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Zhao Y, Du B, Chakraborty P, Denham N, Massé S, Lai PF, Azam MA, Billia F, Thavendiranathan P, Abdel‐Qadir H, Lopaschuk GD, Nanthakumar K. Impaired Cardiac AMPK (5'-Adenosine Monophosphate-Activated Protein Kinase) and Ca 2+-Handling, and Action Potential Duration Heterogeneity in Ibrutinib-Induced Ventricular Arrhythmia Vulnerability. J Am Heart Assoc 2024; 13:e032357. [PMID: 38842296 PMCID: PMC11255774 DOI: 10.1161/jaha.123.032357] [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: 12/11/2023] [Accepted: 04/03/2024] [Indexed: 06/07/2024]
Abstract
BACKGROUND We recently demonstrated that acute administration of ibrutinib, a Bruton's tyrosine kinase inhibitor used in chemotherapy for blood malignancies, increases ventricular arrhythmia (VA) vulnerability. A pathway of ibrutinib-induced vulnerability to VA that can be modulated for cardioprotection remains unclear. METHODS AND RESULTS The effects of ibrutinib on cardiac electrical activity and Ca2+ dynamics were investigated in Langendorff-perfused hearts using optical mapping. We also conducted Western blotting analysis to evaluate the impact of ibrutinib on various regulatory and Ca2+-handling proteins in rat cardiac tissues. Treatment with ibrutinib (10 mg/kg per day) for 4 weeks was associated with an increased VA inducibility (72.2%±6.3% versus 38.9±7.0% in controls, P<0.002) and shorter action potential durations during pacing at various frequencies (P<0.05). Ibrutinib also decreased heart rate thresholds for beat-to-beat duration alternans of the cardiac action potential (P<0.05). Significant changes in myocardial Ca2+ transients included lower amplitude alternans ratios (P<0.05), longer times-to-peak (P<0.05), and greater spontaneous intracellular Ca2+ elevations (P<0.01). We also found lower abundance and phosphorylation of myocardial AMPK (5'-adenosine monophosphate-activated protein kinase), indicating reduced AMPK activity in hearts after ibrutinib treatment. An acute treatment with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside ameliorated abnormalities in action potential and Ca2+ dynamics, and significantly reduced VA inducibility (37.1%±13.4% versus 72.2%±6.3% in the absence of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, P<0.05) in hearts from ibrutinib-treated rats. CONCLUSIONS VA vulnerability inflicted by ibrutinib may be mediated in part by an impairment of myocardial AMPK activity. Pharmacological activation of AMPK may be a protective strategy against ibrutinib-induced cardiotoxicity.
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MESH Headings
- Animals
- Adenine/analogs & derivatives
- Adenine/pharmacology
- Piperidines/pharmacology
- Action Potentials/drug effects
- Pyrimidines/pharmacology
- AMP-Activated Protein Kinases/metabolism
- Pyrazoles/pharmacology
- Male
- Arrhythmias, Cardiac/chemically induced
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/physiopathology
- Arrhythmias, Cardiac/prevention & control
- Protein Kinase Inhibitors/pharmacology
- Heart Rate/drug effects
- Isolated Heart Preparation
- Calcium/metabolism
- Rats
- Disease Models, Animal
- Rats, Sprague-Dawley
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/pathology
- Calcium Signaling/drug effects
- Time Factors
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Affiliation(s)
- Yanan Zhao
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
- China‐Japan Union Hospital of Jilin UniversityChangchunChina
| | - Beibei Du
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
- China‐Japan Union Hospital of Jilin UniversityChangchunChina
| | - Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
| | - Nathan Denham
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
| | - Patrick F.H. Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
| | - Filio Billia
- Toronto General Hospital Research InstituteTorontoCanada
- Ted Rogers Centre for Heart ResearchTorontoCanada
| | | | - Husam Abdel‐Qadir
- Toronto General Hospital Research InstituteTorontoCanada
- Ted Rogers Centre for Heart ResearchTorontoCanada
| | | | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General HospitalTorontoCanada
- Toronto General Hospital Research InstituteTorontoCanada
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2
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Seibertz F, Voigt N. High-throughput methods for cardiac cellular electrophysiology studies: the road to personalized medicine. Am J Physiol Heart Circ Physiol 2024; 326:H938-H949. [PMID: 38276947 PMCID: PMC11279751 DOI: 10.1152/ajpheart.00599.2023] [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: 09/26/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 01/27/2024]
Abstract
Personalized medicine refers to the tailored application of medical treatment at an individual level, considering the specific genotype or phenotype of each patient for targeted therapy. In the context of cardiovascular diseases, implementing personalized medicine is challenging due to the high costs involved and the slow pace of identifying the pathogenicity of genetic variants, deciphering molecular mechanisms of disease, and testing treatment approaches. Scalable cellular models such as human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) serve as useful in vitro tools that reflect individual patient genetics and retain clinical phenotypes. High-throughput functional assessment of these constructs is necessary to rapidly assess cardiac pathogenicity and test new therapeutics if personalized medicine is to become a reality. High-throughput photometry recordings of single cells coupled with potentiometric probes offer cost-effective alternatives to traditional patch-clamp assessments of cardiomyocyte action potential characteristics. Importantly, automated patch-clamp (APC) is rapidly emerging in the pharmaceutical industry and academia as a powerful method to assess individual membrane-bound ionic currents and ion channel biophysics over multiple cells in parallel. Now amenable to primary cell and hiPSC-CM measurement, APC represents an exciting leap forward in the characterization of a multitude of molecular mechanisms that underlie clinical cardiac phenotypes. This review provides a summary of state-of-the-art high-throughput electrophysiological techniques to assess cardiac electrophysiology and an overview of recent works that successfully integrate these methods into basic science research that could potentially facilitate future implementation of personalized medicine at a clinical level.
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Affiliation(s)
- Fitzwilliam Seibertz
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells," Georg-August University Göttingen, Göttingen, Germany
- Nanion Technologies, GmbH, Munich, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells," Georg-August University Göttingen, Göttingen, Germany
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3
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Nearing BD, Verrier RL. Novel application of convolutional neural networks for artificial intelligence-enabled modified moving average analysis of P-, R-, and T-wave alternans for detection of risk for atrial and ventricular arrhythmias. J Electrocardiol 2024; 83:12-20. [PMID: 38185007 DOI: 10.1016/j.jelectrocard.2023.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 01/09/2024]
Abstract
BACKGROUND T-wave alternans (TWA) analysis was shown in >14,000 individuals studied worldwide over the past two decades to be a useful tool to assess risk for cardiovascular mortality and sudden arrhythmic death. TWA analysis by the modified moving average (MMA) method is FDA-cleared and CMS-reimbursed (CAG-00293R2). OBJECTIVE Because the MMA technique is inherently suitable for dynamic tracking of alternans levels, it was selected for development of artificial intelligence (AI)-enabled algorithms using convolutional neural networks (CNN) to achieve rapid, efficient, and accurate assessment of P-wave alternans (PWA), R-wave alternans (RWA), and TWA. METHODS The novel application of CNN algorithms to enhance MMA analysis generated efficient and powerful pattern-recognition algorithms for highly accurate alternans quantification. Algorithm reliability and accuracy were verified using simulated ECGs achieving R2 ≥ 0.99 (p < 0.01) in response to noise inputs and artifacts that emulate real-life conditions. RESULTS Accuracy of the new AI-MMA algorithms in TWA analysis (n = 5) was significantly improved over unsupervised, automated MMA output (p = 0.036) and did not differ from conventional MMA analysis with expert overreading (p = 0.21). Accuracy of AI-MMA in PWA analysis (n = 45) was significantly improved over unsupervised, automated MMA output (p < 0.005) and did not differ from conventional MMA analysis with expert overreading (p = 0.89). TWA and PWA by AI-MMA were correlated with conventional MMA output over-read by an expert reader (R2 = 0.7765, R2 = 0.9504, respectively). CONCLUSION This novel technique for AI-MMA analysis could be suitable for use in diverse in-hospital and out-of-hospital monitoring systems, including cardiac implantable electronic devices and smartwatches, for tracking atrial and ventricular arrhythmia risk.
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Affiliation(s)
- Bruce D Nearing
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Richard L Verrier
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
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4
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Hegemann N, Barth L, Döring Y, Voigt N, Grune J. Implications for neutrophils in cardiac arrhythmias. Am J Physiol Heart Circ Physiol 2024; 326:H441-H458. [PMID: 38099844 PMCID: PMC11219058 DOI: 10.1152/ajpheart.00590.2023] [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: 09/22/2023] [Revised: 12/08/2023] [Accepted: 12/13/2023] [Indexed: 02/03/2024]
Abstract
Cardiac arrhythmias commonly occur as a result of aberrant electrical impulse formation or conduction in the myocardium. Frequently discussed triggers include underlying heart diseases such as myocardial ischemia, electrolyte imbalances, or genetic anomalies of ion channels involved in the tightly regulated cardiac action potential. Recently, the role of innate immune cells in the onset of arrhythmic events has been highlighted in numerous studies, correlating leukocyte expansion in the myocardium to increased arrhythmic burden. Here, we aim to call attention to the role of neutrophils in the pathogenesis of cardiac arrhythmias and their expansion during myocardial ischemia and infectious disease manifestation. In addition, we will elucidate molecular mechanisms associated with neutrophil activation and discuss their involvement as direct mediators of arrhythmogenicity.
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Affiliation(s)
- Niklas Hegemann
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité (DHZC), Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Centre for Cardiovascular Research (DZHK), Berlin, Germany
| | - Lukas Barth
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité (DHZC), Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Centre for Cardiovascular Research (DZHK), Berlin, Germany
| | - Yannic Döring
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg August University Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg August University Göttingen, Göttingen, Germany
- German Centre for Cardiovascular Research (DZHK), Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Jana Grune
- Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum der Charité (DHZC), Berlin, Germany
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Centre for Cardiovascular Research (DZHK), Berlin, Germany
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5
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Chakraborty P, Aggarwal AK, Nair MKK, Massé S, Riazi S, Nanthakumar K. Restoration of calcium release synchrony: A novel target for heart failure and ventricular arrhythmia. Heart Rhythm 2023; 20:1773-1781. [PMID: 37678492 DOI: 10.1016/j.hrthm.2023.08.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/13/2023] [Accepted: 08/31/2023] [Indexed: 09/09/2023]
Abstract
Myocardial calcium (Ca2+) signaling plays a crucial role in contractile function and membrane electrophysiology. An abnormal myocardial Ca2+ transient is linked to heart failure and ventricular arrhythmias. At the subcellular level, the synchronous release of Ca2+ sparks from sarcoplasmic Ca2+ release units determines the configuration and amplitude of the global Ca2+ transient. This narrative review evaluates the role of aberrant Ca2+ release synchrony in the pathophysiology of cardiomyopathies and ventricular arrhythmias. The potential therapeutic benefits of restoration of Ca2+ release synchrony in heart failure and ventricular arrhythmias are also discussed.
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Affiliation(s)
- Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; Heart Rhythm Institute, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | - Arjun K Aggarwal
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Madhav Krishna Kumar Nair
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
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6
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Zhou Y, Huang S, Li C, Qiao Y, Liu Q, Chen T, Wang J, Liu Y. Glucagon-Like Peptide-1 (GLP-1) Rescue Diabetic Cardiac Dysfuntions in Human iPSC-Derived Cardiomyocytes. Adv Biol (Weinh) 2023; 7:e2200130. [PMID: 36373695 DOI: 10.1002/adbi.202200130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/29/2022] [Indexed: 11/16/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) can improve cardiac function and cardiovascular outcomes in diabetic cardiomyopathy; however, the beneficial effect of GLP-1 on human diabetic cardiomyocytes (DCMs) and its mechanism have not been fully elucidated. Here, the DCMs model by human-induced pluripotent stem cells-derived cardiomyocytes is developed. Two subtypes of GLP-1, GLP-17-36 and GLP-19-36 , are evaluated for their efficacy on the DCMs model. Diabetogenic condition is sufficient to induce most characteristics of diabetic cardiomyopathy in vitro, such as cardiac hypertrophy, lipid accumulation, impaired calcium transients, and abnormal electrophysiological properties. GLP-17-36 and GLP-19-36 can restore cardiomyocyte hypertrophic phenotype, impaired calcium transient frequency, abnormal action potential amplitude, depolarization, and repolarization velocity. Interestingly, RNA-seq reveals different pathways altered by GLP-17-36 and GLP-19-36 , respectively. Differentially expressed gene analysis reveals that possible targets of GLP-17-36 involve the regulation of mitotic nuclear division and extracellular matrix-receptor interaction, while possible targets of GLP-19-36 involve kinetochore assembly, and the complement and coagulation cascades. This study demonstrates the therapeutic effects of GLP-1 on human DCMs and provides a novel platform to unveil the cellular mechanisms of diabetic cardiomyopathy, shedding light on discovering better targets for novel therapeutic interventions.
