1
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Semmler L, Jeising T, Huettemeister J, Bathe-Peters M, Georgoula K, Roshanbin R, Sander P, Fu S, Bode D, Hohendanner F, Pieske B, Annibale P, Schiattarella GG, Oeing CU, Heinzel FR. Impairment of the adrenergic reserve associated with exercise intolerance in a murine model of heart failure with preserved ejection fraction. Acta Physiol (Oxf) 2024; 240:e14124. [PMID: 38436094 DOI: 10.1111/apha.14124] [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: 08/03/2023] [Revised: 12/27/2023] [Accepted: 02/20/2024] [Indexed: 03/05/2024]
Abstract
AIM Exercise intolerance is the central symptom in patients with heart failure with preserved ejection fraction. In the present study, we investigated the adrenergic reserve both in vivo and in cardiomyocytes of a murine cardiometabolic HFpEF model. METHODS 12-week-old male C57BL/6J mice were fed regular chow (control) or a high-fat diet and L-NAME (HFpEF) for 15 weeks. At 27 weeks, we performed (stress) echocardiography and exercise testing and measured the adrenergic reserve and its modulation by nitric oxide and reactive oxygen species in left ventricular cardiomyocytes. RESULTS HFpEF mice (preserved left ventricular ejection fraction, increased E/e', pulmonary congestion [wet lung weight/TL]) exhibited reduced exercise capacity and a reduction of stroke volume and cardiac output with adrenergic stress. In ventricular cardiomyocytes isolated from HFpEF mice, sarcomere shortening had a higher amplitude and faster relaxation compared to control animals. Increased shortening was caused by a shift of myofilament calcium sensitivity. With addition of isoproterenol, there were no differences in sarcomere function between HFpEF and control mice. This resulted in a reduced inotropic and lusitropic reserve in HFpEF cardiomyocytes. Preincubation with inhibitors of nitric oxide synthases or glutathione partially restored the adrenergic reserve in cardiomyocytes in HFpEF. CONCLUSION In this murine HFpEF model, the cardiac output reserve on adrenergic stimulation is impaired. In ventricular cardiomyocytes, we found a congruent loss of the adrenergic inotropic and lusitropic reserve. This was caused by increased contractility and faster relaxation at rest, partially mediated by nitro-oxidative signaling.
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Affiliation(s)
- Lukas Semmler
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Tobias Jeising
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Judith Huettemeister
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Marc Bathe-Peters
- Receptor Signalling Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Konstantina Georgoula
- Receptor Signalling Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Rashin Roshanbin
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
| | - Paulina Sander
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Shu Fu
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - David Bode
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Felix Hohendanner
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Burkert Pieske
- Division of Cardiology, Department of Internal Medicine, University Medicine Rostock, Rostock, Germany
| | - Paolo Annibale
- Receptor Signalling Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Gabriele G Schiattarella
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Translational Approaches in Heart Failure and Cardiometabolic Disease, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Christian U Oeing
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, German Heart Center Charité (DHZC) - Campus Virchow-Klinikum, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- 2. Medizinische Klinik - Kardiologie, Angiologie, Intensivmedizin, Städtisches Klinikum Dresden, Dresden, Germany
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2
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Tonko JB, Lambiase PD. The proarrhythmogenic role of autonomics and emerging neuromodulation approaches to prevent sudden death in cardiac ion channelopathies. Cardiovasc Res 2024; 120:114-131. [PMID: 38195920 PMCID: PMC10936753 DOI: 10.1093/cvr/cvae009] [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: 09/18/2023] [Revised: 11/06/2023] [Accepted: 11/30/2023] [Indexed: 01/11/2024] Open
Abstract
Ventricular arrhythmias in cardiac channelopathies are linked to autonomic triggers, which are sub-optimally targeted in current management strategies. Improved molecular understanding of cardiac channelopathies and cellular autonomic signalling could refine autonomic therapies to target the specific signalling pathways relevant to the specific aetiologies as well as the central nervous system centres involved in the cardiac autonomic regulation. This review summarizes key anatomical and physiological aspects of the cardiac autonomic nervous system and its impact on ventricular arrhythmias in primary inherited arrhythmia syndromes. Proarrhythmogenic autonomic effects and potential therapeutic targets in defined conditions including the Brugada syndrome, early repolarization syndrome, long QT syndrome, and catecholaminergic polymorphic ventricular tachycardia will be examined. Pharmacological and interventional neuromodulation options for these cardiac channelopathies are discussed. Promising new targets for cardiac neuromodulation include inhibitory and excitatory G-protein coupled receptors, neuropeptides, chemorepellents/attractants as well as the vagal and sympathetic nuclei in the central nervous system. Novel therapeutic strategies utilizing invasive and non-invasive deep brain/brain stem stimulation as well as the rapidly growing field of chemo-, opto-, or sonogenetics allowing cell-specific targeting to reduce ventricular arrhythmias are presented.
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Affiliation(s)
- Johanna B Tonko
- Institute of Cardiovascular Science, University College London, 5 University Street, London WC1E 6JF, London, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, 5 University Street, London WC1E 6JF, London, UK
- Department for Cardiology, Bart’s Heart Centre, West Smithfield EC1A 7BE, London, UK
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3
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Sleiman Y, Lacampagne A, Meli AC. Correction: "Ryanopathies" and RyR2 dysfunctions: can we further decipher them using in vitro human disease models? Cell Death Dis 2022; 13:1014. [PMID: 36450727 PMCID: PMC9712522 DOI: 10.1038/s41419-022-05468-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Yvonne Sleiman
- PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France
| | - Alain Lacampagne
- PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France
| | - Albano C Meli
- PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France.
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4
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Jaouadi H, Chabrak S, Lahbib S, Abdelhak S, Zaffran S. Identification of two variants in AGRN and RPL3L genes in a patient with catecholaminergic polymorphic ventricular tachycardia suggesting new candidate disease genes and digenic inheritance. Clin Case Rep 2022; 10:e05339. [PMID: 35341025 PMCID: PMC8858789 DOI: 10.1002/ccr3.5339] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 01/03/2022] [Accepted: 01/14/2022] [Indexed: 11/30/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmogenic syndrome characterized by life-threatening arrhythmias, a normal resting electrocardiogram and the absence of overt structural heart abnormalities. Mutations in RyR2 gene account for the large part of CPVT cases. Less frequently, mutations in CASQ2 gene have been linked to the recessive form of the disease. Overall, approximately 35% of CPVT patients remain without a genetic etiology implying that other genes might be found causative of the disease. Here, we present a 6-year-old boy born to first-degree related parents, with a typical phenotype of CPVT and a family history of sudden cardiac death of his brother at 7 years. A trio-based whole exome sequencing was performed, and we identified a homozygous variant in AGRN gene and a heterozygous variant in RPL3L gene. We hypothesized that the presence of the homozygous variant in AGRN accounts for the CPVT phenotype in this family and the heterozygous variant in RPL3L gene may act as a modifier gene. Further studies are needed to determine the role of these genes in CPVT.
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Affiliation(s)
- Hager Jaouadi
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05Institut Pasteur de TunisTunisTunisia
- Aix Marseille UniversitéINSERM, Marseille Medical GeneticsMarseilleFrance
| | - Sonia Chabrak
- Faculty of Medicine of TunisUniversité Tunis El ManarTunisTunisia
| | - Saida Lahbib
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05Institut Pasteur de TunisTunisTunisia
| | - Sonia Abdelhak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05Institut Pasteur de TunisTunisTunisia
| | - Stéphane Zaffran
- Aix Marseille UniversitéINSERM, Marseille Medical GeneticsMarseilleFrance
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5
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Sadredini M, Manotheepan R, Lehnart SE, Anderson ME, Sjaastad I, Stokke MK. The oxidation-resistant CaMKII-MM281/282VV mutation does not prevent arrhythmias in CPVT1. Physiol Rep 2021; 9:e15030. [PMID: 34558218 PMCID: PMC8461029 DOI: 10.14814/phy2.15030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 11/24/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1) is an inherited arrhythmogenic disorder caused by missense mutations in the cardiac ryanodine receptors (RyR2), that result in increased β-adrenoceptor stimulation-induced diastolic Ca2+ leak. We have previously shown that exercise training prevents arrhythmias in CPVT1, potentially by reducing the oxidation of Ca2+ /calmodulin-dependent protein kinase type II (CaMKII). Therefore, we tested whether an oxidation-resistant form of CaMKII protects mice carrying the CPVT1-causative mutation RyR2-R2474S (RyR2-RS) against arrhythmias. Antioxidant treatment (N-acetyl-L-cysteine) reduced the frequency of β-adrenoceptor stimulation-induced arrhythmogenic Ca2+ waves in isolated cardiomyocytes from RyR2-RS mice. To test whether the prevention of CaMKII oxidation exerts an antiarrhythmic effect, mice expressing the oxidation-resistant CaMKII-MM281/282VV variant (MMVV) were crossed with RyR2-RS mice to create a double transgenic model (RyR2-RS/MMVV). Wild-type mice served as controls. Telemetric ECG surveillance revealed an increased incidence of ventricular tachycardia and an increased arrhythmia score in both RyR2-RS and RyR2-RS/MMVV compared to wild-type mice, both following a β-adrenoceptor challenge (isoprenaline i.p.), and following treadmill exercise combined with a β-adrenoceptor challenge. There were no differences in the incidence of arrhythmias between RyR2-RS and RyR2-RS/MMVV mice. Furthermore, no differences were observed in β-adrenoceptor stimulation-induced Ca2+ waves in RyR2-RS/MMVV compared to RyR2-RS. In conclusion, antioxidant treatment reduces β-adrenoceptor stimulation-induced Ca2+ waves in RyR2-RS cardiomyocytes. However, oxidation-resistant CaMKII-MM281/282VV does not protect RyR2-RS mice from β-adrenoceptor stimulation-induced Ca2+ waves or arrhythmias. Hence, alternative oxidation-sensitive targets need to be considered to explain the beneficial effect of antioxidant treatment on Ca2+ waves in cardiomyocytes from RyR2-RS mice.
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Affiliation(s)
- Mani Sadredini
- Institute for Experimental Medical Research and KG Jebsen Cardiac Research CentreOslo University Hospital and University of OsloOsloNorway
| | - Ravinea Manotheepan
- Institute for Experimental Medical Research and KG Jebsen Cardiac Research CentreOslo University Hospital and University of OsloOsloNorway
| | - Stephan E. Lehnart
- Heart Research Center GöttingenDepartment of Cardiology and PulmonologyUniversity Medical Center GöttingenGeorg August University GöttingenGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
- DZHK (German Centre for Cardiovascular Research)GöttingenGermany
| | - Mark E. Anderson
- Division of CardiologyDepartment of MedicineThe Johns Hopkins University School of MedicineBaltimoreUSA
| | - Ivar Sjaastad
- Institute for Experimental Medical Research and KG Jebsen Cardiac Research CentreOslo University Hospital and University of OsloOsloNorway
| | - Mathis K. Stokke
- Institute for Experimental Medical Research and KG Jebsen Cardiac Research CentreOslo University Hospital and University of OsloOsloNorway
- Department of CardiologyOslo University HospitalRikshospitaletOsloNorway
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6
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Trum M, Riechel J, Wagner S. Cardioprotection by SGLT2 Inhibitors-Does It All Come Down to Na +? Int J Mol Sci 2021; 22:ijms22157976. [PMID: 34360742 PMCID: PMC8347698 DOI: 10.3390/ijms22157976] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/22/2021] [Accepted: 07/22/2021] [Indexed: 12/15/2022] Open
Abstract
Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are emerging as a new treatment strategy for heart failure with reduced ejection fraction (HFrEF) and—depending on the wistfully awaited results of two clinical trials (DELIVER and EMPEROR-Preserved)—may be the first drug class to improve cardiovascular outcomes in patients suffering from heart failure with preserved ejection fraction (HFpEF). Proposed mechanisms of action of this class of drugs are diverse and include metabolic and hemodynamic effects as well as effects on inflammation, neurohumoral activation, and intracellular ion homeostasis. In this review we focus on the growing body of evidence for SGLT2i-mediated effects on cardiac intracellular Na+ as an upstream mechanism. Therefore, we will first give a short overview of physiological cardiomyocyte Na+ handling and its deterioration in heart failure. On this basis we discuss the salutary effects of SGLT2i on Na+ homeostasis by influencing NHE1 activity, late INa as well as CaMKII activity. Finally, we highlight the potential relevance of these effects for systolic and diastolic dysfunction as well as arrhythmogenesis.
