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Ni H, Morotti S, Zhang X, Dobrev D, Grandi E. Integrative human atrial modelling unravels interactive protein kinase A and Ca2+/calmodulin-dependent protein kinase II signalling as key determinants of atrial arrhythmogenesis. Cardiovasc Res 2023; 119:2294-2311. [PMID: 37523735 DOI: 10.1093/cvr/cvad118] [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: 02/24/2023] [Revised: 05/18/2023] [Accepted: 06/05/2023] [Indexed: 08/02/2023] Open
Abstract
AIMS Atrial fibrillation (AF), the most prevalent clinical arrhythmia, is associated with atrial remodelling manifesting as acute and chronic alterations in expression, function, and regulation of atrial electrophysiological and Ca2+-handling processes. These AF-induced modifications crosstalk and propagate across spatial scales creating a complex pathophysiological network, which renders AF resistant to existing pharmacotherapies that predominantly target transmembrane ion channels. Developing innovative therapeutic strategies requires a systems approach to disentangle quantitatively the pro-arrhythmic contributions of individual AF-induced alterations. METHODS AND RESULTS Here, we built a novel computational framework for simulating electrophysiology and Ca2+-handling in human atrial cardiomyocytes and tissues, and their regulation by key upstream signalling pathways [i.e. protein kinase A (PKA), and Ca2+/calmodulin-dependent protein kinase II (CaMKII)] involved in AF-pathogenesis. Populations of atrial cardiomyocyte models were constructed to determine the influence of subcellular ionic processes, signalling components, and regulatory networks on atrial arrhythmogenesis. Our results reveal a novel synergistic crosstalk between PKA and CaMKII that promotes atrial cardiomyocyte electrical instability and arrhythmogenic triggered activity. Simulations of heterogeneous tissue demonstrate that this cellular triggered activity is further amplified by CaMKII- and PKA-dependent alterations of tissue properties, further exacerbating atrial arrhythmogenesis. CONCLUSIONS Our analysis reveals potential mechanisms by which the stress-associated adaptive changes turn into maladaptive pro-arrhythmic triggers at the cellular and tissue levels and identifies potential anti-AF targets. Collectively, our integrative approach is powerful and instrumental to assemble and reconcile existing knowledge into a systems network for identifying novel anti-AF targets and innovative approaches moving beyond the traditional ion channel-based strategy.
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Affiliation(s)
- Haibo Ni
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Xianwei Zhang
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montréal, Canada
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
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2
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Koyani CN, Scheruebel S, Jin G, Kolesnik E, Zorn-Pauly K, Mächler H, Hoefler G, von Lewinski D, Heinzel FR, Pelzmann B, Malle E. Hypochlorite-Modified LDL Induces Arrhythmia and Contractile Dysfunction in Cardiomyocytes. Antioxidants (Basel) 2021; 11:25. [PMID: 35052529 PMCID: PMC8772905 DOI: 10.3390/antiox11010025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 02/05/2023] Open
Abstract
Neutrophil-derived myeloperoxidase (MPO) and its potent oxidant, hypochlorous acid (HOCl), gained attention as important oxidative mediators in cardiac damage and dysfunction. As cardiomyocytes generate low-density lipoprotein (LDL)-like particles, we aimed to identify the footprints of proatherogenic HOCl-LDL, which adversely affects cellular signalling cascades in various cell types, in the human infarcted myocardium. We performed immunohistochemistry for MPO and HOCl-LDL in human myocardial tissue, investigated the impact of HOCl-LDL on electrophysiology and contractility in primary cardiomyocytes, and explored underlying mechanisms in HL-1 cardiomyocytes and human atrial appendages using immunoblot analysis, qPCR, and silencing experiments. HOCl-LDL reduced ICa,L and IK1, and increased INaL, leading to altered action potential characteristics and arrhythmic events including early- and delayed-afterdepolarizations. HOCl-LDL altered the expression and function of CaV1.2, RyR2, NCX1, and SERCA2a, resulting in impaired contractility and Ca2+ homeostasis. Elevated superoxide anion levels and oxidation of CaMKII were mediated via LOX-1 signaling in HL-1 cardiomyocytes. Furthermore, HOCl-LDL-mediated alterations of cardiac contractility and electrophysiology, including arrhythmic events, were ameliorated by the CaMKII inhibitor KN93 and the INaL blocker, ranolazine. This study provides an explanatory framework for the detrimental effects of HOCl-LDL compared to native LDL and cardiac remodeling in patients with high MPO levels during the progression of cardiovascular disease.
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Affiliation(s)
- Chintan N. Koyani
- Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria;
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Susanne Scheruebel
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Ge Jin
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
- The 2nd Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Ewald Kolesnik
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Klaus Zorn-Pauly
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Heinrich Mächler
- Department of Surgery, Division of Cardiac Surgery, Medical University of Graz, 8036 Graz, Austria;
| | - Gerald Hoefler
- Diagnostic and Research Center for Molecular BioMedicine, Diagnostic and Research Institute of Pathology, Medical University of Graz, 8010 Graz, Austria;
| | - Dirk von Lewinski
- Department of Internal Medicine, Division of Cardiology, Medical University of Graz, 8036 Graz, Austria; (G.J.); (E.K.); (D.v.L.)
| | - Frank R. Heinzel
- Department of Internal Medicine and Cardiology, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, 13353 Berlin, Germany;
- Deutsches Zentrum für Herz-Kreislauf-Forschung (German Centre for Cardiovascular Research), Partner Site Berlin, 10785 Berlin, Germany
| | - Brigitte Pelzmann
- Division of Biophysics, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria; (S.S.); (K.Z.-P.)
| | - Ernst Malle
- Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, 8010 Graz, Austria;
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3
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Gaur N, Qi XY, Benoist D, Bernus O, Coronel R, Nattel S, Vigmond EJ. A computational model of pig ventricular cardiomyocyte electrophysiology and calcium handling: Translation from pig to human electrophysiology. PLoS Comput Biol 2021; 17:e1009137. [PMID: 34191797 PMCID: PMC8277015 DOI: 10.1371/journal.pcbi.1009137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 07/13/2021] [Accepted: 06/01/2021] [Indexed: 12/01/2022] Open
Abstract
The pig is commonly used as an experimental model of human heart disease, including for the study of mechanisms of arrhythmia. However, there exist differences between human and porcine cellular electrophysiology: The pig action potential (AP) has a deeper phase-1 notch, a longer duration at 50% repolarization, and higher plateau potentials than human. Ionic differences underlying the AP include larger rapid delayed-rectifier and smaller inward-rectifier K+-currents (IKr and IK1 respectively) in humans. AP steady-state rate-dependence and restitution is steeper in pigs. Porcine Ca2+ transients can have two components, unlike human. Although a reliable computational model for human ventricular myocytes exists, one for pigs is lacking. This hampers translation from results obtained in pigs to human myocardium. Here, we developed a computational model of the pig ventricular cardiomyocyte AP using experimental datasets of the relevant ionic currents, Ca2+-handling, AP shape, AP duration restitution, and inducibility of triggered activity and alternans. To properly capture porcine Ca2+ transients, we introduced a two-step process with a faster release in the t-tubular region, followed by a slower diffusion-induced release from a non t-tubular subcellular region. The pig model behavior was compared with that of a human ventricular cardiomyocyte (O’Hara-Rudy) model. The pig, but not the human model, developed early afterdepolarizations (EADs) under block of IK1, while IKr block led to EADs in the human but not in the pig model. At fast rates (pacing cycle length = 400 ms), the human cell model was more susceptible to spontaneous Ca2+ release-mediated delayed afterdepolarizations (DADs) and triggered activity than pig. Fast pacing led to alternans in human but not pig. Developing species-specific models incorporating electrophysiology and Ca2+-handling provides a tool to aid translating antiarrhythmic and arrhythmogenic assessment from the bench to the clinic. The pig is an animal commonly used experimentally to study diseases of the heart, as well as investigate therapies to treat them, such as drugs. However, although similar, pigs differ from humans in certain aspects which may mean experimental results do not always directly translate between species. We propose a mathematical model of porcine electrophysiology which can serve as a tool to understand differences between the species and translate responses. Using new measurements along with values from literature, we built a computer model of porcine cardiac myocyte which replicated voltage and calcium behaviour over a range of pacing frequencies. The pig cell had a two-stage calcium release, unlike humans with a single stage. We predict that pigs and humans differ in the type of potassium current block that makes them most susceptible to cardiac arrhythmia. The model we developed can elucidate important differences between human and pig arrhythmia response.
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Affiliation(s)
- Namit Gaur
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Univ. Bordeaux, IMB, UMR 5251, Talence, France
| | - Xiao-Yan Qi
- Montreal Heart Institute and Université de Montréal, Montreal, Canada
| | - David Benoist
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Univ. Bordeaux, Inserm, CRCTB, U1045, Pessac, France
| | - Olivier Bernus
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Univ. Bordeaux, Inserm, CRCTB, U1045, Pessac, France
| | - Ruben Coronel
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Stanley Nattel
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Montreal Heart Institute and Université de Montréal, Montreal, Canada
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Edward J. Vigmond
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
- Univ. Bordeaux, IMB, UMR 5251, Talence, France
- * E-mail:
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Ca 2+/calmodulin kinase II-dependent regulation of β IV-spectrin modulates cardiac fibroblast gene expression, proliferation, and contractility. J Biol Chem 2021; 297:100893. [PMID: 34153319 PMCID: PMC8294584 DOI: 10.1016/j.jbc.2021.100893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 06/10/2021] [Accepted: 06/17/2021] [Indexed: 01/26/2023] Open
Abstract
Fibrosis is a pronounced feature of heart disease and the result of dysregulated activation of resident cardiac fibroblasts (CFs). Recent work identified stress-induced degradation of the cytoskeletal protein βIV-spectrin as an important step in CF activation and cardiac fibrosis. Furthermore, loss of βIV-spectrin was found to depend on Ca2+/calmodulin-dependent kinase II (CaMKII). Therefore, we sought to determine the mechanism for CaMKII-dependent regulation of βIV-spectrin and CF activity. Computational screening and MS revealed a critical serine residue (S2250 in mouse and S2254 in human) in βIV-spectrin phosphorylated by CaMKII. Disruption of βIV-spectrin/CaMKII interaction or alanine substitution of βIV-spectrin Ser2250 (βIV-S2254A) prevented CaMKII-induced degradation, whereas a phosphomimetic construct (βIV-spectrin with glutamic acid substitution at serine 2254 [βIV-S2254E]) showed accelerated degradation in the absence of CaMKII. To assess the physiological significance of this phosphorylation event, we expressed exogenous βIV-S2254A and βIV-S2254E constructs in βIV-spectrin-deficient CFs, which have increased proliferation and fibrotic gene expression compared with WT CFs. βIV-S2254A but not βIV-S2254E normalized CF proliferation, gene expression, and contractility. Pathophysiological targeting of βIV-spectrin phosphorylation and subsequent degradation was identified in CFs activated with the profibrotic ligand angiotensin II, resulting in increased proliferation and signal transducer and activation of transcription 3 nuclear accumulation. While therapeutic delivery of exogenous WT βIV-spectrin partially reversed these trends, βIV-S2254A completely negated increased CF proliferation and signal transducer and activation of transcription 3 translocation. Moreover, we observed βIV-spectrin phosphorylation and associated loss in total protein within human heart tissue following heart failure. Together, these data illustrate a considerable role for the βIV-spectrin/CaMKII interaction in activating profibrotic signaling.
