC-RyR signalling becomes defective. The purpose of the present study was to reveal the ultrastructural mechanism underlying the defective LCC-RyR signalling and contractility. METHODS AND RESULTS In rat models of heart failure produced by transverse aortic constriction surgery, stereological analysis of transmission electron microscopic images showed that the volume density and the surface area of junctional SRs and those of SR-coupled TTs were both decreased in failing heart cells. The TT-SR junctions were displaced or missing from the Z-line areas. Moreover, the spatial span of individual TT-SR junctions was markedly reduced in failing heart cells. Numerical simulation and junctophilin-2 knockdown experiments demonstrated that the decrease in junction size (and thereby the constitutive LCC and RyR numbers) led to a scattered delay of Ca(2+) release activation. CONCLUSIONS The shrinking and eventual absence of TT-SR junctions are important mechanisms underlying the desynchronized and inhomogeneous Ca(2+) release and the decreased contractile strength in heart failure. Maintaining the nanoscopic integrity of TT-SR junctions thus represents a therapeutic strategy against heart failure and related cardiomyopathies.
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Affiliation(s)
- Hao-Di Wu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Key Laboratory of Cell Proliferation and Differentiation, Key Laboratory of Molecular Cardiovascular Sciences, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Third Hospital, and College of Life Sciences, Peking University, Beijing 100871, China
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Grubb S, Calloe K, Thomsen MB. Impact of KChIP2 on Cardiac Electrophysiology and the Progression of Heart Failure. Front Physiol 2012; 3:118. [PMID: 22586403 PMCID: PMC3343377 DOI: 10.3389/fphys.2012.00118] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/11/2012] [Indexed: 01/16/2023] Open
Abstract
Electrophysiological remodeling of cardiac potassium ion channels is important in the progression of heart failure. A reduction of the transient outward potassium current (Ito) in mammalian heart failure is consistent with a reduced expression of potassium channel interacting protein 2 (KChIP2, a KV4 subunit). Approaches have been made to investigate the role of KChIP2 in shaping cardiac Ito, including the use of transgenic KChIP2 deficient mice and viral overexpression of KChIP2. The interplay between Ito and myocardial calcium handling is pivotal in the development of heart failure, and is further strengthened by the dual role of KChIP2 as a functional subunit on both KV4 and CaV1.2. Moreover, the potential arrhythmogenic consequence of reduced Ito may contribute to the high relative incidence of sudden death in the early phases of human heart failure. With this review, we offer an overview of the insights into the physiological and pathological roles of KChIP2 and we discuss the limitations of translating the molecular basis of electrophysiological remodeling from animal models of heart failure to the clinical setting.
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Affiliation(s)
- Søren Grubb
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen Copenhagen, Denmark
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31
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Delayed endosome-dependent CamKII and p38 kinase signaling in cardiomyocytes destabilizes Kv4.3 mRNA. J Mol Cell Cardiol 2012; 52:971-7. [PMID: 22266351 DOI: 10.1016/j.yjmcc.2012.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 12/20/2011] [Accepted: 01/03/2012] [Indexed: 12/22/2022]
Abstract
The Kv4.3 transient outward current (I(to)) channel, which produces early repolarization in human cardiomyocytes, is downregulated with cardiac pathology. This is evident in cultured neonatal rat cardiomyocytes in which Angiotensin II (Ang II) acts via p38 mitogen-activated protein kinase (p38K) to increase apoptosis and induce Kv4.3 mRNA destabilization to downregulate the channel protein. However, it is not understood how p38K activation, which is activated transiently for minutes, induces downstream effects hours later. Here we show that there is a second phase of p38K activation. Inhibiting this delayed p38K activation eliminated Kv4.3 mRNA destabilization. Furthermore, inhibiting endosome generation left the transient activation of p38K intact, but blocked delayed p38K activation and the Kv4.3 effect. CamKII was also found to be required for delayed p38K activation and Kv4.3 mRNA destabilization. Finally, CamKII methionine oxidation and activation are biphasic, with the delayed phase requiring endosomes. Hence, in addition to participating in channel traffic, cardiomyocyte endosomes control channel mRNA expression by mediating delayed oxidative CamKII-p38K signaling.