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7
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Sander P, Feng M, Schweitzer MK, Wilting F, Gutenthaler SM, Arduino DM, Fischbach S, Dreizehnter L, Moretti A, Gudermann T, Perocchi F, Schredelseker J. Approved drugs ezetimibe and disulfiram enhance mitochondrial Ca 2+ uptake and suppress cardiac arrhythmogenesis. Br J Pharmacol 2021; 178:4518-4532. [PMID: 34287836 DOI: 10.1111/bph.15630] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 06/21/2021] [Accepted: 06/30/2021] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Treatment of cardiac arrhythmia remains challenging due to severe side effects of common anti-arrhythmic drugs. We previously demonstrated that mitochondrial Ca2+ uptake in cardiomyocytes represents a promising new candidate structure for safer drug therapy. However, druggable agonists of mitochondrial Ca2+ uptake suitable for preclinical and clinical studies are still missing. EXPERIMENTAL APPROACH Herewe screened 727 compounds with a history of use in human clinical trials in a three-step screening approach. As a primary screening platform we used a permeabilized HeLa cell-based mitochondrial Ca2+ uptake assay. Hits were validated in cultured HL-1 cardiomyocytes and finally tested for anti-arrhythmic efficacy in three translational models: a Ca2+ overload zebrafish model and cardiomyocytes of both a mouse model for catecholaminergic polymorphic ventricular tachycardia (CPVT) and induced pluripotent stem cell derived cardiomyocytes from a CPVT patient. KEY RESULTS We identifiedtwo candidate compounds, the clinically approved drugs ezetimibe and disulfiram, which stimulate SR-mitochondria Ca2+ transfer at nanomolar concentrations. This is significantly lower compared to the previously described mitochondrial Ca2+ uptake enhancers (MiCUps) efsevin, a gating modifier of the voltage-dependent anion channel 2, and kaempferol, an agonist of the mitochondrial Ca2+ uniporter. Both substances restored rhythmic cardiac contractions in a zebrafish cardiac arrhythmia model and significantly suppressed arrhythmogenesis in freshly isolated ventricular cardiomyocytes from a CPVT mouse model as well as induced pluripotent stem cell derived cardiomyocytes from a CPVT patient. CONCLUSION AND IMPLICATIONS Taken together we identified ezetimibe and disulfiram as novel MiCUps and efficient suppressors of arrhythmogenesis and as such as, promising candidates for future preclinical and clinical studies.
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Affiliation(s)
- Paulina Sander
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Michael Feng
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Neuherberg, Germany
| | - Maria K Schweitzer
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Fabiola Wilting
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Sophie M Gutenthaler
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Daniela M Arduino
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Neuherberg, Germany
| | - Sandra Fischbach
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany
| | - Lisa Dreizehnter
- I. Department of Medicine, Cardiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Alessandra Moretti
- I. Department of Medicine, Cardiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.,Partner Site Munich Heart Alliance (MHA), Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany.,Partner Site Munich Heart Alliance (MHA), Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Munich, Germany
| | - Fabiana Perocchi
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München, Neuherberg, Germany.,Munich Cluster for Systems Neurology, Munich, Germany
| | - Johann Schredelseker
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Munich, Germany.,Partner Site Munich Heart Alliance (MHA), Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Munich, Germany
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8
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Identification of loss-of-function RyR2 mutations associated with idiopathic ventricular fibrillation and sudden death. Biosci Rep 2021; 41:228220. [PMID: 33825858 PMCID: PMC8062958 DOI: 10.1042/bsr20210209] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/24/2021] [Accepted: 04/06/2021] [Indexed: 11/23/2022] Open
Abstract
Mutations in cardiac ryanodine receptor (RyR2) are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). Most CPVT RyR2 mutations characterized are gain-of-function (GOF), indicating enhanced RyR2 function as a major cause of CPVT. Loss-of-function (LOF) RyR2 mutations have also been identified and are linked to a distinct entity of cardiac arrhythmia termed RyR2 Ca2+ release deficiency syndrome (CRDS). Exercise stress testing (EST) is routinely used to diagnose CPVT, but it is ineffective for CRDS. There is currently no effective diagnostic tool for CRDS in humans. An alternative strategy to assess the risk for CRDS is to directly determine the functional impact of the associated RyR2 mutations. To this end, we have functionally screened 18 RyR2 mutations that are associated with idiopathic ventricular fibrillation (IVF) or sudden death. We found two additional RyR2 LOF mutations E4146K and G4935R. The E4146K mutation markedly suppressed caffeine activation of RyR2 and abolished store overload induced Ca2+ release (SOICR) in human embryonic kidney 293 (HEK293) cells. E4146K also severely reduced cytosolic Ca2+ activation and abolished luminal Ca2+ activation of single RyR2 channels. The G4935R mutation completely abolished caffeine activation of and [3H]ryanodine binding to RyR2. Co-expression studies showed that the G4935R mutation exerted dominant negative impact on the RyR2 wildtype (WT) channel. Interestingly, the RyR2-G4935R mutant carrier had a negative EST, and the E4146K carrier had a family history of sudden death during sleep, which are different from phenotypes of typical CPVT. Thus, our data further support the link between RyR2 LOF and a new entity of cardiac arrhythmias distinct from CPVT.
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9
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Ljubojević-Holzer S, Kraler S, Djalinac N, Abdellatif M, Voglhuber J, Schipke J, Schmidt M, Kling KM, Franke GT, Herbst V, Zirlik A, von Lewinski D, Scherr D, Rainer PP, Kohlhaas M, Nickel A, Mühlfeld C, Maack C, Sedej S. Loss of autophagy protein ATG5 impairs cardiac capacity in mice and humans through diminishing mitochondrial abundance and disrupting Ca2+ cycling. Cardiovasc Res 2021; 118:1492-1505. [PMID: 33752242 PMCID: PMC9074988 DOI: 10.1093/cvr/cvab112] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 03/19/2021] [Indexed: 12/13/2022] Open
Abstract
Aims Autophagy protects against the development of cardiac hypertrophy and failure. While aberrant Ca2+ handling promotes myocardial remodelling and contributes to contractile dysfunction, the role of autophagy in maintaining Ca2+ homeostasis remains elusive. Here, we examined whether Atg5 deficiency-mediated autophagy promotes early changes in subcellular Ca2+ handling in ventricular cardiomyocytes, and whether those alterations associate with compromised cardiac reserve capacity, which commonly precedes the onset of heart failure. Methods and results RT–qPCR and immunoblotting demonstrated reduced Atg5 gene and protein expression and decreased abundancy of autophagy markers in hypertrophied and failing human hearts. The function of ATG5 was examined using cardiomyocyte-specific Atg5-knockout mice (Atg5−/−). Before manifesting cardiac dysfunction, Atg5−/− mice showed compromised cardiac reserve in response to β-adrenergic stimulation. Consequently, effort intolerance and maximal oxygen consumption were reduced during treadmill-based exercise tolerance testing. Mechanistically, cellular imaging revealed that Atg5 deprivation did not alter spatial and functional organization of intracellular Ca2+ stores or affect Ca2+ cycling in response to slow pacing or upon acute isoprenaline administration. However, high-frequency stimulation exposed stunted amplitude of Ca2+ transients, augmented nucleoplasmic Ca2+ load, and increased CaMKII activity, especially in the nuclear region of hypertrophied Atg5−/− cardiomyocytes. These changes in Ca2+ cycling were recapitulated in hypertrophied human cardiomyocytes. Finally, ultrastructural analysis revealed accumulation of mitochondria with reduced volume and size distribution, meanwhile functional measurements showed impaired redox balance in Atg5−/− cardiomyocytes, implying energetic unsustainability due to overcompensation of single mitochondria, particularly under increased workload. Conclusion Loss of cardiac Atg5-dependent autophagy reduces mitochondrial abundance and causes subtle alterations in subcellular Ca2+ cycling upon increased workload in mice. Autophagy-related impairment of Ca2+ handling is progressively worsened by β-adrenergic signalling in ventricular cardiomyocytes, thereby leading to energetic exhaustion and compromised cardiac reserve.
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Affiliation(s)
- Senka Ljubojević-Holzer
- Department of Cardiology, Medical University of Graz, Graz, Austria.,BioTechMed Graz, Graz, Austria
| | - Simon Kraler
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Nataša Djalinac
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | | | - Julia Voglhuber
- Department of Cardiology, Medical University of Graz, Graz, Austria.,BioTechMed Graz, Graz, Austria
| | - Julia Schipke
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Marlene Schmidt
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Katharina-Maria Kling
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Greta Therese Franke
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Viktoria Herbst
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Andreas Zirlik
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | | | - Daniel Scherr
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Peter P Rainer
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Michael Kohlhaas
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Alexander Nickel
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Christian Mühlfeld
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
| | - Christoph Maack
- Department of Translational Research, Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Simon Sedej
- Department of Cardiology, Medical University of Graz, Graz, Austria.,BioTechMed Graz, Graz, Austria.,Faculty of Medicine, University of Maribor, Maribor, Slovenia
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10
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Sun B, Yao J, Ni M, Wei J, Zhong X, Guo W, Zhang L, Wang R, Belke D, Chen YX, Lieve KVV, Broendberg AK, Roston TM, Blankoff I, Kammeraad JA, von Alvensleben JC, Lazarte J, Vallmitjana A, Bohne LJ, Rose RA, Benitez R, Hove-Madsen L, Napolitano C, Hegele RA, Fill M, Sanatani S, Wilde AAM, Roberts JD, Priori SG, Jensen HK, Chen SRW. Cardiac ryanodine receptor calcium release deficiency syndrome. Sci Transl Med 2021; 13:eaba7287. [PMID: 33536282 DOI: 10.1126/scitranslmed.aba7287] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 12/07/2020] [Indexed: 11/02/2022]
Abstract
Cardiac ryanodine receptor (RyR2) gain-of-function mutations cause catecholaminergic polymorphic ventricular tachycardia, a condition characterized by prominent ventricular ectopy in response to catecholamine stress, which can be reproduced on exercise stress testing (EST). However, reports of sudden cardiac death (SCD) have emerged in EST-negative individuals who have loss-of-function (LOF) RyR2 mutations. The clinical relevance of RyR2 LOF mutations including their pathogenic mechanism, diagnosis, and treatment are all unknowns. Here, we performed clinical and genetic evaluations of individuals who suffered from SCD and harbored an LOF RyR2 mutation. We carried out electrophysiological studies using a programed electrical stimulation protocol consisting of a long-burst, long-pause, and short-coupled (LBLPS) ventricular extra-stimulus. Linkage analysis of RyR2 LOF mutations in six families revealed a combined logarithm of the odds ratio for linkage score of 11.479 for a condition associated with SCD with negative EST. A RyR2 LOF mouse model exhibited no catecholamine-provoked ventricular arrhythmias as in humans but did have substantial cardiac electrophysiological remodeling and an increased propensity for early afterdepolarizations. The LBLPS pacing protocol reliably induced ventricular arrhythmias in mice and humans having RyR2 LOF mutations, whose phenotype is otherwise concealed before SCD. Furthermore, treatment with quinidine and flecainide abolished LBLPS-induced ventricular arrhythmias in model mice. Thus, RyR2 LOF mutations underlie a previously unknown disease entity characterized by SCD with normal EST that we have termed RyR2 Ca2+ release deficiency syndrome (CRDS). Our study provides insights into the mechanism of CRDS, reports a specific CRDS diagnostic test, and identifies potentially efficacious anti-CRDS therapies.
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Affiliation(s)
- Bo Sun
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
- Medical School, Kunming University of Science and Technology, Kunming 650504, China
| | - Jinjing Yao
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Mingke Ni
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Xiaowei Zhong
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Wenting Guo
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Lin Zhang
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Darrell Belke
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Yong-Xiang Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Krystien V V Lieve
- Amsterdam University Medical Centre, location AMC, Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam 1105AZ, Netherlands
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands
| | - Anders K Broendberg
- Department of Cardiology, Aarhus University Hospital, and Department of Clinical Medicine, Health, Aarhus University, Palle Juul-Jensens Blv 99, DK-8200 Aarhus N, Denmark
| | - Thomas M Roston
- Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Ivan Blankoff
- C.H.U. Charleroi, Hôpital Civil Marie Curie Chaussée de Bruxelles 140 6042 Charleroi, Belgium
| | - Janneke A Kammeraad
- Department of Pediatric Cardiology, Sophia Children's Hospital, Erasmus University Medical Centre, Doctor Molewaterplein 40, 3015 GD Rotterdam, Netherlands
| | - Johannes C von Alvensleben
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado, Aurora, CO 80045, USA
| | - Julieta Lazarte
- Department of Medicine and Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Alexander Vallmitjana
- Department of Automatic Control, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain
| | - Loryn J Bohne
- Departments of Cardiac Sciences and Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Robert A Rose
- Departments of Cardiac Sciences and Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Raul Benitez
- Department of Automatic Control, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain
| | - Leif Hove-Madsen
- Biomedical Research Institute Barcelona (IIBB-CSIC) and IIB Sant Pau, Hospital de Sant Pau, Barcelona 08025, Spain
| | - Carlo Napolitano
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands
- Division of Cardiology and Molecular Cardiology, IRCCS Maugeri Foundation-University of Pavia, 27100 Pavia, Italy
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
| | - Robert A Hegele
- Department of Medicine and Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5B7, Canada
| | - Michael Fill
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
| | - Shubhayan Sanatani
- Child and Family Research Institute, Department of Pediatrics, University of British Columbia, Vancouver, BC V6H 3V4, Canada.
| | - Arthur A M Wilde
- Amsterdam University Medical Centre, location AMC, Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam 1105AZ, Netherlands.
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON N6A 5A5, Canada.
| | - Silvia G Priori
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands.
- Division of Cardiology and Molecular Cardiology, IRCCS Maugeri Foundation-University of Pavia, 27100 Pavia, Italy
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
- Molecular Cardiology Laboratory, Centro de Investigaciones Cardiovasculares Carlos III, 28029 Madrid, Spain
| | - Henrik K Jensen
- Department of Cardiology, Aarhus University Hospital, and Department of Clinical Medicine, Health, Aarhus University, Palle Juul-Jensens Blv 99, DK-8200 Aarhus N, Denmark.
| | - S R Wayne Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4Z6, Canada.