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Affiliation(s)
- Ying Zhou
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, 109 Longmian Avenue, Nanjing, 211166, China
| | - Shuting Huang
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, 109 Longmian Avenue, Nanjing, 211166, China
| | - Chengwu Li
- HELP Therapeutics, 568 Longmian Avenue, Nanjing, 211166, China
| | - Yue Qiao
- Department of Endocrinology, The Second Hospital of Jilin University, 218 Ziqiang Street, Changchun, 210031, China
| | - Qing Liu
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, 109 Longmian Avenue, Nanjing, 211166, China
| | - Taotao Chen
- HELP Therapeutics, 568 Longmian Avenue, Nanjing, 211166, China
| | - Jiaxian Wang
- HELP Therapeutics, 568 Longmian Avenue, Nanjing, 211166, China
| | - Yu Liu
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, 109 Longmian Avenue, Nanjing, 211166, China
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7
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Kanaporis G, Martinez‐Hernandez E, Blatter LA. Calcium- and voltage-driven atrial alternans: Insight from [Ca] i and V m asynchrony. Physiol Rep 2023; 11:e15703. [PMID: 37226365 PMCID: PMC10209431 DOI: 10.14814/phy2.15703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/26/2023] Open
Abstract
Cardiac alternans is defined as beat-to-beat alternations in contraction strength, action potential duration (APD), and Ca transient (CaT) amplitude. Cardiac excitation-contraction coupling relies on the activity of two bidirectionally coupled excitable systems, membrane voltage (Vm ) and Ca release. Alternans has been classified as Vm - or Ca-driven, depending whether a disturbance of Vm or [Ca]i regulation drives the alternans. We determined the primary driver of pacing induced alternans in rabbit atrial myocytes, using combined patch clamp and fluorescence [Ca]i and Vm measurements. APD and CaT alternans are typically synchronized; however, uncoupling between APD and CaT regulation can lead to CaT alternans in the absence of APD alternans, and APD alternans can fail to precipitate CaT alternans, suggesting a considerable degree of independence of CaT and APD alternans. Using alternans AP voltage clamp protocols with extra APs showed that most frequently the pre-existing CaT alternans pattern prevailed after the extra-beat, indicating that alternans is Ca-driven. In electrically coupled cell pairs, dyssynchrony of APD and CaT alternans points to autonomous regulation of CaT alternans. Thus, with three novel experimental protocols, we collected evidence for Ca-driven alternans; however, the intimately intertwined regulation of Vm and [Ca]i precludes entirely independent development of CaT and APD alternans.
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Affiliation(s)
- G. Kanaporis
- Department of Physiology & BiophysicsRush University Medical CenterChicagoIllinoisUSA
| | - E. Martinez‐Hernandez
- Department of Physiology & BiophysicsRush University Medical CenterChicagoIllinoisUSA
| | - L. A. Blatter
- Department of Physiology & BiophysicsRush University Medical CenterChicagoIllinoisUSA
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8
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Abstract
Cardiac alternans arises from dynamical instabilities in the electrical and calcium cycling systems of the heart, and often precedes ventricular arrhythmias and sudden cardiac death. In this review, we integrate clinical observations with theory and experiment to paint a holistic portrait of cardiac alternans: the underlying mechanisms, arrhythmic manifestations and electrocardiographic signatures. We first summarize the cellular and tissue mechanisms of alternans that have been demonstrated both theoretically and experimentally, including 3 voltage-driven and 2 calcium-driven alternans mechanisms. Based on experimental and simulation results, we describe their relevance to mechanisms of arrhythmogenesis under different disease conditions, and their link to electrocardiographic characteristics of alternans observed in patients. Our major conclusion is that alternans is not only a predictor, but also a causal mechanism of potentially lethal ventricular and atrial arrhythmias across the full spectrum of arrhythmia mechanisms that culminate in functional reentry, although less important for anatomic reentry and focal arrhythmias.
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Affiliation(s)
- Zhilin Qu
- Departments of Medicine (Cardiology), Physiology, and Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - James N. Weiss
- Departments of Medicine (Cardiology), Physiology, and Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA
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9
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Banach K, Blatter LA. The 'Reverse FDUF' Mechanism of Atrial Excitation-Contraction Coupling Sustains Calcium Alternans-A Hypothesis. Biomolecules 2022; 13:biom13010007. [PMID: 36671392 PMCID: PMC9855423 DOI: 10.3390/biom13010007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/07/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Cardiac calcium alternans is defined as beat-to-beat alternations of Ca transient (CaT) amplitude and has been linked to cardiac arrhythmia, including atrial fibrillation. We investigated the mechanism of atrial alternans in isolated rabbit atrial myocytes using high-resolution line scan confocal Ca imaging. Alternans was induced by increasing the pacing frequency until stable alternans was observed (1.6-2.5 Hz at room temperature). In atrial myocytes, action potential-induced Ca release is initiated in the cell periphery and subsequently propagates towards the cell center by Ca-induced Ca release (CICR) in a Ca wave-like fashion, driven by the newly identified 'fire-diffuse-uptake-fire' (FDUF) mechanism. The development of CaT alternans was accompanied by characteristic changes of the spatio-temporal organization of the CaT. During the later phase of the CaT, central [Ca]i exceeded peripheral [Ca]i that was indicative of a reversal of the subcellular [Ca]i gradient from centripetal to centrifugal. This gradient reversal resulted in a reversal of CICR propagation, causing a secondary Ca release during the large-amplitude alternans CaT, thereby prolonging the CaT, enhancing Ca-release refractoriness and reducing Ca release on the subsequent beat, thus enhancing the degree of CaT alternans. Here, we propose the 'reverse FDUF' mechanism as a novel cellular mechanism of atrial CaT alternans, which explains how the uncoupling of central from peripheral Ca release leads to the reversal of propagating CICR and to alternans.
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Affiliation(s)
- Kathrin Banach
- Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL 60612, USA
| | - Lothar A. Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
- Correspondence:
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10
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Kwek XY, Hall AR, Lim WW, Katwadi K, Soong PL, Grishina E, Lin KH, Crespo-Avilan G, Yap EP, Ismail NI, Chinda K, Chung YY, Wei H, Shim W, Montaigne D, Tinker A, Ong SB, Hausenloy DJ. Role of cardiac mitofusins in cardiac conduction following simulated ischemia-reperfusion. Sci Rep 2022; 12:21049. [PMID: 36473917 PMCID: PMC9727036 DOI: 10.1038/s41598-022-25625-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial dysfunction induced by acute cardiac ischemia-reperfusion (IR), may increase susceptibility to arrhythmias by perturbing energetics, oxidative stress production and calcium homeostasis. Although changes in mitochondrial morphology are known to impact on mitochondrial function, their role in cardiac arrhythmogenesis is not known. To assess action potential duration (APD) in cardiomyocytes from the Mitofusins-1/2 (Mfn1/Mfn2)-double-knockout (Mfn-DKO) compared to wild-type (WT) mice, optical-electrophysiology was conducted. To measure conduction velocity (CV) in atrial and ventricular tissue from the Mfn-DKO and WT mice, at both baseline and following simulated acute IR, multi-electrode array (MEA) was employed. Intracellular localization of connexin-43 (Cx43) at baseline was evaluated by immunohistochemistry, while Cx-43 phosphorylation was assessed by Western-blotting. Mfn-DKO cardiomyocytes demonstrated an increased APD. At baseline, CV was significantly lower in the left ventricle of the Mfn-DKO mice. CV decreased with simulated-ischemia and returned to baseline levels during simulated-reperfusion in WT but not in atria of Mfn-DKO mice. Mfn-DKO hearts displayed increased Cx43 lateralization, although phosphorylation of Cx43 at Ser-368 did not differ. In summary, Mfn-DKO mice have increased APD and reduced CV at baseline and impaired alterations in CV following cardiac IR. These findings were associated with increased Cx43 lateralization, suggesting that the mitofusins may impact on post-MI cardiac-arrhythmogenesis.
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Affiliation(s)
- Xiu-Yi Kwek
- grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore
| | - Andrew R. Hall
- grid.83440.3b0000000121901201The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, London, UK
| | - Wei-Wen Lim
- grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore ,grid.428397.30000 0004 0385 0924Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore, Singapore
| | - Khairunnisa Katwadi
- grid.428397.30000 0004 0385 0924Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore, Singapore
| | - Poh Loong Soong
- grid.4280.e0000 0001 2180 6431Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore ,grid.4280.e0000 0001 2180 6431Cardiovascular Translational Program, Cardiovascular Research Institute (CVRI), National University of Singapore, Singapore, Singapore ,grid.412106.00000 0004 0621 9599Department of Medicine, National University Hospital of Singapore (NUHS), Singapore, Singapore ,Ternion Biosciences, Singapore, Singapore
| | | | | | - Gustavo Crespo-Avilan
- grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore ,grid.428397.30000 0004 0385 0924Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore, Singapore ,grid.8664.c0000 0001 2165 8627Department of Biochemistry, Medical Faculty, Justus Liebig-University, Giessen, Germany
| | - En Ping Yap
- grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore
| | - Nur Izzah Ismail
- grid.10784.3a0000 0004 1937 0482Centre for Cardiovascular Genomics and Medicine (CCGM), Lui Che Woo Institute of Innovative Medicine, Chinese University of Hong Kong (CUHK), Hong Kong, SAR China ,grid.10784.3a0000 0004 1937 0482Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong (CUHK), Hong Kong, SAR China ,Hong Kong Hub of Paediatric Excellence (HK HOPE), Hong Kong Children’s Hospital (HKCH), Kowloon Bay, Hong Kong, SAR China
| | - Kroekkiat Chinda
- grid.412029.c0000 0000 9211 2704Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand ,grid.412029.c0000 0000 9211 2704Integrative Cardiovascular Research Unit, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Ying Ying Chung
- grid.428397.30000 0004 0385 0924Centre for Vision Research, Duke-National University of Singapore Medical School, Singapore, Singapore
| | - Heming Wei
- grid.414963.d0000 0000 8958 3388Research Laboratory, KK Women’s & Children’s Hospital, Singapore, Singapore
| | - Winston Shim
- grid.486188.b0000 0004 1790 4399Health and Social Sciences Cluster, Singapore Institute of Technology, Singapore, Singapore
| | - David Montaigne
- grid.503422.20000 0001 2242 6780Inserm, CHU Lille, Institut Pasteur Lille, U1011-European Genomic Institute for Diabetes (EGID), University of Lille, 59000 Lille, France
| | - Andrew Tinker
- grid.4868.20000 0001 2171 1133Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
| | - Sang-Bing Ong
- grid.10784.3a0000 0004 1937 0482Centre for Cardiovascular Genomics and Medicine (CCGM), Lui Che Woo Institute of Innovative Medicine, Chinese University of Hong Kong (CUHK), Hong Kong, SAR China ,grid.10784.3a0000 0004 1937 0482Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong (CUHK), Hong Kong, SAR China ,Hong Kong Hub of Paediatric Excellence (HK HOPE), Hong Kong Children’s Hospital (HKCH), Kowloon Bay, Hong Kong, SAR China ,grid.9227.e0000000119573309Joint Laboratory of Bioresources and Molecular Research of Common Diseases, Kunming Institute of Zoology-The Chinese University of Hong Kong (KIZ-CUHK), Chinese Academy of Sciences, Kunming, Yunnan China ,grid.10784.3a0000 0004 1937 0482Shenzhen Research Institute (SZRI), Chinese University of Hong Kong (CUHK), Shenzhen, China
| | - Derek J. Hausenloy
- grid.419385.20000 0004 0620 9905National Heart Research Institute Singapore, National Heart Centre, Singapore, Singapore ,grid.83440.3b0000000121901201The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, London, UK ,grid.428397.30000 0004 0385 0924Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore, Singapore ,grid.4280.e0000 0001 2180 6431Yong Loo Lin School of Medicine, National University Singapore, Singapore, Singapore
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11
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Martinez-Hernandez E, Kanaporis G, Blatter LA. Mechanism of carvedilol induced action potential and calcium alternans. Channels (Austin) 2022; 16:97-112. [PMID: 35501948 PMCID: PMC9067505 DOI: 10.1080/19336950.2022.2055521] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Carvedilol is a nonspecific β-blocker clinically used for the treatment of cardiovascular diseases but has also been shown to have profound effects on excitation-contraction coupling and Ca signaling at the cellular level. We investigate the mechanism by which carvedilol facilitates Ca transient (CaT) and action potential duration (APD) alternans in rabbit atrial myocytes. Carvedilol lowered the frequency threshold for pacing-induced CaT alternans and facilitated alternans in a concentration-dependent manner. Carvedilol prolonged the sarcoplasmic reticulum (SR) Ca release refractoriness by significantly increasing the time constant τ of recovery of SR Ca release; however, no changes in L-type calcium current recovery from inactivation or SR Ca load were found after carvedilol treatment. Carvedilol enhanced the degree of APD alternans nearly two-fold. Carvedilol slowed the APD restitution kinetics and steepened the APD restitution curve at the pacing frequency (2 Hz) where alternans were elicited. No effect on the CaT or APD alternans ratios was observed in experiments with a different β-blocker (metoprolol), excluding the possibility that the carvedilol effect on CaT and APD alternans was determined by its β-blocking properties. These data suggest that carvedilol contributes to the generation of CaT and APD alternans in atrial myocytes by modulating the restitution of CaT and APD.
