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Kursanov A, Balakina-Vikulova NA, Solovyova O, Panfilov A, Katsnelson LB. In silico analysis of the contribution of cardiomyocyte-fibroblast electromechanical interaction to the arrhythmia. Front Physiol 2023; 14:1123609. [PMID: 36969594 PMCID: PMC10036780 DOI: 10.3389/fphys.2023.1123609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/27/2023] [Indexed: 03/12/2023] Open
Abstract
Although fibroblasts are about 5–10 times smaller than cardiomyocytes, their number in the ventricle is about twice that of cardiomyocytes. The high density of fibroblasts in myocardial tissue leads to a noticeable effect of their electromechanical interaction with cardiomyocytes on the electrical and mechanical functions of the latter. Our work focuses on the analysis of the mechanisms of spontaneous electrical and mechanical activity of the fibroblast-coupled cardiomyocyte during its calcium overload, which occurs in a variety of pathologies, including acute ischemia. For this study, we developed a mathematical model of the electromechanical interaction between cardiomyocyte and fibroblasts and used it to simulate the impact of overloading cardiomyocytes. In contrast to modeling only the electrical interaction between cardiomyocyte and fibroblasts, the following new features emerge in simulations with the model that accounts for both electrical and mechanical coupling and mechano-electrical feedback loops in the interacting cells. First, the activity of mechanosensitive ion channels in the coupled fibroblasts depolarizes their resting potential. Second, this additional depolarization increases the resting potential of the coupled myocyte, thus augmenting its susceptibility to triggered activity. The triggered activity associated with the cardiomyocyte calcium overload manifests itself in the model either as early afterdepolarizations or as extrasystoles, i.e., extra action potentials and extra contractions. Analysis of the model simulations showed that mechanics contribute significantly to the proarrhythmic effects in the cardiomyocyte overloaded with calcium and coupled with fibroblasts, and that mechano-electrical feedback loops in both the cardiomyocyte and fibroblasts play a key role in this phenomenon.
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Affiliation(s)
- Alexander Kursanov
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
- Laboratory of Mathematical Modeling in Physiology and Medicine Based on Supercomputers, Ural Federal University, Ekaterinburg, Russia
| | - Nathalie A. Balakina-Vikulova
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
- Laboratory of Mathematical Modeling in Physiology and Medicine Based on Supercomputers, Ural Federal University, Ekaterinburg, Russia
| | - Olga Solovyova
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
- Laboratory of Mathematical Modeling in Physiology and Medicine Based on Supercomputers, Ural Federal University, Ekaterinburg, Russia
| | - Alexander Panfilov
- Laboratory of Mathematical Modeling in Physiology and Medicine Based on Supercomputers, Ural Federal University, Ekaterinburg, Russia
| | - Leonid B. Katsnelson
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
- Laboratory of Mathematical Modeling in Physiology and Medicine Based on Supercomputers, Ural Federal University, Ekaterinburg, Russia
- *Correspondence: Leonid B. Katsnelson,
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2
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Wang Y, Zhang X, Wen Y, Li S, Lu X, Xu R, Li C. Endoplasmic Reticulum-Mitochondria Contacts: A Potential Therapy Target for Cardiovascular Remodeling-Associated Diseases. Front Cell Dev Biol 2021; 9:774989. [PMID: 34858991 PMCID: PMC8631538 DOI: 10.3389/fcell.2021.774989] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
Cardiovascular remodeling occurs in cardiomyocytes, collagen meshes, and vascular beds in the progress of cardiac insufficiency caused by a variety of cardiac diseases such as chronic ischemic heart disease, chronic overload heart disease, myocarditis, and myocardial infarction. The morphological changes that occur as a result of remodeling are the critical pathological basis for the occurrence and development of serious diseases and also determine morbidity and mortality. Therefore, the inhibition of remodeling is an important approach to prevent and treat heart failure and other related diseases. The endoplasmic reticulum (ER) and mitochondria are tightly linked by ER-mitochondria contacts (ERMCs). ERMCs play a vital role in different signaling pathways and provide a satisfactory structural platform for the ER and mitochondria to interact and maintain the normal function of cells, mainly by involving various cellular life processes such as lipid metabolism, calcium homeostasis, mitochondrial function, ER stress, and autophagy. Studies have shown that abnormal ERMCs may promote the occurrence and development of remodeling and participate in the formation of a variety of cardiovascular remodeling-associated diseases. This review focuses on the structure and function of the ERMCs, and the potential mechanism of ERMCs involved in cardiovascular remodeling, indicating that ERMCs may be a potential target for new therapeutic strategies against cardiovascular remodeling-induced diseases.
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Affiliation(s)
- Yu Wang
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China.,Emergency Department, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xinrong Zhang
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Ya Wen
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Sixuan Li
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Xiaohui Lu
- Emergency Department, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Ran Xu
- Jinan Tianqiao People's Hospital, Jinan, China
| | - Chao Li
- Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
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3
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Jiao L, Machuki JO, Wu Q, Shi M, Fu L, Adekunle AO, Tao X, Xu C, Hu X, Yin Z, Sun H. Estrogen and calcium handling proteins: new discoveries and mechanisms in cardiovascular diseases. Am J Physiol Heart Circ Physiol 2020; 318:H820-H829. [PMID: 32083972 DOI: 10.1152/ajpheart.00734.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Estrogen deficiency is considered to be an important factor leading to cardiovascular diseases (CVDs). Indeed, the prevalence of CVDs in postmenopausal women exceeds that of premenopausal women and men of the same age. Recent research findings provide evidence that estrogen plays a pivotal role in the regulation of calcium homeostasis and therefore fine-tunes normal cardiomyocyte contraction and relaxation processes. Disruption of calcium homeostasis is closely associated with the pathological mechanism of CVDs. Thus, this paper maps out and summarizes the effects and mechanisms of estrogen on calcium handling proteins in cardiac myocytes, including L-type Ca2+ channel, the sarcoplasmic reticulum Ca2+ release channel named ryanodine receptor, sarco(endo)plasmic reticulum Ca2+-ATPase, and sodium-calcium exchanger. In so doing, we provide theoretical and experimental evidence for the successful design of estrogen-based prevention and treatment therapies for CVDs.