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL 60612, USA
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11
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Shah C, Jiwani S, Limbu B, Weinberg S, Deo M. Delayed afterdepolarization-induced triggered activity in cardiac purkinje cells mediated through cytosolic calcium diffusion waves. Physiol Rep 2020; 7:e14296. [PMID: 31872561 PMCID: PMC6928245 DOI: 10.14814/phy2.14296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cardiac Purkinje cells (PCs) are more susceptible to action potential abnormalities as compared to ventricular myocytes (VMs), which could be associated with their distinct intracellular calcium handling. We developed a detailed biophysical model of a mouse cardiac PC, which importantly reproduces the experimentally observed biphasic cytosolic calcium waves. The model includes a stochastic gating formulation for the opening and closing of ryanodine receptor (RyR) channels, simulated with a Monte Carlo method, to accurately reproduce cytosolic calcium wave propagation and the effects of spontaneous calcium release events. Simulations predict that during an action potential, smaller cytosolic calcium wavelets propagated from the sarcolemma towards the center of the cell and initiated larger magnitude cell‐wide calcium waves via a calcium‐induced‐calcium release mechanism. In the presence of RyR mutations, frequent spontaneous calcium leaks from sarcoplasmic reticulum (SR) initiated calcium waves, which upon reaching the cell periphery produced delayed afterdepolarizations (DADs) via sodium‐calcium exchanger (NCX) and T‐type calcium (ICaT) channel activation. In the presence of isoproterenol‐mediated effects, DADs induced triggered activity by reactivation of fast sodium channels. Based on our model, we found that the activation of either L‐type calcium channels (ICaL), ICaT, sodium‐potassium exchanger (INaK) or NCX is sufficient for occurrence of triggered activity; however, a partial blockade of ICaT or INaK is essential for its successful termination. Our modeling study highlights valuable insights into the mechanisms of DAD‐induced triggered activity mediated via cytosolic calcium waves in cardiac PCs and may elucidate the increased arrhythmogeneity in PCs.
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Affiliation(s)
- Chirag Shah
- School of Medicine, Eastern Virginia Medical School, Norfolk, Virginia
| | - Sohel Jiwani
- Department of Engineering, Norfolk State University, Norfolk, Virginia
| | - Bijay Limbu
- Department of Engineering, Norfolk State University, Norfolk, Virginia
| | - Seth Weinberg
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio
| | - Makarand Deo
- Department of Engineering, Norfolk State University, Norfolk, Virginia
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12
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Ljubojevic-Holzer S, Herren AW, Djalinac N, Voglhuber J, Morotti S, Holzer M, Wood BM, Abdellatif M, Matzer I, Sacherer M, Radulovic S, Wallner M, Ivanov M, Wagner S, Sossalla S, von Lewinski D, Pieske B, Brown JH, Sedej S, Bossuyt J, Bers DM. CaMKIIδC Drives Early Adaptive Ca 2+ Change and Late Eccentric Cardiac Hypertrophy. Circ Res 2020; 127:1159-1178. [PMID: 32821022 PMCID: PMC7547876 DOI: 10.1161/circresaha.120.316947] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Supplemental Digital Content is available in the text. CaMKII (Ca2+-Calmodulin dependent protein kinase) δC activation is implicated in pathological progression of heart failure (HF) and CaMKIIδC transgenic mice rapidly develop HF and arrhythmias. However, little is known about early spatio-temporal Ca2+ handling and CaMKII activation in hypertrophy and HF.
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Affiliation(s)
- Senka Ljubojevic-Holzer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.).,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej)
| | - Anthony W Herren
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Natasa Djalinac
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Julia Voglhuber
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej)
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Michael Holzer
- Otto-Loewi Research Centre, Division of Pharmacology (M.H.), Medical University of Graz, Austria
| | - Brent M Wood
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Mahmoud Abdellatif
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Ingrid Matzer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Michael Sacherer
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Snjezana Radulovic
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Markus Wallner
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Milan Ivanov
- Institute for Medical Research, University of Belgrade, Serbia (M.I.)
| | - Stefan Wagner
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany (S.W., S. Sossalla)
| | - Samuel Sossalla
- Klinik für Kardiologie und Pneumologie, Georg-August-Universität Göttingen, Germany (S. Sossalla).,Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany (S.W., S. Sossalla)
| | - Dirk von Lewinski
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine Berlin, Germany (B.P.)
| | - Joan Heller Brown
- Department of Pharmacology, University of California San Diego, La Jolla (J.H.B.)
| | - Simon Sedej
- Department of Cardiology (S.L.-H., N.D., J.V., M.A., I.M., M.S., S.R., M.W., D.v.L., S. Sedej), Medical University of Graz, Austria.,BioTechMed Graz, Austria (S.L.-H., J.V., S. Sedej).,Faculty of Medicine, Institute of Physiology, University of Maribor, Slovenia (S. Sedej)
| | - Julie Bossuyt
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA (S.L.-H., A.W.H., S.M., B.M.W., J.B., D.M.B.)
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13
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Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare congenital arrhythmogenic disorder induced by physical or emotional stress. It mainly affects children and younger adults and is characterized by rapid polymorphic and bidirectional ventricular tachycardia. Symptoms can include dizziness, palpitations, and presyncope, which may progress to syncope, hypotonia, convulsive movements, and sudden cardiac death. CPVT is the result of perturbations in Ca ion handling in the sarcoplasmic reticulum of cardiac myocytes. Mutations in the cardiac ryanodine receptor gene and the calsequestrin isoform 2 gene are most commonly seen in familial CPVT patients. Under catecholaminergic stimulation, either mutation can result in an excess Ca load during diastole resulting in delayed after depolarization and subsequent arrhythmogenesis. The current first-line treatment for CPVT is β-blocker therapy. Other therapeutic interventions that can be used in conjunction with β-blockers include moderate exercise training, flecainide, left cardiac sympathetic denervation, and implantable cardioverter-defibrillators. Several potential therapeutic interventions, including verapamil, dantrolene, JTV519, and gene therapy, are also discussed.
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14
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Ca 2+/calmodulin-dependent protein kinase II is essential in hyperacute pressure overload. J Mol Cell Cardiol 2019; 138:212-221. [PMID: 31836540 DOI: 10.1016/j.yjmcc.2019.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 11/20/2019] [Accepted: 12/08/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND Activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) is established as a central intracellular trigger for various cardiac pathologies such as hypertrophy, heart failure or arrhythmias in animals and humans suggesting CaMKII as a promising target protein for future medical treatments. However, the physiological role of CaMKII is scarcely well defined. AIM & METHODS To investigate the role of CaMKII in hyperacute pressure overload, we evaluated the effects of pressure overload induced by transverse aortic constriction (TAC) on survival, cardiac function, protein expression and excitation-contraction coupling (ECC) in female WT littermate vs. AC3-I mice 2 days after TAC (2d post TAC). AC3-I mice express the CaMKII inhibitor autocamtide-3 related inhibitory peptide (AiP) under the control of the α-myosin heavy chain promotor in the heart. RESULTS CaMKII activation is significantly increased in WT TAC vs. sham mice 2d post TAC. Interestingly, survival is significantly reduced in AC3-I animals within the first five days after TAC compared to WT TAC littermates, while systolic cardiac function is markedly reduced in AC3-I TAC vs. AC3-I sham mice, but preserved in WT TAC vs. WT sham mice. Proteins regulating ECC such as ryanodine receptors (RyR2) and phospholamban (PLB) are hypophosphorylated at their CaMKII phosphorylation site in AC3-I TAC mice, but hyperphosphorylated in WT TAC mice compared to controls. In isolated cardiomyocytes fractional shortening is significantly impaired in AC3-I compared to WT mice 2d post TAC, and CaMKII incubation with AiP mimics the AC3-I phenotype in cardiomyocytes from WT TAC mice in vitro. In summary, this suggests cardiac dysfunction due to CaMKII inhibition as a potential cause of increased mortality in AC3-I TAC mice. However, proarrhythmic spontaneous Ca2+ release events (SCR) appear less frequent in cardiomyocytes from AC3-I TAC mice than in WT TAC mice. CONCLUSIONS Our data indicate that excessive CaMKII inhibition as present in AC3-I transgenic mice leads to an impaired adaptation of ECC to hyperacute pressure overload resulting in diminished cardiac contractility and increased death. Thus, our data suggest that in pressure overload the activation of CaMKII is a pivotal, but previously unknown part of hyperacute stress physiology in the heart, while CaMKII inhibition, albeit potentially antiarrhythmic, can be detrimental. This should be taken into account for future studies with CaMKII inhibitors as therapeutic agents.
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15
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Ortmans S, Daval C, Aguilar M, Compagno P, Cadrin-Tourigny J, Dyrda K, Rivard L, Tadros R. Pharmacotherapy in inherited and acquired ventricular arrhythmia in structurally normal adult hearts. Expert Opin Pharmacother 2019; 20:2101-2114. [DOI: 10.1080/14656566.2019.1669561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Staniel Ortmans
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Charline Daval
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Martin Aguilar
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Electrophysiology service, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Pablo Compagno
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Julia Cadrin-Tourigny
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, Quebec, Canada
| | - Katia Dyrda
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Lena Rivard
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Electrophysiology service, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Rafik Tadros
- Electrophysiology service, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, Quebec, Canada
- Department of Physiology and Pharmacology, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada
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16
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Park SJ, Zhang D, Qi Y, Li Y, Lee KY, Bezzerides VJ, Yang P, Xia S, Kim SL, Liu X, Lu F, Pasqualini FS, Campbell PH, Geva J, Roberts AE, Kleber AG, Abrams DJ, Pu WT, Parker KK. Insights Into the Pathogenesis of Catecholaminergic Polymorphic Ventricular Tachycardia From Engineered Human Heart Tissue. Circulation 2019; 140:390-404. [PMID: 31311300 PMCID: PMC6750809 DOI: 10.1161/circulationaha.119.039711] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Modeling of human arrhythmias with induced pluripotent stem cell-derived cardiomyocytes has focused on single-cell phenotypes. However, arrhythmias are the emergent properties of cells assembled into tissues, and the impact of inherited arrhythmia mutations on tissue-level properties of human heart tissue has not been reported. METHODS Here, we report an optogenetically based, human engineered tissue model of catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmia caused by mutation of the cardiac ryanodine channel and triggered by exercise. We developed a human induced pluripotent stem cell-derived cardiomyocyte-based platform to study the tissue-level properties of engineered human myocardium. We investigated pathogenic mechanisms in CPVT by combining this novel platform with genome editing. RESULTS In our model, CPVT tissues were vulnerable to developing reentrant rhythms when stimulated by rapid pacing and catecholamine, recapitulating hallmark features of the disease. These conditions elevated diastolic Ca2+ levels and increased temporal and spatial dispersion of Ca2+ wave speed, creating a vulnerable arrhythmia substrate. Using Cas9 genome editing, we pinpointed a single catecholamine-driven phosphorylation event, ryanodine receptor-serine 2814 phosphorylation by Ca2+/calmodulin-dependent protein kinase II, that is required to unmask the arrhythmic potential of CPVT tissues. CONCLUSIONS Our study illuminates the molecular and cellular pathogenesis of CPVT and reveals a critical role of calmodulin-dependent protein kinase II-dependent reentry in the tissue-scale mechanism of this disease. We anticipate that this approach will be useful for modeling other inherited and acquired cardiac arrhythmias.
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Affiliation(s)
- Sung-Jin Park
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Donghui Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.).,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Yan Qi
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Yifei Li
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.).,Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu (Y.L.)
| | - Keel Yong Lee
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Vassilios J Bezzerides
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Pengcheng Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Shutao Xia
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Sean L Kim
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Xujie Liu
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Fujian Lu
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Francesco S Pasqualini
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Patrick H Campbell
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Judith Geva
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Amy E Roberts
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Andre G Kleber
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (A.G.K.)
| | - Dominic J Abrams
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - William T Pu
- Harvard Stem Cell Institute (W.T.P., K.K.P.), Harvard University, Cambridge, MA.,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Kevin Kit Parker
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA.,Harvard Stem Cell Institute (W.T.P., K.K.P.), Harvard University, Cambridge, MA.,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.).,Sogang-Harvard Research Center for Disease Biophysics, Sogang University, Seoul, South Korea (K.K.P.). Dr Park is currently at the Coulter Department of Biomedical Engineering, Georgia Institute of Technology, and Emory University School of Medicine, Atlanta
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17
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Thomas D, Christ T, Fabritz L, Goette A, Hammwöhner M, Heijman J, Kockskämper J, Linz D, Odening KE, Schweizer PA, Wakili R, Voigt N. German Cardiac Society Working Group on Cellular Electrophysiology state-of-the-art paper: impact of molecular mechanisms on clinical arrhythmia management. Clin Res Cardiol 2018; 108:577-599. [PMID: 30306295 DOI: 10.1007/s00392-018-1377-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/24/2018] [Indexed: 12/19/2022]
Abstract
Cardiac arrhythmias remain a common challenge and are associated with significant morbidity and mortality. Effective and safe rhythm control strategies are a primary, yet unmet need in everyday clinical practice. Despite significant pharmacological and technological advances, including catheter ablation and device-based therapies, the development of more effective alternatives is of significant interest to increase quality of life and to reduce symptom burden, hospitalizations and mortality. The mechanistic understanding of pathophysiological pathways underlying cardiac arrhythmias has advanced profoundly, opening up novel avenues for mechanism-based therapeutic approaches. Current management of arrhythmias, however, is primarily guided by clinical and demographic characteristics of patient groups as opposed to individual, patient-specific mechanisms and pheno-/genotyping. With this state-of-the-art paper, the Working Group on Cellular Electrophysiology of the German Cardiac Society aims to close the gap between advanced molecular understanding and clinical decision-making in cardiac electrophysiology. The significance of cellular electrophysiological findings for clinical arrhythmia management constitutes the main focus of this document. Clinically relevant knowledge of pathophysiological pathways of arrhythmias and cellular mechanisms of antiarrhythmic interventions are summarized. Furthermore, the specific molecular background for the initiation and perpetuation of atrial and ventricular arrhythmias and mechanism-based strategies for therapeutic interventions are highlighted. Current "hot topics" in atrial fibrillation are critically appraised. Finally, the establishment and support of cellular and translational electrophysiology programs in clinical rhythmology departments is called for to improve basic-science-guided patient management.