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Affiliation(s)
| | - Giedrius Kanaporis
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois, USA
| | - Lothar A. Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois, USA,CONTACT Lothar A. Blatter Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL60612, USA
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12
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Si D, Chakraborty P, Azam MA, Nair MKK, Massé S, Lai PF, Labos C, Riazi S, Nanthakumar K. Synchronizing systolic calcium release with azumolene in an experimental model. Heart Rhythm O2 2022; 3:568-576. [PMID: 36340488 PMCID: PMC9626747 DOI: 10.1016/j.hroo.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background Post-defibrillation myocardial contractile dysfunction adversely affects the survival of patients after cardiac arrest. Attenuation of diastolic calcium (Ca2+) overload by stabilization of the cardiac ryanodine receptor (RyR2) is found to reduce refibrillation after long-duration ventricular fibrillation (LDVF). Objective In the present study, we explored the effects of RyR2 stabilization by azumolene on systolic Ca2+ release synchrony and myocardial contractility. Methods After completion of baseline optical mapping, Langendorff-perfused rabbit hearts were subjected to global ischemia followed by reperfusion with azumolene or deionized distilled water (vehicle). Following reperfusion, LDVF was induced with burst pacing. In the first series of experiments (n = 16), epicardial Ca2+ transient was analyzed for Ca2+ transient amplitude alternans and dispersion of Ca2+ transient amplitude alternans index (CAAI). In the second series of experiments following the same protocol (n = 12), ventricular contractility was assessed by measuring the left ventricular pressure. Results Ischemic LDVF led to greater CAAI (0.06 ± 0.02 at baseline vs 0.12 ± 0.02 post-LDVF, P < .01) and magnitude of dispersion of CAAI (0.04 ± 0.01 vs 0.09 ± 0.01, P < .01) in control hearts. In azumolene-treated hearts, no significant changes in CAAI (0.05 ± 0.01 vs 0.05 ± 0.01, P = .84) and dispersion of CAAI (0.04 ± 0.01 vs 0.04 ± 0.01, P = .99) were noted following ischemic LDVF. Ischemic LDVF was associated with reduction in left ventricular developed pressure (100% vs 36.8% ± 6.1%, P = .002) and dP/dtmax (100% vs 45.3% ± 6.5%, P = .003) in control hearts, but these reductions were mitigated (left ventricular developed pressure: 100% vs 74.0% ± 8.1%, P = .052, dP/dtmax: 100% vs 80.8% ± 7.9%, P = .09) in azumolene-treated hearts. Conclusion Treatment with azumolene is associated with improvement of systolic Ca2+ release synchrony and myocardial contractility following ischemic LDVF.
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Affiliation(s)
- Daoyuan Si
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
- Department of Cardiology, China-Japan Union Hospital, Jilin University, Changchun, China
| | - Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Madhav Krishna Kumar Nair
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | - Patrick F.H. Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
| | | | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia and Pain Management, University Health Network, Toronto, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Canada
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13
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Bossuyt J, Borst JM, Verberckmoes M, Bailey LRJ, Bers DM, Hegyi B. Protein Kinase D1 Regulates Cardiac Hypertrophy, Potassium Channel Remodeling, and Arrhythmias in Heart Failure. J Am Heart Assoc 2022; 11:e027573. [PMID: 36172952 DOI: 10.1161/jaha.122.027573] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Structural and electrophysiological remodeling characterize heart failure (HF) enhancing arrhythmias. PKD1 (protein kinase D1) is upregulated in HF and mediates pathological hypertrophic signaling, but its role in K+ channel remodeling and arrhythmogenesis in HF is unknown. Methods and Results We performed echocardiography, electrophysiology, and expression analysis in wild-type and PKD1 cardiomyocyte-specific knockout (cKO) mice following transverse aortic constriction (TAC). PKD1-cKO mice exhibited significantly less cardiac hypertrophy post-TAC and were protected from early decline in cardiac contractile function (3 weeks post-TAC) but not the progression to HF at 7 weeks post-TAC. Wild-type mice exhibited ventricular action potential duration prolongation at 8 weeks post-TAC, which was attenuated in PKD1-cKO, consistent with larger K+ currents via the transient outward current, sustained current, inward rectifier K+ current, and rapid delayed rectifier K+ current and increased expression of corresponding K+ channels. Conversely, reduction of slowly inactivating K+ current was independent of PKD1 in HF. Acute PKD inhibition slightly increased transient outward current in TAC and sham wild-type myocytes but did not alter other K+ currents. Sham PKD1-cKO versus wild-type also exhibited larger transient outward current and faster early action potential repolarization. Tachypacing-induced action potential duration alternans in TAC animals was increased and independent of PKD1, but diastolic arrhythmogenic activities were reduced in PKD1-cKO. Conclusions Our data indicate an important role for PKD1 in the HF-related hypertrophic response and K+ channel downregulation. Therefore, PKD1 inhibition may represent a therapeutic strategy to reduce hypertrophy and arrhythmias; however, PKD1 inhibition may not prevent disease progression and reduced contractility in HF.
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Affiliation(s)
- Julie Bossuyt
- Department of Pharmacology University of California Davis CA
| | - Johanna M Borst
- Department of Pharmacology University of California Davis CA
| | | | | | - Donald M Bers
- Department of Pharmacology University of California Davis CA
| | - Bence Hegyi
- Department of Pharmacology University of California Davis CA
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14
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Novaes GM, Alvarez-Lacalle E, Muñoz SA, dos Santos RW. An ensemble of parameters from a robust Markov-based model reproduces L-type calcium currents from different human cardiac myocytes. PLoS One 2022; 17:e0266233. [PMID: 35381041 PMCID: PMC8982880 DOI: 10.1371/journal.pone.0266233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 03/16/2022] [Indexed: 11/18/2022] Open
Abstract
The development of modeling structures at the channel level that can integrate subcellular and cell models and properly reproduce different experimental data is of utmost importance in cardiac electrophysiology. In contrast to gate-based models, Markov Chain models are well suited to promote the integration of the subcellular level of the cardiomyocyte to the whole cell. In this paper, we develop Markov Chain models for the L-type Calcium current that can reproduce the electrophysiology of two established human models for the ventricular and Purkinje cells. In addition, instead of presenting a single set of parameters, we present a collection of set of parameters employing Differential Evolution algorithms that can properly reproduce very different protocol data. We show the importance of using an ensemble of a set of parameter values to obtain proper results when considering a second protocol that suppresses calcium inactivation and mimics a pathological condition. We discuss how model discrepancy, data availability, and parameter identifiability can influence the choice of the size of the collection. In summary, we have modified two cardiac models by proposing new Markov Chain models for the L-type Calcium. We keep the original whole-cell dynamics by reproducing the same characteristic action potential and calcium dynamics, whereas the Markov chain-based description of the L-type Calcium channels allows novel small spatial scale simulations of subcellular processes. Finally, the use of collections of parameters was crucial for addressing model discrepancy, identifiability issues, and avoiding fitting parameters overly precisely, i.e., overfitting.
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Affiliation(s)
- Gustavo Montes Novaes
- Graduate Program in Computational Modeling, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil
- Department of Physics, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
- Department of Computation and Mechanics, Federal Center of Technological Education of Minas Gerais, Leopoldina, MG, Brazil
- * E-mail:
| | | | - Sergio Alonso Muñoz
- Department of Physics, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Rodrigo Weber dos Santos
- Graduate Program in Computational Modeling, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil
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15
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Verrier RL, Libbus I, Nearing BD, KenKnight BH. Multifactorial Benefits of Chronic Vagus Nerve Stimulation on Autonomic Function and Cardiac Electrical Stability in Heart Failure Patients With Reduced Ejection Fraction. Front Physiol 2022; 13:855756. [PMID: 35431984 PMCID: PMC9005779 DOI: 10.3389/fphys.2022.855756] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 02/21/2022] [Indexed: 12/20/2022] Open
Abstract
Heart failure with reduced left ventricular ejection fraction is a progressive disease that claims > 352,000 lives annually in the United States alone. Despite the development of an extensive array of pharmacologic and device therapies, prognosis remains poor. Disruption in autonomic balance in the form of heightened sympathetic nerve activity and reduced vagal tone have been established as major causes of heart failure progression. Interest in chronic neuromodulation mediated by vagus nerve stimulation (VNS) has intensified in recent years. This review focuses on four main goals: (1) To review the preclinical evidence that supports the concept of a cardioprotective effect of VNS on autonomic function and cardiac electrical stability along with the underlying putative mechanisms. (2) To present the initial clinical experience with chronic VNS in patients with heart failure and highlight the controversial aspects of the findings. (3) To discuss the latest findings of the multifactorial effects of VNS on autonomic tone, baroreceptor sensitivity, and cardiac electrical stability and the state-of-the-art methods employed to monitor these relationships. (4) To discuss the implications of the current findings and the gaps in knowledge that require attention in future investigations.
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Affiliation(s)
- Richard L. Verrier
- Beth Israel Deaconess Medical Center, Department of Medicine, Division of Cardiovascular Medicine, Harvard Medical School, Boston, MA, United States
- *Correspondence: Richard L. Verrier, , orcid.org/0000-0001-5602-6793
| | - Imad Libbus
- LivaNova USA, Inc., Houston, TX, United States
| | - Bruce D. Nearing
- Beth Israel Deaconess Medical Center, Department of Medicine, Division of Cardiovascular Medicine, Harvard Medical School, Boston, MA, United States
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16
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Chakraborty P, Massé S, Azam MA, Thollon C, Niri A, Lai PFH, Bouly M, Riazi S, Nanthakumar K. Effects of azumolene on arrhythmia substrate in a model of recurrent long-duration ventricular fibrillation. Biochem Biophys Res Commun 2022; 600:123-129. [PMID: 35219100 DOI: 10.1016/j.bbrc.2022.02.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 02/09/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND Proarrhythmic risk of conventional anti-arrhythmic agents is linked to unintended modulation of membrane voltage dynamics. We have demonstrated that the anti-fibrillatory effect of azumolene is mediated via stabilization of the hyperphosphorylated ryanodine receptor (RyR2), leading to attenuation of diastolic calcium leak. However, the concomitant effects on membrane voltage dynamics have not been evaluated yet. METHODS After baseline optical mapping, Langendorff-perfused rabbit hearts treated with azumolene, or vehicle, were subjected to global ischemia-reperfusion (I/R) followed by two episodes of long-duration ventricular fibrillation (LDVF). Simultaneous dual epicardial calcium transient (CaT) and voltage dynamics were studied optically. RESULTS Pre-treatment with azumolene was associated with higher CaT amplitude alternans ratios (0.94 ± 0.02 vs. 0.78 ± 0.03 in control hearts, at 6 Hz; p = 0.005; and action potential amplitude alternans ratio (0.95 ± 0.02 vs. 0.78 ± 0.04 at 6.0 Hz; p = 0.02), and reduction of action potential duration (APD80) dispersion (9.0 ± 4.8 msec vs. 19.3 ± 6.6 msec at 6.0 Hz p = 0.02) and optical action potential upstroke rise time (26.3 ± 2.6 msec in control vs. 13.8 ± 0.6 msec at 6.0 Hz, p = 0.02) after LDVF. No change in action potential duration (APD) was noted with azumolene treatment. CONCLUSION In a model of ischemic recurrent LDVF, treatment with azumolene led to reduction of cardiac alternans, i.e., calcium and voltage alternans. Unlike conventional anti-arrhythmic agents, reduction of action potential upstroke rise time and preservation of action potential duration following azumolene treatment may reduce the proarrhythmia risk.
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Affiliation(s)
- Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | | | - Ahmed Niri
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Patrick F H Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Muriel Bouly
- Institut de Recherches Internationales Servier (IRIS), Suresnes, France
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
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17
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Increased cytosolic calcium buffering contributes to a cellular arrhythmogenic substrate in iPSC-cardiomyocytes from patients with dilated cardiomyopathy. Basic Res Cardiol 2022; 117:5. [PMID: 35499658 PMCID: PMC9061684 DOI: 10.1007/s00395-022-00912-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 01/31/2023]
Abstract
Dilated cardiomyopathy (DCM) is a major risk factor for heart failure and is associated with the development of life-threatening cardiac arrhythmias. Using a patient-specific induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) model harbouring a mutation in cardiac troponin T (R173W), we aim to examine the cellular basis of arrhythmogenesis in DCM patients with this mutation. iPSC from control (Ctrl) and DCM-TnT-R173W donors from the same family were differentiated into iPSC-CM and analysed through optical action potential (AP) recordings, simultaneous measurement of cytosolic calcium concentration ([Ca2+]i) and membrane currents and separately assayed using field stimulation to detect the threshold for AP- and [Ca2+]i-alternans development. AP duration was unaltered in TnT-R173W iPSC-CM. Nevertheless, TnT-R173W iPSC-CM showed a strikingly low stimulation threshold for AP- and [Ca2+]i-alternans. Myofilaments are known to play a role as intracellular Ca2+ buffers and here we show increased Ca2+ affinity of intracellular buffers in TnT-R173W cells, indicating increased myofilament sensitivity to Ca2+. Similarly, EMD57033, a myofilament Ca2+ sensitiser, replicated the abnormal [Ca2+]i dynamics observed in TnT-R173W samples and lowered the threshold for alternans development. In contrast, application of a Ca2+ desensitiser (blebbistatin) to TnT-R173W iPSC-CM was able to phenotypically rescue Ca2+ dynamics, normalising Ca2+ transient profile and minimising the occurrence of Ca2+ alternans at physiological frequencies. This finding suggests that increased Ca2+ buffering likely plays a major arrhythmogenic role in patients with DCM, specifically in those with mutations in cardiac troponin T. In addition, we propose that modulation of myofilament Ca2+ sensitivity could be an effective anti-arrhythmic target for pharmacological management of this disease.