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Affiliation(s)
- Lijuan Jiao
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | | | - Qi Wu
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Mingjin Shi
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Lu Fu
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | | | - Xi Tao
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Chenxi Xu
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Xide Hu
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Zeyuan Yin
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Hong Sun
- Department of Physiology, Xuzhou Medical University, Xuzhou, Jiangsu, China
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4
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Connolly A, Kelly A, Campos FO, Myles R, Smith G, Bishop MJ. Ventricular Endocardial Tissue Geometry Affects Stimulus Threshold and Effective Refractory Period. Biophys J 2018; 115:2486-2498. [PMID: 30503533 PMCID: PMC6301915 DOI: 10.1016/j.bpj.2018.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 10/15/2018] [Accepted: 11/05/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Understanding the biophysical processes by which electrical stimuli applied to cardiac tissue may result in local activation is important in both the experimental and clinical electrophysiology laboratory environments, as well as for gaining a more in-depth knowledge of the mechanisms of focal-trigger-induced arrhythmias. Previous computational models have predicted that local myocardial tissue architecture alone may significantly modulate tissue excitability, affecting both the local stimulus current required to excite the tissue and the local effective refractory period (ERP). In this work, we present experimental validation of this structural modulation of local tissue excitability on the endocardial tissue surface, use computational models to provide mechanistic understanding of this phenomena in relation to localized changes in electrotonic loading, and demonstrate its implications for the capture of afterdepolarizations. METHODS AND RESULTS Experiments on rabbit ventricular wedge preparations showed that endocardial ridges (surfaces of negative mean curvature) had a stimulus capture threshold that was 0.21 ± 0.03 V less than endocardial grooves (surfaces of positive mean curvature) for pairwise comparison (24% reduction, corresponding to 56.2 ± 6.4% of the energy). When stimulated at the minimal stimulus strength for capture, ridge locations showed a shorter ERP than grooves (n = 6, mean pairwise difference 7.4 ± 4.2 ms). When each site was stimulated with identical-strength stimuli, the difference in ERP was further increased (mean pairwise difference 15.8 ± 5.3 ms). Computational bidomain models of highly idealized cylindrical endocardial structures qualitatively agreed with these findings, showing that such changes in excitability are driven by structural modulation in electrotonic loading, quantifying this relationship as a function of surface curvature. Simulations further showed that capture of delayed afterdepolarizations was more likely in trabecular ridges than grooves, driven by this difference in loading. CONCLUSIONS We have demonstrated experimentally and explained mechanistically in computer simulations that the ability to capture tissue on the endocardial surface depends upon the local tissue architecture. These findings have important implications for deepening our understanding of excitability differences related to anatomical structure during stimulus application that may have important applications in the translation of novel experimental optogenetics pacing strategies. The uncovered preferential vulnerability to capture of afterdepolarizations of endocardial ridges, compared to grooves, provides important insight for understanding the mechanisms of focal-trigger-induced arrhythmias.
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Affiliation(s)
- Adam Connolly
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Allen Kelly
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Fernando O Campos
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Rachel Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Godfrey Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Martin J Bishop
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
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5
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Arvanitis DA, Vafiadaki E, Johnson DM, Kranias EG, Sanoudou D. The Histidine-Rich Calcium Binding Protein in Regulation of Cardiac Rhythmicity. Front Physiol 2018; 9:1379. [PMID: 30319456 PMCID: PMC6171002 DOI: 10.3389/fphys.2018.01379] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 09/11/2018] [Indexed: 12/16/2022] Open
Abstract
Sudden unexpected cardiac death (SCD) accounts for up to half of all-cause mortality of heart failure patients. Standardized cardiology tools such as electrocardiography, cardiac imaging, electrophysiological and serum biomarkers cannot accurately predict which patients are at risk of life-threatening arrhythmic episodes. Recently, a common variant of the histidine-rich calcium binding protein (HRC), the Ser96Ala, was identified as a potent biomarker of malignant arrhythmia triggering in these patients. HRC has been shown to be involved in the regulation of cardiac sarcoplasmic reticulum (SR) Ca2+ cycling, by binding and storing Ca2+ in the SR, as well as interacting with the SR Ca2+ uptake and release complexes. The underlying mechanisms, elucidated by studies at the molecular, biochemical, cellular and intact animal levels, indicate that transversion of Ser96 to Ala results in abolishment of an HRC phosphorylation site by Fam20C kinase and dysregulation of SR Ca2+ cycling. This is mediated through aberrant SR Ca2+ release by the ryanodine receptor (RyR2) quaternary complex, due to the impaired HRC/triadin interaction, and depressed SR Ca2+ uptake by the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2) pump, due to the impaired HRC/SERCA2 interaction. Pharmacological intervention with KN-93, an inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII), in the HRC Ser96Ala mouse model, reduced the occurrence of malignant cardiac arrhythmias. Herein, we summarize the current evidence on the pivotal role of HRC in the regulation of cardiac rhythmicity and the importance of HRC Ser96Ala as a genetic modifier for arrhythmias in the setting of heart failure.
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Affiliation(s)
- Demetrios A Arvanitis
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Daniel M Johnson
- Department of Cardiothoracic Surgery, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Evangelia G Kranias
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece.,Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Despina Sanoudou
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece.,Clinical Genomics and Pharmacogenomics Unit, 4th Department of Internal Medicine, Attikon Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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6
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Sprenkeler DJ, Bossu A, Beekman JDM, Schoenmakers M, Vos MA. An Augmented Negative Force-Frequency Relationship and Slowed Mechanical Restitution Are Associated With Increased Susceptibility to Drug-Induced Torsade de Pointes Arrhythmias in the Chronic Atrioventricular Block Dog. Front Physiol 2018; 9:1086. [PMID: 30135660 PMCID: PMC6092493 DOI: 10.3389/fphys.2018.01086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/23/2018] [Indexed: 11/30/2022] Open
Abstract
Introduction: In the chronic AV-block (CAVB) dog model, structural, contractile, and electrical remodeling occur, which predispose the heart to dofetilide-induced Torsade de Pointes (TdP) arrhythmias. Previous studies found a relation between electrical remodeling and inducibility of TdP, while structural remodeling is not a prerequisite for arrhythmogenesis. In this study, we prospectively assessed the relation between in vivo markers of contractile remodeling and TdP inducibility. Methods: In 18 anesthetized dogs, the maximal first derivative of left ventricular pressure (LV dP/dtmax) was assessed at acute AV-block (AAVB) and after 2 weeks of chronic AV-block (CAVB2). Using pacing protocols, three markers of contractile remodeling, i.e., force-frequency relationship (FFR), mechanical restitution (MR), and post-extrasystolic potentiation (PESP) were determined. Infusion of dofetilide (0.025 mg/kg in 5 min) was used to test for TdP inducibility. Results: After infusion of dofetilide, 1/18 dogs and 12/18 were susceptible to TdP-arrhythmias at AAVB and CAVB2, respectively (p = 0.001). The inducible dogs at CAVB2 showed augmented contractility at a CL of 1200 ms (2354 ± 168 mmHg/s in inducible dogs versus 1091 ± 59 mmHg/s in non-inducible dogs, p < 0.001) with a negative FFR, while the non-inducible dogs retained their positive FFR. The time constant (TC) of the MR curve was significantly higher in the inducible dogs (158 ± 7 ms versus 97 ± 8 ms, p < 0.0001). Furthermore, a linear correlation was found between a weighted score of the number and severity of arrhythmias and contractile parameters, i.e., contractility at CL of 1200 ms (r = 0.73, p = 0.002), the slope of the FFR (r = -0.58, p = 0.01) and the TC of MR (r = 0.66, p = 0.003). Thus, more severe arrhythmias were seen in dogs with the most pronounced contractile remodeling. Conclusion: Contractile remodeling is concomitantly observed with susceptibility to dofetilide-induced TdP-arrhythmias. The inducible dogs show augmented contractile remodeling compared to non-inducible dogs, as seen by a negative FFR, higher maximal response of MR and PESP and slowed MR kinetics. These altered contractility parameters could reflect disrupted Ca2+ handling and Ca2+-overload, which predispose the heart to delayed- and early afterdepolarizations that could trigger TdP-arrhythmias.