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Affiliation(s)
- Dierk Thomas
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany. .,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiovascular Medicine, Division of Rhythmology, University Hospital Münster, Münster, Germany
| | - Andreas Goette
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Matthias Hammwöhner
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jens Kockskämper
- Biochemical and Pharmacological Center (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Dominik Linz
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, SA, Australia.,Experimental Electrophysiology, University Hospital of Saarland, Homburg, Saar, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute for Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Freiburg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.,Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany
| | - Reza Wakili
- Department of Cardiology and Vascular Medicine, Medical Faculty, West German Heart Center, University Hospital Essen, Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany.
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18
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Bögeholz N, Pauls P, Bauer BK, Schulte JS, Frommeyer G, Dechering DG, Boknik P, Kirchhefer U, Müller FU, Pott C, Eckardt L. Overexpression of the Na + /Ca 2+ exchanger influences ouabain-mediated spontaneous Ca 2+ activity but not positive inotropy. Fundam Clin Pharmacol 2018; 33:43-51. [PMID: 30092622 DOI: 10.1111/fcp.12404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 07/16/2018] [Accepted: 08/01/2018] [Indexed: 12/01/2022]
Abstract
Administration of digitalis in heart failure (HF) increases quality of life but does not carry a prognostic benefit. Digitalis is an indirect inhibitor of the Na+ /Ca2+ exchanger (NCX), which is overexpressed in HF. We therefore used the cardiac glycoside ouabain in Ca2+ imaging experiments and patch-clamp experiments in isolated ventricular myocytes from nonfailing transgenic NCX overexpressor mice (OE). In field-stimulated myocytes, ouabain (1-100 μm) increased the amplitude of the Ca2+ transient in OE and wild-type (WT) similarly. Ouabain-mediated spontaneous Ca2+ -activity was significantly more pronounced in OE compared to WT myocytes at higher concentrations (100 μm). Also, at very high concentrations (1000 μm) of ouabain, the number of cells with hypercontraction leading to cell death was higher in OE. Ouabain (10 μm) shortened the action potential duration in both genotypes. Our findings suggest that the proarrhythmic but not the inotropic effects of cardiac glycosides are enhanced by increased NCX expression. This may offer an explanation for the observed lack of prognostic benefit but increased quality of life in HF, which is accompanied by NCX upregulation.
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Affiliation(s)
- Nils Bögeholz
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Paul Pauls
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany.,Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Bastian K Bauer
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Jan S Schulte
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Gerrit Frommeyer
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Dirk G Dechering
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Frank U Müller
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Christian Pott
- Department of Cardiology, Schüchtermann-Klinik, Ulmenallee 5-11, 49214, Bad Rothenfelde, Germany
| | - Lars Eckardt
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
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19
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Cao ZZ, Tian YJ, Hao J, Zhang PH, Liu ZP, Jiang WZ, Zeng ML, Zhang PP, Ma JH. Barbaloin inhibits ventricular arrhythmias in rabbits by modulating voltage-gated ion channels. Acta Pharmacol Sin 2018; 39:357-370. [PMID: 29072259 DOI: 10.1038/aps.2017.93] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/17/2017] [Indexed: 12/15/2022] Open
Abstract
Barbaloin (10-β-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone) is extracted from the aloe plant and has been reported to have anti-inflammatory, antitumor, antibacterial, and other biological activities. Here, we investigated the effects of barbaloin on cardiac electrophysiology, which has not been reported thus far. Cardiac action potentials (APs) and ionic currents were recorded in isolated rabbit ventricular myocytes using whole-cell patch-clamp technique. Additionally, the antiarrhythmic effect of barbaloin was examined in Langendorff-perfused rabbit hearts. In current-clamp recording, application of barbaloin (100 and 200 μmol/L) dose-dependently reduced the action potential duration (APD) and the maximum depolarization velocity (Vmax), and attenuated APD reverse-rate dependence (RRD) in ventricular myocytes. Furthermore, barbaloin (100 and 200 μmol/L) effectively eliminated ATX II-induced early afterdepolarizations (EADs) and Ca2+-induced delayed afterdepolarizations (DADs) in ventricular myocytes. In voltage-clamp recording, barbaloin (10-200 μmol/L) dose-dependently inhibited L-type calcium current (ICa.L) and peak sodium current (INa.P) with IC50 values of 137.06 and 559.80 μmol/L, respectively. Application of barbaloin (100, 200 μmol/L) decreased ATX II-enhanced late sodium current (INa.L) by 36.6%±3.3% and 71.8%±6.5%, respectively. However, barbaloin up to 800 μmol/L did not affect the inward rectifier potassium current (IK1) or the rapidly activated delayed rectifier potassium current (IKr) in ventricular myocytes. In Langendorff-perfused rabbit hearts, barbaloin (200 μmol/L) significantly inhibited aconitine-induced ventricular arrhythmias. These results demonstrate that barbaloin has potential as an antiarrhythmic drug.
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20
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Abstract
PURPOSE OF REVIEW Cardiomyopathies due to genetic mutations are a heterogeneous group of disorders that comprise diseases of contractility, myocardial relaxation, and arrhythmias. Our goal here is to discuss a limited list of genetically inherited cardiomyopathies and the specific therapeutic strategies used to treat them. RECENT FINDINGS Research into the molecular pathophysiology of the development of these cardiomyopathies is leading to the development of novel treatment approaches. Therapies targeting these specific mutations with gene therapy vectors are on the horizon, while other therapies which indirectly affect the physiologic derangements of the mutations are currently being studied and used clinically. Many of these therapies are older medications being given new roles such as mexiletine for Brugada syndrome and diflunisal for transthyretin amyloid cardiomyopathy. A newer targeted therapy, the inhibitor of myosin ATPase MYK-461, has been shown to suppress the development of ventricular hypertrophy, fibrosis, and myocyte disarray and is being studied as a potential therapy in patients with hypertrophic cardiomyopathy. While this field is too large to be completely contained in a single review, we present a large cross section of recent developments in the field of therapeutics for inherited cardiomyopathies. New therapies are on the horizon, and their development will likely result in improved outcomes for patients inflicted by these conditions.
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Affiliation(s)
- Kenneth Varian
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk J3-4, Cleveland, OH, 44195, USA
| | - W H Wilson Tang
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk J3-4, Cleveland, OH, 44195, USA. .,Center for Clinical Genomics, Cleveland Clinic, Cleveland, OH, USA.
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21
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Schweitzer MK, Wilting F, Sedej S, Dreizehnter L, Dupper NJ, Tian Q, Moretti A, My I, Kwon O, Priori SG, Laugwitz KL, Storch U, Lipp P, Breit A, Mederos y Schnitzler M, Gudermann T, Schredelseker J. Suppression of Arrhythmia by Enhancing Mitochondrial Ca 2+ Uptake in Catecholaminergic Ventricular Tachycardia Models. JACC Basic Transl Sci 2017; 2:737-747. [PMID: 29354781 PMCID: PMC5774336 DOI: 10.1016/j.jacbts.2017.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 11/30/2022]
Abstract
Cardiovascular disease-related deaths frequently arise from arrhythmias, but treatment options are limited due to perilous side effects of commonly used antiarrhythmic drugs. Cardiac rhythmicity strongly depends on cardiomyocyte Ca2+ handling and prevalent cardiac diseases are causally associated with perturbations in intracellular Ca2+ handling. Therefore, intracellular Ca2+ transporters are lead candidate structures for novel and safer antiarrhythmic therapies. Mitochondria and mitochondrial Ca2+ transport proteins are important regulators of cardiac Ca2+ handling. Here we evaluated the potential of pharmacological activation of mitochondrial Ca2+ uptake for the treatment of cardiac arrhythmia. To this aim,we tested substances that enhance mitochondrial Ca2+ uptake for their ability to suppress arrhythmia in a murine model for ryanodine receptor 2 (RyR2)-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT) in vitro and in vivo and in induced pluripotent stem cell-derived cardiomyocytes from a CPVT patient. In freshly isolated cardiomyocytes of RyR2R4496C/WT mice efsevin, a synthetic agonist of the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane, prevented the formation of diastolic Ca2+ waves and spontaneous action potentials. The antiarrhythmic effect of efsevin was abolished by blockade of the mitochondrial Ca2+ uniporter (MCU), but could be reproduced using the natural MCU activator kaempferol. Both mitochondrial Ca2+ uptake enhancers (MiCUps), efsevin and kaempferol, significantly reduced episodes of stress-induced ventricular tachycardia in RyR2R4496C/WT mice in vivo and abolished diastolic, arrhythmogenic Ca2+ events in human iPSC-derived cardiomyocytes.
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Affiliation(s)
- Maria K. Schweitzer
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Fabiola Wilting
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Simon Sedej
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Lisa Dreizehnter
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Nathan J. Dupper
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California
| | - Qinghai Tian
- Institute for Molecular Cell Biology, University Medical Center, Saarland University, Homburg/Saar, Germany
| | - Alessandra Moretti
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Ilaria My
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Ohyun Kwon
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California
| | - Silvia G. Priori
- Molecular Cardiology, Istituto di ricovero e cura a carattere scientifico (IRCCS) Salvatore Maugeri Foundation, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Karl-Ludwig Laugwitz
- Department of Medicine (Cardiology), Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Ursula Storch
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Peter Lipp
- Institute for Molecular Cell Biology, University Medical Center, Saarland University, Homburg/Saar, Germany
| | - Andreas Breit
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Mederos y Schnitzler
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner Site Munich Heart Alliance, Munich, Germany
| | - Johann Schredelseker
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
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22
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Liu Y, Wei J, Wong King Yuen SM, Sun B, Tang Y, Wang R, Van Petegem F, Chen SRW. CPVT-associated cardiac ryanodine receptor mutation G357S with reduced penetrance impairs Ca2+ release termination and diminishes protein expression. PLoS One 2017; 12:e0184177. [PMID: 28961276 PMCID: PMC5621672 DOI: 10.1371/journal.pone.0184177] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/18/2017] [Indexed: 11/18/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is one of the most lethal inherited cardiac arrhythmias mostly linked to cardiac ryanodine receptor (RyR2) mutations with high disease penetrance. Interestingly, a novel RyR2 mutation G357S discovered in a large family of more than 1400 individuals has reduced penetrance. The molecular basis for the incomplete disease penetrance in this family is unknown. To gain insights into the variable disease expression in this family, we determined the impact of the G357S mutation on RyR2 function and expression. We assessed spontaneous Ca2+ release in HEK293 cells expressing RyR2 wildtype and the G357S mutant during store Ca2+ overload, also known as store overload induced Ca2+ release (SOICR). We found that the G357S mutation reduced the percentage of RyR2-expressing cells that showed SOICR. However, in cells that displayed SOICR, G357S reduced the thresholds for the activation and termination of SOICR. Furthermore, G357S decreased the thermal stability of the N-terminal domain of RyR2, and markedly reduced the protein expression of the full-length RyR2. On the other hand, the G357S mutation did not alter the Ca2+ activation of [3H]ryanodine binding or the Ca2+ induced release of Ca2+ from the intracellular stores in HEK293 cells. These data indicate that the CPVT-associated G357S mutation enhances the arrhythmogenic SOICR and reduces RyR2 protein expression, which may be attributable to the incomplete penetrance of CPVT in this family.
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Affiliation(s)
- Yingjie Liu
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Siobhan M Wong King Yuen
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada
| | - Bo Sun
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Yijun Tang
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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23
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Maizels L, Huber I, Arbel G, Tijsen AJ, Gepstein A, Khoury A, Gepstein L. Patient-Specific Drug Screening Using a Human Induced Pluripotent Stem Cell Model of Catecholaminergic Polymorphic Ventricular Tachycardia Type 2. Circ Arrhythm Electrophysiol 2017. [PMID: 28630169 DOI: 10.1161/circep.116.004725] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Catecholaminergic polymorphic ventricular tachycardia type 2 (CPVT2) results from autosomal recessive CASQ2 mutations, causing abnormal Ca2+-handling and malignant ventricular arrhythmias. We aimed to establish a patient-specific human induced pluripotent stem cell (hiPSC) model of CPVT2 and to use the generated hiPSC-derived cardiomyocytes to gain insights into patient-specific disease mechanism and pharmacotherapy. METHODS AND RESULTS hiPSC cardiomyocytes were derived from a CPVT2 patient (D307H-CASQ2 mutation) and from healthy controls. Laser-confocal Ca2+ and voltage imaging showed significant Ca2+-transient irregularities, marked arrhythmogenicity manifested by early afterdepolarizations and triggered arrhythmias, and reduced threshold for store overload-induced Ca2+-release events in the CPVT2-hiPSC cardiomyocytes when compared with healthy control cells. Pharmacological studies revealed the prevention of adrenergic-induced arrhythmias by β-blockers (propranolol and carvedilol), flecainide, and the neuronal sodium-channel blocker riluzole; a direct antiarrhythmic action of carvedilol (independent of its α/β-adrenergic blocking activity), flecainide, and riluzole; and suppression of abnormal Ca2+ cycling by the ryanodine stabilizer JTV-519 and carvedilol. Mechanistic insights were gained on the different antiarrhythmic actions of the aforementioned drugs, with carvedilol and JTV-519 (but not flecainide or riluzole) acting primarily through sarcoplasmic reticulum stabilization. Finally, comparable outcomes were found between flecainide and labetalol antiarrhythmic effects in vitro and the clinical results in the same patient. CONCLUSIONS These results demonstrate the ability of hiPSCs cardiomyocytes to recapitulate CPVT2 disease phenotype and drug response in the culture dish, to provide novel insights into disease and drug therapy mechanisms, and potentially to tailor patient-specific drug therapy.