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18
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Optogenetic manipulation of cardiac electrical dynamics using sub-threshold illumination: dissecting the role of cardiac alternans in terminating rapid rhythms. Basic Res Cardiol 2022; 117:25. [PMID: 35488105 PMCID: PMC9054908 DOI: 10.1007/s00395-022-00933-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/01/2022] [Accepted: 04/18/2022] [Indexed: 02/01/2023]
Abstract
Cardiac action potential (AP) shape and propagation are regulated by several key dynamic factors such as ion channel recovery and intracellular Ca2+ cycling. Experimental methods for manipulating AP electrical dynamics commonly use ion channel inhibitors that lack spatial and temporal specificity. In this work, we propose an approach based on optogenetics to manipulate cardiac electrical activity employing a light-modulated depolarizing current with intensities that are too low to elicit APs (sub-threshold illumination), but are sufficient to fine-tune AP electrical dynamics. We investigated the effects of sub-threshold illumination in isolated cardiomyocytes and whole hearts by using transgenic mice constitutively expressing a light-gated ion channel (channelrhodopsin-2, ChR2). We find that ChR2-mediated depolarizing current prolongs APs and reduces conduction velocity (CV) in a space-selective and reversible manner. Sub-threshold manipulation also affects the dynamics of cardiac electrical activity, increasing the magnitude of cardiac alternans. We used an optical system that uses real-time feedback control to generate re-entrant circuits with user-defined cycle lengths to explore the role of cardiac alternans in spontaneous termination of ventricular tachycardias (VTs). We demonstrate that VT stability significantly decreases during sub-threshold illumination primarily due to an increase in the amplitude of electrical oscillations, which implies that cardiac alternans may be beneficial in the context of self-termination of VT.
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19
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Cooper BL, Gloschat C, Swift LM, Prudencio T, McCullough D, Jaimes R, Posnack NG. KairoSight: Open-Source Software for the Analysis of Cardiac Optical Data Collected From Multiple Species. Front Physiol 2021; 12:752940. [PMID: 34777017 PMCID: PMC8586513 DOI: 10.3389/fphys.2021.752940] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 09/27/2021] [Indexed: 01/09/2023] Open
Abstract
Cardiac optical mapping, also known as optocardiography, employs parameter-sensitive fluorescence dye(s) to image cardiac tissue and resolve the electrical and calcium oscillations that underly cardiac function. This technique is increasingly being used in conjunction with, or even as a replacement for, traditional electrocardiography. Over the last several decades, optical mapping has matured into a “gold standard” for cardiac research applications, yet the analysis of optical signals can be challenging. Despite the refinement of software tools and algorithms, significant programming expertise is often required to analyze large optical data sets, and data analysis can be laborious and time-consuming. To address this challenge, we developed an accessible, open-source software script that is untethered from any subscription-based programming language. The described software, written in python, is aptly named “KairoSight” in reference to the Greek word for “opportune time” (Kairos) and the ability to “see” voltage and calcium signals acquired from cardiac tissue. To demonstrate analysis features and highlight species differences, we employed experimental datasets collected from mammalian hearts (Langendorff-perfused rat, guinea pig, and swine) dyed with RH237 (transmembrane voltage) and Rhod-2, AM (intracellular calcium), as well as human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) dyed with FluoVolt (membrane potential), and Fluo-4, AM (calcium indicator). We also demonstrate cardiac responsiveness to ryanodine (ryanodine receptor modulator) and isoproterenol (beta-adrenergic agonist) and highlight regional differences after an ablation injury. KairoSight can be employed by both basic and clinical scientists to analyze complex cardiac optical mapping datasets without requiring dedicated computer science expertise or proprietary software.
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Affiliation(s)
- Blake L Cooper
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States.,Department of Pharmacology and Physiology, George Washington University, Washington, DC, United States
| | - Chris Gloschat
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States
| | - Luther M Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States
| | - Tomas Prudencio
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States
| | - Rafael Jaimes
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, DC, United States.,Children's National Heart Institute, Children's National Hospital, Washington, DC, United States.,Department of Pharmacology and Physiology, George Washington University, Washington, DC, United States.,Department of Pediatrics, George Washington University, Washington, DC, United States
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20
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Millet J, Aguilar-Sanchez Y, Kornyeyev D, Bazmi M, Fainstein D, Copello JA, Escobar AL. Thermal modulation of epicardial Ca2+ dynamics uncovers molecular mechanisms of Ca2+ alternans. J Gen Physiol 2021; 153:211659. [PMID: 33410862 PMCID: PMC7797898 DOI: 10.1085/jgp.202012568] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 11/02/2020] [Accepted: 11/30/2020] [Indexed: 01/16/2023] Open
Abstract
Ca2+ alternans (Ca-Alts) are alternating beat-to-beat changes in the amplitude of Ca2+ transients that frequently occur during tachycardia, ischemia, or hypothermia that can lead to sudden cardiac death. Ca-Alts appear to result from a variation in the amount of Ca2+ released from the sarcoplasmic reticulum (SR) between two consecutive heartbeats. This variable Ca2+ release has been attributed to the alternation of the action potential duration, delay in the recovery from inactivation of RYR Ca2+ release channel (RYR2), or an incomplete Ca2+ refilling of the SR. In all three cases, the RYR2 mobilizes less Ca2+ from the SR in an alternating manner, thereby generating an alternating profile of the Ca2+ transients. We used a new experimental approach, fluorescence local field optical mapping (FLOM), to record at the epicardial layer of an intact heart with subcellular resolution. In conjunction with a local cold finger, a series of images were recorded within an area where the local cooling induced a temperature gradient. Ca-Alts were larger in colder regions and occurred without changes in action potential duration. Analysis of the change in the enthalpy and Q10 of several kinetic processes defining intracellular Ca2+ dynamics indicated that the effects of temperature change on the relaxation of intracellular Ca2+ transients involved both passive and active mechanisms. The steep temperature dependency of Ca-Alts during tachycardia suggests Ca-Alts are generated by insufficient SERCA-mediated Ca2+ uptake into the SR. We found that Ca-Alts are heavily dependent on intra-SR Ca2+ and can be promoted through partial pharmacologic inhibition of SERCA2a. Finally, the FLOM experimental approach has the potential to help us understand how arrhythmogenesis correlates with the spatial distribution of metabolically impaired myocytes along the myocardium.
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Affiliation(s)
- Jose Millet
- Institute of Information and Communication Technologies, Universitat Politècnica de València and Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Valencia, Spain
| | - Yuriana Aguilar-Sanchez
- Department of Physiology and Biophysics, School of Medicine, Rush University Medical Center, Chicago, IL.,School of Natural Sciences, University of California, Merced, Merced, CA
| | - Dmytro Kornyeyev
- Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
| | - Maedeh Bazmi
- School of Natural Sciences, University of California, Merced, Merced, CA
| | - Diego Fainstein
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Entre Ríos, Argentina.,Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
| | - Julio A Copello
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL
| | - Ariel L Escobar
- Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
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21
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Santos-Miranda A, Costa AD, Joviano-Santos JV, Rhana P, Bruno AS, Rocha P, Cau SB, Vieira LQ, Cruz JS, Roman-Campos D. Inhibition of calcium/calmodulin (Ca 2+ /CaM)-Calcium/calmodulin-dependent protein kinase II (CaMKII) axis reduces in vitro and ex vivo arrhythmias in experimental Chagas disease. FASEB J 2021; 35:e21901. [PMID: 34569665 DOI: 10.1096/fj.202101060r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 11/11/2022]
Abstract
Chagasic cardiomyopathy (CCC) is one of the main causes of heart failure and sudden death in Latin America. To date, there is no available medication to prevent or reverse the onset of cardiac symptoms. CCC occurs in a scenario of disrupted calcium dynamics and enhanced oxidative stress, which combined, may favor the hyper activation of calcium/calmodulin (Ca2+ /CaM)-calcium/calmodulin-dependent protein kinase II (CaMKII) (Ca2+ /CaM-CaMKII) pathway, which is fundamental for heart physiology and it is implicated in other cardiac diseases. Here, we evaluated the association between Ca2+ /CaM-CaMKII in the electro-mechanical (dys)function of the heart in the early stage of chronic experimental Trypanosoma cruzi infection. We observed that in vitro and ex vivo inhibition of Ca2+ /CaM-CaMKII reversed the arrhythmic profile of isolated hearts and isolated left-ventricles cardiomyocytes. The benefits of the limited Ca2+ /CaM-CaMKII activation to cardiomyocytes' electrical properties are partially related to the restoration of Ca2+ dynamics in a damaged cellular environment created after T. cruzi infection. Moreover, Ca2+ /CaM-CaMKII inhibition prevented the onset of arrhythmic contractions on isolated heart preparations of chagasic mice and restored the responsiveness to the increase in the left-ventricle pre-load. Taken together, our data provide the first experimental evidence for the potential of targeting Ca2+ /CaM-CaMKII pathway as a novel therapeutic target to treat CCC.
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Affiliation(s)
| | - Alexandre D Costa
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Paula Rhana
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Alexandre Santos Bruno
- Department of Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Peter Rocha
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Stefany Bruno Cau
- Department of Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Leda Q Vieira
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Jader S Cruz
- Department of Biochemistry and Immunology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Danilo Roman-Campos
- Department of Biophysics, Universidade Federal de São Paulo, São Paulo, Brazil
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22
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Hegyi B, Shimkunas R, Jian Z, Izu LT, Bers DM, Chen-Izu Y. Mechanoelectric coupling and arrhythmogenesis in cardiomyocytes contracting under mechanical afterload in a 3D viscoelastic hydrogel. Proc Natl Acad Sci U S A 2021; 118:e2108484118. [PMID: 34326268 PMCID: PMC8346795 DOI: 10.1073/pnas.2108484118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The heart pumps blood against the mechanical afterload from arterial resistance, and increased afterload may alter cardiac electrophysiology and contribute to life-threatening arrhythmias. However, the cellular and molecular mechanisms underlying mechanoelectric coupling in cardiomyocytes remain unclear. We developed an innovative patch-clamp-in-gel technology to embed cardiomyocytes in a three-dimensional (3D) viscoelastic hydrogel that imposes an afterload during regular myocyte contraction. Here, we investigated how afterload affects action potentials, ionic currents, intracellular Ca2+ transients, and cell contraction of adult rabbit ventricular cardiomyocytes. We found that afterload prolonged action potential duration (APD), increased transient outward K+ current, decreased inward rectifier K+ current, and increased L-type Ca2+ current. Increased Ca2+ entry caused enhanced Ca2+ transients and contractility. Moreover, elevated afterload led to discordant alternans in APD and Ca2+ transient. Ca2+ alternans persisted under action potential clamp, indicating that the alternans was Ca2+ dependent. Furthermore, all these afterload effects were significantly attenuated by inhibiting nitric oxide synthase 1 (NOS1). Taken together, our data reveal a mechano-chemo-electrotransduction (MCET) mechanism that acutely transduces afterload through NOS1-nitric oxide signaling to modulate the action potential, Ca2+ transient, and contractility. The MCET pathway provides a feedback loop in excitation-Ca2+ signaling-contraction coupling, enabling autoregulation of contractility in cardiomyocytes in response to afterload. This MCET mechanism is integral to the individual cardiomyocyte (and thus the heart) to intrinsically enhance its contractility in response to the load against which it has to do work. While this MCET is largely compensatory for physiological load changes, it may also increase susceptibility to arrhythmias under excessive pathological loading.
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Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Rafael Shimkunas
- Department of Pharmacology, University of California, Davis, CA 95616
- Department of Biomedical Engineering, University of California, Davis, CA 95616
| | - Zhong Jian
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Leighton T Izu
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616;
- Department of Biomedical Engineering, University of California, Davis, CA 95616
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA 95616
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23
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Sadredini M, Haugsten Hansen M, Frisk M, Louch WE, Lehnart SE, Sjaastad I, Stokke MK. CaMKII inhibition has dual effects on spontaneous Ca 2+ release and Ca 2+ alternans in ventricular cardiomyocytes from mice with a gain-of-function RyR2 mutation. Am J Physiol Heart Circ Physiol 2021; 321:H446-H460. [PMID: 34270372 DOI: 10.1152/ajpheart.00011.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In conditions with abnormally increased activity of the cardiac ryanodine receptor (RyR2), Ca2+/calmodulin-dependent protein kinase II (CaMKII) can contribute to a further destabilization of RyR2 that results in triggered arrhythmias. Therefore, inhibition of CaMKII in such conditions has been suggested as a strategy to suppress RyR2 activity and arrhythmias. However, suppression of RyR2 activity can lead to the development of arrhythmogenic Ca2+ alternans. The aim of this study was to test whether the suppression of RyR2 activity caused by inhibition of CaMKII increases propensity for Ca2+ alternans. We studied spontaneous Ca2+ release events and Ca2+ alternans in isolated left ventricular cardiomyocytes from mice carrying the gain-of-function RyR2 mutation RyR2-R2474S and from wild-type mice. CaMKII inhibition by KN-93 effectively decreased the frequency of spontaneous Ca2+ release events in RyR2-R2474S cardiomyocytes exposed to the β-adrenoceptor agonist isoprenaline. However, KN-93-treated RyR2-R2474S cardiomyocytes also showed increased propensity for Ca2+ alternans and increased Ca2+ alternans ratio compared with both an inactive analog of KN-93 and with vehicle-treated controls. This increased propensity for Ca2+ alternans was explained by prolongation of Ca2+ release refractoriness. Importantly, the increased propensity for Ca2+ alternans in KN-93-treated RyR2-R2474S cardiomyocytes did not surpass that of wild type. In conclusion, inhibition of CaMKII efficiently reduces spontaneous Ca2+ release but promotes Ca2+ alternans in RyR2-R2474S cardiomyocytes with a gain-of-function RyR2 mutation. The dominant effect in RyR2-R2474S is to reduce spontaneous Ca2+ release, which supports this intervention as a therapeutic strategy in this specific condition. However, future studies on CaMKII inhibition in conditions with increased propensity for Ca2+ alternans should include investigation of both phenomena.NEW & NOTEWORTHY Genetically increased RyR2 activity promotes arrhythmogenic Ca2+ release. Inhibition of CaMKII suppresses RyR2 activity and arrhythmogenic Ca2+ release. Suppression of RyR2 activity prolongs refractoriness of Ca2+ release. Prolonged refractoriness of Ca2+ release leads to arrhythmogenic Ca2+ alternans. CaMKII inhibition promotes Ca2+ alternans by prolonging Ca2+ release refractoriness.