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Role of Oxidation-Dependent CaMKII Activation in the Genesis of Abnormal Action Potentials in Atrial Cardiomyocytes: A Simulation Study. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1597012. [PMID: 32685443 PMCID: PMC7327560 DOI: 10.1155/2020/1597012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 05/20/2020] [Accepted: 06/02/2020] [Indexed: 01/04/2023]
Abstract
Atrial fibrillation is a common cardiac arrhythmia with an increasing incidence rate. Particularly for the aging population, understanding the underlying mechanisms of atrial arrhythmia is important in designing clinical treatment. Recently, experiments have shown that atrial arrhythmia is associated with oxidative stress. In this study, an atrial cell model including oxidative-dependent Ca2+/calmodulin- (CaM-) dependent protein kinase II (CaMKII) activation was developed to explore the intrinsic mechanisms of atrial arrhythmia induced by oxidative stress. The simulation results showed that oxidative stress caused early afterdepolarizations (EADs) of action potentials by altering the dynamics of transmembrane currents and intracellular calcium cycling. Oxidative stress gradually elevated the concentration of calcium ions in the cytoplasm by enhancing the L-type Ca2+ current and sarcoplasmic reticulum (SR) calcium release. Owing to increased intracellular calcium concentration, the inward Na+/Ca2+ exchange current was elevated which slowed down the repolarization of the action potential. Thus, the action potential was prolonged and the L-type Ca2+ current was reactivated, resulting in the genesis of EAD. Furthermore, based on the atrial single-cell model, a two-dimensional (2D) ideal tissue model was developed to explore the effect of oxidative stress on the electrical excitation wave conduction in 2D tissue. Simulation results demonstrated that, under oxidative stress conditions, EAD hindered the conduction of electrical excitation and caused an unstable spiral wave, which could disrupt normal cardiac rhythm and cause atrial arrhythmia. This study showed the effects of excess reactive oxygen species on calcium cycling and action potential in atrial myocytes and provided insights regarding atrial arrhythmia induced by oxidative stress.
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6
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Chang PC, Wo HT, Lee HL, Lin SF, Chu Y, Wen MS, Chou CC. Sacubitril/Valsartan Therapy Ameliorates Ventricular Tachyarrhythmia Inducibility in a Rabbit Myocardial Infarction Model. J Card Fail 2020; 26:527-537. [PMID: 32209390 DOI: 10.1016/j.cardfail.2020.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 03/16/2020] [Accepted: 03/18/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Coronary artery disease is the most common cause of heart failure (HF) in developed countries. The aim of this study was to elucidate the mechanisms of reduction of arrhythmias after sacubitril/valsartan (LCZ696) therapy in a myocardial infarction (MI)-HF rabbit model. METHODS AND RESULTS Chronic MI in rabbits with HF were divided into 3 groups: placebo control, valsartan 30 mg/day and LCZ696 60 mg/day. After 4 weeks of therapy, an electrophysiologic study and a dual voltage-calcium optical mapping study were performed. The LCZ696 group had significantly better left ventricular ejection fraction and lower ventricular tachyarrhythmia inducibility than the valsartan and placebo groups. The most common ventricular tachyarrhythmia pattern was 1 or 2 ectopic beats originating from the peri-infarct areas, followed by re-entrant beats surrounding phase singularity points. Compared to the valsartan and placebo groups, the LCZ696 group had significantly shorter action-potential duration, shorter intracellular calcium tau constant, faster conduction velocity, and shorter pacing cycle length to induce arrhythmogenic alternans. LCZ696 therapy reduced the phosphorylated calmodulin-dependent protein kinase II (CaMKII-p) expression. CONCLUSIONS In a rabbit model with chronic MI and HF, LCZ696 therapy ameliorated postinfarct heart function impairment and electrophysiologic remodeling and altered CaMKII-p expression, leading to reduced ventricular tachyarrhythmia inducibility.
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Affiliation(s)
- Po-Cheng Chang
- Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou; Chang Gung University College of Medicine, Taoyuan
| | - Hung-Ta Wo
- Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou
| | - Hui-Ling Lee
- Department of Anesthesia, Chang Gung Memorial Hospital, Taipei
| | - Shien-Fong Lin
- Institute of Biomedical Engineering, National Chiao Tung University, Hsin Chu, Taiwan
| | - Yen Chu
- Division of Thoracic Surgery, Chang Gung Memorial Hospital, Linkou; Chang Gung University College of Medicine, Taoyuan
| | - Ming-Shien Wen
- Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou; Chang Gung University College of Medicine, Taoyuan
| | - Chung-Chuan Chou
- Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou; Chang Gung University College of Medicine, Taoyuan.
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7
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Dries E, Amoni M, Vandenberk B, Johnson DM, Gilbert G, Nagaraju CK, Puertas RD, Abdesselem M, Santiago DJ, Roderick HL, Claus P, Willems R, Sipido KR. Altered adrenergic response in myocytes bordering a chronic myocardial infarction underlies in vivo triggered activity and repolarization instability. J Physiol 2020; 598:2875-2895. [PMID: 31900932 PMCID: PMC7496440 DOI: 10.1113/jp278839] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/01/2020] [Indexed: 01/24/2023] Open
Abstract
Key points Ventricular arrhythmias are a major complication after myocardial infarction (MI), associated with sympathetic activation. The structurally heterogeneous peri‐infarct zone is a known substrate, but the functional role of the myocytes is less well known. Recordings of monophasic action potentials in vivo reveal that the peri‐infarct zone is a source of delayed afterdepolarizations (DADs) and has a high beat‐to‐beat variability of repolarization (BVR) during adrenergic stimulation (isoproterenol, ISO). Myocytes isolated from the peri‐infarct region have more DADs and spontaneous action potentials, with spontaneous Ca2+ release, under ISO. These myocytes also have reduced repolarization reserve and increased BVR. Other properties of post‐MI remodelling are present in both peri‐infarct and remote myocytes. These data highlight the importance of altered myocyte adrenergic responses in the peri‐infarct region as source and substrate of post‐MI arrhythmias.
Abstract Ventricular arrhythmias are a major early complication after myocardial infarction (MI). The heterogeneous peri‐infarct zone forms a substrate for re‐entry while arrhythmia initiation is often associated with sympathetic activation. We studied the mechanisms triggering these post‐MI arrhythmias in vivo and their relation to regional myocyte remodelling. In pigs with chronic MI (6 weeks), in vivo monophasic action potentials were simultaneously recorded in the peri‐infarct and remote regions during adrenergic stimulation with isoproterenol (isoprenaline; ISO). Sham animals served as controls. During infusion of ISO in vivo, the incidence of delayed afterdepolarizations (DADs) and beat‐to‐beat variability of repolarization (BVR) was higher in the peri‐infarct than in the remote region. Myocytes isolated from the peri‐infarct region, in comparison to myocytes from the remote region, had more DADs, associated with spontaneous Ca2+ release, and a higher incidence of spontaneous action potentials (APs) when exposed to ISO (9.99 ± 4.2 vs. 0.16 ± 0.05 APs/min, p = 0.004); these were suppressed by CaMKII inhibition. Peri‐infarct myocytes also had reduced repolarization reserve and increased BVR (26 ± 10 ms vs. 9 ± 7 ms, P < 0.001), correlating with DAD activity. In contrast to these regional distinctions under ISO, alterations in Ca2+ handling at baseline and myocyte hypertrophy were present throughout the left ventricle (LV). Expression of some of the related genes was, however, different between the regions. In conclusion, altered myocyte adrenergic responses in the peri‐infarct but not the remote region provide a source of triggered activity in vivo and of repolarization instability amplifying the substrate for re‐entry. These findings stimulate further exploration of region‐specific therapies targeting myocytes and autonomic modulation. Ventricular arrhythmias are a major complication after myocardial infarction (MI), associated with sympathetic activation. The structurally heterogeneous peri‐infarct zone is a known substrate, but the functional role of the myocytes is less well known. Recordings of monophasic action potentials in vivo reveal that the peri‐infarct zone is a source of delayed afterdepolarizations (DADs) and has a high beat‐to‐beat variability of repolarization (BVR) during adrenergic stimulation (isoproterenol, ISO). Myocytes isolated from the peri‐infarct region have more DADs and spontaneous action potentials, with spontaneous Ca2+ release, under ISO. These myocytes also have reduced repolarization reserve and increased BVR. Other properties of post‐MI remodelling are present in both peri‐infarct and remote myocytes. These data highlight the importance of altered myocyte adrenergic responses in the peri‐infarct region as source and substrate of post‐MI arrhythmias.