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32
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Su F, Shi M, Yan Z, Ou D, Li J, Lu Z, Zheng Q. Simvastatin modulates remodeling of Kv4.3 expression in rat hypertrophied cardiomyocytes. Int J Biol Sci 2012; 8:236-48. [PMID: 22253567 PMCID: PMC3258563 DOI: 10.7150/ijbs.8.236] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 12/31/2011] [Indexed: 12/17/2022] Open
Abstract
Objectives: Hypertrophy has been shown to be associated with arrhythmias which can be caused by abnormal remodeling of the Kv4-family of transient potassium channels. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) have recently been shown to exert pleiotropic protective effects in cardiovascular diseases, including anti-arrhythmias. It is hypothesized that remodeling of Kv4.3 occurs in rat hypertrophied cardiomyocytes and is regulated by simvastatin. Methods: Male Sprague-Dawley rats and neonatal rat ventricular myocytes (NRVMs) underwent abdominal aortic banding (AAB) for 7 weeks and angiotensin II (AngII) treatment, respectively, to induce cardiac hypertrophy. Kv4.3 expression by NRVMs and myocardium (subepicardial and subendocardial) in the left ventricle was measured. The transient outward potassium current (Ito) of NRVMs was recorded using a whole-cell patch-clamp method. Results: Expression of the Kv4.3 transcript and protein was significantly reduced in myocardium (subepicardial and subendocardial) in the left ventricle and in NRVMs. Simvastatin partially prevented the reduction of Kv4.3 expression in NRVMs and subepicardial myocardium but not in the subendocardial myocardium. Hypertrophied NRVMs exhibited a significant reduction in the Ito current and this effect was partially reversed by simvastatin. Conclusions: Simvastatin alleviated the reduction of Kv4.3 expression, Ito currents in hypertrophied NRVMs and alleviated the reduced Kv4.3 expression in subepicardial myocardium from the hypertrophied left ventricle. It can be speculated that among the pleiotropic effects of simvastatin, the anti-arrhythmia effect is partly mediated by its effect on Kv4.3.
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Affiliation(s)
- Feifei Su
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
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Hatano A, Okada JI, Hisada T, Sugiura S. Critical role of cardiac t-tubule system for the maintenance of contractile function revealed by a 3D integrated model of cardiomyocytes. J Biomech 2012; 45:815-23. [PMID: 22226404 DOI: 10.1016/j.jbiomech.2011.11.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2011] [Indexed: 11/27/2022]
Abstract
T-tubules in mammalian ventricular myocytes constitute an elaborate system for coupling membrane depolarization with intracellular Ca(2+) signaling to control cardiac contraction. Deletion of t-tubules (detubulation) has been reported in heart diseases, although the complex nature of the cardiac excitation-contraction (E-C) coupling process makes it difficult to experimentally establish causal relationships between detubulation and cardiac dysfunction. Alternatively, numerical simulations incorporating the t-tubule system have been proposed to elucidate its functional role. However, the majority of models treat the subcellular spaces as lumped compartments, and are thus unable to dissect the impact of morphological changes in t-tubules. We developed a 3D finite element model of cardiomyocytes in which subcellular components including t-tubules, myofibrils, sarcoplasmic reticulum, and mitochondria were modeled and realistically arranged. Based on this framework, physiological E-C coupling was simulated by simultaneously solving the reaction-diffusion equation and the mechanical equilibrium for the mathematical models of electrophysiology and contraction distributed among these subcellular components. We then examined the effect of detubulation in this model by comparing with and without the t-tubule system. This model reproduced the Ca(2+) transients and contraction observed in experimental studies, including the response to beta-adrenergic stimulation, and provided detailed information beyond the limits of experimental approaches. In particular, the analysis of sarcomere dynamics revealed that the asynchronous contraction caused by a large detubulated region can lead to impairment of myocyte contractile efficiency. These data clearly demonstrate the importance of the t-tubule system for the maintenance of contractile function.
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Affiliation(s)
- Asuka Hatano
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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Li XC, Wei L, Zhang GQ, Bai ZL, Hu YY, Zhou P, Bai SH, Chai Z, Lakatta EG, Hao XM, Wang SQ. Ca2+ cycling in heart cells from ground squirrels: adaptive strategies for intracellular Ca2+ homeostasis. PLoS One 2011; 6:e24787. [PMID: 21935466 PMCID: PMC3173481 DOI: 10.1371/journal.pone.0024787] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 08/17/2011] [Indexed: 12/21/2022] Open
Abstract
Heart tissues from hibernating mammals, such as ground squirrels, are able to endure hypothermia, hypoxia and other extreme insulting factors that are fatal for human and nonhibernating mammals. This study was designed to understand adaptive mechanisms involved in intracellular Ca2+ homeostasis in cardiomyocytes from the mammalian hibernator, ground squirrel, compared to rat. Electrophysiological and confocal imaging experiments showed that the voltage-dependence of L-type Ca2+ current (ICa) was shifted to higher potentials in ventricular myocytes from ground squirrels vs. rats. The elevated threshold of ICa did not compromise the Ca2+-induced Ca2+ release, because a higher depolarization rate and a longer duration of action potential compensated the voltage shift of ICa. Both the caffeine-sensitive and caffeine-resistant components of cytosolic Ca2+ removal were more rapid in ground squirrels. Ca2+ sparks in ground squirrels exhibited larger amplitude/size and much lower frequency than in rats. Due to the high ICa threshold, low SR Ca2+ leak and rapid cytosolic Ca2+ clearance, heart cells from ground squirrels exhibited better capability in maintaining intracellular Ca2+ homeostasis than those from rats and other nonhibernating mammals. These findings not only reveal adaptive mechanisms of hibernation, but also provide novel strategies against Ca2+ overload-related heart diseases.