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Affiliation(s)
- David J Sprenkeler
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alexandre Bossu
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Jet D M Beekman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marieke Schoenmakers
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
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7
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de Godoy CMG, Vasques ÊR, Caricati-Neto A, Tavares JGP, Alves BJ, Duarte J, Miranda-Ferreira R, Lima MA, Nader HB, Tersariol ILDS. Heparin Oligosaccharides Have Antiarrhythmic Effect by Accelerating the Sodium-Calcium Exchanger. Front Cardiovasc Med 2018; 5:67. [PMID: 29930947 PMCID: PMC5999778 DOI: 10.3389/fcvm.2018.00067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 05/17/2018] [Indexed: 01/15/2023] Open
Abstract
Background: Blockage of the Na+/Ca2+ exchanger (NCX) is used to determine the role of NCX in arrhythmogenesis. Trisulfated heparin disaccharide (TD) and Low Molecular Weight Heparins (LMWHs) can directly interact with the NCX and accelerate its activity. Objective: In this work, we investigated the antiarrhythmic effect of heparin oligosaccharides related to the NCX activity. Methods: The effects of heparin oligosaccharides were tested on the NCX current (patch clamping) and intracellular calcium transient in rat cardiomyocytes. The effects of heparin oligosaccharides were further investigated in arrhythmia induced in isolated rat atria and rats in vivo. Results: The intracellular Ca2+ concentration decreases upon treatment with either enoxaparin or ardeparin. These drugs abolished arrhythmia induction in isolated atria. The NCX antagonist KB-R7943 abolished the enoxaparin or ardeparin antiarrhythmic effects in isolated atria. In the in vivo measurements, injection of TD 15 min both before coronary occlusion or immediately after reperfusion, significantly prevented the occurrence of reperfusion-induced arrhythmias (ventricular arrhythmia and total AV block) and reduced the lethality rate. The patch clamping experiments showed that, mechanistically, TD increases the forward mode NCX current. Conclusion: Together, the data shows that heparin oligosaccharides may constitute a new class of antiarrhythmic drug that acts by accelerating the forward mode NCX under calcium overload.
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Affiliation(s)
- Carlos M G de Godoy
- Institute of Science and Technology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ênio R Vasques
- Department of Gastroenterology (LIM 37), Medical School, University of São Paulo, São Paulo, Brazil.,Núcleo de Pesquisas Tecnológicas, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
| | - Afonso Caricati-Neto
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - José G P Tavares
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Beatriz J Alves
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juliana Duarte
- Núcleo de Pesquisas Tecnológicas, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
| | | | - Marcelo A Lima
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Helena B Nader
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ivarne L Dos Santos Tersariol
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil.,Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
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8
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Ríos E. Perspectives on "Control of Ca release from within the cardiac sarcoplasmic reticulum". J Gen Physiol 2017; 149:833-836. [PMID: 28798278 PMCID: PMC5583715 DOI: 10.1085/jgp.201711847] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 07/24/2017] [Indexed: 12/11/2022] Open
Abstract
Five groups of experts unravel the complex modulation of a function crucial for the beating heart.
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Affiliation(s)
- Eduardo Ríos
- Section of Cellular Signaling, Department of Physiology and Biophysics, Rush University, Chicago, IL
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9
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Campos FO, Shiferaw Y, Prassl AJ, Boyle PM, Vigmond EJ, Plank G. Stochastic spontaneous calcium release events trigger premature ventricular complexes by overcoming electrotonic load. Cardiovasc Res 2015; 107:175-83. [PMID: 25969391 DOI: 10.1093/cvr/cvv149] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 05/07/2015] [Indexed: 12/21/2022] Open
Abstract
AIMS Premature ventricular complexes (PVCs) due to spontaneous calcium (Ca) release (SCR) events at the cell level can precipitate ventricular arrhythmias. However, the mechanistic link between SCRs and PVC formation remains incompletely understood. The aim of this study was to investigate the conditions under which delayed afterdepolarizations resulting from stochastic subcellular SCR events can overcome electrotonic source-sink mismatch, leading to PVC initiation. METHODS AND RESULTS A stochastic subcellular-scale mathematical model of SCR was incorporated in a realistic model of the rabbit ventricles and Purkinje system (PS). Elevated levels of diastolic sarcoplasmic reticulum Ca(2+) (CaSR) were imposed until triggered activity was observed, allowing us to compile statistics on probability, timing, and location of PVCs. At CaSR≥ 1500 µmol/L PVCs originated in the PS. When SCR was incapacitated in the PS, PVCs also emerged in the ventricles, but at a higher CaSR (≥1550 µmol/L) and with longer waiting times. For each model configuration tested, the probability of PVC occurrence increased from 0 to 100% within a well-defined critical CaSR range; this transition was much more abrupt in organ-scale models (∼50 µmol/L CaSR range) than in the tissue strand (∼100 µmol/L) or single-cell (∼450 µmol/L) models. Among PVCs originating in the PS, ∼68% were located near Purkinje-ventricular junctions (<1 mm). CONCLUSION SCR events overcome source-sink mismatch to trigger PVCs at a critical CaSR threshold. Above this threshold, PVCs emerge due to increased probability and reduced variability in timing of SCR events, leading to significant diastolic depolarization. Sites of lower electronic load, such as the PS, are preferential locations for triggering.
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Affiliation(s)
| | - Yohannes Shiferaw
- Department of Physics, California State University, Northridge, CA, USA
| | - Anton J Prassl
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - Patrick M Boyle
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Edward J Vigmond
- LIRYC Institute, University of Bordeaux, Bordeaux, France Department of Electrical and Computer Engineering, University of Calgary, Calgary, Canada
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Graz, Austria
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10
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Affiliation(s)
- Roger J Hajjar
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY (R.J.H.); and NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital and Imperial College, London, UK (A.R.L.).
| | - Alexander R Lyon
- From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY (R.J.H.); and NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital and Imperial College, London, UK (A.R.L.)