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Affiliation(s)
- Eef Dries
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Matthew Amoni
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Bert Vandenberk
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Daniel M Johnson
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium.,Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Guillaume Gilbert
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Chandan K Nagaraju
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Rosa Doñate Puertas
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Mouna Abdesselem
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Demetrio J Santiago
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium.,Laboratory of Molecular Cardiology, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), C. Melchor Fernández Almagro 3, 28029, Madrid, Spain
| | - H Llewelyn Roderick
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Piet Claus
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Rik Willems
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Karin R Sipido
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
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8
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Takla M, Huang CLH, Jeevaratnam K. The cardiac CaMKII-Na v1.5 relationship: From physiology to pathology. J Mol Cell Cardiol 2020; 139:190-200. [PMID: 31958466 DOI: 10.1016/j.yjmcc.2019.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/20/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
The SCN5A gene encodes Nav1.5, which, as the cardiac voltage-gated Na+ channel's pore-forming α subunit, is crucial for the initiation and propagation of atrial and ventricular action potentials. The arrhythmogenic propensity of inherited SCN5A mutations implicates the Na+ channel in determining cardiomyocyte excitability under normal conditions. Cytosolic kinases have long been known to alter the kinetic profile of Nav1.5 inactivation via phosphorylation of specific residues. Recent substantiation of both the role of calmodulin-dependent kinase II (CaMKII) in modulating the properties of the Nav1.5 inactivation gate and the significant rise in oxidation-dependent autonomous CaMKII activity in structural heart disease has raised the possibility of a novel pathway for acquired arrhythmias - the CaMKII-Nav1.5 relationship. The aim of this review is to: (1) outline the relationship's translation from physiological adaptation to pathological vicious circle; and (2) discuss the relative merits of each of its components as pharmacological targets.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
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9
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Song Z, Xie LH, Weiss JN, Qu Z. A Spatiotemporal Ventricular Myocyte Model Incorporating Mitochondrial Calcium Cycling. Biophys J 2019; 117:2349-2360. [PMID: 31623883 PMCID: PMC6990377 DOI: 10.1016/j.bpj.2019.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/19/2019] [Accepted: 09/09/2019] [Indexed: 12/27/2022] Open
Abstract
Intracellular calcium (Ca2+) cycling dynamics in cardiac myocytes are spatiotemporally generated by stochastic events arising from a spatially distributed network of coupled Ca2+ release units that interact with an intertwined mitochondrial network. In this study, we developed a spatiotemporal ventricular myocyte model that integrates mitochondria-related Ca2+ cycling components into our previously developed ventricular myocyte model consisting of a three-dimensional Ca2+ release unit network. Mathematical formulations of mitochondrial membrane potential, mitochondrial Ca2+ cycling, mitochondrial permeability transition pore stochastic opening and closing, intracellular reactive oxygen species signaling, and oxidized Ca2+/calmodulin-dependent protein kinase II signaling were incorporated into the model. We then used the model to simulate the effects of mitochondrial depolarization on mitochondrial Ca2+ cycling, Ca2+ spark frequency, and Ca2+ amplitude, which agree well with experimental data. We also simulated the effects of the strength of mitochondrial Ca2+ uniporters and their spatial localization on intracellular Ca2+ cycling properties, which substantially affected diastolic and systolic Ca2+ levels in the mitochondria but exhibited only a small effect on sarcoplasmic reticulum and cytosolic Ca2+ levels under normal conditions. We show that mitochondrial depolarization can cause Ca2+ waves and Ca2+ alternans, which agrees with previous experimental observations. We propose that this new, to our knowledge, spatiotemporal ventricular myocyte model, incorporating properties of mitochondrial Ca2+ cycling and reactive-oxygen-species-dependent signaling, will be useful for investigating the effects of mitochondria on intracellular Ca2+ cycling and action potential dynamics in ventricular myocytes.
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Affiliation(s)
- Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, New Jersey
| | - James N Weiss
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
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10
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Patel NJ, Nassal DM, Greer-Short AD, Unudurthi SD, Scandling BW, Gratz D, Xu X, Kalyanasundaram A, Fedorov VV, Accornero F, Mohler PJ, Gooch KJ, Hund TJ. βIV-Spectrin/STAT3 complex regulates fibroblast phenotype, fibrosis, and cardiac function. JCI Insight 2019; 4:131046. [PMID: 31550236 DOI: 10.1172/jci.insight.131046] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/18/2019] [Indexed: 01/30/2023] Open
Abstract
Increased fibrosis is a characteristic remodeling response to biomechanical and neurohumoral stress and a determinant of cardiac mechanical and electrical dysfunction in disease. Stress-induced activation of cardiac fibroblasts (CFs) is a critical step in the fibrotic response, although the precise sequence of events underlying activation of these critical cells in vivo remain unclear. Here, we tested the hypothesis that a βIV-spectrin/STAT3 complex is essential for maintenance of a quiescent phenotype (basal nonactivated state) in CFs. We reported increased fibrosis, decreased cardiac function, and electrical impulse conduction defects in genetic and acquired mouse models of βIV-spectrin deficiency. Loss of βIV-spectrin function promoted STAT3 nuclear accumulation and transcriptional activity, and it altered gene expression and CF activation. Furthermore, we demonstrate that a quiescent phenotype may be restored in βIV-spectrin-deficient fibroblasts by expressing a βIV-spectrin fragment including the STAT3-binding domain or through pharmacological STAT3 inhibition. We found that in vivo STAT3 inhibition abrogates fibrosis and cardiac dysfunction in the setting of global βIV-spectrin deficiency. Finally, we demonstrate that fibroblast-specific deletion of βIV-spectrin is sufficient to induce fibrosis and decreased cardiac function. We propose that the βIV-spectrin/STAT3 complex is a determinant of fibroblast phenotype and fibrosis, with implications for remodeling response in cardiovascular disease (CVD).
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Affiliation(s)
- Nehal J Patel
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Drew M Nassal
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Amara D Greer-Short
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Sathya D Unudurthi
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Benjamin W Scandling
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Daniel Gratz
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Xianyao Xu
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Anuradha Kalyanasundaram
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Physiology and Cell Biology, and
| | - Vadim V Fedorov
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Physiology and Cell Biology, and
| | - Federica Accornero
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Physiology and Cell Biology, and
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Physiology and Cell Biology, and.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Keith J Gooch
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Thomas J Hund
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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11
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CaMKII Activity in the Inflammatory Response of Cardiac Diseases. Int J Mol Sci 2019; 20:ijms20184374. [PMID: 31489895 PMCID: PMC6770001 DOI: 10.3390/ijms20184374] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 12/20/2022] Open
Abstract
Inflammation is a physiological process by which the body responds to external insults and stress conditions, and it is characterized by the production of pro-inflammatory mediators such as cytokines. The acute inflammatory response is solved by removing the threat. Conversely, a chronic inflammatory state is established due to a prolonged inflammatory response and may lead to tissue damage. Based on the evidence of a reciprocal regulation between inflammation process and calcium unbalance, here we described the involvement of a calcium sensor in cardiac diseases with inflammatory drift. Indeed, the Ca2+/calmodulin-dependent protein kinase II (CaMKII) is activated in several diseases with an inflammatory component, such as myocardial infarction, ischemia/reperfusion injury, pressure overload/hypertrophy, and arrhythmic syndromes, in which it actively regulates pro-inflammatory signaling, among which includes nuclear factor kappa-B (NF-κB), thus contributing to pathological cardiac remodeling. Thus, CaMKII may represent a key target to modulate the severity of the inflammatory-driven degeneration.
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12
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Yoo S, Aistrup G, Shiferaw Y, Ng J, Mohler PJ, Hund TJ, Waugh T, Browne S, Gussak G, Gilani M, Knight BP, Passman R, Goldberger JJ, Wasserstrom JA, Arora R. Oxidative stress creates a unique, CaMKII-mediated substrate for atrial fibrillation in heart failure. JCI Insight 2018; 3:120728. [PMID: 30385719 DOI: 10.1172/jci.insight.120728] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 09/27/2018] [Indexed: 12/31/2022] Open
Abstract
The precise mechanisms by which oxidative stress (OS) causes atrial fibrillation (AF) are not known. Since AF frequently originates in the posterior left atrium (PLA), we hypothesized that OS, via calmodulin-dependent protein kinase II (CaMKII) signaling, creates a fertile substrate in the PLA for triggered activity and reentry. In a canine heart failure (HF) model, OS generation and oxidized-CaMKII-induced (Ox-CaMKII-induced) RyR2 and Nav1.5 signaling were increased preferentially in the PLA (compared with left atrial appendage). Triggered Ca2+ waves (TCWs) in HF PLA myocytes were particularly sensitive to acute ROS inhibition. Computational modeling confirmed a direct relationship between OS/CaMKII signaling and TCW generation. CaMKII phosphorylated Nav1.5 (CaMKII-p-Nav1.5 [S571]) was located preferentially at the intercalated disc (ID), being nearly absent at the lateral membrane. Furthermore, a decrease in ankyrin-G (AnkG) in HF led to patchy dropout of CaMKII-p-Nav1.5 at the ID, causing its distribution to become spatially heterogeneous; this corresponded to preferential slowing and inhomogeneity of conduction noted in the HF PLA. Computational modeling illustrated how conduction slowing (e.g., due to increase in CaMKII-p-Nav1.5) interacts with fibrosis to cause reentry in the PLA. We conclude that OS via CaMKII leads to substrate for triggered activity and reentry in HF PLA by mechanisms independent of but complementary to fibrosis.
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Affiliation(s)
- Shin Yoo
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Gary Aistrup
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Yohannes Shiferaw
- Department of Physics, California State University, Northridge, California, USA
| | - Jason Ng
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Peter J Mohler
- Dorothy M. Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Thomas J Hund
- Dorothy M. Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Trent Waugh
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Suzanne Browne
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Georg Gussak
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Mehul Gilani
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Bradley P Knight
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rod Passman
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Jeffrey J Goldberger
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - J Andrew Wasserstrom
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rishi Arora
- Feinberg Cardiovascular Research and Renal Institute, Northwestern University-Feinberg School of Medicine, Chicago, Illinois, USA
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13
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Yang R, Ernst P, Song J, Liu XM, Huke S, Wang S, Zhang JJ, Zhou L. Mitochondrial-Mediated Oxidative Ca 2+/Calmodulin-Dependent Kinase II Activation Induces Early Afterdepolarizations in Guinea Pig Cardiomyocytes: An In Silico Study. J Am Heart Assoc 2018; 7:e008939. [PMID: 30371234 PMCID: PMC6201444 DOI: 10.1161/jaha.118.008939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 06/07/2018] [Indexed: 12/23/2022]
Abstract
Background Oxidative stress-mediated Ca2+/calmodulin-dependent protein kinase II (Ca MKII) phosphorylation of cardiac ion channels has emerged as a critical contributor to arrhythmogenesis in cardiac pathology. However, the link between mitochondrial-derived reactive oxygen species (md ROS ) and increased Ca MKII activity in the context of cardiac arrhythmias has not been fully elucidated and is difficult to establish experimentally. Methods and Results We hypothesize that pathological md ROS can cause erratic action potentials through the oxidation-dependent Ca MKII activation pathway. We further propose that Ca MKII -dependent phosphorylation of sarcolemmal slow Na+ channels alone is sufficient to elicit early afterdepolarizations. To test the hypotheses, we expanded our well-established guinea pig cardiomyocyte excitation- contraction coupling, mitochondrial energetics, and ROS - induced- ROS - release model by incorporating oxidative Ca MKII activation and Ca MKII -dependent Na+ channel phosphorylation in silico. Simulations show that md ROS mediated-Ca MKII activation elicits early afterdepolarizations by augmenting the late Na+ currents, which can be suppressed by blocking L-type Ca2+ channels or Na+/Ca2+ exchangers. Interestingly, we found that oxidative Ca MKII activation-induced early afterdepolarizations are sustained even after md ROS has returned to its physiological levels. Moreover, mitochondrial-targeting antioxidant treatment can suppress the early afterdepolarizations, but only if given in an appropriate time window. Incorporating concurrent md ROS -induced ryanodine receptors activation further exacerbates the proarrhythmogenic effect of oxidative Ca MKII activation. Conclusions We conclude that oxidative Ca MKII activation-dependent Na channel phosphorylation is a critical pathway in mitochondria-mediated cardiac arrhythmogenesis.