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Affiliation(s)
- Mani Sadredini
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway
| | - Marie Haugsten Hansen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway
| | - Stephan E Lehnart
- Department of Cardiology and Pulmonology, Heart Research Center Göttingen, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Göttingen, Germany
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway
| | - Mathis Korseberg Stokke
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,KG Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway.,Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
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24
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Borile G, Zaglia T, E. Lehnart S, Mongillo M. Multiphoton Imaging of Ca 2+ Instability in Acute Myocardial Slices from a RyR2R2474S Murine Model of Catecholaminergic Polymorphic Ventricular Tachycardia. J Clin Med 2021; 10:jcm10132821. [PMID: 34206855 PMCID: PMC8269190 DOI: 10.3390/jcm10132821] [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: 05/17/2021] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 12/27/2022] Open
Abstract
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is a familial stress-induced arrhythmia syndrome, mostly caused by mutations in Ryanodine receptor 2 (RyR2), the sarcoplasmic reticulum (SR) Ca2+ release channel in cardiomyocytes. Pathogenetic mutations lead to gain of function in the channel, causing arrhythmias by promoting diastolic spontaneous Ca2+ release (SCR) from the SR and delayed afterdepolarizations. While the study of Ca2+ dynamics in single cells from murine CPVT models has increased our understanding of the disease pathogenesis, questions remain on the mechanisms triggering the lethal arrhythmias at tissue level. Here, we combined subcellular analysis of Ca2+ signals in isolated cardiomyocytes and in acute thick ventricular slices of RyR2R2474S knock-in mice, electrically paced at different rates (1–5 Hz), to identify arrhythmogenic Ca2+ dynamics, from the sub- to the multicellular perspective. In both models, RyR2R2474S cardiomyocytes had increased propensity to develop SCR upon adrenergic stimulation, which manifested, in the slices, with Ca2+ alternans and synchronous Ca2+ release events in neighboring cardiomyocytes. Analysis of Ca2+ dynamics in multiple cells in the tissue suggests that SCRs beget SCRs in contiguous cells, overcoming the protective electrotonic myocardial coupling, and potentially generating arrhythmia triggering foci. We suggest that intercellular interactions may underscore arrhythmic propensity in CPVT hearts with ‘leaky’ RyR2.
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Affiliation(s)
- Giulia Borile
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (G.B.); (T.Z.)
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy
| | - Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (G.B.); (T.Z.)
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy
| | - Stephan E. Lehnart
- Heart Research Heart Research Center Göttingen, Cellular Biophysics and Translational Cardi-Ology Section, Department of Cardiology & Pulmonology, University Medical Center Göttingen, 37073 Göttingen, Germany;
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, 37073 Göttingen, Germany
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (G.B.); (T.Z.)
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy
- Correspondence: ; Tel.: +39-049-7923229; Fax: +39-049-7923250
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25
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Inhibition of Ca 2+-dependent protein kinase C rescues high calcium-induced pro-arrhythmogenic cardiac alternans in rabbit hearts. Pflugers Arch 2021; 473:1315-1327. [PMID: 34145500 DOI: 10.1007/s00424-021-02574-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/22/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
Cardiac alternans closely linked to calcium dysregulation is a crucial risk factor for fatal arrhythmia causing especially sudden death. Calcium overload is well-known to activate Ca2+-dependent protein kinase C (PKC); however, the effects of PKC on arrhythmogenic cardiac alternans have not yet been investigated. This study aimed to determine the contributions of PKC activities in cardiac alternans associated with calcium cycling disturbances. In the present study, action potential duration alternans (APD-ALT) induced by high free intracellular calcium ([Ca2+]i) exerted not only in a calcium concentration-dependent manner but also in a frequency-dependent manner. High [Ca2+]i-induced APD-ALT was suppressed by not only BAPTA-AM but also nifedipine. On the other hand, PKC inhibitors BIM and Gö 6976 eliminated high [Ca2+]i-induced APD-ALT, and PKC activator PMA was found to induce APD-ALT at normal [Ca2+]i condition. Furthermore, BIM effectively prevented calcium transient alternans (CaT-ALT) and even CaT disorders caused by calcium overload. Moreover, BIM not only eliminated electrocardiographic T-wave alternans (TWA) caused by calcium dysregulation, but also lowered the incidence of ventricular arrhythmias in isolated hearts. What's more, BIM prevented the expression of PKC α upregulated by calcium overload in high calcium-perfused hearts. We firstly found that pharmacologically inhibiting Ca2+-dependent PKC over-activation suppressed high [Ca2+]i-induced cardiac alternans. This recognition indicates that inhibition of PKC activities may become a therapeutic target for the prevention of pro-arrhythmogenic cardiac alternans associated with calcium dysregulation.
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26
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Tsai YN, Hsiao YW, Lin SF, Chan YH, Hsieh YC, Tang WH, Lee AS, Huang YT, Li HY, Chao TF, Higa S, Wu TJ, Chang SL, Chen SA. Proinflammatory Cytokine Modulates Intracellular Calcium Handling and Enhances Ventricular Arrhythmia Susceptibility. Front Cardiovasc Med 2021; 8:623510. [PMID: 33796569 PMCID: PMC8007768 DOI: 10.3389/fcvm.2021.623510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Background: The mechanism of Interleukin-17 (IL-17) induced ventricular arrhythmia (VA) remains unclear. This study aimed to investigate the effect of intracellular calcium (Cai) handling and VA susceptibility by IL-17. Methods: The electrophysiological properties of isolated perfused rabbit hearts under IL-17 (20 ng/ml, N = 6) and the IL-17 with neutralizer (0.4 μg/ml, N = 6) were evaluated using an optical mapping system. The action potential duration (APD) and Cai transient duration (CaiTD) were examined, and semiquantitative reverse transcriptase-polymerase chain reaction analysis of ion channels was performed. Results: There were longer APD80, CaiTD80 and increased thresholds of APD and CaiTD alternans, the maximum slope of APD restitution and induction of VA threshold in IL-17 group compared with those in IL-17 neutralizer and baseline groups. During ventricular fibrillation, the number of phase singularities and dominant frequency were both significantly greater in IL-17 group than in baseline group. The mRNA expressions of the Na+/Ca2+ exchanger, phospholamban, and ryanodine receptor Ca2+ release channel were upregulated, and the subunit of L-type Ca2+ current and sarcoplasmic reticulum Ca2+-ATPase 2a were significantly reduced in IL-17 group compared to baseline and IL-17 neutralizer group. Conclusions: IL-17 enhanced CaiTD and APD alternans through disturbances in calcium handling, which may increase VA susceptibility.
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Affiliation(s)
- Yung-Nan Tsai
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Ya-Wen Hsiao
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shien-Fong Lin
- Institute of Biomedical Engineering, National Chiao-Tung University, Hsin-Chu, Taiwan
| | - Yi-Hsin Chan
- Division of Cardiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yu-Cheng Hsieh
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Internal Medicine, Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Wei-Hua Tang
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, National Yang-Ming University Hospital, Yilan, Taiwan
| | - An-Sheng Lee
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
| | - Yu-Ting Huang
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Hsing-Yuan Li
- Division of Cardiology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Tze-Fan Chao
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Urasoe, Japan
| | - Tsu-Juey Wu
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Internal Medicine, Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Shih-Lin Chang
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Ann Chen
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Internal Medicine, Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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27
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Zhang JZ, Belbachir N, Zhang T, Liu Y, Shrestha R, Wu JC. Effects of Cryopreservation on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Assessing Drug Safety Response Profiles. Stem Cell Reports 2021; 16:168-181. [PMID: 33338435 PMCID: PMC7897580 DOI: 10.1016/j.stemcr.2020.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 12/19/2022] Open
Abstract
Burgeoning applications of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in disease modeling, regenerative medicine, and drug screening have broadened the usage of hiPSC-CMs and entailed their long-term storage. Cryopreservation is the most common approach to store hiPSC-CMs. However, the effects of cryopreservation and recovery on hiPSC-CMs remain poorly understood. Here, we characterized the transcriptome, electro-mechanical function, and drug response of fresh hiPSC-CMs without cryopreservation and recovered hiPSC-CMs from cryopreservation. We found that recovered hiPSC-CMs showed upregulation of cell cycle genes, similar or reduced contractility, Ca2+ transients, and field potential duration. When subjected to treatment of drugs that affect electrophysiological properties, recovered hiPSC-CMs showed an altered drug response and enhanced propensity for drug-induced cardiac arrhythmic events. In conclusion, fresh and recovered hiPSC-CMs do not always show comparable molecular and physiological properties. When cryopreserved hiPSC-CMs are used for assessing drug-induced cardiac liabilities, the altered drug sensitivity needs to be considered.
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Affiliation(s)
- Joe Z Zhang
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Nadjet Belbachir
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Tiejun Zhang
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Yu Liu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Rajani Shrestha
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Joseph C Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA; Molecular Imaging Program at Stanford, Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.
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28
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Blatter LA, Kanaporis G, Martinez-Hernandez E, Oropeza-Almazan Y, Banach K. Excitation-contraction coupling and calcium release in atrial muscle. Pflugers Arch 2021; 473:317-329. [PMID: 33398498 DOI: 10.1007/s00424-020-02506-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/03/2020] [Accepted: 12/16/2020] [Indexed: 01/02/2023]
Abstract
In cardiac muscle, the process of excitation-contraction coupling (ECC) describes the chain of events that links action potential induced myocyte membrane depolarization, surface membrane ion channel activation, triggering of Ca2+ induced Ca2+ release from the sarcoplasmic reticulum (SR) Ca2+ store to activation of the contractile machinery that is ultimately responsible for the pump function of the heart. Here we review similarities and differences of structural and functional attributes of ECC between atrial and ventricular tissue. We explore a novel "fire-diffuse-uptake-fire" paradigm of atrial ECC and Ca2+ release that assigns a novel role to the SR SERCA pump and involves a concerted "tandem" activation of the ryanodine receptor Ca2+ release channel by cytosolic and luminal Ca2+. We discuss the contribution of the inositol 1,4,5-trisphosphate (IP3) receptor Ca2+ release channel as an auxiliary pathway to Ca2+ signaling, and we review IP3 receptor-induced Ca2+ release involvement in beat-to-beat ECC, nuclear Ca2+ signaling, and arrhythmogenesis. Finally, we explore the topic of electromechanical and Ca2+ alternans and its ramifications for atrial arrhythmia.
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Affiliation(s)
- L A Blatter
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA.
| | - G Kanaporis
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - E Martinez-Hernandez
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - Y Oropeza-Almazan
- Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA
| | - K Banach
- Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL, 60612, USA
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29
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Du B, Chakraborty P, Azam MA, Massé S, Lai PFH, Niri A, Si D, Thavendiranathan P, Abdel-Qadir H, Billia F, Nanthakumar K. Acute Effects of Ibrutinib on Ventricular Arrhythmia in Spontaneously Hypertensive Rats. JACC: CARDIOONCOLOGY 2020; 2:614-629. [PMID: 34396273 PMCID: PMC8352013 DOI: 10.1016/j.jaccao.2020.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/26/2020] [Accepted: 08/30/2020] [Indexed: 12/19/2022]
Abstract
Background The Bruton's Tyrosine Kinase Inhibitor ibrutinib is associated with ventricular arrhythmia (VA) and sudden death. However, the pro-arrhythmic electrophysiological dysregulation that results from ibrutinib with age and cardiovascular disease is unknown. Objectives This study sought to investigate the acute effects of ibrutinib on left ventricular (LV) VA vulnerability, cytosolic calcium dynamics, and membrane electrophysiology in old and young spontaneous hypertensive rats (SHRs). Methods Langendorff-perfused hearts of young (10 to 14 weeks) and old (10 to 14 months) SHRs were treated with ibrutinib (0.1 μmol/l) or vehicle for 30 min. Simultaneously, LV epicardial action potential and cytosolic calcium transients were optically mapped following an incremental pacing protocol. Calcium and action potential dynamics parameters were analyzed. VA vulnerability was assessed by electrically inducing ventricular fibrillations (VFs) in each heart. Western blot analysis was performed on LV tissues. Results Ibrutinib treatment resulted in higher vulnerability to VF in old SHR hearts (27.5 ± 7.5% vs. 5.7 ± 3.7%; p = 0.026) but not in young SHR hearts (8.0 ± 4.9% vs. 0%; p = 0.193). In old SHR hearts, following ibrutinib treatment, action potential duration (APD) alternans (p = 0.008) and APD alternans spatial discordance (p = 0.027) were more prominent. Moreover, calcium transient duration 50 was longer (p = 0.032), calcium amplitude alternans ratio was significantly lower (p = 0.001), and time-to-peak of calcium amplitude was shorter (p = 0.037). In young SHR hearts, there were no differences in calcium and APD dynamics. Conclusions Ibrutinib-induced VA is associated with old age in SHR. Acute dysregulation of calcium and repolarization dynamics play important roles in ibrutinib-induced VF.