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11
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Hong T, Yang H, Zhang SS, Cho HC, Kalashnikova M, Sun B, Zhang H, Bhargava A, Grabe M, Olgin J, Gorelik J, Marbán E, Jan LY, Shaw RM. Cardiac BIN1 folds T-tubule membrane, controlling ion flux and limiting arrhythmia. Nat Med 2014; 20:624-32. [PMID: 24836577 PMCID: PMC4048325 DOI: 10.1038/nm.3543] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 03/24/2014] [Indexed: 11/08/2022]
Abstract
Cardiomyocyte T tubules are important for regulating ion flux. Bridging integrator 1 (BIN1) is a T-tubule protein associated with calcium channel trafficking that is downregulated in failing hearts. Here we find that cardiac T tubules normally contain dense protective inner membrane folds that are formed by a cardiac isoform of BIN1. In mice with cardiac Bin1 deletion, T-tubule folding is decreased, which does not change overall cardiomyocyte morphology but leads to free diffusion of local extracellular calcium and potassium ions, prolonging action-potential duration and increasing susceptibility to ventricular arrhythmias. We also found that T-tubule inner folds are rescued by expression of the BIN1 isoform BIN1+13+17, which promotes N-WASP-dependent actin polymerization to stabilize the T-tubule membrane at cardiac Z discs. BIN1+13+17 recruits actin to fold the T-tubule membrane, creating a 'fuzzy space' that protectively restricts ion flux. When the amount of the BIN1+13+17 isoform is decreased, as occurs in acquired cardiomyopathy, T-tubule morphology is altered, and arrhythmia can result.
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Affiliation(s)
- TingTing Hong
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Huanghe Yang
- Departments of Physiology, Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Shan-Shan Zhang
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Hee Cheol Cho
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Mariya Kalashnikova
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Baiming Sun
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Hao Zhang
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Anamika Bhargava
- Imperial Center for Translational and Experimental Medicine, Imperial College, London, UK
| | - Michael Grabe
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Jeffrey Olgin
- Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Julia Gorelik
- Imperial Center for Translational and Experimental Medicine, Imperial College, London, UK
| | - Eduardo Marbán
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Lily Y. Jan
- Departments of Physiology, Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, USA
| | - Robin M. Shaw
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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12
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SHI SHAOBO, LIU TAO, LI YAFENG, QIN MU, TANG YANHONG, SHEN JERRYY, LIANG JINJUN, YANG BO, HUANG CONGXIN. Chronic N-Methyl-d-Aspartate Receptor Activation Induces Cardiac Electrical Remodeling and Increases Susceptibility to Ventricular Arrhythmias. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2014; 37:1367-77. [PMID: 24888504 DOI: 10.1111/pace.12430] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/17/2014] [Accepted: 04/23/2014] [Indexed: 11/26/2022]
Affiliation(s)
- SHAOBO SHI
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
- Cardiovascular Research Institute; Wuhan University; Wuhan PR China
| | - TAO LIU
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
- Cardiovascular Research Institute; Wuhan University; Wuhan PR China
| | - YAFENG LI
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
- Cardiovascular Research Institute; Wuhan University; Wuhan PR China
| | - MU QIN
- The First Clinical Medical College of Three Gorges University; Yichang PR China
| | - YANHONG TANG
- Cardiovascular Research Institute; Wuhan University; Wuhan PR China
| | - JERRY Y. SHEN
- Department of Family Medicine; College of Community Health Sciences; University of Alabama; Tuscaloosa Alabama
| | - JINJUN LIANG
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
| | - BO YANG
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
| | - CONGXIN HUANG
- Department of Cardiology; Renmin Hospital of Wuhan University; Wuhan PR China
- Cardiovascular Research Institute; Wuhan University; Wuhan PR China
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MacDonald JK, Pyle WG, Reitz CJ, Howlett SE. Cardiac contraction, calcium transients, and myofilament calcium sensitivity fluctuate with the estrous cycle in young adult female mice. Am J Physiol Heart Circ Physiol 2014; 306:H938-53. [DOI: 10.1152/ajpheart.00730.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This study established conditions to induce regular estrous cycles in female C57BL/6J mice and investigated the impact of the estrous cycle on contractions, Ca2+ transients, and underlying cardiac excitation-contraction (EC)-coupling mechanisms. Daily vaginal smears from group-housed virgin female mice were stained to distinguish estrous stage (proestrus, estrus, metestrus, diestrus). Ventricular myocytes were isolated from anesthetized mice. Contractions and Ca2+ transients were measured simultaneously (4 Hz, 37°C). Interestingly, mice did not exhibit regular cycles unless they were exposed to male pheromones in bedding added to their cages. Field-stimulated myocytes from mice in estrus had larger contractions (∼2-fold increase), larger Ca2+ transients (∼1.11-fold increase), and longer action potentials (>2-fold increase) compared with other stages. Larger contractions and Ca2+ transients were not observed in estrus myocytes voltage-clamped with shorter action potentials. Voltage-clamp experiments also demonstrated that estrous stage had no effect on Ca2+ current, EC-coupling gain, diastolic Ca2+, sarcoplasmic reticulum (SR) Ca2+ content, or fractional release. Although contractions were largest in estrus, myofilament Ca2+ sensitivity was lowest (EC50 values ∼1.15-fold higher) in conjunction with increased phosphorylation of myosin binding protein C in estrus. Contractions were enhanced in ventricular myocytes from mice in estrus because action potential prolongation increased SR Ca2+ release. These findings demonstrate that cyclical changes in reproductive hormones associated with the estrous cycle can influence myocardial electrical and contractile function and modify Ca2+ homeostasis. However, such changes are unlikely to occur in female mice housed in groups under conventional conditions, since these mice do not exhibit regular estrous cycles.
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Affiliation(s)
| | - W. Glen Pyle
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Cristine J. Reitz
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Susan E. Howlett
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
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Coppini R, Ferrantini C, Mazzoni L, Sartiani L, Olivotto I, Poggesi C, Cerbai E, Mugelli A. Regulation of intracellular Na(+) in health and disease: pathophysiological mechanisms and implications for treatment. Glob Cardiol Sci Pract 2013; 2013:222-42. [PMID: 24689024 PMCID: PMC3963757 DOI: 10.5339/gcsp.2013.30] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 09/01/2013] [Indexed: 12/19/2022] Open
Abstract
Transmembrane sodium (Na+) fluxes and intracellular sodium homeostasis are central players in the physiology of the cardiac myocyte, since they are crucial for both cell excitability and for the regulation of the intracellular calcium concentration. Furthermore, Na+ fluxes across the membrane of mitochondria affect the concentration of protons and calcium in the matrix, regulating mitochondrial function. In this review we first analyze the main molecular determinants of sodium fluxes across the sarcolemma and the mitochondrial membrane and describe their role in the physiology of the healthy myocyte. In particular we focus on the interplay between intracellular Ca2+ and Na+. A large part of the review is dedicated to discuss the changes of Na+ fluxes and intracellular Na+ concentration([Na+]i) occurring in cardiac disease; we specifically focus on heart failure and hypertrophic cardiomyopathy, where increased intracellular [Na+]i is an established determinant of myocardial dysfunction. We review experimental evidence attributing the increase of [Na+]i to either decreased Na+ efflux (e.g. via the Na+/K+ pump) or increased Na+ influx into the myocyte (e.g. via Na+ channels). In particular, we focus on the role of the “late sodium current” (INaL), a sustained component of the fast Na+ current of cardiac myocytes, which is abnormally enhanced in cardiac diseases and contributes to both electrical and contractile dysfunction. We analyze the pathophysiological role of INaL enhancement in heart failure and hypertrophic cardiomyopathy and the consequences of its pharmacological modulation, highlighting the clinical implications. The central role of Na+ fluxes and intracellular Na+ physiology and pathophysiology of cardiac myocytes has been highlighted by a large number of recent works. The possibility of modulating Na+ inward fluxes and [Na+]i with specific INaL inhibitors, such as ranolazine, has made Na+a novel suitable target for cardiac therapy, potentially capable of addressing arrhythmogenesis and diastolic dysfunction in severe conditions such as heart failure and hypertrophic cardiomyopathy.