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Affiliation(s)
- Leonid Maizels
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Irit Huber
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Gil Arbel
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Anke J Tijsen
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Amira Gepstein
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Asaad Khoury
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.)
| | - Lior Gepstein
- From the Rappaport Faculty of Medicine and Research Institute (L.M., I.H., G.A., A.J.T., A.G., L.G.); and Rambam Health Care Campus; Technion-Institute of Technology; Haifa, Israel (A.K., L.G.).
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24
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Reduced threshold for store overload-induced Ca 2+ release is a common defect of RyR1 mutations associated with malignant hyperthermia and central core disease. Biochem J 2017; 474:2749-2761. [PMID: 28687594 DOI: 10.1042/bcj20170282] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/30/2017] [Accepted: 07/06/2017] [Indexed: 12/21/2022]
Abstract
Mutations in the skeletal muscle ryanodine receptor (RyR1) cause malignant hyperthermia (MH) and central core disease (CCD), whereas mutations in the cardiac ryanodine receptor (RyR2) lead to catecholaminergic polymorphic ventricular tachycardia (CPVT). Most disease-associated RyR1 and RyR2 mutations are located in the N-terminal, central, and C-terminal regions of the corresponding ryanodine receptor (RyR) isoform. An increasing body of evidence demonstrates that CPVT-associated RyR2 mutations enhance the propensity for spontaneous Ca2+ release during store Ca2+ overload, a process known as store overload-induced Ca2+ release (SOICR). Considering the similar locations of disease-associated RyR1 and RyR2 mutations in the RyR structure, we hypothesize that like CPVT-associated RyR2 mutations, MH/CCD-associated RyR1 mutations also enhance SOICR. To test this hypothesis, we determined the impact on SOICR of 12 MH/CCD-associated RyR1 mutations E2347-del, R2163H, G2434R, R2435L, R2435H, and R2454H located in the central region, and Y4796C, T4826I, L4838V, A4940T, G4943V, and P4973L located in the C-terminal region of the channel. We found that all these RyR1 mutations reduced the threshold for SOICR. Dantrolene, an acute treatment for MH, suppressed SOICR in HEK293 cells expressing the RyR1 mutants R164C, Y523S, R2136H, R2435H, and Y4796C. Interestingly, carvedilol, a commonly used β-blocker that suppresses RyR2-mediated SOICR, also inhibits SOICR in these RyR1 mutant HEK293 cells. Therefore, these results indicate that a reduced SOICR threshold is a common defect of MH/CCD-associated RyR1 mutations, and that carvedilol, like dantrolene, can suppress RyR1-mediated SOICR. Clinical studies of the effectiveness of carvedilol as a long-term treatment for MH/CCD or other RyR1-associated disorders may be warranted.
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Gómez-Hurtado N, Domínguez-Rodríguez A, Mateo P, Fernández-Velasco M, Val-Blasco A, Aizpún R, Sabourin J, Gómez AM, Benitah JP, Delgado C. Beneficial effects of leptin treatment in a setting of cardiac dysfunction induced by transverse aortic constriction in mouse. J Physiol 2017; 595:4227-4243. [PMID: 28374413 DOI: 10.1113/jp274030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/20/2017] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Leptin, is a 16 kDa pleiotropic peptide not only primarily secreted by adipocytes, but also produced by other tissues, including the heart. Controversy exists regarding the adverse and beneficial effects of leptin on the heart We analysed the effect of a non-hypertensive dose of leptin on cardiac function, [Ca2+ ]i handling and cellular electrophysiology, which participate in the genesis of pump failure and related arrhythmias, both in control mice and in mice subjected to chronic pressure-overload by transverse aorta constriction. We find that leptin activates mechanisms that contribute to cardiac dysfunction under physiological conditions. However, after the establishment of pressure overload, an increase in leptin levels has protective cardiac effects with respect to rescuing the cellular heart failure phenotype. These beneficial effects of leptin involve restoration of action potential duration via normalization of transient outward potassium current and sarcoplasmic reticulum Ca2+ content via rescue of control sarcoplasmic/endoplasmic reticulum Ca2+ ATPase levels and ryanodine receptor function modulation, leading to normalization of Ca2+ handling parameters. ABSTRACT Leptin, is a 16 kDa pleiotropic peptide not only primary secreted by adipocytes, but also produced by other tissues, including the heart. Evidence indicates that leptin may have either adverse or beneficial effects on the heart. To obtain further insights, in the present study, we analysed the effect of leptin treatment on cardiac function, [Ca2+ ]i handling and cellular electrophysiology, which participate in the genesis of pump failure and related arrhythmias, both in control mice and in mice subjected to chronic pressure-overload by transverse aorta constriction (TAC). Three weeks after surgery, animals received either leptin (0.36 mg kg-1 day-1 ) or vehicle via osmotic minipumps for 3 weeks. Echocardiographic measurements showed that, although leptin treatment was deleterious on cardiac function in sham, leptin had a cardioprotective effect following TAC. [Ca2+ ]i transient in cardiomyocytes followed similar pattern. Patch clamp experiments showed prolongation of action potential duration (APD) in TAC and leptin-treated sham animals, whereas, following TAC, leptin reduced the APD towards control values. APD variations were associated with decreased transient outward potassium current and Kv4.2 and KChIP2 protein expression. TAC myocytes showed a higher incidence of triggered activities and spontaneous Ca2+ waves. These proarrhythmic manifestations, related to Ca2+ /calmodulin-dependent protein kinase II and ryanodine receptor phosphorylation, were reduced by leptin. The results of the present study demonstrate that, although leptin treatment was deleterious on cardiac function in control animals, leptin had a cardioprotective effect following TAC, normalizing cardiac function and reducing arrhythmogeneity at the cellular level.
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Affiliation(s)
- Nieves Gómez-Hurtado
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain.,UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France.,Division of Clinical Pharmacology, Oates Institute for Experimental Therapeutics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Alejandro Domínguez-Rodríguez
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France.,Institute of Biomedicine of Seville/CIBER-CV, Seville, Spain
| | - Philippe Mateo
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | | | | | - Rafael Aizpún
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain
| | - Jessica Sabourin
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Ana María Gómez
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Jean-Pierre Benitah
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Carmen Delgado
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain.,Biomedical Research Institute Alberto Sols/CIBER-CV, Madrid, Spain
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Stochastic initiation and termination of calcium-mediated triggered activity in cardiac myocytes. Proc Natl Acad Sci U S A 2017; 114:E270-E279. [PMID: 28049836 DOI: 10.1073/pnas.1614051114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Cardiac myocytes normally initiate action potentials in response to a current stimulus that depolarizes the membrane above an excitation threshold. Aberrant excitation can also occur due to spontaneous calcium (Ca2+) release (SCR) from intracellular stores after the end of a preceding action potential. SCR drives the Na+/Ca2+ exchange current inducing a "delayed afterdepolarization" that can in turn trigger an action potential if the excitation threshold is reached. This "triggered activity" is known to cause arrhythmias, but how it is initiated and terminated is not understood. Using computer simulations of a ventricular myocyte model, we show that initiation and termination are inherently random events. We determine the probability of those events from statistical measurements of the number of beats before initiation and before termination, respectively, which follow geometric distributions. Moreover, we elucidate the origin of randomness by a statistical analysis of SCR events, which do not follow a Poisson process observed in other eukaryotic cells. Due to synchronization of Ca2+ releases during the action potential upstroke, waiting times of SCR events after the upstroke are narrowly distributed, whereas SCR amplitudes follow a broad normal distribution with a width determined by fluctuations in the number of independent Ca2+ wave foci. This distribution enables us to compute the probabilities of initiation and termination of bursts of triggered activity that are maintained by a positive feedback between the action potential upstroke and SCR. Our results establish a theoretical framework for interpreting complex and varied manifestations of triggered activity relevant to cardiac arrhythmias.
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Cardioprotection and lifespan extension by the natural polyamine spermidine. Nat Med 2016; 22:1428-1438. [PMID: 27841876 DOI: 10.1038/nm.4222] [Citation(s) in RCA: 751] [Impact Index Per Article: 93.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/24/2016] [Indexed: 12/13/2022]
Abstract
Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.
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del Canto I, Such-Miquel L, Brines L, Soler C, Zarzoso M, Calvo C, Parra G, Tormos Á, Alberola A, Millet J, Such L, Chorro FJ. Effects of JTV-519 on stretch-induced manifestations of mechanoelectric feedback. Clin Exp Pharmacol Physiol 2016; 43:1062-1070. [DOI: 10.1111/1440-1681.12630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 07/16/2016] [Accepted: 08/01/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Irene del Canto
- Department of Medicine; Valencia University “Estudi General”; Valencia Spain
| | - Luis Such-Miquel
- Department of Physiotherapy; Valencia University “Estudi General”; Valencia Spain
| | - Laia Brines
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Carlos Soler
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Manuel Zarzoso
- Department of Physiotherapy; Valencia University “Estudi General”; Valencia Spain
| | - Conrado Calvo
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Germán Parra
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Álvaro Tormos
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Antonio Alberola
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - José Millet
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Luis Such
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Francisco J. Chorro
- Department of Medicine; Valencia University “Estudi General”; Valencia Spain
- Department of Cardiology; Valencia University Clinic Hospital; INCLIVA; Valencia Spain
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Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) has emerged as key enzyme in many cardiac pathologies, especially heart failure (HF), myocardial infarction and cardiomyopathies, thus leading to contractile dysfunction and malignant arrhythmias. While many pathways leading to CaMKII activation have been elucidated in recent years, hardly any clinically viable compounds affecting CaMKII activity have progressed from basic in vitro science to in vivo studies. This review focuses on recent advances in anti-arrhythmic strategies involving CaMKII. Specifically, both inhibition of CaMKII itself to prevent arrhythmias, as well as anti-arrhythmic approaches affecting CaMKII activity via alterations in signaling cascades upstream and downstream of CaMKII will be discussed.
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Affiliation(s)
- Julian Mustroph
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany
| | - Stefan Neef
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany
| | - Lars S Maier
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany.
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30
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Choy L, Yeo JM, Tse V, Chan SP, Tse G. Cardiac disease and arrhythmogenesis: Mechanistic insights from mouse models. IJC HEART & VASCULATURE 2016; 12:1-10. [PMID: 27766308 PMCID: PMC5064289 DOI: 10.1016/j.ijcha.2016.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/02/2016] [Indexed: 12/19/2022]
Abstract
The mouse is the second mammalian species, after the human, in which substantial amount of the genomic information has been analyzed. With advances in transgenic technology, mutagenesis is now much easier to carry out in mice. Consequently, an increasing number of transgenic mouse systems have been generated for the study of cardiac arrhythmias in ion channelopathies and cardiomyopathies. Mouse hearts are also amenable to physical manipulation such as coronary artery ligation and transverse aortic constriction to induce heart failure, radiofrequency ablation of the AV node to model complete AV block and even implantation of a miniature pacemaker to induce cardiac dyssynchrony. Last but not least, pharmacological models, despite being simplistic, have enabled us to understand the physiological mechanisms of arrhythmias and evaluate the anti-arrhythmic properties of experimental agents, such as gap junction modulators, that may be exert therapeutic effects in other cardiac diseases. In this article, we examine these in turn, demonstrating that primary inherited arrhythmic syndromes are now recognized to be more complex than abnormality in a particular ion channel, involving alterations in gene expression and structural remodelling. Conversely, in cardiomyopathies and heart failure, mutations in ion channels and proteins have been identified as underlying causes, and electrophysiological remodelling are recognized pathological features. Transgenic techniques causing mutagenesis in mice are extremely powerful in dissecting the relative contributions of different genes play in producing disease phenotypes. Mouse models can serve as useful systems in which to explore how protein defects contribute to arrhythmias and direct future therapy.
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Affiliation(s)
- Lois Choy
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, SW7 2AZ, UK
| | - Vivian Tse
- Department of Physiology, McGill University, Canada
| | - Shing Po Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
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31
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Kornyeyev D, El-Bizri N, Hirakawa R, Nguyen S, Viatchenko-Karpinski S, Yao L, Rajamani S, Belardinelli L. Contribution of the late sodium current to intracellular sodium and calcium overload in rabbit ventricular myocytes treated by anemone toxin. Am J Physiol Heart Circ Physiol 2016; 310:H426-35. [DOI: 10.1152/ajpheart.00520.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 12/02/2015] [Indexed: 12/19/2022]
Abstract
Pathological enhancement of late Na+ current ( INa) can potentially modify intracellular ion homeostasis and contribute to cardiac dysfunction. We tested the hypothesis that modulation of late INa can be a source of intracellular Na+ ([Na+]i) overload. Late INa was enhanced by exposing rabbit ventricular myocytes to Anemonia sulcata toxin II (ATX-II) and measured using whole cell patch-clamp technique. [Na+]i was determined with fluorescent dye Asante NaTRIUM Green-2 AM. Pacing-induced changes in the dye fluorescence measured at 37°C were more pronounced in ATX-II-treated cells than in control (dye washout prevented calibration). At 22–24°C, resting [Na+]i was 6.6 ± 0.8 mM. Treatment with 5 nM ATX-II increased late INa 8.7-fold. [Na+]i measured after 2 min of electrical stimulation (1 Hz) was 10.8 ± 1.5 mM and 22.1 ± 1.6 mM ( P < 0.001) in the absence and presence of 5 nM ATX-II, respectively. Inhibition of late INa with GS-967 (1 μM) prevented Na+i accumulation. A strong positive correlation was observed between the late INa and the pacing-induced increase of [Na+]i ( R2 = 0.88) and between the rise in [Na+]i and the increases in cytosolic Ca2+ ( R2 = 0.96). ATX-II, tetrodotoxin, or GS-967 did not affect [Na+]i in quiescent myocytes suggesting that late INa was solely responsible for triggering the ATX-II effect on [Na+]i. Experiments with pinacidil and E4031 indicate that prolongation of the action potential contributes to as much as 50% of the [Na+]i overload associated with the increase in late INa caused by ATX-II. Enhancement of late INa can cause intracellular Na+ overload in ventricular myocytes.