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Key Words
- AF, atrial fibrillation
- AMPK, adenosine monophosphate-activated protein kinase
- APD, action potential duration
- CA, calcium alternans
- CaMKII, Ca2+/calmodulin-dependent protein kinase II
- CaT, calcium transient
- CaTD, calcium transient duration
- DAD, delayed afterdepolarization
- EAD, early afterpolarization
- LV, left ventricular
- PI3K, phosphoinositide 3-kinase
- PLB, phospholamban
- SCaE, spontaneous calcium elevation
- SHR, spontaneous hypertension rat
- SR, sarcoplasmic reticulum
- VA, ventricular arrhythmia
- VF, ventricular fibrillation
- action potential duration alternans
- calcium handling
- ibrutinib
- spatial discordant repolarization
- ventricular arrythmias
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Affiliation(s)
- Beibei Du
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada.,Department of Cardiology, The Third Hospital of Jilin University, Jilin Provincial Cardiovascular Research Institute, Changchun, China
| | - Praloy Chakraborty
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Patrick F H Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Ahmed Niri
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Daoyuan Si
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada.,Department of Cardiology, The Third Hospital of Jilin University, Jilin Provincial Cardiovascular Research Institute, Changchun, China
| | - Paaladinesh Thavendiranathan
- Ted Rogers Program in Cardiotoxicity Prevention, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Husam Abdel-Qadir
- Ted Rogers Program in Cardiotoxicity Prevention, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Filio Billia
- Ted Rogers Program in Cardiotoxicity Prevention, Peter Munk Cardiac Center, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
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30
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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31
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Nearing BD, Anand IS, Libbus I, Dicarlo LA, Kenknight BH, Verrier RL. Vagus Nerve Stimulation Provides Multiyear Improvements in Autonomic Function and Cardiac Electrical Stability in the ANTHEM-HF Study. J Card Fail 2020; 27:208-216. [PMID: 33049374 DOI: 10.1016/j.cardfail.2020.10.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Patients with heart failure with reduced left ventricular ejection fraction (LVEF) (HFrEF) experience long-term deterioration of autonomic function and cardiac electrical stability linked to increased mortality risk. The Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure (ANTHEM-HF) trial reported improved heart rate variability (HRV) and heart rate turbulence (HRT) and reduced T-wave alternans (TWA) after 12 months of vagus nerve stimulation (VNS). We investigated whether the benefits of chronic VNS persist in the long term. METHODS AND RESULTS Effects of chronic VNS on heart rate, HRV, HRT, TWA, R-wave and T-wave heterogeneity (RWH, TWH), and nonsustained ventricular tachycardia (NSVT) incidence were evaluated in all ANTHEM-HF patients with ambulatory ECG data at 24 and 36 months (n = 25). Autonomic markers improved significantly at 24 and 36 months compared to baseline [heart rate, square root of the mean squared differences of successive normal-to-normal intervals (rMSSD), standard deviation of the normal-to-normal intervals (SDNN), HF-HRV, HRT slope, P < 0.05]. Peak TWA levels remained reduced at 24 and 36 months (P < 0.0001). Reductions in RWH and TWH at 6 and 12 months persisted at 24 and 36 months (P < 0.01). NSVT decreased at 12, 24, and 36 months (P < 0.025). No sudden cardiac deaths, ventricular fibrillation, or sustained ventricular tachycardia occurred. CONCLUSION In symptomatic patients with HFrEF, chronic VNS appears to confer wide-ranging, persistent improvements in autonomic tone (HRV), baroreceptor sensitivity (HRT), and cardiac electrical stability (TWA, RWH, TWH).
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Affiliation(s)
- Bruce D Nearing
- Beth Israel Deaconess Medical Center, Division of Cardiovascular Medicine, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts
| | | | | | | | | | - Richard L Verrier
- Beth Israel Deaconess Medical Center, Division of Cardiovascular Medicine, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts.
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32
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Orini M, Yanni J, Taggart P, Hanson B, Hayward M, Smith A, Zhang H, Colman M, Jones G, Jie X, Dobrzynski H, Boyett MR, Lambiase PD. Mechanistic insights from targeted molecular profiling of repolarization alternans in the intact human heart. Europace 2020; 21:981-989. [PMID: 30753421 PMCID: PMC6545501 DOI: 10.1093/europace/euz007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/17/2018] [Accepted: 01/21/2019] [Indexed: 02/05/2023] Open
Abstract
AIMS Action potential duration (APD) alternans is an established precursor or arrhythmia and sudden cardiac death. Important differences in fundamental electrophysiological properties relevant to arrhythmia exist between experimental models and the diseased in vivo human heart. To investigate mechanisms of APD alternans using a novel approach combining intact heart and cellular cardiac electrophysiology in human in vivo. METHODS AND RESULTS We developed a novel approach combining intact heart electrophysiological mapping during cardiac surgery with rapid on-site data analysis to guide myocardial biopsies for laboratory analysis, thereby linking repolarization dynamics observed at the organ level with underlying ion channel expression. Alternans-susceptible and alternans-resistant regions were identified by an incremental pacing protocol. Biopsies from these sites (n = 13) demonstrated greater RNA expression in Calsequestrin (CSQN) and Ryanodine (RyR) and ion channels underlying IK1 and Ito at alternans-susceptible sites. Electrical restitution properties (n = 7) showed no difference between alternans-susceptible and resistant sites, whereas spatial gradients of repolarization were greater in alternans-susceptible than in alternans-resistant sites (P = 0.001). The degree of histological fibrosis between alternans-susceptible and resistant sites was equivalent. Mathematical modelling of these changes indicated that both CSQN and RyR up-regulation are key determinants of APD alternans. CONCLUSION Combined intact heart and cellular electrophysiology show that regions of myocardium in the in vivo human heart exhibiting APD alternans are associated with greater expression of CSQN and RyR and show no difference in restitution properties compared to non-alternans regions. In silico modelling identifies up-regulation and interaction of CSQN with RyR as a major mechanism underlying APD alternans.
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Affiliation(s)
- Michele Orini
- Institute of Cardiovascular Science, University College London, London, UK.,Department of Electrophysiology, Barts Heart Centre at St Bartholomew's Hospital, London, UK
| | - Joseph Yanni
- Division of Cardiovascular Science, University of Manchester, Manchester, UK
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, UK
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, UK
| | - Martin Hayward
- Department of Cardiothoracic Surgery, The Heart Hospital, University College London Hospitals, London, UK
| | - Andrew Smith
- Department of Electrophysiology, Barts Heart Centre at St Bartholomew's Hospital, London, UK
| | - Henggui Zhang
- Division of Cardiovascular Science, University of Manchester, Manchester, UK.,School of Physics and Astronomy, University of Manchester, Manchester, UK
| | | | - Gareth Jones
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - Xiao Jie
- Institute of Cardiovascular Science, University College London, London, UK
| | - Halina Dobrzynski
- Division of Cardiovascular Science, University of Manchester, Manchester, UK
| | - Mark R Boyett
- Division of Cardiovascular Science, University of Manchester, Manchester, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, UK.,Department of Electrophysiology, Barts Heart Centre at St Bartholomew's Hospital, London, UK
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Njegic A, Wilson C, Cartwright EJ. Targeting Ca 2 + Handling Proteins for the Treatment of Heart Failure and Arrhythmias. Front Physiol 2020; 11:1068. [PMID: 33013458 PMCID: PMC7498719 DOI: 10.3389/fphys.2020.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022] Open
Abstract
Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca2+) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca2+ is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca2+ cycling and signaling play a vital role in maintaining Ca2+ homeostasis. Changes to the expression levels and function of Ca2+-channels, pumps and associated intracellular handling proteins contribute to altered Ca2+ homeostasis in CVD. The remodeling of Ca2+-handling proteins therefore results in impaired Ca2+ cycling, Ca2+ leak from the sarcoplasmic reticulum and reduced Ca2+ clearance, all of which contributes to increased intracellular Ca2+. Currently, approved treatments for targeting Ca2+ handling dysfunction in CVD are focused on Ca2+ channel blockers. However, whilst Ca2+ channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca2+ homeostasis, this review will address the molecular changes to proteins associated with both Ca2+-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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Affiliation(s)
- Alexandra Njegic
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom
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Oropeza-Almazán Y, Blatter LA. Mitochondrial calcium uniporter complex activation protects against calcium alternans in atrial myocytes. Am J Physiol Heart Circ Physiol 2020; 319:H873-H881. [PMID: 32857593 DOI: 10.1152/ajpheart.00375.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cardiac alternans, defined as beat-to-beat alternations in action potential duration, cytosolic Ca transient (CaT) amplitude, and cardiac contraction is associated with atrial fibrillation (AF) and sudden cardiac death. At the cellular level, cardiac alternans is linked to abnormal intracellular calcium handling during excitation-contraction coupling. We investigated how pharmacological activation or inhibition of cytosolic Ca sequestration via mitochondrial Ca uptake and mitochondrial Ca retention affects the occurrence of pacing-induced CaT alternans in isolated rabbit atrial myocytes. Cytosolic CaTs were recorded using Fluo-4 fluorescence microscopy. Alternans was quantified as the alternans ratio (AR = 1 - CaTsmall/CaTlarge, where CaTsmall and CaTlarge are the amplitudes of the small and large CaTs of a pair of alternating CaTs). Inhibition of mitochondrial Ca sequestration via mitochondrial Ca uniporter complex (MCUC) with Ru360 enhanced the severity of CaT alternans (AR increase) and lowered the pacing frequency threshold for alternans. In contrast, stimulation of MCUC mediated mitochondrial Ca uptake with spermine-rescued alternans (AR decrease) and increased the alternans pacing threshold. Direct measurement of mitochondrial [Ca] in membrane permeabilized myocytes with Fluo-4 loaded mitochondria revealed that spermine enhanced and accelerated mitochondrial Ca uptake. Stimulation of mitochondrial Ca retention by preventing mitochondrial Ca efflux through the mitochondrial permeability transition pore with cyclosporin A also protected from alternans and increased the alternans pacing threshold. Pharmacological manipulation of MCUC activity did not affect sarcoplasmic reticulum Ca load. Our results suggest that activation of Ca sequestration by mitochondria protects from CaT alternans and could be a potential therapeutic target for cardiac alternans and AF prevention.NEW & NOTEWORTHY This study provides conclusive evidence that mitochondrial Ca uptake and retention protects from Ca alternans, whereas uptake inhibition enhances Ca alternans. The data suggest pharmacological mitochondrial Ca cycling modulation as a potential therapeutic strategy for alternans-related cardiac arrhythmia prevention.
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Affiliation(s)
| | - Lothar A Blatter
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois
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35
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Fakuade FE, Steckmeister V, Seibertz F, Gronwald J, Kestel S, Menzel J, Pronto JRD, Taha K, Haghighi F, Kensah G, Pearman CM, Wiedmann F, Teske AJ, Schmidt C, Dibb KM, El-Essawi A, Danner BC, Baraki H, Schwappach B, Kutschka I, Mason FE, Voigt N. Altered atrial cytosolic calcium handling contributes to the development of postoperative atrial fibrillation. Cardiovasc Res 2020; 117:1790-1801. [PMID: 32520995 PMCID: PMC8208741 DOI: 10.1093/cvr/cvaa162] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/04/2020] [Accepted: 06/04/2020] [Indexed: 01/14/2023] Open
Abstract
Aims Atrial fibrillation (AF) is a commonly occurring arrhythmia after cardiac surgery (postoperative AF, poAF) and is associated with poorer outcomes. Considering that reduced atrial contractile function is a predictor of poAF and that Ca2+ plays an important role in both excitation–contraction coupling and atrial arrhythmogenesis, this study aims to test whether alterations of intracellular Ca2+ handling contribute to impaired atrial contractility and to the arrhythmogenic substrate predisposing patients to poAF. Methods and results Right atrial appendages were obtained from patients in sinus rhythm undergoing open-heart surgery. Cardiomyocytes were investigated by simultaneous measurement of [Ca2+]i and action potentials (APs, patch-clamp). Patients were followed-up for 6 days to identify those with and without poAF. Speckle-tracking analysis of preoperative echocardiography revealed reduced left atrial contraction strain in poAF patients. At the time of surgery, cellular Ca2+ transients (CaTs) and the sarcoplasmic reticulum (SR) Ca2+ content were smaller in the poAF group. CaT decay was slower in poAF, but the decay of caffeine-induced Ca2+ transients was unaltered, suggesting preserved sodium-calcium exchanger function. In agreement, western blots revealed reduced SERCA2a expression in poAF patients but unaltered phospholamban expression/phosphorylation. Computational modelling indicated that reduced SERCA activity promotes occurrence of CaT and AP alternans. Indeed, alternans of CaT and AP occurred more often and at lower stimulation frequencies in atrial myocytes from poAF patients. Resting membrane potential and AP duration were comparable between both groups at various pacing frequencies (0.25–8 Hz). Conclusions Biochemical, functional, and modelling data implicate reduced SERCA-mediated Ca2+ reuptake into the SR as a major contributor to impaired preoperative atrial contractile function and to the pre-existing arrhythmogenic substrate in patients developing poAF.