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Affiliation(s)
- Raffaele Coppini
- Department NeuroFarBa, Division of Pharmacology, University of Florence, Italy
| | - Cecilia Ferrantini
- Department of Clinical and Experimental Medicine, division of Physiology, University of Florence, Italy
| | - Luca Mazzoni
- Department NeuroFarBa, Division of Pharmacology, University of Florence, Italy
| | - Laura Sartiani
- Department NeuroFarBa, Division of Pharmacology, University of Florence, Italy
| | - Iacopo Olivotto
- Referral Center for Cardiomyopathies, Careggi University Hospital, Florence, Italy
| | - Corrado Poggesi
- Department of Clinical and Experimental Medicine, division of Physiology, University of Florence, Italy
| | - Elisabetta Cerbai
- Department NeuroFarBa, Division of Pharmacology, University of Florence, Italy
| | - Alessandro Mugelli
- Department NeuroFarBa, Division of Pharmacology, University of Florence, Italy
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Fares E, Pyle WG, Ray G, Rose RA, Denovan-Wright EM, Chen RP, Howlett SE. The impact of ovariectomy on calcium homeostasis and myofilament calcium sensitivity in the aging mouse heart. PLoS One 2013; 8:e74719. [PMID: 24058623 PMCID: PMC3776741 DOI: 10.1371/journal.pone.0074719] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/05/2013] [Indexed: 12/20/2022] Open
Abstract
This study determined whether deficiency of ovarian estrogen starting very early in life promoted age-associated Ca(2+) dysregulation and contractile dysfunction in isolated ventricular myocytes. Myocytes were isolated from anesthetized C57BL/6 female mice. Animals received an ovariectomy or sham-operation at one month and were aged to ~24 months. Excitation-contraction coupling parameters were compared in fura-2 loaded myocytes (37°C). While Ca(2+) transients were larger and faster in field-stimulated myocytes from ovariectomized mice, ovariectomy had no effect on peak fractional shortening. Similarly, ovariectomy had no effect on fractional shortening measured in vivo by echocardiography (values were 60.5 ± 2.9 vs. 60.3 ± 2.5% in sham and ovariectomized, respectively; n=5 mice/group). Ovariectomy did decrease myofilament Ca(2+) sensitivity, as evidenced by a 26% increase in the Ca(2+) required to activate actomyosin MgATPase in ovariectomized hearts. Larger Ca(2+) transients were attributable to a 48% increase in peak Ca(2+) current, along with an increase in the amplitude, width and frequency of Ca(2+) sparks measured in fluo-4 loaded myocytes. These changes in Ca(2+) handling were not due to increased expression of Ca(2+) channels (Cav1.2), sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) or Na(+)-Ca(2+) exchanger in ovariectomized hearts. However, ovariectomy increased sarcoplasmic reticulum Ca(2+) stores by ~90% and promoted spontaneous Ca(2+) release from the sarcoplasmic reticulum when compared to sham controls. These observations demonstrate that long-term ovariectomy promotes intracellular Ca(2+) dysregulation, reduces myofilament Ca(2+) sensitivity and increases spontaneous Ca(2+) release in the aging female heart.
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Affiliation(s)
- Elias Fares
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W. Glen Pyle
- Cardiovascular Research Group, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Gibanananda Ray
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert A. Rose
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - Robert P. Chen
- Pediatric Cardiology, IWK Health Centre and Dalhousie University, Halifax, Nova Scotia, Canada
| | - Susan E. Howlett
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
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Guo H, Mao H, Pan G, Zhang H, Fan G, Li W, Zhou K, Zhu Y, Yanagihara N, Gao X. Antagonism of Cortex Periplocae extract-induced catecholamines secretion by Panax notoginseng saponins in cultured bovine adrenal medullary cells by drug combinations. JOURNAL OF ETHNOPHARMACOLOGY 2013; 147:447-55. [PMID: 23524165 DOI: 10.1016/j.jep.2013.03.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 03/10/2013] [Accepted: 03/11/2013] [Indexed: 05/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Traditional Chinese Medicine (TCM) operates on the general principle that compatible components of different herbal decoction may work together to synergistically enhance therapeutic efficacy or reduce adverse effects. Cortex Periplocae is an herb that has been used in TCM clinics for a long time in the treatment of chronic heart failure. However, recently, the use of this herb has been restricted because of widespread abuse and misapplications. Radix Notoginseng is another herb that is used in TCM because of its protective role on cardiomyocytes. From our previous studies on these two herbs in a mouse model, we observed an increased LD50 after oral administration of Cortex Periplocae extract (CPE) and Panax notoginseng saponins (PNS) in a ratio of 1:1 compared with Cortex Periplocae extract used alone. AIM OF THE STUDY This study aimed to investigate whether there are mutual synergistic effects of the two herbal extracts, CPE and PNS, on catecholamines (CAs) secretion, and their possible underlying mechanism(s) for such effects. MATERIALS AND METHODS CPE and PNS were quantified by the LC-MS/MS method. HPLC-ECD was used to determine the CAs secreted into the medium by bovine adrenal medulla cells (BAMCs) and calcium influx was measured using a Calcium 4 reagent kit. RESULTS We found that the stimulatory effect of CPE on CAs secretion was inhibited when used together with PNS. For a better clarification of the different constituents of the extracts, a quantitative analysis was carried out. Periplocin was found to be the main active component of CPE valued as 0.99% and saponins were the principal constituents of PNS. These results also showed that CPE increased the secretion of CAs in a dose-dependent manner while the actions of PNS were seen to be inhibitory. Periplocin monomer of CPE could be implicated for the actions of CPE since it plays the role of increasing the ACh-induced CAs secretion in a calcium-dependent manner. We therefore conclude that; CPE and PNS exert antagonistic effects in regulating the concentration of intracellular calcium. CONCLUSIONS PNS inhibits CPE-induced CAs secretion by suppressing calcium influx in bovine adrenal medulla cells while periplocin, one of the main components of CPE has the same secretagogue effect as CPE.