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Affiliation(s)
- Ruilin Yang
- Key Laboratory for Mechanism Theory and Equipment Design of Ministry of EducationTianjin UniversityTianjinChina
- Department of MedicineUniversity of Alabama at BirminghamAL
| | - Patrick Ernst
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamAL
| | - Jiajia Song
- Department of MedicineUniversity of Alabama at BirminghamAL
| | - Xiaoguang M. Liu
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamAL
| | - Sabine Huke
- Department of MedicineUniversity of Alabama at BirminghamAL
| | - Shuxin Wang
- Key Laboratory for Mechanism Theory and Equipment Design of Ministry of EducationTianjin UniversityTianjinChina
| | - Jianyi Jay Zhang
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamAL
| | - Lufang Zhou
- Department of MedicineUniversity of Alabama at BirminghamAL
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamAL
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14
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Morotti S, Grandi E. Quantitative systems models illuminate arrhythmia mechanisms in heart failure: Role of the Na + -Ca 2+ -Ca 2+ /calmodulin-dependent protein kinase II-reactive oxygen species feedback. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2018; 11:e1434. [PMID: 30015404 DOI: 10.1002/wsbm.1434] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/29/2018] [Accepted: 06/16/2018] [Indexed: 12/22/2022]
Abstract
Quantitative systems modeling aims to integrate knowledge in different research areas with models describing biological mechanisms and dynamics to gain a better understanding of complex clinical syndromes. Heart failure (HF) is a chronic complex cardiac disease that results from structural or functional disorders impairing the ability of the ventricle to fill with or eject blood. Highly interactive and dynamic changes in mechanical, structural, neurohumoral, metabolic, and electrophysiological properties collectively predispose the failing heart to cardiac arrhythmias, which are responsible for about a half of HF deaths. Multiscale cardiac modeling and simulation integrate structural and functional data from HF experimental models and patients to improve our mechanistic understanding of this complex arrhythmia syndrome. In particular, they allow investigating how disease-induced remodeling alters the coupling of electrophysiology, Ca2+ and Na+ handling, contraction, and energetics that lead to rhythm derangements. The Ca2+ /calmodulin-dependent protein kinase II, which expression and activity are enhanced in HF, emerges as a critical hub that modulates the feedbacks between these various subsystems and promotes arrhythmogenesis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Models of Systems Properties and Processes > Mechanistic Models Models of Systems Properties and Processes > Cellular Models Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California
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15
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Onal B, Gratz D, Hund TJ. Ca 2+/calmodulin-dependent kinase II-dependent regulation of atrial myocyte late Na + current, Ca 2+ cycling, and excitability: a mathematical modeling study. Am J Physiol Heart Circ Physiol 2017; 313:H1227-H1239. [PMID: 28842436 DOI: 10.1152/ajpheart.00185.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) affects more than three million people per year in the United States and is associated with high morbidity and mortality. Both electrical and structural remodeling contribute to AF, but the molecular pathways underlying AF pathogenesis are not well understood. Recently, a role for Ca2+/calmodulin-dependent protein kinase II (CaMKII) in the regulation of persistent "late" Na+ current ( INa,L) has been identified. Although INa,L inhibition is emerging as a potential antiarrhythmic strategy in patients with AF, little is known about the mechanism linking INa,L to atrial arrhythmogenesis. A computational approach was used to test the hypothesis that increased CaMKII-activated INa,L in atrial myocytes disrupts Ca2+ homeostasis, promoting arrhythmogenic afterdepolarizations. Dynamic CaMKII activity and regulation of multiple downstream targets [ INa,L, L-type Ca2+ current, phospholamban, and the ryanodine receptor sarcoplasmic reticulum Ca2+-release channel (RyR2)] were incorporated into an existing well-validated computational model of the human atrial action potential. Model simulations showed that constitutive CaMKII-dependent phosphorylation of Nav1.5 and the subsequent increase in INa,L effectively disrupt intracellular atrial myocyte ion homeostasis and CaMKII signaling. Specifically, increased INa,L promotes intracellular Ca2+ overload via forward-mode Na+/Ca2+ exchange activity, which greatly increases RyR2 open probability beyond that observed for CaMKII-dependent phosphorylation of RyR2 alone. Increased INa,L promotes atrial myocyte repolarization defects (afterdepolarizations and alternans) in the setting of acute β-adrenergic stimulation. We anticipate that our modeling efforts will help identify new mechanisms for atrial NaV1.5 regulation with direct relevance for human AF. NEW & NOTEWORTHY Here, we present a novel computational model to study the effects of late Na+ current ( INa,L) in human atrial myocytes. Simulations predict that INa,L promotes intracellular accumulation of Ca2+, with subsequent dysregulation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) signaling and ryanodine receptor 2-mediated Ca2+ release. Although INa,L plays a small role in regulating atrial myocyte excitability at baseline, CaMKII-dependent enhancement of the current promoted arrhythmogenic dynamics. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/camkii-dependent-regulation-of-atrial-late-sodium-current-and-excitability/ .
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Affiliation(s)
- Birce Onal
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center , Columbus, Ohio.,Department of Biomedical Engineering, College of Engineering, The Ohio State University , Columbus, Ohio
| | - Daniel Gratz
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center , Columbus, Ohio.,Department of Biomedical Engineering, College of Engineering, The Ohio State University , Columbus, Ohio
| | - Thomas J Hund
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center , Columbus, Ohio.,Department of Biomedical Engineering, College of Engineering, The Ohio State University , Columbus, Ohio.,Department of Internal Medicine, The Ohio State University Wexner Medical Center , Columbus, Ohio
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16
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Abstract
Mathematical modeling has been used for over half a century to advance our understanding of cardiac electrophysiology and arrhythmia mechanisms. Notably, computational studies using mathematical models of the cardiac action potential (AP) have provided important insight into the fundamental nature of cell excitability, mechanisms underlying both acquired and inherited arrhythmia, and potential therapies. Ultimately, an approach that tightly integrates mathematical modeling and experimental techniques has great potential to accelerate discovery. Despite the increasing acceptance of mathematical modeling as a powerful tool in cardiac electrophysiology research, there remain significant barriers to its more widespread use in the field, due in part to the increasing complexity of models and growing need for specialization. To help bridge the gap between experimental and theoretical worlds that stands as a barrier to transformational breakthroughs, we present LongQt, which has the following key features: Cross-platform, threaded application with accessible graphical user interface. Facilitates advanced computational cardiac electrophysiology and arrhythmia studies. Does not require advanced programming skills.
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Affiliation(s)
- Birce Onal
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, USA
| | - Daniel Gratz
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Thomas Hund
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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17
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Foteinou PT, Greenstein JL, Winslow RL. Mechanistic Investigation of the Arrhythmogenic Role of Oxidized CaMKII in the Heart. Biophys J 2016; 109:838-49. [PMID: 26287635 DOI: 10.1016/j.bpj.2015.06.064] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 05/16/2015] [Accepted: 06/30/2015] [Indexed: 10/23/2022] Open
Abstract
Oxidative stress and calcium (Ca(2+))/calmodulin (CaM)-dependent protein kinase II (CaMKII) both play important roles in the pathogenesis of cardiac disease. Although the pathophysiological relevance of reactive oxygen species (ROS) and CaMKII has been appreciated for some time, recent work has shown that ROS can directly oxidize CaMKII, leading to its persistent activity and an increase of the likelihood of cellular arrhythmias such as early afterdepolarizations (EADs). Because CaMKII modulates the function of many proteins involved in excitation-contraction coupling, elucidation of its role in cardiac function, in both healthy and oxidative stress conditions, is challenging. To investigate this role, we have developed a model of CaMKII activation that includes both the phosphorylation-dependent and the newly identified oxidation-dependent activation pathways. This model is incorporated into our previous local-control model of the cardiac myocyte that describes excitation-contraction coupling via stochastic simulation of individual Ca(2+) release units and CaMKII-mediated phosphorylation of L-type Ca(2+) channels (LCCs), ryanodine receptors and sodium (Na(+)) channels. The model predicts the experimentally measured slow-rate dependence of H2O2-induced EADs. Upon increased H2O2, simulations suggest that selective activation of late Na(+) current (INaL), although it prolongs action potential duration, is not by itself sufficient to produce EADs. Similar results are obtained if CaMKII effects on LCCs and ryanodine receptors are considered separately. However, EADs emerge upon simultaneous activation of both LCCs and Na(+) channels. Further modeling results implicate activation of the Na(+)-Ca(2+) exchanger (NCX) as an important player in the generation of EADs. During bradycardia, the emergence of H2O2-induced EADs was correlated with a shift in the timing of NCX current reversal toward the plateau phase earlier in the action potential. Using the timing of NCX current reversal as an indicator event for EADs, the model identified counterintuitive ionic changes-difficult to experimentally dissect-that have the greatest influence on ROS-related arrhythmia propensity.
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Affiliation(s)
- Panagiota T Foteinou
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Joseph L Greenstein
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Raimond L Winslow
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland.
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18
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Sovari AA. Cellular and Molecular Mechanisms of Arrhythmia by Oxidative Stress. Cardiol Res Pract 2016; 2016:9656078. [PMID: 26981310 PMCID: PMC4770129 DOI: 10.1155/2016/9656078] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/10/2016] [Indexed: 12/25/2022] Open
Abstract
Current therapies for arrhythmia using ion channel blockade, catheter ablation, or an implantable cardioverter defibrillator have limitations, and it is important to search for new antiarrhythmic therapeutic targets. Both atrial fibrillation and heart failure, a condition with increased arrhythmic risk, are associated with excess amount of reactive oxygen species (ROS). There are several possible ways for ROS to induce arrhythmia. ROS can cause focal activity and reentry. ROS alter multiple cardiac ionic currents. ROS promote cardiac fibrosis and impair gap junction function, resulting in reduced myocyte coupling and facilitation of reentry. In order to design effective antioxidant drugs for treatment of arrhythmia, it is essential to explore the molecular mechanisms by which ROS exert these arrhythmic effects. Activation of Ca(2+)/CaM-dependent kinase II, c-Src tyrosine kinase, protein kinase C, and abnormal splicing of cardiac sodium channels are among the recently discovered molecular mechanisms of ROS-induced arrhythmia.