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Affiliation(s)
- Funsho E Fakuade
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Vanessa Steckmeister
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Fitzwilliam Seibertz
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Judith Gronwald
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Stefanie Kestel
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Julia Menzel
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Molecular Biology, University Medical Centre, Humboldtallee 23, 37075 Göttingen, Germany
| | - Julius Ryan D Pronto
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Karim Taha
- Department of Cardiology, University Medical Centre, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands.,Netherlands Heart Institute, Holland Heart House, Moreelsepark 1, 3511 EP Utrecht, The Netherlands
| | - Fereshteh Haghighi
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - George Kensah
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Charles M Pearman
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Felix Wiedmann
- Department of Cardiology, University Medical Center Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany
| | - Arco J Teske
- Department of Cardiology, University Medical Centre, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands
| | - Constanze Schmidt
- Department of Cardiology, University Medical Center Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Aschraf El-Essawi
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, Klinikum Braunschweig, Braunschweig, Germany
| | - Bernhard C Danner
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Hassina Baraki
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Blanche Schwappach
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Molecular Biology, University Medical Centre, Humboldtallee 23, 37075 Göttingen, Germany
| | - Ingo Kutschka
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Fleur E Mason
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
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Lan BL, Liew YW, Toda M, Kamsani SH. Flickering of cardiac state before the onset and termination of atrial fibrillation. CHAOS (WOODBURY, N.Y.) 2020; 30:053137. [PMID: 32491883 DOI: 10.1063/1.5130524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Complex dynamical systems can shift abruptly from a stable state to an alternative stable state at a tipping point. Before the critical transition, the system either slows down in its recovery rate or flickers between the basins of attraction of the alternative stable states. Whether the heart critically slows down or flickers before it transitions into and out of paroxysmal atrial fibrillation (PAF) is still an open question. To address this issue, we propose a novel definition of cardiac states based on beat-to-beat (RR) interval fluctuations derived from electrocardiogram data. Our results show the cardiac state flickers before PAF onset and termination. Prior to onset, flickering is due to a "tug-of-war" between the sinus node (the natural pacemaker) and atrial ectopic focus/foci (abnormal pacemakers), or the pacing by the latter interspersed among the pacing by the former. It may also be due to an abnormal autonomic modulation of the sinus node. This abnormal modulation may be the sole cause of flickering prior to termination since atrial ectopic beats are absent. Flickering of the cardiac state could potentially be used as part of an early warning or screening system for PAF and guide the development of new methods to prevent or terminate PAF. The method we have developed to define system states and use them to detect flickering can be adapted to study critical transition in other complex systems.
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Affiliation(s)
- Boon Leong Lan
- Electrical and Computer Systems Engineering & Advanced Engineering Platform, School of Engineering, Monash University, 47500 Bandar Sunway, Malaysia
| | - Yew Wai Liew
- Electrical and Computer Systems Engineering & Advanced Engineering Platform, School of Engineering, Monash University, 47500 Bandar Sunway, Malaysia
| | - Mikito Toda
- Laboratory of Non-equilibrium Dynamics, Research Group of Physics, Faculty Division of Natural Sciences, Nara Women's University, Nara 630-8506, Japan
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Linking cellular energy state to atrial fibrillation pathogenesis: Potential role of adenosine monophosphate-activated protein kinase. Heart Rhythm 2020; 17:1398-1404. [PMID: 32268208 DOI: 10.1016/j.hrthm.2020.03.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 03/28/2020] [Indexed: 01/01/2023]
Abstract
Adenosine monophosphate-activated protein kinase (AMPK) is the cellular stress-sensing molecule. Apart from maintaining cellular energy balance, AMPK controls expression and regulation of ion channels and ion transporters, including cytosolic Ca2+ handling proteins. Emerging evidence suggests that metabolic impairment plays a crucial role in the pathogenesis of atrial fibrillation. AMPK activation is thought to be protective by preventing metabolic stress, favorably modulating membrane electrophysiology including cytosolic Ca2+ dynamics; preventing cellular growth; and hypertrophic remodeling. This review considers current concepts and evidence from clinical and experimental studies regarding the role of AMPK in atrial fibrillation.
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38
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Pang TD, Nearing BD, Krishnamurthy KB, Olin B, Schachter SC, Verrier RL. Cardiac electrical instability in newly diagnosed/chronic epilepsy tracked by Holter and ECG patch. Neurology 2020; 93:450-458. [PMID: 31477610 DOI: 10.1212/wnl.0000000000008077] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/05/2019] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE We hypothesized that cardiac electrical instability and abnormal autonomic tone result from cumulative cardiac injury sustained in recurrent seizures. We tested this hypothesis by comparing T-wave alternans (TWA) and heart rate variability (HRV), both established markers of sudden cardiac death (SCD) risk, in patients with chronic as compared to newly diagnosed epilepsy. METHODS In this prospective, observational cohort study, patients (newly diagnosed epilepsy, n = 6, age 41.8 ± 6.8 years; chronic epilepsy, n = 6, age 40.2 ± 5.6 years [p = 0.85]) were monitored either with Holter recorder alone or simultaneously with 14-day Zio XT extended continuous ECG patch monitor. TWA was assessed by Food and Drug Administration-cleared Modified Moving Average analysis; HRV was calculated by rMSSD. RESULTS TWA levels in chronic epilepsy were significantly higher than in newly diagnosed epilepsy (62 ± 5.4 vs 35 ± 1.3 μV, p < 0.002); the latter did not differ from healthy control adults. In all patients with chronic epilepsy, TWA exceeded the established ≥47-μV TWA cutpoint and rMSSD HRV was inversely related to TWA levels. Patients with chronic epilepsy exhibited elevated TWA levels equivalently on Holter and ECG patch recordings (p = 0.38) with a high correlation (r 2 = 0.99, p < 0.01) across 24 hours. CONCLUSION Based on the limited number of patients studied, it appears that chronic epilepsy, the common use of sodium channel antagonists, or other factors are associated with higher TWA levels and simultaneously with lower rMSSD HRV, which is suggestive of autonomic dysfunction or higher sympathetic tone. The ECG patch monitor used has equivalent accuracy to Holter monitoring for TWA and HRV and permits longer-term ECG sampling.
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Affiliation(s)
- Trudy D Pang
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK
| | - Bruce D Nearing
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK
| | - Kaarkuzhali Babu Krishnamurthy
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK
| | - Bryan Olin
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK
| | - Steven C Schachter
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK
| | - Richard L Verrier
- From Beth Israel Deaconess Medical Center (T.D.P., B.D.N., K.B.K., S.C.S., R.L.V.), Harvard Medical School, Boston, MA; and LivaNova PLC (B.O.), London, UK.
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Federico M, Valverde CA, Mattiazzi A, Palomeque J. Unbalance Between Sarcoplasmic Reticulum Ca 2 + Uptake and Release: A First Step Toward Ca 2 + Triggered Arrhythmias and Cardiac Damage. Front Physiol 2020; 10:1630. [PMID: 32038301 PMCID: PMC6989610 DOI: 10.3389/fphys.2019.01630] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 12/24/2019] [Indexed: 12/19/2022] Open
Abstract
The present review focusses on the regulation and interplay of cardiac SR Ca2+ handling proteins involved in SR Ca2+ uptake and release, i.e., SERCa2/PLN and RyR2. Both RyR2 and SERCA2a/PLN are highly regulated by post-translational modifications and/or different partners' proteins. These control mechanisms guarantee a precise equilibrium between SR Ca2+ reuptake and release. The review then discusses how disruption of this balance alters SR Ca2+ handling and may constitute a first step toward cardiac damage and malignant arrhythmias. In the last part of the review, this concept is exemplified in different cardiac diseases, like prediabetic and diabetic cardiomyopathy, digitalis intoxication and ischemia-reperfusion injury.
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Affiliation(s)
- Marilén Federico
- Centro de Investigaciones Cardiovasculares "Dr. Horacio E. Cingolani", CCT-La Plata/CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Carlos A Valverde
- Centro de Investigaciones Cardiovasculares "Dr. Horacio E. Cingolani", CCT-La Plata/CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Alicia Mattiazzi
- Centro de Investigaciones Cardiovasculares "Dr. Horacio E. Cingolani", CCT-La Plata/CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Julieta Palomeque
- Centro de Investigaciones Cardiovasculares "Dr. Horacio E. Cingolani", CCT-La Plata/CONICET, Facultad de Cs. Médicas, Universidad Nacional de La Plata, La Plata, Argentina.,Centro de Altos Estudios en Ciencias Humanas y de la Salud, Universidad Abierta Interamericana, Buenos Aires, Argentina
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40
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Resiniferatoxin reduces ventricular arrhythmias in heart failure via selectively blunting cardiac sympathetic afferent projection into spinal cord in rats. Eur J Pharmacol 2020; 867:172836. [DOI: 10.1016/j.ejphar.2019.172836] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 11/25/2019] [Accepted: 11/29/2019] [Indexed: 12/13/2022]
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Nánási PP, Szabó Z, Kistamás K, Horváth B, Virág L, Jost N, Bányász T, Almássy J, Varró A. Implication of frequency-dependent protocols in antiarrhythmic and proarrhythmic drug testing. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 157:76-83. [PMID: 31726065 DOI: 10.1016/j.pbiomolbio.2019.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 01/20/2023]
Abstract
It has long been known that the electrophysiological effects of many cardioactive drugs strongly depend on the rate dependent frequency. This was recognized first for class I antiarrhythmic agents: their Vmax suppressive effect was attenuated at long cycle lengths. Later many Ca2+ channel blockers were also found to follow such kinetics. The explanation was provided by the modulated and the guarded receptor theories. Regarding the duration of cardiac action potentials (APD) an opposite frequency-dependence was observed, i.e. the drug-induced changes in APD were proportional with the cycle length of stimulation, therefore it was referred as "reverse rate-dependency". The beat-to-beat, or short term variability of APD (SV) has been recognized as an important proarrhythmic mechanism, its magnitude can be used as an arrhythmia predictor. SV is modulated by several cardioactive agents, however, these drugs modify also APD itself. In order to clear the drug-specific effects on SV from the concomitant unspecific APD-change related ones, the term of "relative variability" was introduced. Relative variability is increased by ion channel blockers that decrease the negative feedback control of APD (i.e. blockers of ICa, IKr and IKs) and also by elevation of cytosolic Ca2+. Cardiac arrhythmias are also often categorized according to the characteristic heart rate (tachy- and bradyarrhythmias). Tachycardia is proarrhythmic primarily due to the concomitant Ca2+ overload causing delayed afterdepolarizations. Early afterdepolarizations (EADs) are complications of the bradycardic heart. What is common in the reverse rate-dependent nature of drug action on APD, increased SV and EAD incidence associated with bradycardia.
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Affiliation(s)
- Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Zoltán Szabó
- Department of Emergency Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary; MTA-SZTE Research Group for Cardiovascular Pharmacology, Szeged, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary; MTA-SZTE Research Group for Cardiovascular Pharmacology, Szeged, Hungary.
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Zaglia T, Di Bona A, Mongillo M. A Light Wand to Untangle the Myocardial Cell Network. Methods Protoc 2019; 2:E34. [PMID: 31164614 PMCID: PMC6632158 DOI: 10.3390/mps2020034] [Citation(s) in RCA: 5] [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: 03/21/2019] [Revised: 04/24/2019] [Accepted: 04/28/2019] [Indexed: 12/30/2022] Open
Abstract
The discovery of optogenetics has revolutionized research in neuroscience by providing the tools for noninvasive, cell-type selective modulation of membrane potential and cellular function in vitro and in vivo. Rhodopsin-based optogenetics has later been introduced in experimental cardiology studies and used as a tool to photoactivate cardiac contractions or to identify the sites, timing, and location most effective for defibrillating impulses to interrupt cardiac arrhythmias. The exploitation of cell-selectivity of optogenetics, and the generation of model organisms with myocardial cell type targeted expression of opsins has started to yield novel and sometimes unexpected notions on myocardial biology. This review summarizes the main results, the different uses, and the prospective developments of cardiac optogenetics.
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Affiliation(s)
- Tania Zaglia
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, via Giustiniani 2, 35128 Padova, Italy.
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35122 Padova, Italy.
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy.
| | - Anna Di Bona
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, via Giustiniani 2, 35128 Padova, Italy.
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy.
| | - Marco Mongillo
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, via Giustiniani 2, 35128 Padova, Italy.
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35122 Padova, Italy.
- CNR Institute of Neuroscience, Viale G. Colombo 3, 35121 Padova, Italy.
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O'Shea C, Holmes AP, Yu TY, Winter J, Wells SP, Correia J, Boukens BJ, De Groot JR, Chu GS, Li X, Ng GA, Kirchhof P, Fabritz L, Rajpoot K, Pavlovic D. ElectroMap: High-throughput open-source software for analysis and mapping of cardiac electrophysiology. Sci Rep 2019; 9:1389. [PMID: 30718782 PMCID: PMC6362081 DOI: 10.1038/s41598-018-38263-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/21/2018] [Indexed: 02/04/2023] Open
Abstract
The ability to record and analyse electrical behaviour across the heart using optical and electrode mapping has revolutionised cardiac research. However, wider uptake of these technologies is constrained by the lack of multi-functional and robustly characterised analysis and mapping software. We present ElectroMap, an adaptable, high-throughput, open-source software for processing, analysis and mapping of complex electrophysiology datasets from diverse experimental models and acquisition modalities. Key innovation is development of standalone module for quantification of conduction velocity, employing multiple methodologies, currently not widely available to researchers. ElectroMap has also been designed to support multiple methodologies for accurate calculation of activation, repolarisation, arrhythmia detection, calcium handling and beat-to-beat heterogeneity. ElectroMap implements automated signal segmentation, ensemble averaging and integrates optogenetic approaches. Here we employ ElectroMap for analysis, mapping and detection of pro-arrhythmic phenomena in silico, in cellulo, animal model and in vivo patient datasets. We anticipate that ElectroMap will accelerate innovative cardiac research and enhance the uptake, application and interpretation of mapping technologies leading to novel approaches for arrhythmia prevention.