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Affiliation(s)
- Hao Guo
- Tianjin State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
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Miragoli M, Novak P, Ruenraroengsak P, Shevchuk AI, Korchev YE, Lab MJ, Tetley TD, Gorelik J. Functional interaction between charged nanoparticles and cardiac tissue: a new paradigm for cardiac arrhythmia? Nanomedicine (Lond) 2013; 8:725-737. [PMID: 23140503 PMCID: PMC4890656 DOI: 10.2217/nnm.12.125] [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] [Indexed: 12/25/2022] Open
Abstract
AIM To investigate the effect of surface charge of therapeutic nanoparticles on sarcolemmal ionic homeostasis and the initiation of arrhythmias. MATERIALS & METHODS Cultured neonatal rat myocytes were exposed to 50 nm-charged polystyrene latex nanoparticles and examined using a combination of hopping probe scanning ion conductance microscopy, optical recording of action potential characteristics and patch clamp. RESULTS Positively charged, amine-modified polystyrene latex nanoparticles showed cytotoxic effects and induced large-scale damage to cardiomyocyte membranes leading to calcium alternans and cell death. By contrast, negatively charged, carboxyl-modified polystyrene latex nanoparticles (NegNPs) were not overtly cytotoxic but triggered formation of 50-250-nm nanopores in the membrane. Cells exposed to NegNPs revealed pro-arrhythmic events, such as delayed afterdepolarizations, reduction in conduction velocity and pathological increment of action potential duration together with an increase in ionic current throughout the membrane, carried by the nanopores. CONCLUSION The utilization of charged nanoparticles is a novel concept for targeting cardiac excitability. However, this unique nanoscopic investigation reveals an altered electrophysiological substrate, which sensitized the heart cells towards arrhythmias.
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Affiliation(s)
- Michele Miragoli
- Myocardial Function Unit, National Heart & Lung Institute, Imperial College London, 4th floor, Imperial Centre for Translational & Experimental Medicine, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
- Centre of Excellence for Toxicological Research, exISPESL- INAIL, Dept of Evolution & Functional Biology, Section of Physiology, University of Parma, 43124 Parma, Italy
| | - Pavel Novak
- Myocardial Function Unit, National Heart & Lung Institute, Imperial College London, 4th floor, Imperial Centre for Translational & Experimental Medicine, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
- Division of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Pakatip Ruenraroengsak
- Lung Cell Biology, Section of Pharmacology & Toxicology, National Heart & Lung Institute, Dovehouse Street, Imperial College London, London, SW3 6LY, UK
| | - Andrew I Shevchuk
- Division of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
- Institute for Life Sciences, University of Southampton 3046, Life Sciences Building 85, Highfield, Southampton, SO17 1BJ, UK
| | - Yuri E Korchev
- Division of Medicine, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Max J Lab
- Myocardial Function Unit, National Heart & Lung Institute, Imperial College London, 4th floor, Imperial Centre for Translational & Experimental Medicine, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
| | - Teresa D Tetley
- Lung Cell Biology, Section of Pharmacology & Toxicology, National Heart & Lung Institute, Dovehouse Street, Imperial College London, London, SW3 6LY, UK
| | - Julia Gorelik
- Myocardial Function Unit, National Heart & Lung Institute, Imperial College London, 4th floor, Imperial Centre for Translational & Experimental Medicine, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK
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18
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Sex differences in mechanisms of cardiac excitation-contraction coupling. Pflugers Arch 2013; 465:747-63. [PMID: 23417603 PMCID: PMC3651827 DOI: 10.1007/s00424-013-1233-0] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 01/29/2013] [Accepted: 01/30/2013] [Indexed: 11/25/2022]
Abstract
The incidence and expression of cardiovascular diseases differs between the sexes. This is not surprising, as cardiac physiology differs between men and women. Clinical and basic science investigations have shown important sex differences in cardiac structure and function. The pervasiveness of sex differences suggests that such differences must be fundamental, likely operating at a cellular level. Indeed, studies have shown that isolated ventricular myocytes from female animals have smaller and slower contractions and underlying calcium transients compared to males. Recent evidence suggests that this arises from sex differences in components of the cardiac excitation–contraction coupling pathway, the sequence of events linking myocyte depolarization to calcium release from the sarcoplasmic reticulum and subsequent contraction. The concept that sex hormones may regulate intracellular calcium at the level of the cardiomyocyte is important, as levels of these hormones decline in both men and women as the incidence of cardiovascular disease rises. This review focuses on the impact of sex on cardiac contraction, in particular at the cellular level, and highlights specific components of the excitation–contraction coupling pathway that differ between the sexes. Understanding sex hormone regulation of calcium homeostasis in the heart may reveal new avenues for therapeutic strategies to treat cardiac dysfunction and cardiovascular diseases.
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19
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Gaeta SA, Christini DJ. Non-linear dynamics of cardiac alternans: subcellular to tissue-level mechanisms of arrhythmia. Front Physiol 2012; 3:157. [PMID: 22783195 PMCID: PMC3389489 DOI: 10.3389/fphys.2012.00157] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/05/2012] [Indexed: 12/22/2022] Open
Abstract
Cardiac repolarization alternans is a rhythm disturbance of the heart in which rapid stimulation elicits a beat-to-beat alternation in the duration of action potentials and magnitude of intracellular calcium transients in individual cardiac myocytes. Although this phenomenon has been identified as a potential precursor to dangerous reentrant arrhythmias and sudden cardiac death, significant uncertainty remains regarding its mechanism and no clinically practical means of halting its occurrence or progression currently exists. Cardiac alternans has well-characterized tissue, cellular, and subcellular manifestations, the mechanisms and interplay of which are an active area of research.