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Affiliation(s)
- Xiao-Chen Li
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Ling Wei
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Guang-Qin Zhang
- Research Division of Pharmacology, China Pharmaceutical University, Nanjing, China
| | - Zai-Ling Bai
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Ying-Ying Hu
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Peng Zhou
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Shu-Hua Bai
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Zhen Chai
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Xue-Mei Hao
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
| | - Shi-Qiang Wang
- State Key Lab of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing, China
- * E-mail:
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Rondelet B, Dewachter C, Kerbaul F, Kang X, Fesler P, Brimioulle S, Naeije R, Dewachter L. Prolonged overcirculation-induced pulmonary arterial hypertension as a cause of right ventricular failure. Eur Heart J 2011; 33:1017-26. [PMID: 21606077 DOI: 10.1093/eurheartj/ehr111] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
AIMS Three-month chronic systemic-to-pulmonary shunting in growing piglets has been reported as an early pulmonary arterial hypertension (PAH) model with preserved right ventricular (RV) function. We sought to determine whether prolonged shunting might be associated with more severe PAH and RV failure. METHODS AND RESULTS Fourteen growing piglets were randomized to a sham operation or the anastomosis of the left innominate artery to the pulmonary arterial trunk. Six months later, the shunt was closed and the animals underwent haemodynamic evaluation followed by tissue sampling for pathobiological assessment. Prolonged shunting had resulted in increased mean pulmonary artery pressure (22 ± 2 versus 17 ± 1 mmHg) and pulmonary arteriolar medial thickness, while cardiac output was decreased. However, RV-arterial coupling was markedly deteriorated, with a ~50% decrease in the ratio of end-systolic to pulmonary arterial elastances (Ees/Ea). Lung tissue expressions of endothelin-1, angiopoietin-1, and bone morphogenetic protein receptor-2 were similarly altered compared with previously observed after 3-month shunting. At the RV tissue level, pro-apoptotic ratio of Bax-to-Bcl-2 expressions and caspase-3 activation were increased, along with an increase in cardiomyocyte size, while expressions in voltage-gated potassium channels (Kv1.5 and Kv2.1) and angiogenic factors (angiopoietin-2 and vascular endothelial growth factor) were decreased. Right ventricular expressions of pro-inflammatory cytokines [interleukin (IL)-1α, IL-1β, tumour necrosis factor-α (TNF-α)] and natriuretic peptide precursors (NPPA and NPPB) were increased. There was an inverse correlation between RV Ees/Ea and pro-apoptotic Bax/Bcl-2 ratios. CONCLUSIONS Prolonged left-to-right shunting in piglets does not further aggravate pulmonary vasculopathy, but is a cause of RV failure, which appears related to an activation of apoptosis and inflammation.
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Affiliation(s)
- Benoit Rondelet
- Physiology Laboratory, Faculty of Medicine, Université Libre de Bruxelles, 808 Lennik Road, 1070 Brussels, Belgium
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Angert D, Berretta RM, Kubo H, Zhang H, Chen X, Wang W, Ogorek B, Barbe M, Houser SR. Repair of the injured adult heart involves new myocytes potentially derived from resident cardiac stem cells. Circ Res 2011; 108:1226-37. [PMID: 21454756 DOI: 10.1161/circresaha.110.239046] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RATIONALE The ability of the adult heart to generate new myocytes after injury is not established. OBJECTIVE Our purpose was to determine whether the adult heart has the capacity to generate new myocytes after injury, and to gain insight into their source. METHODS AND RESULTS Cardiac injury was induced in the adult feline heart by infusing isoproterenol (ISO) for 10 days via minipumps, and then animals were allowed to recover for 7 or 28 days. Cardiac function was measured with echocardiography, and proliferative cells were identified by nuclear incorporation of 5-bromodeoxyuridine (BrdU; 7-day minipump infusion). BrdU was infused for 7 days before euthanasia at days 10, 17, and 38 or during injury and animals euthanized at day 38. ISO caused reduction in cardiac function with evidence of myocyte loss from necrosis. During this injury phase there was a significant increase in the number of proliferative cells in the atria and ventricle, but there was no increase in BrdU+ myocytes. cKit+ cardiac progenitor cells were BrdU labeled during injury. During the first 7 days of recovery there was a significant reduction in cellular proliferation (BrdU incorporation) but a significant increase in BrdU+ myocytes. There was modest improvement in cardiac structure and function during recovery. At day 38, overall cell proliferation was not different than control, but increased numbers of BrdU+ myocytes were found when BrdU was infused during injury. CONCLUSIONS These studies suggest that ISO injury activates cardiac progenitor cells that can differentiate into new myocytes during cardiac repair.