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Affiliation(s)
- Ali A. Sovari
- Cardiac Electrophysiology Section, Heart Institute, Cedars Sinai Medical Center, 127 S. San Vicente Boulevard, A3308, Los Angeles, CA 90048, USA
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19
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Mesubi OO, Anderson ME. Atrial remodelling in atrial fibrillation: CaMKII as a nodal proarrhythmic signal. Cardiovasc Res 2016; 109:542-57. [PMID: 26762270 DOI: 10.1093/cvr/cvw002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/05/2016] [Indexed: 01/10/2023] Open
Abstract
CaMKII is a serine-threonine protein kinase that is abundant in myocardium. Emergent evidence suggests that CaMKII may play an important role in promoting atrial fibrillation (AF) by targeting a diverse array of proteins involved in membrane excitability, cell survival, calcium homeostasis, matrix remodelling, inflammation, and metabolism. Furthermore, CaMKII inhibition appears to protect against AF in animal models and correct proarrhythmic, defective intracellular Ca(2+) homeostasis in fibrillating human atrial cells. This review considers current concepts and evidence from animal and human studies on the role of CaMKII in AF.
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Affiliation(s)
- Olurotimi O Mesubi
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Medicine, The Johns Hopkins University School of Medicine, 1830 E. Monument Street, Suite 9026, Baltimore, MD 21287, USA
| | - Mark E Anderson
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA Department of Medicine, The Johns Hopkins University School of Medicine, 1830 E. Monument Street, Suite 9026, Baltimore, MD 21287, USA Department of Physiology and the Program in Cellular and Molecular Medicine, The Johns Hopkins School of Medicine, Baltimore, MD, USA
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20
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Anderson ME. Oxidant stress promotes disease by activating CaMKII. J Mol Cell Cardiol 2015; 89:160-7. [PMID: 26475411 PMCID: PMC5075238 DOI: 10.1016/j.yjmcc.2015.10.014] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/09/2015] [Accepted: 10/10/2015] [Indexed: 12/31/2022]
Abstract
CaMKII is activated by oxidation of methionine residues residing in the regulatory domain. Oxidized CaMKII (ox-CaMKII) is now thought to participate in cardiovascular and pulmonary diseases and cancer. This invited review summarizes current evidence for the role of ox-CaMKII in disease, considers critical knowledge gaps and suggests new areas for inquiry.
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Affiliation(s)
- Mark E Anderson
- Johns Hopkins Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21287, United States.
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21
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Mollova MY, Katus HA, Backs J. Regulation of CaMKII signaling in cardiovascular disease. Front Pharmacol 2015; 6:178. [PMID: 26379551 PMCID: PMC4548452 DOI: 10.3389/fphar.2015.00178] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/10/2015] [Indexed: 01/08/2023] Open
Abstract
Heart failure (HF) is a major cause of death in the developed countries (Murray and Lopez, 1996; Koitabashi and Kass, 2012). Adverse cardiac remodeling that precedes heart muscle dysfunction is characterized by a myriad of molecular changes affecting the cardiomyocyte. Among these, alterations in protein kinase pathways play often an important mediator role since they link upstream pathologic stress signaling with downstream regulatory programs and thus affect both the structural and functional integrity of the heart muscle. In the context of cardiac disease, a profound understanding for the overriding mechanisms that regulate protein kinase activity (protein-protein interactions, post-translational modifications, or targeting via anchoring proteins) is crucial for the development of specific and effective pharmacological treatment strategies targeting the failing myocardium. In this review, we focus on several mechanisms of upstream regulation of Ca2+-calmodulin-dependent protein kinase II that play a relevant pathophysiological role in the development and progression of cardiovascular disease; precise targeting of these mechanisms might therefore represent novel and promising tools for prevention and treatment of HF.
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Affiliation(s)
- Mariya Y Mollova
- Research Unit Cardiac Epigenetics, Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
| | - Johannes Backs
- Research Unit Cardiac Epigenetics, Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
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22
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Nguyen PK, Wu JC. Large Animal Models of Ischemic Cardiomyopathy: Are They Enough to Bridge the Translational Gap? J Nucl Cardiol 2015; 22:666-72. [PMID: 25777782 DOI: 10.1007/s12350-015-0078-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Patricia K Nguyen
- Stanford Cardiovascular Institute, Stanford University School of Medicine, 300 Pasteur Drive, Grant Building S140, Stanford, CA, 94305-5111, USA,
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23
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Regulation of the cardiac Na+ channel NaV1.5 by post-translational modifications. J Mol Cell Cardiol 2015; 82:36-47. [PMID: 25748040 DOI: 10.1016/j.yjmcc.2015.02.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/28/2015] [Accepted: 02/17/2015] [Indexed: 02/07/2023]
Abstract
The cardiac voltage-gated Na(+) channel, Na(V)1.5, is responsible for the upstroke of the action potential in cardiomyocytes and for efficient propagation of the electrical impulse in the myocardium. Even subtle alterations of Na(V)1.5 function, as caused by mutations in its gene SCN5A, may lead to many different arrhythmic phenotypes in carrier patients. In addition, acquired malfunctions of Na(V)1.5 that are secondary to cardiac disorders such as heart failure and cardiomyopathies, may also play significant roles in arrhythmogenesis. While it is clear that the regulation of Na(V)1.5 protein expression and function tightly depends on genetic mechanisms, recent studies have demonstrated that Na(V)1.5 is the target of various post-translational modifications that are pivotal not only in physiological conditions, but also in disease. In this review, we examine the recent literature demonstrating glycosylation, phosphorylation by Protein Kinases A and C, Ca(2+)/Calmodulin-dependent protein Kinase II, Phosphatidylinositol 3-Kinase, Serum- and Glucocorticoid-inducible Kinases, Fyn and Adenosine Monophosphate-activated Protein Kinase, methylation, acetylation, redox modifications, and ubiquitylation of Na(V)1.5. Modern and sensitive mass spectrometry approaches, applied directly to channel proteins that were purified from native cardiac tissues, have enabled the determination of the precise location of post-translational modification sites, thus providing essential information for understanding the mechanistic details of these regulations. The current challenge is first, to understand the roles of these modifications on the expression and the function of Na(V)1.5, and second, to further identify other chemical modifications. It is postulated that the diversity of phenotypes observed with Na(V)1.5-dependent disorders may partially arise from the complex post-translational modifications of channel protein components.
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24
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Hund TJ, Mohler PJ. Role of CaMKII in cardiac arrhythmias. Trends Cardiovasc Med 2014; 25:392-7. [PMID: 25577293 DOI: 10.1016/j.tcm.2014.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/01/2014] [Accepted: 12/01/2014] [Indexed: 11/30/2022]
Abstract
Protein phosphorylation is a central mechanism in vertebrates for the regulation of signaling. With regard to the cardiovascular system, phosphorylation of myocyte targets is critical for the regulation of excitation contraction coupling, metabolism, intracellular calcium regulation, mitochondrial activity, transcriptional regulation, and cytoskeletal dynamics. In fact, pathways that tune protein kinase signaling have been a mainstay for cardiovascular therapies for the past 60 years. The calcium/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional serine/threonine kinase with numerous roles in human physiology. Dysfunction in CaMKII-based signaling has been linked with a host of cardiovascular phenotypes including heart failure and arrhythmia, and CaMKII levels are elevated in human and animal disease models of heart disease. While nearly a decade has been invested in targeting CaMKII for the treatment of heart failure and arrhythmia phenotypes, to date, approaches to target the molecule for antiarrhythmic benefit have been unsuccessful for reasons that are still not entirely clear, although (1) lack of compound specificity and (2) the multitude of downstream targets are likely contributing factors. This review will provide an update on current pathways regulated by CaMKII with the goal of illustrating potential upstream regulatory mechanisms and downstream targets that may be modulated for the prevention of cardiac electrical defects. While the review will cover multiple aspects of CaMKII dysfunction in cardiovascular disease, we have given special attention to the potential of CaMKII-associated late Na(+) current as a novel therapeutic target for cardiac arrhythmia.
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Affiliation(s)
- Thomas J Hund
- The Dorothy M. Davis Heart & Lung Research Institute, OH; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus, OH
| | - Peter J Mohler
- The Dorothy M. Davis Heart & Lung Research Institute, OH; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH; Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH.
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25
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Glynn P, Unudurthi SD, Hund TJ. Mathematical modeling of physiological systems: an essential tool for discovery. Life Sci 2014; 111:1-5. [PMID: 25064823 DOI: 10.1016/j.lfs.2014.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 06/26/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
Abstract
Mathematical models are invaluable tools for understanding the relationships between components of a complex system. In the biological context, mathematical models help us understand the complex web of interrelations between various components (DNA, proteins, enzymes, signaling molecules etc.) in a biological system, gain better understanding of the system as a whole, and in turn predict its behavior in an altered state (e.g. disease). Mathematical modeling has enhanced our understanding of multiple complex biological processes like enzyme kinetics, metabolic networks, signal transduction pathways, gene regulatory networks, and electrophysiology. With recent advances in high throughput data generation methods, computational techniques and mathematical modeling have become even more central to the study of biological systems. In this review, we provide a brief history and highlight some of the important applications of modeling in biological systems with an emphasis on the study of excitable cells. We conclude with a discussion about opportunities and challenges for mathematical modeling going forward. In a larger sense, the review is designed to help answer a simple but important question that theoreticians frequently face from interested but skeptical colleagues on the experimental side: "What is the value of a model?"
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Affiliation(s)
- Patric Glynn
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Sathya D Unudurthi
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - Thomas J Hund
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH 43210, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
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26
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Saucerman JJ. Modeling mitochondrial ROS: a great balancing act. Biophys J 2014; 105:1287-8. [PMID: 24047977 DOI: 10.1016/j.bpj.2013.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/09/2013] [Accepted: 08/13/2013] [Indexed: 12/24/2022] Open
Affiliation(s)
- Jeffrey J Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia.