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Affiliation(s)
- Dmytro Kornyeyev
- Department of Biology, Gilead Sciences Inc., Foster City, California
| | - Nesrine El-Bizri
- Department of Biology, Gilead Sciences Inc., Foster City, California
| | - Ryoko Hirakawa
- Department of Biology, Gilead Sciences Inc., Foster City, California
| | - Steven Nguyen
- Department of Biology, Gilead Sciences Inc., Foster City, California
| | | | - Lina Yao
- Department of Biology, Gilead Sciences Inc., Foster City, California
| | | | - Luiz Belardinelli
- Department of Biology, Gilead Sciences Inc., Foster City, California
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32
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Ashrafi R, Yon M, Pickavance L, Yanni Gerges J, Davis G, Wilding J, Jian K, Zhang H, Hart G, Boyett M. Altered Left Ventricular Ion Channel Transcriptome in a High-Fat-Fed Rat Model of Obesity: Insight into Obesity-Induced Arrhythmogenesis. J Obes 2016; 2016:7127898. [PMID: 27747100 PMCID: PMC5056006 DOI: 10.1155/2016/7127898] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 06/29/2016] [Accepted: 07/21/2016] [Indexed: 01/03/2023] Open
Abstract
Introduction. Obesity is increasingly common and is associated with an increased prevalence of cardiac arrhythmias. The aim of this study was to see whether in obesity there is proarrhythmic gene expression of ventricular ion channels and related molecules. Methods and Results. Rats were fed on a high-fat diet and compared to control rats on a normal diet (n = 8). After 8 weeks, rats on the high-fat diet showed significantly greater weight gain and higher adiposity. Left ventricle samples were removed at 8 weeks and mRNA expression of ion channels and other molecules was measured using qPCR. Obese rats had significant upregulation of Cav1.2, HCN4, Kir2.1, RYR2, NCX1, SERCA2a, and RYR2 mRNA and downregulation of ERG mRNA. In the case of HCN4, it was confirmed that there was a significant increase in protein expression. The potential effects of the mRNA changes on the ventricular action potential and intracellular Ca2+ transient were predicted using computer modelling. Modelling predicted prolongation of the ventricular action potential and an increase in the intracellular Ca2+ transient, both of which would be expected to be arrhythmogenic. Conclusion. High-fat diet causing obesity results in arrhythmogenic cardiac gene expression of ion channels and related molecules.
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Affiliation(s)
- Reza Ashrafi
- Department of Obesity & Endocrinology, Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, 4th Floor, UCD, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
- *Reza Ashrafi:
| | - Marianne Yon
- Department of Obesity & Endocrinology, Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, 4th Floor, UCD, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - Lucy Pickavance
- Department of Obesity & Endocrinology, Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, 4th Floor, UCD, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - Joseph Yanni Gerges
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, UK
| | - Gershan Davis
- Department of Obesity & Endocrinology, Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, 4th Floor, UCD, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - John Wilding
- Department of Obesity & Endocrinology, Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, 4th Floor, UCD, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - Kun Jian
- Biological Physics Group, School of Physics & Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester M13 9PL, UK
| | - Henggui Zhang
- Biological Physics Group, School of Physics & Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester M13 9PL, UK
| | - George Hart
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, UK
| | - Mark Boyett
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, UK
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Ferrantini C, Coppini R, Scellini B, Ferrara C, Pioner JM, Mazzoni L, Priori S, Cerbai E, Tesi C, Poggesi C. R4496C RyR2 mutation impairs atrial and ventricular contractility. ACTA ACUST UNITED AC 2015; 147:39-52. [PMID: 26666913 PMCID: PMC4692489 DOI: 10.1085/jgp.201511450] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 11/09/2015] [Indexed: 12/11/2022]
Abstract
A ryanodine receptor 2 mutation associated with catecholaminergic polymorphic ventricular tachycardia renders cardiomyocytes incapable of mediating a positive inotropic response. Ryanodine receptor (RyR2) is the major Ca2+ channel of the cardiac sarcoplasmic reticulum (SR) and plays a crucial role in the generation of myocardial force. Changes in RyR2 gating properties and resulting increases in its open probability (Po) are associated with Ca2+ leakage from the SR and arrhythmias; however, the effects of RyR2 dysfunction on myocardial contractility are unknown. Here, we investigated the possibility that a RyR2 mutation associated with catecholaminergic polymorphic ventricular tachycardia, R4496C, affects the contractile function of atrial and ventricular myocardium. We measured isometric twitch tension in left ventricular and atrial trabeculae from wild-type mice and heterozygous transgenic mice carrying the R4496C RyR2 mutation and found that twitch force was comparable under baseline conditions (30°C, 2 mM [Ca2+]o, 1 Hz). However, the positive inotropic responses to high stimulation frequency, 0.1 µM isoproterenol, and 5 mM [Ca2+]o were decreased in R4496C trabeculae, as was post-rest potentiation. We investigated the mechanisms underlying inotropic insufficiency in R4496C muscles in single ventricular myocytes. Under baseline conditions, the amplitude of the Ca2+ transient was normal, despite the reduced SR Ca2+ content. Under inotropic challenge, however, R4496C myocytes were unable to boost the amplitude of Ca2+ transients because they are incapable of properly increasing the amount of Ca2+ stored in the SR because of a larger SR Ca2+ leakage. Recovery of force in response to premature stimuli was faster in R4496C myocardium, despite the unchanged rates of recovery of L-type Ca2+ channel current (ICa-L) and SR Ca2+ content in single myocytes. A faster recovery from inactivation of the mutant R4496C channels could explain this behavior. In conclusion, changes in RyR2 channel gating associated with the R4496C mutation could be directly responsible for the alterations in both ventricular and atrial contractility. The increased RyR2 Po and fractional Ca2+ release from the SR induced by the R4496C mutation preserves baseline contractility despite a slight decrease in SR Ca2+ content, but cannot compensate for the inability to increase SR Ca2+ content during inotropic challenge.
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Affiliation(s)
- Cecilia Ferrantini
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Raffaele Coppini
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Beatrice Scellini
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Claudia Ferrara
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Josè Manuel Pioner
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Luca Mazzoni
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Silvia Priori
- IRCCS Fondazione Salvatore Maugeri, 27100 Pavia, Italy
| | - Elisabetta Cerbai
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Chiara Tesi
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
| | - Corrado Poggesi
- Center for Molecular Medicine and Applied Biophysics, University of Florence, 50121 Florence, Italy
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Abstract
Despite improvements in the therapy of underlying heart disease, sudden cardiac death is a major cause of death worldwide. Disturbed Na and Ca handling is known to be a major predisposing factor for life-threatening tachyarrhythmias. In cardiomyocytes, many ion channels and transporters, including voltage-gated Na and Ca channels, cardiac ryanodine receptors, Na/Ca-exchanger, and SR Ca-ATPase are involved in this regulation. We have learned a lot about the pathophysiological relevance of disturbed ion channel function from monogenetic disorders. Changes in the gating of a single ion channel and the activity of an ion pump suffice to dramatically increase the propensity for arrhythmias even in structurally normal hearts. Nevertheless, patients with heart failure with acquired dysfunction in many ion channels and transporters exhibit profound dysregulation of Na and Ca handling and Ca/calmodulin-dependent protein kinase and are especially prone to arrhythmias. A deeper understanding of the underlying arrhythmic principles is mandatory if we are to improve their outcome. This review addresses basic tachyarrhythmic mechanisms, the underlying ionic mechanisms and the consequences for ion homeostasis, and the situation in complex diseases like heart failure.
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Affiliation(s)
- Stefan Wagner
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.)
| | - Lars S Maier
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.).
| | - Donald M Bers
- From the Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany (S.W., L.S.M.); and Department of Pharmacology, University of California, Davis, CA (D.M.B.)
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Tadros R, Cadrin-Tourigny J, Abadir S, Rivard L, Nattel S, Talajic M, Khairy P. Pharmacotherapy for inherited arrhythmia syndromes: mechanistic basis, clinical trial evidence and practical application. Expert Rev Cardiovasc Ther 2015; 13:769-82. [DOI: 10.1586/14779072.2015.1049156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Maier LS. Some 'brain' in the heart: a novel microdomain with neuronal Na channels responsible for arrhythmias? Cardiovasc Res 2015; 106:4-5. [PMID: 25681398 DOI: 10.1093/cvr/cvv036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lars S Maier
- Department for Internal Medicine II, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, Regensburg 93053, Germany
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37
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Doleschal B, Primessnig U, Wölkart G, Wolf S, Schernthaner M, Lichtenegger M, Glasnov TN, Kappe CO, Mayer B, Antoons G, Heinzel F, Poteser M, Groschner K. TRPC3 contributes to regulation of cardiac contractility and arrhythmogenesis by dynamic interaction with NCX1. Cardiovasc Res 2015; 106:163-73. [PMID: 25631581 PMCID: PMC4362401 DOI: 10.1093/cvr/cvv022] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Aim TRPC3 is a non-selective cation channel, which forms a Ca2+ entry pathway involved in cardiac remodelling. Our aim was to analyse acute electrophysiological and contractile consequences of TRPC3 activation in the heart. Methods and results We used a murine model of cardiac TRPC3 overexpression and a novel TRPC3 agonist, GSK1702934A, to uncover (patho)physiological functions of TRPC3. GSK1702934A induced a transient, non-selective conductance and prolonged action potentials in TRPC3-overexpressing myocytes but lacked significant electrophysiological effects in wild-type myocytes. GSK1702934A transiently enhanced contractility and evoked arrhythmias in isolated Langendorff hearts from TRPC3-overexpressing but not wild-type mice. Interestingly, pro-arrhythmic effects outlasted TRPC3 current activation, were prevented by enhanced intracellular Ca2+ buffering, and suppressed by the NCX inhibitor 3′,4′-dichlorobenzamil hydrochloride. GSK1702934A substantially promoted NCX currents in TRPC3-overexpressing myocytes. The TRPC3-dependent electrophysiologic, pro-arrhythmic, and inotropic actions of GSK1702934A were mimicked by angiotensin II (AngII). Immunocytochemistry demonstrated colocalization of TRPC3 with NCX1 and disruption of local interaction upon channel activation by either GSK1702934A or AngII. Conclusion Cardiac TRPC3 mediates Ca2+ and Na+ entry in proximity of NCX1, thereby elevating cellular Ca2+ levels and contractility. Excessive activation of TRPC3 is associated with transient cellular Ca2+ overload, spatial uncoupling between TRPC3 and NCX1, and arrhythmogenesis. We propose TRPC3-NCX micro/nanodomain communication as determinant of cardiac contractility and susceptibility to arrhythmogenic stimuli.
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Affiliation(s)
| | - Uwe Primessnig
- Department of Cardiology, Medical University of Graz, Graz, Austria Ludwig Boltzmann Institute of Translational Heart Failure Research, Graz, Austria
| | - Gerald Wölkart
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Stefan Wolf
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Michaela Schernthaner
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | | | - Toma N Glasnov
- Institute of Chemistry, University of Graz, Graz, Austria Christian Doppler Laboratory for Continuous Flow Chemistry, Institute of Chemistry, University of Graz, Graz, Austria
| | - C Oliver Kappe
- Institute of Chemistry, University of Graz, Graz, Austria
| | - Bernd Mayer
- Institute of Pharmaceutical Sciences, University of Graz, Graz, Austria
| | - Gudrun Antoons
- Department of Cardiology, Medical University of Graz, Graz, Austria Ludwig Boltzmann Institute of Translational Heart Failure Research, Graz, Austria
| | - Frank Heinzel
- Department of Cardiology, Medical University of Graz, Graz, Austria Ludwig Boltzmann Institute of Translational Heart Failure Research, Graz, Austria
| | - Michael Poteser
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
| | - Klaus Groschner
- Ludwig Boltzmann Institute of Translational Heart Failure Research, Graz, Austria Institute of Biophysics, Medical University of Graz, Harrachgasse 21, Graz 8010, Austria
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Dobrev D, Wehrens XHT. Role of RyR2 phosphorylation in heart failure and arrhythmias: Controversies around ryanodine receptor phosphorylation in cardiac disease. Circ Res 2014; 114:1311-9; discussion 1319. [PMID: 24723656 DOI: 10.1161/circresaha.114.300568] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiac ryanodine receptor type 2 plays a key role in excitation-contraction coupling. The ryanodine receptor type 2 channel protein is modulated by various post-translational modifications, including phosphorylation by protein kinase A and Ca(2+)/calmodulin protein kinase II. Despite extensive research in this area, the functional effects of ryanodine receptor type 2 phosphorylation remain disputed. In particular, the potential involvement of increased ryanodine receptor type 2 phosphorylation in the pathogenesis of heart failure and arrhythmias remains a controversial area, which is discussed in this review article.
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Affiliation(s)
- Dobromir Dobrev
- From the Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (D.D.); and Cardiovascular Research Institute, Departments of Molecular Physiology and Biophysics, and Medicine-Cardiology, Baylor College of Medicine, Houston, TX (X.H.T.W.)