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Affiliation(s)
- David Angert
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Control of Ca2+ release by action potential configuration in normal and failing murine cardiomyocytes. Biophys J 2010; 99:1377-86. [PMID: 20816049 DOI: 10.1016/j.bpj.2010.06.055] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/13/2010] [Accepted: 06/14/2010] [Indexed: 01/15/2023] Open
Abstract
Cardiomyocytes from failing hearts exhibit spatially nonuniform or dyssynchronous sarcoplasmic reticulum (SR) Ca(2+) release. We investigated the contribution of action potential (AP) prolongation in mice with congestive heart failure (CHF) after myocardial infarction. AP recordings from CHF and control myocytes were included in a computational model of the dyad, which predicted more dyssynchronous ryanodine receptor opening during stimulation with the CHF AP. This prediction was confirmed in cardiomyocyte experiments, when cells were alternately stimulated by control and CHF AP voltage-clamp waveforms. However, when a train of like APs was used as the voltage stimulus, the control and CHF AP produced a similar Ca(2+) release pattern. In this steady-state condition, greater integrated Ca(2+) entry during the CHF AP lead to increased SR Ca(2+) content. A resulting increase in ryanodine receptor sensitivity synchronized SR Ca(2+) release in the mathematical model, thus offsetting the desynchronizing effects of reduced driving force for Ca(2+) entry. A modest nondyssynchronous prolongation of Ca(2+) release was nevertheless observed during the steady-state CHF AP, which contributed to increased time-to-peak measurements for Ca(2+) transients in failing cells. Thus, dyssynchronous Ca(2+) release in failing mouse myocytes does not result from electrical remodeling, but rather other alterations such as T-tubule reorganization.
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Abstract
T-wave alternans, a manifestation of repolarization alternans at the cellular level, is associated with lethal cardiac arrhythmias and sudden cardiac death. At the cellular level, several mechanisms can produce repolarization alternans, including: (1) electrical restitution resulting from collective ion channel recovery, which usually occurs at fast heart rates but can also occur at normal heart rates when action potential is prolonged resulting in a short diastolic interval; (2) the transient outward current, which tends to occur at normal or slow heart rates; (3) the dynamics of early after depolarizations, which tends to occur during bradycardia; and (4) intracellular calcium cycling alternans through its interaction with membrane voltage. In this review, we summarize the cellular mechanisms of alternans arising from these different mechanisms, and discuss their roles in arrhythmogenesis in the setting of cardiac disease.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California, USA.
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Heinzel FR, MacQuaide N, Biesmans L, Sipido K. Dyssynchrony of Ca2+ release from the sarcoplasmic reticulum as subcellular mechanism of cardiac contractile dysfunction. J Mol Cell Cardiol 2010; 50:390-400. [PMID: 21075114 DOI: 10.1016/j.yjmcc.2010.11.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 09/30/2010] [Accepted: 11/05/2010] [Indexed: 02/05/2023]
Abstract
Cardiac contractile function depends on coordinated electrical activation throughout the heart. Dyssynchronous electrical activation of the ventricles has been shown to contribute to contractile dysfunction in heart failure, and resynchronization therapy has emerged as a therapeutic concept. At the cellular level, coupling of membrane excitation to myofilament contraction is facilitated by highly organized intracellular structures which coordinate Ca(2+) release. The cytosolic [Ca(2+)] transient triggered by depolarization-induced Ca(2+) influx is the result of a gradable and robust high gain process, Ca(2+)-induced Ca(2+) release (CICR), which integrates subcellular localized Ca(2+) release events. Lack of synchronization of these localized release events can contribute to contractile dysfunction in myocardial hypertrophy and heart failure. Different underlying mechanisms relate to functional and structural changes in sarcolemmal Ca(2+) channels, the sarcoplasmic Ca(2+) release channel or ryanodine receptor, RyR, their intracellular arrangement in close proximity in couplons and the loss of t-tubules. Dyssynchrony at the subcellular level translates in a reduction of the overall gain of CICR at the cellular level and forms an important determinant of myocyte contractility in heart failure.