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27
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Greenstein JL, Foteinou PT, Hashambhoy-Ramsay YL, Winslow RL. Modeling CaMKII-mediated regulation of L-type Ca(2+) channels and ryanodine receptors in the heart. Front Pharmacol 2014; 5:60. [PMID: 24772082 PMCID: PMC3982069 DOI: 10.3389/fphar.2014.00060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/18/2014] [Indexed: 11/13/2022] Open
Abstract
Excitation-contraction coupling (ECC) in the cardiac myocyte is mediated by a number of highly integrated mechanisms of intracellular Ca2+ transport. Voltage- and Ca2+-dependent L-type Ca2+ channels (LCCs) allow for Ca2+ entry into the myocyte, which then binds to nearby ryanodine receptors (RyRs) and triggers Ca2+ release from the sarcoplasmic reticulum in a process known as Ca2+-induced Ca2+ release. The highly coordinated Ca2+-mediated interaction between LCCs and RyRs is further regulated by the cardiac isoform of the Ca2+/calmodulin-dependent protein kinase (CaMKII). Because CaMKII targets and modulates the function of many ECC proteins, elucidation of its role in ECC and integrative cellular function is challenging and much insight has been gained through the use of detailed computational models. Multiscale models that can both reconstruct the detailed nature of local signaling events within the cardiac dyad and predict their functional consequences at the level of the whole cell have played an important role in advancing our understanding of CaMKII function in ECC. Here, we review experimentally based models of CaMKII function with a focus on LCC and RyR regulation, and the mechanistic insights that have been gained through their application.
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Affiliation(s)
- Joseph L Greenstein
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University Baltimore, MD, USA
| | - Panagiota T Foteinou
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University Baltimore, MD, USA
| | - Yasmin L Hashambhoy-Ramsay
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University Baltimore, MD, USA
| | - Raimond L Winslow
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University Baltimore, MD, USA
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28
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Abstract
Calcium/calmodulin (Ca2+/CaM) dependent protein kinase II (CaMKII) has emerged as a key nodal protein in the regulation of cardiac physiology and pathology. Due to the particularly elegant relationship between the structure and function of the kinase, CaMKII is able to translate a diverse set of signaling events into downstream physiological effects. While CaMKII is typically autoinhibited at basal conditions, prolonged rapid Ca2+ cycling can activate the kinase and allow post-translational modifications that depend critically on the biochemical environment of the heart. These modifications result in sustained, autonomous CaMKII activation and have been associated with pathological cardiac signaling. Indeed, improved understanding of CaMKII activation mechanisms could potentially lead to new clinical therapies for the treatment or prevention of cardiovascular disease. Here we review the known mechanisms of CaMKII activation and discuss some of the pathological signaling pathways in which they play a role.
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29
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Mackiewicz U, Gerges JY, Chu S, Duda M, Dobrzynski H, Lewartowski B, Mączewski M. Ivabradine Protects Against Ventricular Arrhythmias in Acute Myocardial Infarction in the Rat. J Cell Physiol 2014; 229:813-23. [DOI: 10.1002/jcp.24507] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 10/31/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Urszula Mackiewicz
- Department of Clinical Physiology; Medical Center of Postgraduate Education; Warsaw Poland
| | - Joseph Y. Gerges
- School of Biomedical Sciences; University of Manchester; Manchester UK
| | - Sandy Chu
- School of Biomedical Sciences; University of Manchester; Manchester UK
| | - Monika Duda
- Department of Clinical Physiology; Medical Center of Postgraduate Education; Warsaw Poland
| | - Halina Dobrzynski
- School of Biomedical Sciences; University of Manchester; Manchester UK
| | - Bohdan Lewartowski
- Department of Clinical Physiology; Medical Center of Postgraduate Education; Warsaw Poland
| | - Michał Mączewski
- Department of Clinical Physiology; Medical Center of Postgraduate Education; Warsaw Poland
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30
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Onal B, Unudurthi SD, Hund TJ. Modeling CaMKII in cardiac physiology: from molecule to tissue. Front Pharmacol 2014; 5:9. [PMID: 24550832 PMCID: PMC3912431 DOI: 10.3389/fphar.2014.00009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 01/16/2014] [Indexed: 12/02/2022] Open
Abstract
Post-translational modification of membrane proteins (e.g., ion channels, receptors) by protein kinases is an essential mechanism for control of excitable cell function. Importantly, loss of temporal and/or spatial control of ion channel post-translational modification is common in congenital and acquired forms of cardiac disease and arrhythmia. The multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates a number of diverse cellular functions in heart, including excitation-contraction coupling, gene transcription, and apoptosis. Dysregulation of CaMKII signaling has been implicated in human and animal models of disease. Understanding of CaMKII function has been advanced by mathematical modeling approaches well-suited to the study of complex biological systems. Early kinetic models of CaMKII function in the brain characterized this holoenzyme as a bistable molecular switch capable of storing information over a long period of time. Models of CaMKII activity have been incorporated into models of the cell and tissue (particularly in the heart) to predict the role of CaMKII in regulating organ function. Disease models that incorporate CaMKII overexpression clearly demonstrate a link between its excessive activity and arrhythmias associated with congenital and acquired heart disease. This review aims at discussing systems biology approaches that have been applied to analyze CaMKII signaling from the single molecule to intact cardiac tissue. In particular, efforts to use computational biology to provide new insight into cardiac disease mechanisms are emphasized.
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Affiliation(s)
- Birce Onal
- The Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University Columbus, OH, USA ; Department of Biomedical Engineering, College of Engineering, The Ohio State University Columbus, OH, USA
| | - Sathya D Unudurthi
- The Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University Columbus, OH, USA
| | - Thomas J Hund
- The Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University Columbus, OH, USA ; Department of Biomedical Engineering, College of Engineering, The Ohio State University Columbus, OH, USA ; Department of Internal Medicine, Wexner Medical Center, The Ohio State University Columbus, OH, USA
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31
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Herren AW, Bers DM, Grandi E. Post-translational modifications of the cardiac Na channel: contribution of CaMKII-dependent phosphorylation to acquired arrhythmias. Am J Physiol Heart Circ Physiol 2013; 305:H431-45. [PMID: 23771687 DOI: 10.1152/ajpheart.00306.2013] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The voltage-gated Na channel isoform 1.5 (NaV1.5) is the pore forming α-subunit of the voltage-gated cardiac Na channel, which is responsible for the initiation and propagation of cardiac action potentials. Mutations in the SCN5A gene encoding NaV1.5 have been linked to changes in the Na current leading to a variety of arrhythmogenic phenotypes, and alterations in the NaV1.5 expression level, Na current density, and/or gating have been observed in acquired cardiac disorders, including heart failure. The precise mechanisms underlying these abnormalities have not been fully elucidated. However, several recent studies have made it clear that NaV1.5 forms a macromolecular complex with a number of proteins that modulate its expression levels, localization, and gating and is the target of extensive post-translational modifications, which may also influence all these properties. We review here the molecular aspects of cardiac Na channel regulation and their functional consequences. In particular, we focus on the molecular and functional aspects of Na channel phosphorylation by the Ca/calmodulin-dependent protein kinase II, which is hyperactive in heart failure and has been causally linked to cardiac arrhythmia. Understanding the mechanisms of altered NaV1.5 expression and function is crucial for gaining insight into arrhythmogenesis and developing novel therapeutic strategies.
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Affiliation(s)
- Anthony W Herren
- Department of Pharmacology, University of California Davis, Davis, California
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32
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Wolf RM, Glynn P, Hashemi S, Zarei K, Mitchell CC, Anderson ME, Mohler PJ, Hund TJ. Atrial fibrillation and sinus node dysfunction in human ankyrin-B syndrome: a computational analysis. Am J Physiol Heart Circ Physiol 2013; 304:H1253-66. [PMID: 23436330 DOI: 10.1152/ajpheart.00734.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ankyrin-B is a multifunctional adapter protein responsible for localization and stabilization of select ion channels, transporters, and signaling molecules in excitable cells including cardiomyocytes. Ankyrin-B dysfunction has been linked with highly penetrant sinoatrial node (SAN) dysfunction and increased susceptibility to atrial fibrillation. While previous studies have identified a role for abnormal ion homeostasis in ventricular arrhythmias, the molecular mechanisms responsible for atrial arrhythmias and SAN dysfunction in human patients with ankyrin-B syndrome are unclear. Here, we develop a computational model of ankyrin-B dysfunction in atrial and SAN cells and tissue to determine the mechanism for increased susceptibility to atrial fibrillation and SAN dysfunction in human patients with ankyrin-B syndrome. Our simulations predict that defective membrane targeting of the voltage-gated L-type Ca(2+) channel Cav1.3 leads to action potential shortening that reduces the critical atrial tissue mass needed to sustain reentrant activation. In parallel, increased fibrosis results in conduction slowing that further increases the susceptibility to sustained reentry in the setting of ankyrin-B dysfunction. In SAN cells, loss of Cav1.3 slows spontaneous pacemaking activity, whereas defects in Na(+)/Ca(2+) exchanger and Na(+)/K(+) ATPase increase variability in SAN cell firing. Finally, simulations of the intact SAN reveal a shift in primary pacemaker site, SAN exit block, and even SAN failure in ankyrin-B-deficient tissue. These studies identify the mechanism for increased susceptibility to atrial fibrillation and SAN dysfunction in human disease. Importantly, ankyrin-B dysfunction involves changes at both the cell and tissue levels that favor the common manifestation of atrial arrhythmias and SAN dysfunction.