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Driessen HE, Bourgonje VJA, van Veen TAB, Vos MA. New antiarrhythmic targets to control intracellular calcium handling. Neth Heart J 2014; 22:198-213. [PMID: 24733689 PMCID: PMC4016334 DOI: 10.1007/s12471-014-0549-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sudden cardiac death due to ventricular arrhythmias is a major problem. Drug therapies to prevent SCD do not provide satisfying results, leading to the demand for new antiarrhythmic strategies. New targets include Ca2+/Calmodulin-dependent protein kinase II (CaMKII), the Na/Ca exchanger (NCX), the Ryanodine receptor (RyR, and its associated protein FKBP12.6 (Calstabin)) and the late component of the sodium current (INa-Late), all related to intracellular calcium (Ca2+) handling. In this review, drugs interfering with these targets (SEA-0400, K201, KN-93, W7, ranolazine, sophocarpine, and GS-967) are evaluated and their future as clinical compounds is considered. These new targets prove to be interesting; however more insight into long-term drug effects is necessary before clinical applicability becomes reality.
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Affiliation(s)
- H E Driessen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, the Netherlands,
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Harraz OF, Altier C. STIM1-mediated bidirectional regulation of Ca(2+) entry through voltage-gated calcium channels (VGCC) and calcium-release activated channels (CRAC). Front Cell Neurosci 2014; 8:43. [PMID: 24605083 PMCID: PMC3932444 DOI: 10.3389/fncel.2014.00043] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/29/2014] [Indexed: 11/13/2022] Open
Abstract
The spatial and temporal regulation of cellular calcium signals is modulated via two main Ca(2+) entry routes. Voltage-gated Ca(2+) channels (VGCC) and Ca(2+)-release activated channels (CRAC) enable Ca(2+) flow into electrically excitable and non-excitable cells, respectively. VGCC are well characterized transducers of electrical activity that allow Ca(2+) signaling into the cell in response to action potentials or subthreshold depolarizing stimuli. The identification of STromal Interaction Molecule (STIM) and Orai proteins has provided significant insights into the understanding of CRAC function and regulation. This review will summarize the current state of knowledge of STIM-Orai interaction and their contribution to cellular Ca(2+) handling mechanisms. We will then discuss the bidirectional actions of STIM1 on VGCC and CRAC. In contrast to the stimulatory role of STIM1 on Orai channel activity that facilitates Ca(2+) entry, recent reports indicated the ability of STIM1 to suppress VGCC activity. This new concept changes our traditional understanding of Ca(2+) handling mechanisms and highlights the existence of dynamically regulated signaling complexes of surface expressed ion channels and intracellular store membrane-embedded Ca(2+) sensors. Overall, STIM1 is emerging as a new class of regulatory proteins that fine-tunes Ca(2+) entry in response to endoplasmic/sarcoplasmic reticulum stress.
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Affiliation(s)
- Osama F Harraz
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Libin Cardiovascular Institute, University of Calgary Calgary, AB, Canada ; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University Alexandria, Egypt
| | - Christophe Altier
- Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases, Inflammation Research Network, University of Calgary Calgary, AB, Canada
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DeSantiago J, Bare DJ, Xiao L, Ke Y, Solaro RJ, Banach K. p21-Activated kinase1 (Pak1) is a negative regulator of NADPH-oxidase 2 in ventricular myocytes. J Mol Cell Cardiol 2014; 67:77-85. [PMID: 24380729 PMCID: PMC3930036 DOI: 10.1016/j.yjmcc.2013.12.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 12/19/2013] [Accepted: 12/21/2013] [Indexed: 12/20/2022]
Abstract
Ischemic conditions reduce the activity of the p21-activated kinase (Pak1) resulting in increased arrhythmic activity. Triggered arrhythmic activity during ischemia is based on changes in cellular ionic balance and the cells Ca(2+) handling properties. In the current study we used isolated mouse ventricular myocytes (VMs) deficient for the expression of Pak1 (Pak1(-/-)) to determine the mechanism by which Pak1 influences the generation of arrhythmic activity during simulated ischemia. The Ca(2+) transient amplitude and kinetics did not significantly change in wild type (WT) and Pak1(-/-) VMs during 15 min of simulated ischemia. However, Pak1(-/-) VMs exhibited an exaggerated increase in [Ca(2+)]i, which resulted in spontaneous Ca(2+) release events and waves. The Ca(2+) overload in Pak1(-/-) VMs could be suppressed with a reverse mode blocker (KB-R7943) of the sodium calcium exchanger (NCX), a cytoplasmic scavenger of reactive oxygen species (ROS; TEMPOL) or a RAC1 inhibitor (NSC23766). Measurements of the cytoplasmic ROS levels revealed that decreased Pak1 activity in Pak1(-/-) VMs or VMs treated with the Pak1 inhibitor (IPA3) enhanced cellular ROS production. The Pak1 dependent increase in ROS was attenuated in VMs deficient for NADPH oxidase 2 (NOX2; p47(phox-/-)) or in VMs where NOX2 was inhibited (gp91ds-tat). Voltage clamp recordings showed increased NCX activity in Pak1(-/-) VMs that depended on enhanced NOX2 induced ROS production. The exaggerated Ca(2+) overload in Pak1(-/-) VMs could be mimicked by low concentrations of ouabain. Overall our data show that Pak1 is a critical negative regulator of NOX2 dependent ROS production and that a latent ROS dependent stimulation of NCX activity can predispose VMs to Ca(2+) overload under conditions where no significant changes in excitation-contraction coupling are yet evident.
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Affiliation(s)
- Jaime DeSantiago
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Medicine, Section of Cardiology, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - Dan J Bare
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Medicine, Section of Cardiology, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - Lei Xiao
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Medicine, Section of Cardiology, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Pulmonary, Critical Care, Sleep and Allergy, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - Yunbo Ke
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Physiology and Biophysics, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - R John Solaro
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Physiology and Biophysics, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - Kathrin Banach
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA; Department of Medicine, Section of Cardiology, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA.
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The ryanodine receptor store-sensing gate controls Ca2+ waves and Ca2+-triggered arrhythmias. Nat Med 2014; 20:184-92. [PMID: 24441828 DOI: 10.1038/nm.3440] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 12/03/2013] [Indexed: 12/12/2022]
Abstract
Spontaneous Ca(2+) release from intracellular stores is important for various physiological and pathological processes. In cardiac muscle cells, spontaneous store overload-induced Ca(2+) release (SOICR) can result in Ca(2+) waves, a major cause of ventricular tachyarrhythmias (VTs) and sudden death. The molecular mechanism underlying SOICR has been a mystery for decades. Here we show that a point mutation, E4872A, in the helix bundle crossing region (the proposed gate) of the cardiac ryanodine receptor (RyR2) completely abolishes luminal, but not cytosolic, Ca(2+) activation of RyR2. The introduction of metal-binding histidines at this site converts RyR2 into a luminal Ni(2+)-gated channel. Mouse hearts harboring a heterozygous RyR2 mutation at this site (E4872Q) are resistant to SOICR and are completely protected against Ca(2+)-triggered VTs. These data show that the RyR2 gate directly senses luminal (store) Ca(2+), explaining the regulation of RyR2 by luminal Ca(2+), the initiation of Ca(2+) waves and Ca(2+)-triggered arrhythmias. This newly identified store-sensing gate structure is conserved in all RyR and inositol 1,4,5-trisphosphate receptor isoforms.
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De Giusti VC, Ciancio MC, Orlowski A, Aiello EA. Modulation of the cardiac sodium/bicarbonate cotransporter by the renin angiotensin aldosterone system: pathophysiological consequences. Front Physiol 2014; 4:411. [PMID: 24478712 PMCID: PMC3894460 DOI: 10.3389/fphys.2013.00411] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/27/2013] [Indexed: 12/22/2022] Open
Abstract
The sodium/bicarbonate cotransporter (NBC) is one of the major alkalinizing mechanisms in the cardiomyocytes. It has been demonstrated the existence of at least two functional isoforms, one that promotes the co-influx of 1 molecule of Na+ per 1 molecule of HCO−3 (electroneutral isoform; NBCn1) and the other one that generates the co-influx of 1 molecule of Na+ per 2 molecules of HCO−3 (electrogenic isoform; NBCe1). Both isoforms are important to maintain intracellular pH (pHi) and sodium concentration ([Na+]i). In addition, NBCe1 generates an anionic repolarizing current that modulates the action potential duration (APD). The renin-angiotensin-aldosterone system (RAAS) is implicated in the modulation of almost all physiological cardiac functions and is also involved in the development and progression of cardiac diseases. It was reported that angiotensin II (Ang II) exhibits an opposite effect on NBC isoforms: it activates NBCn1 and inhibits NBCe1. The activation of NBCn1 leads to an increase in pHi and [Na+]i, which indirectly, due to the stimulation of reverse mode of the Na+/Ca2+ exchanger (NCX), conduces to an increase in the intracellular Ca2+ concentration. On the other hand, the inhibition of NBCe1 generates an APD prolongation, potentially representing a risk of arrhythmias. In the last years, the potentially altered NBC function in pathological scenarios, as cardiac hypertrophy and ischemia-reperfusion, has raised increasing interest among investigators. This review attempts to draw the attention on the relevant regulation of NBC activity by RAAS, since it modulates pHi and [Na+]i, which are involved in the development of cardiac hypertrophy, the damage produced by ischemia-reperfusion and the generation of arrhythmic events, suggesting a potential role of NBC in cardiac diseases.
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Affiliation(s)
- Verónica C De Giusti
- Facultad de Ciencias Médicas, Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, CONICET-La Plata La Plata, Argentina
| | - María C Ciancio
- Facultad de Ciencias Médicas, Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, CONICET-La Plata La Plata, Argentina
| | - Alejandro Orlowski
- Facultad de Ciencias Médicas, Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, CONICET-La Plata La Plata, Argentina
| | - Ernesto A Aiello
- Facultad de Ciencias Médicas, Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, CONICET-La Plata La Plata, Argentina
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Morotti S, Edwards AG, McCulloch AD, Bers DM, Grandi E. A novel computational model of mouse myocyte electrophysiology to assess the synergy between Na+ loading and CaMKII. J Physiol 2014; 592:1181-97. [PMID: 24421356 DOI: 10.1113/jphysiol.2013.266676] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ca(2+)-calmodulin-dependent protein kinase II (CaMKII) hyperactivity in heart failure causes intracellular Na(+) ([Na(+)]i) loading (at least in part by enhancing the late Na(+) current). This [Na(+)]i gain promotes intracellular Ca(2+) ([Ca(2+)]i) overload by altering the equilibrium of the Na(+)-Ca(2+) exchanger to impair forward-mode (Ca(2+) extrusion), and favour reverse-mode (Ca(2+) influx) exchange. In turn, this Ca(2+) overload would be expected to further activate CaMKII and thereby form a pathological positive feedback loop of ever-increasing CaMKII activity, [Na(+)]i, and [Ca(2+)]i. We developed an ionic model of the mouse ventricular myocyte to interrogate this potentially arrhythmogenic positive feedback in both control conditions and when CaMKIIδC is overexpressed as in genetically engineered mice. In control conditions, simulation of increased [Na(+)]i causes the expected increases in [Ca(2+)]i, CaMKII activity, and target phosphorylation, which degenerate into unstable Ca(2+) handling and electrophysiology at high [Na(+)]i gain. Notably, clamping CaMKII activity to basal levels ameliorates but does not completely offset this outcome, suggesting that the increase in [Ca(2+)]i per se plays an important role. The effect of this CaMKII-Na(+)-Ca(2+)-CaMKII feedback is more striking in CaMKIIδC overexpression, where high [Na(+)]i causes delayed afterdepolarizations, which can be prevented by imposing low [Na(+)]i, or clamping CaMKII phosphorylation of L-type Ca(2+) channels, ryanodine receptors and phospholamban to basal levels. In this setting, Na(+) loading fuels a vicious loop whereby increased CaMKII activation perturbs Ca(2+) and membrane potential homeostasis. High [Na(+)]i is also required to produce instability when CaMKII is further activated by increased Ca(2+) loading due to β-adrenergic activation. Our results support recent experimental findings of a synergistic interaction between perturbed Na(+) fluxes and CaMKII, and suggest that pharmacological inhibition of intracellular Na(+) loading can contribute to normalizing Ca(2+) and membrane potential dynamics in heart failure.
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Affiliation(s)
- S Morotti
- Department of Pharmacology, University of California Davis, 451 Health Sciences Drive, GBSF rm 3502, Davis, CA 95616, USA.