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How does the shape of the cardiac action potential control calcium signaling and contraction in the heart? J Mol Cell Cardiol 2010; 49:901-3. [PMID: 20850450 DOI: 10.1016/j.yjmcc.2010.09.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 08/19/2010] [Accepted: 09/08/2010] [Indexed: 11/21/2022]
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Undrovinas NA, Maltsev VA, Belardinelli L, Sabbah HN, Undrovinas A. Late sodium current contributes to diastolic cell Ca2+ accumulation in chronic heart failure. J Physiol Sci 2010; 60:245-57. [PMID: 20490740 PMCID: PMC2891122 DOI: 10.1007/s12576-010-0092-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 04/06/2010] [Indexed: 12/19/2022]
Abstract
We elucidate the role of late Na+ current (INaL) for diastolic intracellular Ca2+ (DCa) accumulation in chronic heart failure (HF). HF was induced in 19 dogs by multiple coronary artery microembolizations; 6 normal dogs served as control. Ca2+ transients were recorded in field-paced (0.25 or 1.5 Hz) fluo-4-loaded ventricular myocytes (VM). INaL and action potentials were recorded by patch-clamp. Failing VM, but not normal VM, exhibited (1) prolonged action potentials and Ca2+ transients at 0.25 Hz, (2) substantial DCa accumulation at 1.5 Hz, and (3) spontaneous Ca2+ releases, which occurred after 1.5 Hz stimulation trains in ~31% cases. Selective INaL blocker ranolazine (10 microM) or the prototypical Na+ channel blocker tetrodotoxin (2 microM) reversibly improved function of failing VM. The DCa accumulation and the beneficial effect of INaL blockade were reproduced in silico using an excitation-contraction coupling model. We conclude that INaL contributes to diastolic Ca2+ accumulation and spontaneous Ca2+ release in HF.
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Affiliation(s)
| | - Victor A. Maltsev
- National Institute on Aging, Intramural Research Program, NIH, Baltimore, MD USA
| | | | - Hani N. Sabbah
- Department of Internal Medicine, Henry Ford Hospital, Detroit, MI USA
| | - Albertas Undrovinas
- Department of Internal Medicine, Henry Ford Hospital, Detroit, MI USA
- Cardiovascular Research, Henry Ford Hospital, Education and Research Bldg. Room 4015, 2799 West Grand Boulevard, Detroit, MI 48202-2689 USA
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Wei S, Guo A, Chen B, Kutschke W, Xie YP, Zimmerman K, Weiss RM, Anderson ME, Cheng H, Song LS. T-tubule remodeling during transition from hypertrophy to heart failure. Circ Res 2010; 107:520-31. [PMID: 20576937 DOI: 10.1161/circresaha.109.212324] [Citation(s) in RCA: 312] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
RATIONALE The transverse tubule (T-tubule) system is the ultrastructural substrate for excitation-contraction coupling in ventricular myocytes; T-tubule disorganization and loss are linked to decreased contractility in end stage heart failure (HF). OBJECTIVE We sought to examine (1) whether pathological T-tubule remodeling occurs early in compensated hypertrophy and, if so, how it evolves during the transition from hypertrophy to HF; and (2) the role of junctophilin-2 in T-tubule remodeling. METHODS AND RESULTS We investigated T-tubule remodeling in relation to ventricular function during HF progression using state-of-the-art confocal imaging of T-tubules in intact hearts, using a thoracic aortic banding rat HF model. We developed a quantitative T-tubule power (TT(power)) index to represent the integrity of T-tubule structure. We found that discrete local loss and global reorganization of the T-tubule system (leftward shift of TT(power) histogram) started early in compensated hypertrophy in left ventricular (LV) myocytes, before LV dysfunction, as detected by echocardiography. With progression from compensated hypertrophy to early and late HF, T-tubule remodeling spread from the LV to the right ventricle, and TT(power) histograms of both ventricles gradually shifted leftward. The mean LV TT(power) showed a strong correlation with ejection fraction and heart weight to body weight ratio. Over the progression to HF, we observed a gradual reduction in the expression of a junctophilin protein (JP-2) implicated in the formation of T-tubule/sarcoplasmic reticulum junctions. Furthermore, we found that JP-2 knockdown by gene silencing reduced T-tubule structure integrity in cultured adult ventricular myocytes. CONCLUSIONS T-tubule remodeling in response to thoracic aortic banding stress begins before echocardiographically detectable LV dysfunction and progresses over the development of overt structural heart disease. LV T-tubule remodeling is closely associated with the severity of cardiac hypertrophy and predicts LV function. Thus, T-tubule remodeling may constitute a key mechanism underlying the transition from compensated hypertrophy to HF.