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Affiliation(s)
- Stephen A. Gaeta
- Department of Physiology, Biophysics and Systems
Biology, Weill Cornell Medical CollegeNew York, NY, USA
| | - David J. Christini
- Department of Physiology, Biophysics and Systems
Biology, Weill Cornell Medical CollegeNew York, NY, USA
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20
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Rossier MF, Pagano S, Python M, Maturana AD, James RW, Mach F, Roux-Lombard P, Vuilleumier N. Antiapolipoprotein A-1 IgG chronotropic effects require nongenomic action of aldosterone on L-type calcium channels. Endocrinology 2012; 153:1269-78. [PMID: 22253414 DOI: 10.1210/en.2011-1835] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Autoantibodies to apolipoprotein A-1 (antiapoA-1 IgG) have been shown to be associated with higher resting heart rate and morbidity in myocardial infarction patients and to behave as a chronotropic agent in the presence of aldosterone on isolated neonatal rat ventricular cardiomyocytes (NRVC). We aimed at identifying the pathways accounting for this aldosterone-dependent antiapoA-1 IgG-positive chronotropic effect on NRVC. The rate of regular spontaneous contractions was determined on NRVC in the presence of different steroid hormones and antagonists. AntiapoA-1 IgG chronotropic response was maximal within 20 min and observed only in aldosterone-pretreated cells but not in those exposed to other steroids. The positive antiapoA-1 IgG chronotropic effect was already significant after 5 min aldosterone preincubation, was dependent on 3-kinase and protein kinase A activities, was not inhibited by actinomycin D, and was fully abrogated by eplerenone (but not by spironolactone), demonstrating the dependence on a nongenomic action of aldosterone elicited through the mineralocorticoid receptor (MR). Under oxidative conditions (but not under normal redox state), corticosterone mimicked the permissive action of aldosterone on the antiapoA-1 IgG chronotropic response. Pharmacological and patch-clamp studies identified L-type calcium channels as crucial effectors of antiapoA-1 IgG chronotropic action, involving two converging pathways that increase the channel activity. The first one involves the rapid, nongenomic activation of the phosphatidylinositol 3-kinase enzyme by MR, and the second one requires a constitutive basal protein kinase A activity. In conclusion, our results indicate that, on NRVC, the aldosterone-dependent chronotropic effects of antiapoA-1 IgG involve the nongenomic activation of L-type calcium channels.
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Affiliation(s)
- Michel F Rossier
- Service of Endocrinology and Diabetology, Department of Internal Medicine, Geneva University Hospitals, Geneva, Switzerland
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21
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Hatch F, Lancaster MK, Jones SA. Aging is a primary risk factor for cardiac arrhythmias: disruption of intracellular Ca2+ regulation as a key suspect. Expert Rev Cardiovasc Ther 2012; 9:1059-67. [PMID: 21878050 DOI: 10.1586/erc.11.112] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Aging is an inevitable time-dependent progression associated with a functional decline of the cardiovascular system even in 'healthy' individuals. Age positively correlates with an increasing risk of cardiac problems including arrhythmias. Not only the prevalence but also the severity of arrhythmias escalates with age. The reasons for this are multifactorial but dysregulation of intracellular calcium within the heart is likely to play a key role in initiating and perpetuating these life-threatening events. We now know that several aspects of cardiac calcium regulation significantly change with advancing age - changes that could produce electrical instability. Further development of knowledge of the mechanisms underlying these changes will allow us to reduce what currently is an inevitable increase in the incidence of arrhythmias in the elderly.
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Affiliation(s)
- Fiona Hatch
- Biological Sciences and HYMS, University of Hull, Kingston-Upon-Hull, UK
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22
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Fares E, Parks RJ, MacDonald JK, Egar JM, Howlett SE. Ovariectomy enhances SR Ca2+ release and increases Ca2+ spark amplitudes in isolated ventricular myocytes. J Mol Cell Cardiol 2012; 52:32-42. [DOI: 10.1016/j.yjmcc.2011.09.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 08/18/2011] [Accepted: 09/02/2011] [Indexed: 11/24/2022]
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23
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Leenhardt A, Messali A, Labbé JP, Denjoy I, Dejode P, Maison-Blanche P, Kedra A, Extramiana F. Les post-dépolarisations. ARCHIVES OF CARDIOVASCULAR DISEASES SUPPLEMENTS 2011. [DOI: 10.1016/s1878-6480(11)70389-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Arrhythmogenic potential of oxidative stress in atrial myocytes. Int J Cardiol 2011; 150:219-21. [PMID: 21641666 DOI: 10.1016/j.ijcard.2011.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 05/13/2011] [Indexed: 01/01/2023]
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Shimoda LA, Polak J. Hypoxia. 4. Hypoxia and ion channel function. Am J Physiol Cell Physiol 2011; 300:C951-67. [PMID: 21178108 PMCID: PMC3093942 DOI: 10.1152/ajpcell.00512.2010] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 12/16/2010] [Indexed: 12/19/2022]
Abstract
The ability to sense and respond to oxygen deprivation is required for survival; thus, understanding the mechanisms by which changes in oxygen are linked to cell viability and function is of great importance. Ion channels play a critical role in regulating cell function in a wide variety of biological processes, including neuronal transmission, control of ventilation, cardiac contractility, and control of vasomotor tone. Since the 1988 discovery of oxygen-sensitive potassium channels in chemoreceptors, the effect of hypoxia on an assortment of ion channels has been studied in an array of cell types. In this review, we describe the effects of both acute and sustained hypoxia (continuous and intermittent) on mammalian ion channels in several tissues, the mode of action, and their contribution to diverse cellular processes.
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Affiliation(s)
- Larissa A Shimoda
- Div. of Pulmonary and Critical Care Medicine, Johns Hopkins University, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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Fan X, Ma J, Wan W, Zhang P, Wang C, Wu L. Increased intracellular calcium concentration causes electrical turbulence in guinea pig ventricular myocytes. SCIENCE CHINA-LIFE SCIENCES 2011; 54:240-7. [PMID: 21416323 DOI: 10.1007/s11427-011-4146-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 12/21/2010] [Indexed: 01/25/2023]
Abstract
Dysregulation of intracellular Ca(2+) homeostasis is associated with various pathological conditions and arrhythmogenesis of the heart. The objective of this study was to investigate the effects of an acute increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) on the electrophysiology of ventricular myocytes by mimicking intracellular Ca(2+) overload. The [Ca(2+)](i) was clamped to either a controlled (65-100 nmol L(-1)) or increased (1 μmol L(-1)) level. The transmembrane action potentials and ionic currents were recorded using whole-cell patch clamp techniques. We found that the acute increase in [Ca(2+)](i) shortened the action potential duration, reduced the action potential amplitude, maximum depolarization velocity and resting membrane potential, caused delayed after-depolarizations (DADs), and triggered activity-compared with these parameters in the control. The increased [Ca(2+)](i) augmented late I (Na) in a time-dependent manner, reduced I (CaL) and I (K1), and increased I (Kr) but not I (Ks). The results of this study can be used to explain calcium overload-induced ventricular arrhythmias.