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Sedej S, Schmidt A, Denegri M, Walther S, Matovina M, Arnstein G, Gutschi EM, Windhager I, Ljubojević S, Negri S, Heinzel FR, Bisping E, Vos MA, Napolitano C, Priori SG, Kockskämper J, Pieske B. Subclinical abnormalities in sarcoplasmic reticulum Ca(2+) release promote eccentric myocardial remodeling and pump failure death in response to pressure overload. J Am Coll Cardiol 2013; 63:1569-79. [PMID: 24315909 DOI: 10.1016/j.jacc.2013.11.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/31/2013] [Accepted: 11/01/2013] [Indexed: 12/26/2022]
Abstract
OBJECTIVES This study sought to explore whether subclinical alterations of sarcoplasmic reticulum (SR) Ca(2+) release through cardiac ryanodine receptors (RyR2) aggravate cardiac remodeling in mice carrying a human RyR2(R4496C+/-) gain-of-function mutation in response to pressure overload. BACKGROUND RyR2 dysfunction causes increased diastolic SR Ca(2+) release associated with arrhythmias and contractile dysfunction in inherited and acquired cardiac diseases, such as catecholaminergic polymorphic ventricular tachycardia and heart failure (HF). METHODS Functional and structural properties of wild-type and catecholaminergic polymorphic ventricular tachycardia-associated RyR2(R4496C+/-) hearts were characterized under conditions of pressure overload induced by transverse aortic constriction (TAC). RESULTS Wild-type and RyR2(R4496C+/-) hearts had comparable structural and functional properties at baseline. After TAC, RyR2(R4496C+/-) hearts responded with eccentric hypertrophy, substantial fibrosis, ventricular dilation, and reduced fractional shortening, ultimately resulting in overt HF. RyR2(R4496C+/-)-TAC cardiomyocytes showed increased incidence of spontaneous SR Ca(2+) release events, reduced Ca(2+) transient peak amplitude, and SR Ca(2+) content as well as reduced SR Ca(2+)-ATPase 2a and increased Na(+)/Ca(2+)-exchanger protein expression. HF phenotype in RyR2(R4496C+/-)-TAC mice was associated with increased mortality due to pump failure but not tachyarrhythmic events. RyR2-stabilizer K201 markedly reduced Ca(2+) spark frequency in RyR2(R4496C+/-)-TAC cardiomyocytes. Mini-osmotic pump infusion of K201 prevented deleterious remodeling and improved survival in RyR2(R4496C+/-)-TAC mice. CONCLUSIONS The combination of subclinical congenital alteration of SR Ca(2+) release and pressure overload promoted eccentric remodeling and HF death in RyR2(R4496C+/-) mice, and pharmacological RyR2 stabilization prevented this deleterious interaction. These findings suggest potential clinical relevance for patients with acquired or inherited gain-of-function of RyR2-mediated SR Ca(2+) release.
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Affiliation(s)
- Simon Sedej
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria.
| | - Albrecht Schmidt
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Marco Denegri
- IRCCS Salvatore Maugeri Foundation and Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Stefanie Walther
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Marinko Matovina
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Georg Arnstein
- Department of Cardiology, Medical University of Graz, Graz, Austria
| | - Eva-Maria Gutschi
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
| | | | - Senka Ljubojević
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
| | - Sara Negri
- IRCCS Salvatore Maugeri Foundation and Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Frank R Heinzel
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
| | - Egbert Bisping
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Carlo Napolitano
- IRCCS Salvatore Maugeri Foundation and Department of Molecular Medicine, University of Pavia, Pavia, Italy; Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York
| | - Silvia G Priori
- IRCCS Salvatore Maugeri Foundation and Department of Molecular Medicine, University of Pavia, Pavia, Italy; Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York
| | - Jens Kockskämper
- Institute of Pharmacology and Clinical Pharmacy, Philipps-University of Marburg, Marburg, Germany
| | - Burkert Pieske
- Department of Cardiology, Medical University of Graz, Graz, Austria; Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria.
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Aiello EA, De Giusti VC. Regulation of the cardiac sodium/bicarbonate cotransporter by angiotensin II: potential Contribution to structural, ionic and electrophysiological myocardial remodelling. Curr Cardiol Rev 2013; 9:24-32. [PMID: 23116057 PMCID: PMC3584305 DOI: 10.2174/157340313805076340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 08/15/2012] [Accepted: 09/13/2012] [Indexed: 12/15/2022] Open
Abstract
The sodium/ bicarbonate cotransporter (NBC) is, with the Na+/H+ exchanger (NHE), an important alkalinizing mechanism that maintains cellular intracellular pH (pHi). In the heart exists at least three isoforms of NBC, one that promotes the co-influx of 1 molecule of Na+ per 1molecule of HCO3-(electroneutral isoform; nNBC) and two others that generates the co-influx of 1 molecule of Na+ per 2 molecules of HCO3- (electrogenic isoforms; eNBC). In addition, the eNBC generates an anionic repolarizing current that modulate the cardiac action potential (CAP), adding to such isoforms the relevance to modulate the electrophysiological function of the heart. Angiotensin II (Ang II) is one of the main hormones that regulate cardiac physiology. The alkalinizing mechanisms (NHE and NBC) are stimulated by Ang II, increasing pHi and intracellular Na+ concentration, which indirectly, due to the stimulation of the Na+/Ca2+ exchanger (NCX) operating in the reverse form, leads to an increase in the intracellular Ca2+ concentration. Interestingly, it has been shown that Ang II exhibits an opposite effect on NBC isoforms: it activates the nNBC and inhibits the eNBC. This inhibition generates a CAP prolongation, which could directly increase the intracellular Ca2+ concentration. The regulation of the intracellular Na+ and Ca2+ concentrations is crucial for the cardiac cellular physiology, but these ions are also involved in the development of cardiac hypertrophy and the damage produced by ischemia-reperfusion, suggesting a potential role of NBC in cardiac diseases.
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Affiliation(s)
- Ernesto Alejandro Aiello
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900, La Plata, Argentina.
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The CPVT-associated RyR2 mutation G230C enhances store overloadinduced Ca2+ release and destabilizes the N-terminal domains. Biochem J 2013; 454:123-31. [DOI: 10.1042/bj20130594] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CPVT (catecholaminergic polymorphic ventricular tachycardia) is an inherited life-threatening arrhythmogenic disorder. CPVT is caused by DADs (delayed after-depolarizations) that are induced by spontaneous Ca2+ release during SR (sarcoplasmic reticulum) Ca2+ overload, a process also known as SOICR (store-overload-induced Ca2+ release). A number of mutations in the cardiac ryanodine receptor RyR2 are linked to CPVT. Many of these CPVT-associated RyR2 mutations enhance the propensity for SOICR and DADs by sensitizing RyR2 to luminal or luminal/cytosolic Ca2+ activation. Recently, a novel CPVT RyR2 mutation, G230C, was found to increase the cytosolic, but not the luminal, Ca2+ sensitivity of single RyR2 channels in lipid bilayers. This observation led to the suggestion of a SOICR-independent disease mechanism for the G230C mutation. However, the cellular impact of this mutation on SOICR is yet to be determined. To this end, we generated stable inducible HEK (human embryonic kidney)-293 cell lines expressing the RyR2 WT (wild-type) and the G230C mutant. Using single-cell Ca2+ imaging, we found that the G230C mutation markedly enhanced the propensity for SOICR and reduced the SOICR threshold. Furthermore, the G230C mutation increased the sensitivity of single RyR2 channels to both luminal and cytosolic Ca2+ activation and the Ca2+-dependent activation of [3H]ryanodine binding. In addition, the G230C mutation decreased the thermal stability of the N-terminal region (amino acids 1–547) of RyR2. These data suggest that the G230C mutation enhances the propensity for SOICR by sensitizing the channel to luminal and cytosolic Ca2+ activation, and that G230C has an intrinsic structural impact on the N-terminal domains of RyR2.
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Bai Y, Jones PP, Guo J, Zhong X, Clark RB, Zhou Q, Wang R, Vallmitjana A, Benitez R, Hove-Madsen L, Semeniuk L, Guo A, Song LS, Duff HJ, Chen SRW. Phospholamban knockout breaks arrhythmogenic Ca²⁺ waves and suppresses catecholaminergic polymorphic ventricular tachycardia in mice. Circ Res 2013; 113:517-26. [PMID: 23856523 DOI: 10.1161/circresaha.113.301678] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE Phospholamban (PLN) is an inhibitor of cardiac sarco(endo)plasmic reticulum Ca²⁺ ATPase. PLN knockout (PLN-KO) enhances sarcoplasmic reticulum Ca²⁺ load and Ca²⁺ leak. Conversely, PLN-KO accelerates Ca²⁺ sequestration and aborts arrhythmogenic spontaneous Ca²⁺ waves (SCWs). An important question is whether these seemingly paradoxical effects of PLN-KO exacerbate or protect against Ca²⁺-triggered arrhythmias. OBJECTIVE We investigate the impact of PLN-KO on SCWs, triggered activities, and stress-induced ventricular tachyarrhythmias (VTs) in a mouse model of cardiac ryanodine-receptor (RyR2)-linked catecholaminergic polymorphic VT. METHODS AND RESULTS We generated a PLN-deficient, RyR2-mutant mouse model (PLN-/-/RyR2-R4496C+/-) by crossbreeding PLN-KO mice with catecholaminergic polymorphic VT-associated RyR2-R4496C mutant mice. Ca²⁺ imaging and patch-clamp recording revealed cell-wide propagating SCWs and triggered activities in RyR2-R4496C+/- ventricular myocytes during sarcoplasmic reticulum Ca²⁺ overload. PLN-KO fragmented these cell-wide SCWs into mini-waves and Ca²⁺ sparks and suppressed the triggered activities evoked by sarcoplasmic reticulum Ca²⁺ overload. Importantly, these effects of PLN-KO were reverted by partially inhibiting sarco(endo)plasmic reticulum Ca²⁺ ATPase with 2,5-di-tert-butylhydroquinone. However, Bay K, caffeine, or Li⁺ failed to convert mini-waves to cell-wide SCWs in PLN-/-/RyR2-R4496C+/- ventricular myocytes. Furthermore, ECG analysis showed that PLN-KO mice are not susceptible to stress-induced VTs. On the contrary, PLN-KO protected RyR2-R4496C mutant mice from stress-induced VTs. CONCLUSIONS Our results demonstrate that despite severe sarcoplasmic reticulum Ca²⁺ leak, PLN-KO suppresses triggered activities and stress-induced VTs in a mouse model of catecholaminergic polymorphic VT. These data suggest that breaking up cell-wide propagating SCWs by enhancing Ca²⁺ sequestration represents an effective approach for suppressing Ca²⁺-triggered arrhythmias.
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Affiliation(s)
- Yunlong Bai
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
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Lascano EC, Said M, Vittone L, Mattiazzi A, Mundiña-Weilenmann C, Negroni JA. Role of CaMKII in post acidosis arrhythmias: a simulation study using a human myocyte model. J Mol Cell Cardiol 2013; 60:172-83. [PMID: 23624090 DOI: 10.1016/j.yjmcc.2013.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/15/2013] [Accepted: 04/15/2013] [Indexed: 02/08/2023]
Abstract
Postacidotic arrhythmias have been associated to increased sarcoplasmic reticulum (SR) Ca(2+) load and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation. However, the molecular mechanisms underlying these arrhythmias are still unclear. To better understand this process, acidosis produced by CO2 increase from 5% to 30%, resulting in intracellular pH (pHi) change from 7.15 to 6.7, was incorporated into a myocyte model of excitation-contraction coupling and contractility, including acidotic inhibition of L-type Ca(2+) channel (I(CaL)), Na(+)-Ca(2+) exchanger, Ca(2+) release through the SR ryanodine receptor (RyR2) (I(rel)), Ca(2+) reuptake by the SR Ca(2+) ATPase2a (I(up)), Na(+)-K(+) pump, K(+) efflux through the inward rectifier K(+) channel and the transient outward K(+) flow (I(to)) together with increased activity of the Na(+)-H(+) exchanger (I(NHE)). Simulated CaMKII regulation affecting I(rel), I(up), I(CaL), I(NHE) and I(to) was introduced in the model to partially compensate the acidosis outcome. Late Na(+) current increase by CaMKII was also incorporated. Using this scheme and assuming that diastolic Ca(2+) leak through the RyR2 was modulated by the resting state of this channel and the difference between SR and dyadic cleft [Ca(2+)], postacidotic delayed after depolarizations (DADs) were triggered upon returning to normal pHi after 6 min acidosis. The model showed that DADs depend on SR Ca(2+) load and on increased Ca(2+) leak through RyR2. This postacidotic arrhythmogenic pattern relies mainly on CaMKII effect on I(CaL) and I(up), since its individual elimination produced the highest DAD reduction. The model further revealed that during the return to normal pHi, DADs are fully determined by SR Ca(2+) load at the end of acidosis. Thereafter, DADs are maintained by SR Ca(2+) reloading by Ca(2+) influx through the reverse NCX mode during the time period in which [Na(+)]i is elevated.
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Affiliation(s)
- Elena C Lascano
- Department of Biology, Universidad Favaloro, Buenos Aires, Argentina.
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Maxwell JT, Domeier TL, Blatter LA. β-adrenergic stimulation increases the intra-SR Ca termination threshold for spontaneous Ca waves in cardiac myocytes. Channels (Austin) 2013; 7:206-10. [PMID: 23510939 DOI: 10.4161/chan.24173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
β-adrenergic stimulation of cardiac myocytes enhances intracellular calcium cycling, which frequently associates with pro-arrhythmic Ca waves. The threshold level of free calcium in the sarcoplasmic reticulum ([Ca]SR) where waves initiate is increased during β-adrenergic stimulation. ( 1) Here, we measured [Ca]SR directly to monitor the [Ca]SR level at which spontaneous Ca waves terminated (termination threshold) during β-adrenergic stimulation. Compared with control conditions, application of the β-adrenergic receptor agonist isoproterenol (ISO; 1 μM) resulted in an increase in basal [Ca]SR and an increase in the [Ca]SR at which spontaneous Ca waves terminated. When [Ca]SR was experimentally matched, ISO stimulation resulted in a decrease in the depletion amplitude of the waves. Sensitization of ryanodine receptor SR Ca release channels to Ca with a low dose of caffeine in the presence of ISO was able to decrease the termination threshold compared with control conditions. Therefore, the Ca wave termination level may represent an important mode of altering Ca depletion from the SR and reducing the arrhythmogenic potential during β-adrenergic stimulation.
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Affiliation(s)
- Joshua T Maxwell
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL, USA
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