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Affiliation(s)
- Sheng Wei
- Institute of Molecular Medicine, Peking University, Beijing, China
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Cooper PJ, Soeller C, Cannell MB. Excitation-contraction coupling in human heart failure examined by action potential clamp in rat cardiac myocytes. J Mol Cell Cardiol 2010; 49:911-7. [PMID: 20430038 DOI: 10.1016/j.yjmcc.2010.04.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 04/09/2010] [Accepted: 04/20/2010] [Indexed: 11/29/2022]
Abstract
The effect of the loss of the notch in the human action potential (AP) during heart failure was examined by voltage clamping rat ventricular myocytes with human APs and recording intracellular Ca(2+) with fluorescent dyes. Loss of the notch resulted in about a 50% reduction in the initial phase of the Ca(2+) transient due to reduced ability of the L-type Ca(2+) channel to trigger release. The failing human AP increased non-uniformity of cytosolic Ca(2+), with some cellular regions failing to elicit Ca(2+)-induced Ca(2+) release from the sarcoplasmic reticulum. In addition, there was an increase in the occurrence of late Ca(2+) sparks. Monte-Carlo simulations of spark activation by L-type Ca(2+) current supported the idea that the decreased synchrony of Ca(2+) spark production associated with the loss of the notch could be explained by reduced Ca(2+) influx from open Ca(2+) channels. We conclude that the notch of the AP is critical for efficient and synchronous EC coupling and that the loss of the notch will reduce the SR Ca(2+) release in heart failure, without changes in (for example) SR Ca(2+)-ATPase uptake.
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Affiliation(s)
- Patricia J Cooper
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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There goes the neighborhood: pathological alterations in T-tubule morphology and consequences for cardiomyocyte Ca2+ handling. J Biomed Biotechnol 2010; 2010:503906. [PMID: 20396394 PMCID: PMC2852607 DOI: 10.1155/2010/503906] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 01/15/2010] [Indexed: 12/19/2022] Open
Abstract
T-tubules are invaginations of the cardiomyocyte membrane into the cell interior which form a tortuous network. T-tubules provide proximity between the electrically excitable cell membrane and the sarcoplasmic reticulum, the main intracellular Ca2+ store. Tight coupling between the rapidly spreading action potential and Ca2+ release units in the SR membrane ensures synchronous Ca2+ release throughout the cardiomyocyte. This is a requirement for rapid and powerful contraction. In recent years, it has become clear that T-tubule structure and composition are altered in several pathological states which may importantly contribute to contractile defects in these conditions. In this review, we describe the “neighborhood” of proteins in the dyadic cleft which locally controls cardiomyocyte Ca2+ homeostasis and how alterations in T-tubule structure and composition may alter this neighborhood during heart failure, atrial fibrillation, and diabetic cardiomyopathy. Based on this evidence, we propose that T-tubules have the potential to serve as novel therapeutic targets.
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Dong M, Yan S, Chen Y, Niklewski PJ, Sun X, Chenault K, Wang HS. Role of the transient outward current in regulating mechanical properties of canine ventricular myocytes. J Cardiovasc Electrophysiol 2010; 21:697-703. [PMID: 20132386 DOI: 10.1111/j.1540-8167.2009.01708.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION The transient outward current (I(to)) is a major repolarizing current in the heart. Reduction of I(to) density is consistently observed in human heart failure (HF) and animal HF models. It has been proposed that I(to), via its influence on phase-1 repolarization of the action potential, facilitates L-type Ca(2+) current (I(Ca-L)) activation and sarcoplasmic reticulum Ca(2+) release, and that its down-regulation may contribute to the impaired contractility in failing heart. METHODS AND RESULTS We used the dynamic clamp to quantitatively examine the influence of I(to) on the mechanical properties of canine left ventricular myocytes at 34 degrees C. In endocardial myocytes, where the native I(to) is small, simulation of an epicardial-level artificial I(to) accentuated the phase-1 repolarization and significantly suppressed cell shortening. The peak amplitude of Ca(2+) transient was also reduced in the presence of simulated I(to), although the rate of rise of the Ca(2+) transient was increased. Conversely, subtraction, or "blockade" of the native I(to) enhanced contractility in epicardial cells. These results agree with the inverse correlation between I(to) levels and myocyte contractility and Ca(2+) transient amplitude in epicardial and endocardial myocytes. Action potential clamp studies showed that the phase-1 repolarization/I(to) versus I(Ca-L) relationship had an inverted-J shape; small I(to) enhanced peak I(Ca-L) while moderate-to-large I(to) decreased peak I(Ca-L) and markedly reduced early Ca(2+) influx. CONCLUSION Our results show that epicardial-level of I(to) acts as a negative, rather than positive regulator of myocyte mechanical properties in canine ventricular myocytes.