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Affiliation(s)
- Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- EPSRC Centre for Doctoral Training in Physical Sciences for Health, School of Chemistry, University of Birmingham, Birmingham, UK
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Ting Y Yu
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - James Winter
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Simon P Wells
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Physiology, University of Melbourne, Melbourne, Australia
| | - Joao Correia
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Bastiaan J Boukens
- Amsterdam UMC, University of Amsterdam, Department of Anatomy and Physiology, Amsterdam, The Netherlands
| | - Joris R De Groot
- Amsterdam UMC, University of Amsterdam, Heart Center, Department of Cardiology, Amsterdam, The Netherlands
| | - Gavin S Chu
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- NIHR Leicester Biomedical Research Centre, Glenfield Hospital, Leicester, UK
| | - Xin Li
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - G Andre Ng
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- NIHR Leicester Biomedical Research Centre, Glenfield Hospital, Leicester, UK
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, UHB NHS Trust, Birmingham, UK
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, UHB NHS Trust, Birmingham, UK
| | - Kashif Rajpoot
- School of Computer Science, University of Birmingham, Birmingham, UK.
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.
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Romero L, Alvarez-Lacalle E, Shiferaw Y. Stochastic coupled map model of subcellular calcium cycling in cardiac cells. CHAOS (WOODBURY, N.Y.) 2019; 29:023125. [PMID: 30823735 PMCID: PMC7043839 DOI: 10.1063/1.5063462] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In this study, we analyze a nonlinear map model of intracellular calcium (Ca) and voltage in cardiac cells. In this model, Ca release from the sarcoplasmic reticulum (SR) occurs at spatially distributed dyadic junctions that are diffusively coupled. At these junctions, release occurs with a probability that depends on key variables such as the SR load and the diastolic interval. Using this model, we explore how nonlinearity and stochasticity determine the spatial distribution of Ca release events within a cardiac cell. In particular, we identify a novel synchronization transition, which occurs at rapid pacing rates, in which the global Ca transient transitions from a period 2 response to a period 1 response. In the global period 2 response dyadic junctions fire in unison, on average, on alternate beats, while in the period 1 regime, Ca release at individual dyads is highly irregular. A close examination of the spatial distribution of Ca reveals that in the period 1 regime, the system coarsens into spatially out-of-phase regions with a length scale much smaller than the system size, but larger than the spacing between dyads. We have also explored in detail the coupling to membrane voltage. We study first the case of positive coupling, where a large Ca transient promotes a long action potential duration (APD). Here, the coupling to voltage synchronizes Ca release so that the system exhibits a robust period 2 response that is independent of initial conditions. On the other hand, in the case of negative coupling, where a large Ca transient tends to shorten the APD, we find a multitude of metastable states which consist of complex spatially discordant alternans patterns. Using an analogy to equilibrium statistical mechanics, we show that the spatial patterns observed can be explained by a mapping to the Potts model, with an additional term that accounts for a global coupling of spin states. Using this analogy, we argue that Ca cycling in cardiac cells exhibits complex spatiotemporal patterns that emerge via first or second order phase transitions. These results show that voltage and Ca can interact in order to induce complex subcellular responses, which can potentially lead to heart rhythm disorders.
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Affiliation(s)
- Luis Romero
- Department of Physics, California State University, Northridge, California 91330, USA
| | - Enric Alvarez-Lacalle
- Departament de Fisica, Universitat Politècnica de Catalunya, BarcelonaTech, 08028 Barcelona, Spain
| | - Yohannes Shiferaw
- Department of Physics, California State University, Northridge, California 91330, USA
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Pearman CM, Madders GW, Radcliffe EJ, Kirkwood GJ, Lawless M, Watkins A, Smith CE, Trafford AW, Eisner DA, Dibb KM. Increased Vulnerability to Atrial Fibrillation Is Associated With Increased Susceptibility to Alternans in Old Sheep. J Am Heart Assoc 2018; 7:e009972. [PMID: 30520673 PMCID: PMC6405564 DOI: 10.1161/jaha.118.009972] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/17/2018] [Indexed: 12/17/2022]
Abstract
Background Atrial fibrillation ( AF ) is common in the elderly, but rare in the young; however, the changes that occur with age that promote AF are not fully understood. Action potential ( AP ) alternans may be involved in the initiation of AF . Using a translationally relevant model, we investigated whether age-associated atrial vulnerability to AF was associated with susceptibility to AP alternans. Methods and Results AF was induced in conscious young and old sheep using 50 Hz burst pacing. Old sheep were more vulnerable to AF . Monophasic and cellular AP s were recorded from the right atrium in vivo and from myocytes isolated from the left and right atrial appendages. AP alternans occurred at lower stimulation frequencies in old sheep than young in vivo (old, 3.0±0.1 Hz; young, 3.3±0.1 Hz; P<0.05) and in isolated myocytes (old, 1.6±0.1 Hz; young, 2.0±0.1 Hz; P<0.05). Simultaneous recordings of [Ca2+]i and membrane potential in myocytes showed that alternans of AP s and [Ca2+]i often occurred together. However, at low stimulation rates [Ca2+]i alternans could occur without AP alternans, whereas at high stimulation rates AP alternans could still be observed despite disabling Ca2+ cycling using thapsigargin. Conclusions We have shown, for the first time in a large mammalian model, that aging is associated with increased duration of AF and susceptibility to AP alternans. We suggest that instabilities in Ca2+ handling initiate alternans at low stimulation rates, but that AP restitution alone can sustain alternans at higher rates.
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Wang W, Zhang S, Ni H, Garratt CJ, Boyett MR, Hancox JC, Zhang H. Mechanistic insight into spontaneous transition from cellular alternans to arrhythmia-A simulation study. PLoS Comput Biol 2018; 14:e1006594. [PMID: 30500818 PMCID: PMC6291170 DOI: 10.1371/journal.pcbi.1006594] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/12/2018] [Accepted: 10/23/2018] [Indexed: 02/01/2023] Open
Abstract
Cardiac electrical alternans (CEA), manifested as T-wave alternans in ECG, is a clinical biomarker for predicting cardiac arrhythmias and sudden death. However, the mechanism underlying the spontaneous transition from CEA to arrhythmias remains incompletely elucidated. In this study, multiscale rabbit ventricular models were used to study the transition and a potential role of INa in perpetuating such a transition. It was shown CEA evolved into either concordant or discordant action potential (AP) conduction alternans in a homogeneous one-dimensional tissue model, depending on tissue AP duration and conduction velocity (CV) restitution properties. Discordant alternans was able to cause conduction failure in the model, which was promoted by impaired sodium channel with either a reduced or increased channel current. In a two-dimensional homogeneous tissue model, a combined effect of rate- and curvature-dependent CV broke-up alternating wavefronts at localised points, facilitating a spontaneous transition from CEA to re-entry. Tissue inhomogeneity or anisotropy further promoted break-up of re-entry, leading to multiple wavelets. Similar observations have also been seen in human atrial cellular and tissue models. In conclusion, our results identify a mechanism by which CEA spontaneously evolves into re-entry without a requirement for premature ventricular complexes or pre-existing tissue heterogeneities, and demonstrated the important pro-arrhythmic role of impaired sodium channel activity. These findings are model-independent and have potential human relevance.
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Affiliation(s)
- Wei Wang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Shanzhuo Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Haibo Ni
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Clifford J. Garratt
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Mark R. Boyett
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Jules C. Hancox
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Physiology, Pharmacology and Neuroscience, and Cardiovascular Research Laboratories, School of Medical Sciences, University of Bristol, Bristol, United Kingdom
| | - Henggui Zhang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
- Space Institute of Southern China, Shenzhen, China
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Denham NC, Pearman CM, Caldwell JL, Madders GWP, Eisner DA, Trafford AW, Dibb KM. Calcium in the Pathophysiology of Atrial Fibrillation and Heart Failure. Front Physiol 2018; 9:1380. [PMID: 30337881 PMCID: PMC6180171 DOI: 10.3389/fphys.2018.01380] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Atrial fibrillation (AF) is commonly associated with heart failure. A bidirectional relationship exists between the two-AF exacerbates heart failure causing a significant increase in heart failure symptoms, admissions to hospital and cardiovascular death, while pathological remodeling of the atria as a result of heart failure increases the risk of AF. A comprehensive understanding of the pathophysiology of AF is essential if we are to break this vicious circle. In this review, the latest evidence will be presented showing a fundamental role for calcium in both the induction and maintenance of AF. After outlining atrial electrophysiology and calcium handling, the role of calcium-dependent afterdepolarizations and atrial repolarization alternans in triggering AF will be considered. The atrial response to rapid stimulation will be discussed, including the short-term protection from calcium overload in the form of calcium signaling silencing and the eventual progression to diastolic calcium leak causing afterdepolarizations and the development of an electrical substrate that perpetuates AF. The role of calcium in the bidirectional relationship between heart failure and AF will then be covered. The effects of heart failure on atrial calcium handling that promote AF will be reviewed, including effects on both atrial myocytes and the pulmonary veins, before the aspects of AF which exacerbate heart failure are discussed. Finally, the limitations of human and animal studies will be explored allowing contextualization of what are sometimes discordant results.
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Affiliation(s)
- Nathan C. Denham
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | | | | | | | | | | | - Katharine M. Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
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48
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Heart rate variability alters cardiac repolarization and electromechanical dynamics. J Theor Biol 2018; 442:31-43. [DOI: 10.1016/j.jtbi.2018.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 01/05/2018] [Accepted: 01/10/2018] [Indexed: 11/23/2022]
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49
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Winter J, Bishop MJ, Wilder CDE, O'Shea C, Pavlovic D, Shattock MJ. Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart. Front Physiol 2018; 9:16. [PMID: 29410631 PMCID: PMC5787134 DOI: 10.3389/fphys.2018.00016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/08/2018] [Indexed: 11/29/2022] Open
Abstract
Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective: To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results: Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (IKs), sufficient to abolish IKs-mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake into the sarcoplasmic reticulum is a major mechanism by which SNS suppresses alternans in the guinea pig heart. Conclusions: SNS suppresses calcium and action potential alternans in the intact guinea pig heart by an action mediated through accelerated Ca handling and via increased IKs.
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Affiliation(s)
- James Winter
- School of Cardiovascular Medicine and Sciences, King's College London, United Kingdom.,Institute of Cardiovascular Sciences, College of Medicine and Dental Sciences, University of Birmingham, United Kingdom
| | - Martin J Bishop
- Biomedical Engineering Department, King's College London, United Kingdom
| | - Catherine D E Wilder
- School of Cardiovascular Medicine and Sciences, King's College London, United Kingdom
| | - Christopher O'Shea
- Institute of Cardiovascular Sciences, College of Medicine and Dental Sciences, University of Birmingham, United Kingdom
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, College of Medicine and Dental Sciences, University of Birmingham, United Kingdom
| | - Michael J Shattock
- School of Cardiovascular Medicine and Sciences, King's College London, United Kingdom
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50
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Biton Y, Rabinovitch A, Braunstein D, Aviram I, Campbell K, Mironov S, Herron T, Jalife J, Berenfeld O. Causality analysis of leading singular value decomposition modes identifies rotor as the dominant driving normal mode in fibrillation. CHAOS (WOODBURY, N.Y.) 2018; 28:013128. [PMID: 29390625 PMCID: PMC5786449 DOI: 10.1063/1.5021261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 12/28/2017] [Indexed: 06/07/2023]
Abstract
Cardiac fibrillation is a major clinical and societal burden. Rotors may drive fibrillation in many cases, but their role and patterns are often masked by complex propagation. We used Singular Value Decomposition (SVD), which ranks patterns of activation hierarchically, together with Wiener-Granger causality analysis (WGCA), which analyses direction of information among observations, to investigate the role of rotors in cardiac fibrillation. We hypothesized that combining SVD analysis with WGCA should reveal whether rotor activity is the dominant driving force of fibrillation even in cases of high complexity. Optical mapping experiments were conducted in neonatal rat cardiomyocyte monolayers (diameter, 35 mm), which were genetically modified to overexpress the delayed rectifier K+ channel IKr only in one half of the monolayer. Such monolayers have been shown previously to sustain fast rotors confined to the IKr overexpressing half and driving fibrillatory-like activity in the other half. SVD analysis of the optical mapping movies revealed a hierarchical pattern in which the primary modes corresponded to rotor activity in the IKr overexpressing region and the secondary modes corresponded to fibrillatory activity elsewhere. We then applied WGCA to evaluate the directionality of influence between modes in the entire monolayer using clear and noisy movies of activity. We demonstrated that the rotor modes influence the secondary fibrillatory modes, but influence was detected also in the opposite direction. To more specifically delineate the role of the rotor in fibrillation, we decomposed separately the respective SVD modes of the rotor and fibrillatory domains. In this case, WGCA yielded more information from the rotor to the fibrillatory domains than in the opposite direction. In conclusion, SVD analysis reveals that rotors can be the dominant modes of an experimental model of fibrillation. Wiener-Granger causality on modes of the rotor domains confirms their preferential driving influence on fibrillatory modes.
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Affiliation(s)
- Yaacov Biton
- Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Avinoam Rabinovitch
- Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Doron Braunstein
- Physics Department, Sami Shamoon College of Engineering, Beer-Sheva 84100, Israel
| | - Ira Aviram
- Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Katherine Campbell
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Sergey Mironov
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Todd Herron
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan 48109, USA
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