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Affiliation(s)
- Xinrong Fan
- Cardio-Electrophysiological Research Laboratory, Medical College of Wuhan University of Science and Technology, Wuhan 430081, China
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27
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Brigadeau F, Kouakam C, Boule S, Marquie C, Klug D. Les orages rythmiques. ARCHIVES OF CARDIOVASCULAR DISEASES SUPPLEMENTS 2010. [DOI: 10.1016/s1878-6480(10)70372-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Katz G, Arad M, Eldar M. Catecholaminergic polymorphic ventricular tachycardia from bedside to bench and beyond. Curr Probl Cardiol 2009; 34:9-43. [PMID: 19068246 DOI: 10.1016/j.cpcardiol.2008.09.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a primary electrical myocardial disease characterized by exercise- and stress-related ventricular tachycardia manifested as syncope and sudden death. The disease has a heterogeneous genetic basis, with mutations in the cardiac Ryanodine Receptor channel (RyR2) gene accounting for an autosomal-dominant form (CPVT1) in approximately 50% and mutations in the cardiac calsequestrin gene (CASQ2) accounting for an autosomal-recessive form (CPVT2) in up to 2% of CPVT cases. Both RyR2 and calsequestrin are important participants in the cardiac cellular calcium homeostasis. We review the physiology of the cardiac calcium homeostasis, including the cardiac excitation contraction coupling and myocyte calcium cycling. The pathophysiology of cardiac arrhythmias related to myocyte calcium handling and the effects of different modulators are discussed. The putative derangements in myocyte calcium homeostasis responsible for CPVT, as well as the clinical manifestations and therapeutic options available, are described.
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Pathophysiology and pharmacology of the cardiac “late sodium current”. Pharmacol Ther 2008; 119:326-39. [DOI: 10.1016/j.pharmthera.2008.06.001] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2008] [Accepted: 06/04/2008] [Indexed: 12/19/2022]
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Kurebayashi N, Nishizawa H, Nakazato Y, Kurihara H, Matsushita S, Daida H, Ogawa Y. Aberrant cell-to-cell coupling in Ca2+-overloaded guinea pig ventricular muscles. Am J Physiol Cell Physiol 2008; 294:C1419-29. [DOI: 10.1152/ajpcell.00413.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate how intercellular coupling can be changed during Ca2+ overloading of ventricular muscle, we studied Ca2+ signals in individual cells and the histochemistry of the major gap junction channel, connexin43 (Cx43), using multicellular preparations. Papillary muscles were obtained from guinea pig ventricles and loaded with rhod-2. Sequential Ca2+ images of surface cells were obtained with a confocal microscope. In intact muscles, all cells showed simultaneous Ca2+ transients in response to field stimulation over a field of view of 0.3 × 0.3 mm2. In severely Ca2+-overloaded muscles, obtained by high-frequency stimulation in nonflowing Krebs solution, cells became less responsive to stimulation. Furthermore, nonsimultaneous but serial onsets of Ca2+ transients were often detected, suggesting a propagation delay of action potentials. The time lag of the onset between two aligned cells was sometimes as long as 100 ms. Similar lags were also observed in muscles with gap junction channels inhibited by heptanol. To investigate whether the phosphorylation state of Cx43 is affected in Ca2+-overloaded muscles, the distributions of phosphorylated and nonphosphorylated Cx43 were determined using specific antibodies. Most of the Cx43 was phosphorylated in the nonoverloaded muscles, whereas nonphosphorylated Cx43 was significantly elevated in severely Ca2+-overloaded muscles. Our results suggest that the propagation delay of action potential within a small area, a few square millimeters, can be a cause of abnormal conduction and a microreentry in Ca2+-overloaded heart. Inactivation of Na+ channels and inhibition of gap junctional communication may underlie the cell-to-cell propagation delay.
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Abstract
Mammalian Na+/Ca2+ exchangers are members of three branches of a much larger family of transport proteins [the CaCA (Ca2+/cation antiporter) superfamily] whose main role is to provide control of Ca2+ flux across the plasma membranes or intracellular compartments. Since cytosolic levels of Ca2+ are much lower than those found extracellularly or in sequestered stores, the major function of Na+/Ca2+ exchangers is to extrude Ca2+ from the cytoplasm. The exchangers are, however, fully reversible and thus, under special conditions of subcellular localization and compartmentalized ion gradients, Na+/Ca2+ exchangers may allow Ca2+ entry and may play more specialized roles in Ca2+ movement between compartments. The NCX (Na+/Ca2+ exchanger) [SLC (solute carrier) 8] branch of Na+/Ca2+ exchangers comprises three members: NCX1 has been most extensively studied, and is broadly expressed with particular abundance in heart, brain and kidney, NCX2 is expressed in brain, and NCX3 is expressed in brain and skeletal muscle. The NCX proteins subserve a variety of roles, depending upon the site of expression. These include cardiac excitation-contraction coupling, neuronal signalling and Ca2+ reabsorption in the kidney. The NCKX (Na2+/Ca2+-K+ exchanger) (SLC24) branch of Na+/Ca2+ exchangers transport K+ and Ca2+ in exchange for Na+, and comprises five members: NCKX1 is expressed in retinal rod photoreceptors, NCKX2 is expressed in cone photoreceptors and in neurons throughout the brain, NCKX3 and NCKX4 are abundant in brain, but have a broader tissue distribution, and NCKX5 is expressed in skin, retinal epithelium and brain. The NCKX proteins probably play a particularly prominent role in regulating Ca2+ flux in environments which experience wide and frequent fluctuations in Na+ concentration. Until recently, the range of functions that NCKX proteins play was generally underappreciated. This situation is now changing rapidly as evidence emerges for roles including photoreceptor adaptation, synaptic plasticity and skin pigmentation. The CCX (Ca2+/cation exchanger) branch has only one mammalian member, NCKX6 or NCLX (Na+/Ca2+-Li+ exchanger), whose physiological function remains unclear, despite a broad pattern of expression.
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Affiliation(s)
- Jonathan Lytton
- Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1.
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Sipido KR, Bito V, Antoons G, Volders PG, Vos MA. Na/Ca exchange and cardiac ventricular arrhythmias. Ann N Y Acad Sci 2007; 1099:339-48. [PMID: 17446474 DOI: 10.1196/annals.1387.066] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ventricular arrhythmias are a major cause of death in cardiovascular disease. Ca2+ removal from the cell by the electrogenic Na/Ca exchanger is essential for the Ca2+ flux balance during excitation-contraction coupling but also contributes to the electrical events. "Classic" views on the exchanger in arrhythmias include its well-recognized role as depolarizing current underlying delayed afterdepolarizations (DADs) during spontaneous Ca2+ release and the alterations in expression in certain forms of cardiac hypertrophy and heart failure. "Novel" views relate to more subtle roles for the exchanger in arrhythmias. Na/Ca exchange function in disease could be modulated indirectly, through phosphorylation or anchoring proteins. Ongoing studies relate Na/Ca exchange to variability in action potential duration (APD) and early afterdepolarizations (EADs) in a dog model of cardiac hypertrophy and arrhythmias. Further research on drugs that target Na/Ca exchange will have to carefully examine the effects on Ca2+ balance.
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Affiliation(s)
- Karin R Sipido
- Laboratory of Experimental Cardiology, KUL, Campus Gasthuisberg O/N1, 704, Herestraat 49, B-3000 Leuven, Belgium.
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