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Affiliation(s)
- Roseanne M Wolf
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
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33
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Rokita AG, Anderson ME. New therapeutic targets in cardiology: arrhythmias and Ca2+/calmodulin-dependent kinase II (CaMKII). Circulation 2013; 126:2125-39. [PMID: 23091085 DOI: 10.1161/circulationaha.112.124990] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Adam G Rokita
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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34
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Koval OM, Snyder JS, Wolf RM, Pavlovicz RE, Glynn P, Curran J, Leymaster ND, Dun W, Wright PJ, Cardona N, Qian L, Mitchell CC, Boyden PA, Binkley PF, Li C, Anderson ME, Mohler PJ, Hund TJ. Ca2+/calmodulin-dependent protein kinase II-based regulation of voltage-gated Na+ channel in cardiac disease. Circulation 2012; 126:2084-94. [PMID: 23008441 DOI: 10.1161/circulationaha.112.105320] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Human gene variants affecting ion channel biophysical activity and/or membrane localization are linked to potentially fatal cardiac arrhythmias. However, the mechanism for many human arrhythmia variants remains undefined despite more than a decade of investigation. Posttranslational modulation of membrane proteins is essential for normal cardiac function. Importantly, aberrant myocyte signaling has been linked to defects in cardiac ion channel posttranslational modifications and disease. We recently identified a novel pathway for posttranslational regulation of the primary cardiac voltage-gated Na(+) channel (Na(v)1.5) by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). However, a role for this pathway in cardiac disease has not been evaluated. METHODS AND RESULTS We evaluated the role of CaMKII-dependent phosphorylation in human genetic and acquired disease. We report an unexpected link between a short motif in the Na(v)1.5 DI-DII loop, recently shown to be critical for CaMKII-dependent phosphorylation, and Na(v)1.5 function in monogenic arrhythmia and common heart disease. Experiments in heterologous cells and primary ventricular cardiomyocytes demonstrate that the human arrhythmia susceptibility variants (A572D and Q573E) alter CaMKII-dependent regulation of Na(v)1.5, resulting in abnormal channel activity and cell excitability. In silico analysis reveals that these variants functionally mimic the phosphorylated channel, resulting in increased susceptibility to arrhythmia-triggering afterdepolarizations. Finally, we report that this same motif is aberrantly regulated in a large-animal model of acquired heart disease and in failing human myocardium. CONCLUSIONS We identify the mechanism for 2 human arrhythmia variants that affect Na(v)1.5 channel activity through direct effects on channel posttranslational modification. We propose that the CaMKII phosphorylation motif in the Na(v)1.5 DI-DII cytoplasmic loop is a critical nodal point for proarrhythmic changes to Na(v)1.5 in congenital and acquired cardiac disease.
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Affiliation(s)
- Olha M Koval
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Medical Center, 473 W 12th Ave, Columbus, OH 43210, USA
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35
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Swaminathan PD, Purohit A, Hund TJ, Anderson ME. Calmodulin-dependent protein kinase II: linking heart failure and arrhythmias. Circ Res 2012; 110:1661-77. [PMID: 22679140 DOI: 10.1161/circresaha.111.243956] [Citation(s) in RCA: 215] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Understanding relationships between heart failure and arrhythmias, important causes of suffering and sudden death, remains an unmet goal for biomedical researchers and physicians. Evidence assembled over the past decade supports a view that activation of the multifunctional Ca(2+) and calmodulin-dependent protein kinase II (CaMKII) favors myocardial dysfunction and cell membrane electrical instability. CaMKII activation follows increases in intracellular Ca(2+) or oxidation, upstream signals with the capacity to transition CaMKII into a Ca(2+) and calmodulin-independent constitutively active enzyme. Constitutively active CaMKII appears poised to participate in disease pathways by catalyzing the phosphorylation of classes of protein targets important for excitation-contraction coupling and cell survival, including ion channels and Ca(2+) homeostatic proteins, and transcription factors that drive hypertrophic and inflammatory gene expression. This rich diversity of downstream targets helps to explain the potential for CaMKII to simultaneously affect mechanical and electrical properties of heart muscle cells. Proof-of-concept studies from a growing number of investigators show that CaMKII inhibition is beneficial for improving myocardial performance and for reducing arrhythmias. We review the molecular physiology of CaMKII and discuss CaMKII actions at key cellular targets and results of animal models of myocardial hypertrophy, dysfunction, and arrhythmias that suggest CaMKII inhibition may benefit myocardial function while reducing arrhythmias.
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Affiliation(s)
- Paari Dominic Swaminathan
- Division of Cardiovascular Medicine, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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36
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Roberts BN, Yang PC, Behrens SB, Moreno JD, Clancy CE. Computational approaches to understand cardiac electrophysiology and arrhythmias. Am J Physiol Heart Circ Physiol 2012; 303:H766-83. [PMID: 22886409 DOI: 10.1152/ajpheart.01081.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cardiac rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. These impulses spread throughout the cardiac muscle to manifest as electrical waves in the whole heart. Regularity of electrical waves is critically important since they signal the heart muscle to contract, driving the primary function of the heart to act as a pump and deliver blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. For more than 50 years, mathematically based models of cardiac electrical activity have been used to improve understanding of basic mechanisms of normal and abnormal cardiac electrical function. Computer-based modeling approaches to understand cardiac activity are uniquely helpful because they allow for distillation of complex emergent behaviors into the key contributing components underlying them. Here we review the latest advances and novel concepts in the field as they relate to understanding the complex interplay between electrical, mechanical, structural, and genetic mechanisms during arrhythmia development at the level of ion channels, cells, and tissues. We also discuss the latest computational approaches to guiding arrhythmia therapy.
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Affiliation(s)
- Byron N Roberts
- Tri-Institutional MD-PhD Program, Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College/The Rockefeller University/Sloan-Kettering Cancer Institute, Weill Medical College of Cornell University, New York, New York, USA
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37
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Ziv O, Schofield L, Lau E, Chaves L, Patel D, Jeng P, Peng X, Choi BR, Koren G. A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits. Am J Physiol Heart Circ Physiol 2012; 302:H2321-30. [PMID: 22447944 DOI: 10.1152/ajpheart.00031.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ventricular arrhythmias in the setting of a healed myocardial infarction have been studied to a much lesser degree than acute and subacute infarction, due to the pericardial scarring, which results from the traditional open-chest techniques used for myocardial infarction (MI) induction. We sought to develop a segmental MI with low perioperative mortality in the rabbit that allows optimal visualization and therefore improved study of the infarction borderzone. Rabbits underwent MI using endovascular coil occlusion of the first obtuse marginal artery. Three weeks postprocedure, we evaluated our model by echocardiography and electrophysiology studies, optical mapping of isolated hearts, and histological studies. Seventeen rabbits underwent the protocol (12 MI and 5 sham) with a 92% survival to completion of the study (11 MI and 5 sham). MI rabbits demonstrated wall motion abnormalities on echocardiography while shams did not. At electrophysiological study, two MI rabbits had inducible ventricular tachycardia and one had inducible ventricular fibrillation. Isolated hearts demonstrated no pericardial scarring with a smooth, easily identifiable infarct borderzone. Optical mapping of the borderzone region showed successful mapping of peri-infarct reentry formation, with ventricular fibrillation inducible in 11 of 11 MI hearts and 1 of 5 sham hearts. We demonstrate successful high resolution mapping in the borderzone, showing delayed conduction in this region corresponding to late deflections in the QRS on ECG. We report the successful development of a minimally invasive MI via targeted coil delivery to the obtuse marginal artery with an exceptionally high rate of procedural survival and an arrhythmogenic phenotype. This model mimics human post-MI on echocardiography, gross pathology, histology, and electrophysiology.
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Affiliation(s)
- Ohad Ziv
- Cardiovascular Research Center, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, USA
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38
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Oxidation of CaMKII determines the cardiotoxic effects of aldosterone. Nat Med 2011; 17:1610-8. [PMID: 22081025 DOI: 10.1038/nm.2506] [Citation(s) in RCA: 191] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/12/2011] [Indexed: 02/07/2023]
Abstract
Excessive activation of the β-adrenergic, angiotensin II (Ang II) and aldosterone signaling pathways promotes mortality after myocardial infarction, and antagonists targeting these pathways are core therapies for treating this condition. Catecholamines and Ang II activate the multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), the inhibition of which prevents isoproterenol-mediated and Ang II-mediated cardiomyopathy. Here we show that aldosterone exerts direct toxic actions on myocardium by oxidative activation of CaMKII, causing cardiac rupture and increased mortality in mice after myocardial infarction. Aldosterone induces CaMKII oxidation by recruiting NADPH oxidase, and this oxidized and activated CaMKII promotes matrix metalloproteinase 9 (MMP9) expression in cardiomyocytes. Myocardial CaMKII inhibition, overexpression of methionine sulfoxide reductase A (an enzyme that reduces oxidized CaMKII) or NADPH oxidase deficiency prevented aldosterone-enhanced cardiac rupture after myocardial infarction. These findings show that oxidized myocardial CaMKII mediates the cardiotoxic effects of aldosterone on the cardiac matrix and establish CaMKII as a nodal signal for the neurohumoral pathways associated with poor outcomes after myocardial infarction.
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Tavi P, Westerblad H. The role of in vivo Ca²⁺ signals acting on Ca²⁺-calmodulin-dependent proteins for skeletal muscle plasticity. J Physiol 2011; 589:5021-31. [PMID: 21911615 PMCID: PMC3225663 DOI: 10.1113/jphysiol.2011.212860] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 09/12/2011] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle fibres are highly heterogeneous regarding size, metabolism and contractile function. They also show a large capacity for adaptations in response to alterations in the activation pattern. A major part of this activity-dependent plasticity relies on transcriptional alterations controlled by intracellular Ca(2+) signals. In this review we discuss how intracellular Ca(2+) fluctuations induced by activation patterns likely to occur in vivo control muscle properties via effects on Ca(2+)-calmodulin-dependent proteins. We focus on two such Ca(2+) decoders: calcineurin and Ca(2+)-calmodulin-dependent protein kinase II. Inherent Ca(2+) transients during contractions differ rather little between slow- and fast-twitch muscle fibres and this difference is unlikely to have any significant impact on the activity of Ca(2+) decoders. The major exception to this is fatigue-induced changes in Ca(2+) transients that occur in fast-twitch fibres exposed to high-intensity activation typical of slow-twitch motor units. In conclusion, the cascade from neural stimulation pattern to Ca(2+)-dependent transcription is likely to be central in maintaining the fibre phenotypes in both fast- and slow-twitch fibres. Moreover, changes in Ca(2+) signalling (e.g. induced by endurance training) can result in altered muscle properties (e.g. increased mitochondrial biogenesis) and this plasticity involves other signalling pathways.
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Affiliation(s)
- Pasi Tavi
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
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Erickson JR, He BJ, Grumbach IM, Anderson ME. CaMKII in the cardiovascular system: sensing redox states. Physiol Rev 2011; 91:889-915. [PMID: 21742790 DOI: 10.1152/physrev.00018.2010] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The multifunctional Ca(2+)- and calmodulin-dependent protein kinase II (CaMKII) is now recognized to play a central role in pathological events in the cardiovascular system. CaMKII has diverse downstream targets that promote vascular disease, heart failure, and arrhythmias, so improved understanding of CaMKII signaling has the potential to lead to new therapies for cardiovascular disease. CaMKII is a multimeric serine-threonine kinase that is initially activated by binding calcified calmodulin (Ca(2+)/CaM). Under conditions of sustained exposure to elevated Ca(2+)/CaM, CaMKII transitions into a Ca(2+)/CaM-autonomous enzyme by two distinct but parallel processes. Autophosphorylation of threonine-287 in the CaMKII regulatory domain "traps" CaMKII into an open configuration even after Ca(2+)/CaM unbinding. More recently, our group identified a pair of methionines (281/282) in the CaMKII regulatory domain that undergo a partially reversible oxidation which, like autophosphorylation, prevents CaMKII from inactivating after Ca(2+)/CaM unbinding. Here we review roles of CaMKII in cardiovascular disease with an eye to understanding how CaMKII may act as a transduction signal to connect pro-oxidant conditions into specific downstream pathological effects that are relevant to rare and common forms of cardiovascular disease.