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Affiliation(s)
- Min Dong
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575, USA
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Molecular and functional remodeling of Ito by angiotensin II in the mouse left ventricle. J Mol Cell Cardiol 2010; 48:140-51. [DOI: 10.1016/j.yjmcc.2009.08.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 08/20/2009] [Accepted: 08/27/2009] [Indexed: 11/18/2022]
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Piao L, Fang YH, Cadete VJJ, Wietholt C, Urboniene D, Toth PT, Marsboom G, Zhang HJ, Haber I, Rehman J, Lopaschuk GD, Archer SL. The inhibition of pyruvate dehydrogenase kinase improves impaired cardiac function and electrical remodeling in two models of right ventricular hypertrophy: resuscitating the hibernating right ventricle. J Mol Med (Berl) 2009; 88:47-60. [PMID: 19949938 DOI: 10.1007/s00109-009-0524-6] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 08/10/2009] [Accepted: 08/20/2009] [Indexed: 01/03/2023]
Abstract
Right ventricular hypertrophy (RVH) and RV failure contribute to morbidity and mortality in pulmonary arterial hypertension (PAH). The cause of RV dysfunction and the feasibility of therapeutically targeting the RV are uncertain. We hypothesized that RV dysfunction and electrical remodeling in RVH result, in part, from a glycolytic shift in the myocyte, caused by activation of pyruvate dehydrogenase kinase (PDK). We studied two complementary rat models: RVH + PAH (induced by monocrotaline) and RVH + without PAH (induced by pulmonary artery banding (PAB)). Monocrotaline RVH reduced RV O(2)-consumption and enhanced glycolysis. RV 2-fluoro-2-deoxy-glucose uptake, Glut-1 expression, and pyruvate dehydrogenase phosphorylation increased in monocrotaline RVH. The RV monophasic action potential duration and QT(c) interval were prolonged due to decreased expression of repolarizing voltage-gated K(+) channels (Kv1.5, Kv4.2). In the RV working heart model, the PDK inhibitor, dichloroacetate, acutely increased glucose oxidation and cardiac work in monocrotaline RVH. Chronic dichloroacetate therapy improved RV repolarization and RV function in vivo and in the RV Langendorff model. In PAB-induced RVH, a similar reduction in cardiac output and glycolytic shift occurred and it too improved with dichloroacetate. In PAB-RVH, the benefit of dichloroacetate on cardiac output was approximately 1/3 that in monocrotaline RVH. The larger effects in monocrotaline RVH likely reflect dichloroacetate's dual metabolic benefits in that model: regression of vascular disease and direct effects on the RV. Reduction in RV function and electrical remodeling in two models of RVH relevant to human disease (PAH and pulmonic stenosis) result, in part, from a PDK-mediated glycolytic shift in the RV. PDK inhibition partially restores RV function and regresses RVH by restoring RV repolarization and enhancing glucose oxidation. Recognition that a PDK-mediated metabolic shift contributes to contractile and ionic dysfunction in RVH offers insight into the pathophysiology and treatment of RVH.
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Affiliation(s)
- Lin Piao
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, IL 60637, USA
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MacDonnell SM, Weisser-Thomas J, Kubo H, Hanscome M, Liu Q, Jaleel N, Berretta R, Chen X, Brown JH, Sabri AK, Molkentin JD, Houser SR. CaMKII negatively regulates calcineurin-NFAT signaling in cardiac myocytes. Circ Res 2009; 105:316-25. [PMID: 19608982 DOI: 10.1161/circresaha.109.194035] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
RATIONALE Pathological cardiac myocyte hypertrophy is thought to be induced by the persistent increases in intracellular Ca(2+) needed to maintain cardiac function when systolic wall stress is increased. Hypertrophic Ca(2+) binds to calmodulin (CaM) and activates the phosphatase calcineurin (Cn) and CaM kinase (CaMK)II. Cn dephosphorylates cytoplasmic NFAT (nuclear factor of activated T cells), inducing its translocation to the nucleus where it activates antiapoptotic and hypertrophic target genes. Cytoplasmic CaMKII regulates Ca(2+) handling proteins but whether or not it is directly involved in hypertrophic and survival signaling is not known. OBJECTIVE This study explored the hypothesis that cytoplasmic CaMKII reduces NFAT nuclear translocation by inhibiting the phosphatase activity of Cn. METHODS AND RESULTS Green fluorescent protein-tagged NFATc3 was used to determine the cellular location of NFAT in cultured neonatal rat ventricular myocytes (NRVMs) and adult feline ventricular myocytes. Constitutively active (CaMKII-CA) or dominant negative (CaMKII-DN) mutants of cytoplasmic targeted CaMKII(deltac) were used to activate and inhibit cytoplasmic CaMKII activity. In NRVM CaMKII-DN (48.5+/-3%, P<0.01 versus control) increased, whereas CaMKII-CA decreased (5.9+/-1%, P<0.01 versus control) NFAT nuclear translocation (Control: 12.3+/-1%). Cn inhibitors were used to show that these effects were caused by modulation of Cn activity. Increasing Ca(2+) increased Cn-dependent NFAT translocation (to 71.7+/-7%, P<0.01) and CaMKII-CA reduced this effect (to 17.6+/-4%). CaMKII-CA increased TUNEL and caspase-3 activity (P<0.05). CaMKII directly phosphorylated Cn at Ser197 in CaMKII-CA infected NRVMs and in hypertrophied feline hearts. CONCLUSION These data show that activation of cytoplasmic CaMKII inhibits NFAT nuclear translocation by phosphorylation and subsequent inhibition of Cn.