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Affiliation(s)
- Jeffrey R Erickson
- Department of Pharmacology, University of California at Davis, Davis, California 95616, USA.
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42
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Yang JH, Saucerman JJ. Computational models reduce complexity and accelerate insight into cardiac signaling networks. Circ Res 2011; 108:85-97. [PMID: 21212391 DOI: 10.1161/circresaha.110.223602] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cardiac signaling networks exhibit considerable complexity in size and connectivity. The intrinsic complexity of these networks complicates the interpretation of experimental findings. This motivates new methods for investigating the mechanisms regulating cardiac signaling networks and the consequences these networks have on cardiac physiology and disease. Next-generation experimental techniques are also generating a wealth of genomic and proteomic data that can be difficult to analyze or interpret. Computational models are poised to play a key role in addressing these challenges. Computational models have a long history in contributing to the understanding of cardiac physiology and are useful for identifying biological mechanisms, inferring multiscale consequences to cell signaling activities and reducing the complexity of large data sets. Models also integrate well with experimental studies to explain experimental observations and generate new hypotheses. Here, we review the contributions computational modeling approaches have made to the analysis of cardiac signaling networks and forecast opportunities for computational models to accelerate cardiac signaling research.
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Affiliation(s)
- Jason H Yang
- Department of Biomedical Engineering, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, 22908, USA
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43
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Singh MV, Anderson ME. Is CaMKII a link between inflammation and hypertrophy in heart? J Mol Med (Berl) 2011; 89:537-43. [PMID: 21279501 DOI: 10.1007/s00109-011-0727-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 12/09/2010] [Accepted: 01/13/2011] [Indexed: 10/18/2022]
Abstract
Myocardial infarction is a major cause of morbidity and mortality in the developing and developed world. Although current interventions have been successful in prolonging life, they are inadequate because mortality is still high among MI patients. The multifunctional Ca(2+)/calmodulin-dependent protein kinase (CaMKII) plays a key role in the structure and contractility of the myocardium. CaMKII activity is increased in MI hearts and CaMKII promotes cardiac hypertrophy and inflammation, processes consistently activated by myocardial injury. Hypertrophy and inflammation are also related to neurohumoral and redox signaling which uncouple CaMKII activation from Ca(2+)/calmodulin dependence. Thus, CaMKII may act as a nodal point for integrating hypertrophic and inflammatory signaling in myocardium.
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Affiliation(s)
- Madhu V Singh
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, 52242, USA.
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44
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Soltis AR, Saucerman JJ. Synergy between CaMKII substrates and β-adrenergic signaling in regulation of cardiac myocyte Ca(2+) handling. Biophys J 2011; 99:2038-47. [PMID: 20923637 DOI: 10.1016/j.bpj.2010.08.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 07/23/2010] [Accepted: 08/04/2010] [Indexed: 01/10/2023] Open
Abstract
Cardiac excitation-contraction coupling is a highly coordinated process that is controlled by protein kinase signaling pathways, including Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA). Increased CaMKII expression and activity (as occurs during heart failure) destabilizes EC coupling and may lead to sudden cardiac death. To better understand mechanisms of cardiac CaMKII function, we integrated dynamic CaMKII-dependent regulation of key Ca(2+) handling targets with previously validated models of cardiac EC coupling, Ca(2+)/calmodulin-dependent activation of CaMKII, and β-adrenergic activation of PKA. Model predictions are validated against CaMKII-overexpression data from rabbit ventricular myocytes. The model demonstrates how overall changes to Ca(2+) handling during CaMKII overexpression are explained by interactions between individual CaMKII substrates. CaMKII and PKA activities during β-adrenergic stimulation may synergistically facilitate inotropic responses and contribute to a CaMKII-Ca(2+)-CaMKII feedback loop. CaMKII regulated early frequency-dependent acceleration of relaxation and EC coupling gain (which was highly sarcoplasmic reticulum Ca(2+) load-dependent). Additionally, the model identifies CaMKII-dependent ryanodine receptor hyperphosphorylation as a proarrhythmogenic trigger. In summary, we developed a detailed computational model of CaMKII and PKA signaling in cardiac myocytes that provides unique insights into their regulation of normal and pathological Ca(2+) handling.
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Affiliation(s)
- Anthony R Soltis
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
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Fishman GI, Chugh SS, Dimarco JP, Albert CM, Anderson ME, Bonow RO, Buxton AE, Chen PS, Estes M, Jouven X, Kwong R, Lathrop DA, Mascette AM, Nerbonne JM, O'Rourke B, Page RL, Roden DM, Rosenbaum DS, Sotoodehnia N, Trayanova NA, Zheng ZJ. Sudden cardiac death prediction and prevention: report from a National Heart, Lung, and Blood Institute and Heart Rhythm Society Workshop. Circulation 2011; 122:2335-48. [PMID: 21147730 DOI: 10.1161/circulationaha.110.976092] [Citation(s) in RCA: 443] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Glenn I Fishman
- NYU School of Medicine, Division of Cardiology, 522 First Avenue, Smilow 801, New York, NY 10016, USA.
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Abstract
Cardiovascular diseases are among the leading causes of death in the developed world. Developing novel therapies for diseases like heart failure is crucial, but this is hampered by the high attrition rate in drug development. The withdrawal of drugs at the final hurdle of approval is mostly because of their unpredictable effects on normal cardiac rhythm. The advent of cardiac computational modeling in the last 5 decades has aided the understanding of heart function significantly. Recently, these models increasingly have been applied toward designing and understanding therapies for cardiac disease. This article will discuss how cellular models of electrophysiology, cell signaling, and metabolism have been used to investigate pharmacologic therapies for cardiac diseases including arrhythmia, ischemia, and heart failure.
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Affiliation(s)
- Robert K. Amanfu
- Department of Biomedical Engineering, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
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Wolf RM, Mitchell CC, Christensen MD, Mohler PJ, Hund TJ. Defining new insight into atypical arrhythmia: a computational model of ankyrin-B syndrome. Am J Physiol Heart Circ Physiol 2010; 299:H1505-14. [PMID: 20729400 DOI: 10.1152/ajpheart.00503.2010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Normal cardiac excitability depends on the coordinated activity of specific ion channels and transporters within specialized domains at the plasma membrane and sarcoplasmic reticulum. Ion channel dysfunction due to congenital or acquired defects has been linked to human cardiac arrhythmia. More recently, defects in ion channel-associated proteins have been associated with arrhythmia. Ankyrin-B is a multifunctional adapter protein responsible for targeting select ion channels, transporters, cytoskeletal proteins, and signaling molecules in excitable cells, including neurons, pancreatic β-cells, and cardiomyocytes. Ankyrin-B dysfunction has been linked to cardiac arrhythmia in human patients and ankyrin-B heterozygous (ankyrin-B(+/-)) mice with a phenotype characterized by sinus node dysfunction, susceptibility to ventricular arrhythmias, and sudden death ("ankyrin-B syndrome"). At the cellular level, ankyrin-B(+/-) cells have defects in the expression and membrane localization of the Na(+)/Ca(2+) exchanger and Na(+)-K(+)-ATPase, Ca(2+) overload, and frequent afterdepolarizations, which likely serve as triggers for lethal cardiac arrhythmias. Despite knowledge gathered from mouse models and human patients, the molecular mechanism responsible for cardiac arrhythmias in the setting of ankyrin-B dysfunction remains unclear. Here, we use mathematical modeling to provide new insights into the cellular pathways responsible for Ca(2+) overload and afterdepolarizations in ankyrin-B(+/-) cells. We show that the Na(+)/Ca(2+) exchanger and Na(+)-K(+)-ATPase play related, yet distinct, roles in intracellular Ca(2+) accumulation, sarcoplasmic reticulum Ca(2+) overload, and afterdepolarization generation in ankyrin-B(+/-) cells. These findings provide important insights into the molecular mechanisms underlying a human disease and are relevant for acquired human arrhythmia, where ankyrin-B dysfunction has recently been identified.
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Affiliation(s)
- Roseanne M Wolf
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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48
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Decker KF, Rudy Y. Ionic mechanisms of electrophysiological heterogeneity and conduction block in the infarct border zone. Am J Physiol Heart Circ Physiol 2010; 299:H1588-97. [PMID: 20709867 DOI: 10.1152/ajpheart.00362.2010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The increased incidence of arrhythmia in the healing phase after infarction has been linked to remodeling in the epicardial border zone (EBZ). Ionic models of normal zone (NZ) and EBZ myocytes were incorporated into one-dimensional models of propagation to gain mechanistic insights into how ion channel remodeling affects action potential (AP) duration (APD) and refractoriness, vulnerability to conduction block, and conduction safety postinfarction. We found that EBZ tissue exhibited abnormal APD restitution. The remodeled Na(+) current (I(Na)) and L-type Ca(2+) current (I(Ca,L)) promoted increased effective refractory period and prolonged APD at a short diastolic interval. While postrepolarization refractoriness due to remodeled EBZ I(Na) was the primary determinant of the vulnerable window for conduction block at the NZ-to-EBZ transition in response to premature S2 stimuli, altered EBZ restitution also promoted APD dispersion and increased the vulnerable window at fast S1 pacing rates. Abnormal EBZ APD restitution and refractoriness also led to abnormal periodic conduction block patterns for a range of fast S1 pacing rates. In addition, we found that I(Na) remodeling decreased conduction safety in the EBZ but that inward rectifier K(+) current remodeling partially offset this decrease. EBZ conduction was characterized by a weakened AP upstroke and short intercellular delays, which prevented I(Ca,L) and transient outward K(+) current remodeling from playing a role in EBZ conduction in uncoupled tissue. Simulations of a skeletal muscle Na(+) channel SkM1-I(Na) injection into the EBZ suggested that this recently proposed antiarrhythmic therapy has several desirable effects, including normalization of EBZ effective refractory period and APD restitution, elimination of vulnerability to conduction block, and normalization of conduction in tissue with reduced intercellular coupling.
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Affiliation(s)
- Keith F Decker
- Cardiac Bioelectricity and Arrhythmia Center, Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-4899, USA.
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