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Affiliation(s)
- Scott M MacDonnell
- Department of Physiology, Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Xie Y, Garfinkel A, Weiss JN, Qu Z. Cardiac alternans induced by fibroblast-myocyte coupling: mechanistic insights from computational models. Am J Physiol Heart Circ Physiol 2009; 297:H775-84. [PMID: 19482965 DOI: 10.1152/ajpheart.00341.2009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent experimental studies have shown that fibroblasts can electrotonically couple to myocytes via gap junctions. In this study, we investigated how this coupling affects action potential and intracellular calcium (Ca(i)) cycling dynamics in simulated fibroblast-myocyte pairs and in two-dimensional tissue with random fibroblast insertions. We show that a fibroblast coupled with a myocyte generates a gap junction current flowing to the myocyte with two main components: an early pulse of transient outward current, similar to the fast transient outward current, and a later background current during the repolarizing phase. Depending on the relative prominence of the two components, fibroblast-myoycte coupling can 1) prolong or shorten action potential duration (APD), 2) promote or suppress APD alternans due to steep APD restitution (voltage driven) and also result in a novel mechanism of APD alternans at slow heart rates, 3) promote Ca(i)-driven alternans and electromechanically discordant alternans, and 4) promote spatially discordant alternans by two mechanisms: by altering conduction velocity restitution and by heterogeneous fibroblast distribution causing electromechanically concordant and discordant alternans in different regions of the tissue. Thus, through their coupling with myocytes, fibroblasts alter repolarization and Ca(i) cycling alternans at both the cellular and tissue scales, which may play important roles in arrhythmogenesis in diseased cardiac tissue with fibrosis.
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Affiliation(s)
- Yuanfang Xie
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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Dilated cardiomyopathy with increased SR Ca2+ loading preceded by a hypercontractile state and diastolic failure in the alpha(1C)TG mouse. PLoS One 2009; 4:e4133. [PMID: 19125184 PMCID: PMC2607013 DOI: 10.1371/journal.pone.0004133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 11/20/2008] [Indexed: 11/19/2022] Open
Abstract
Mice over-expressing the alpha(1)_subunit (pore) of the L-type Ca2+ channel (alpha(1C)TG) by 4 months (mo) of age exhibit an enlarged heart, hypertrophied myocytes, increased Ca2+ current and Ca2+ transient amplitude, but a normal SR Ca2+ load. With advancing age (8-11 mo), some mice demonstrate advanced hypertrophy but are not in congestive heart failure (NFTG),while others evolve to frank dilated congestive heart failure (FTG). We demonstrate that older NFTG myocytes exhibit a hypercontractile state over a wide range of stimulation frequencies, but maintain a normal SR Ca2+ load compared to age matched non-transgenic (NTG) myocytes. However, at high stimulation rates (2-4 Hz) signs of diastolic contractile failure appear in NFTG cells. The evolution of frank congestive failure in FTG is accompanied by a further increase in heart mass and myocyte size, and phospholamban and ryanodine receptor protein levels and phosphorylation become reduced. In FTG, the SR Ca2+ load increases and Ca2+ release following excitation, increases further. An enhanced NCX function in FTG, as reflected by an accelerated relaxation of the caffeine-induced Ca2+ transient, is insufficient to maintain a normal diastolic Ca2+ during high rates of stimulation. Although a high SR Ca2+ release following excitation is maintained, the hypercontractile state is not maintained at high rates of stimulation, and signs of both systolic and diastolic contractile failure appear. Thus, the dilated cardiomyopathy that evolves in this mouse model exhibits signs of both systolic and diastolic failure, but not a deficient SR Ca2+ loading or release, as occurs in some other cardiomyopathic models.
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