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Lotteau S, Zhang R, Hazan A, Grabar C, Gonzalez D, Aynaszyan S, Philipson KD, Ottolia M, Goldhaber JI. Acute Genetic Ablation of Cardiac Sodium/Calcium Exchange in Adult Mice: Implications for Cardiomyocyte Calcium Regulation, Cardioprotection, and Arrhythmia. J Am Heart Assoc 2021; 10:e019273. [PMID: 34472363 PMCID: PMC8649274 DOI: 10.1161/jaha.120.019273] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Sodium‐calcium (Ca2+) exchanger isoform 1 (NCX1) is the dominant Ca2+ efflux mechanism in cardiomyocytes and is critical to maintaining Ca2+ homeostasis during excitation‐contraction coupling. NCX1 activity has been implicated in the pathogenesis of cardiovascular diseases, but a lack of specific NCX1 blockers complicates experimental interpretation. Our aim was to develop a tamoxifen‐inducible NCX1 knockout (KO) mouse to investigate compensatory adaptations of acute ablation of NCX1 on excitation‐contraction coupling and intracellular Ca2+ regulation, and to examine whether acute KO of NCX1 confers resistance to triggered arrhythmia and ischemia/reperfusion injury. Methods and Results We used the α‐myosin heavy chain promoter (Myh6)‐MerCreMer promoter to create a tamoxifen‐inducible cardiac‐specific NCX1 KO mouse. Within 1 week of tamoxifen injection, NCX1 protein expression and current were dramatically reduced. Diastolic Ca2+ increased despite adaptive reductions in Ca2+ current and action potential duration and compensatory increases in excitation‐contraction coupling gain, sarcoplasmic reticulum Ca2+ ATPase 2 and plasma membrane Ca2+ ATPase. As these adaptations progressed over 4 weeks, diastolic Ca2+ normalized and SR Ca2+ load increased. Left ventricular function remained normal, but mild fibrosis and hypertrophy developed. Transcriptomics revealed modification of cardiovascular‐related gene networks including cell growth and fibrosis. NCX1 KO reduced spontaneous action potentials triggered by delayed afterdepolarizations and reduced scar size in response to ischemia/reperfusion. Conclusions Tamoxifen‐inducible NCX1 KO mice adapt to acute genetic ablation of NCX1 by reducing Ca2+ influx, increasing alternative Ca2+ efflux pathways, and increasing excitation‐contraction coupling gain to maintain contractility at the cost of mild Ca2+‐activated hypertrophy and fibrosis and decreased survival. Nevertheless, KO myocytes are protected against spontaneous action potentials and ischemia/reperfusion injury.
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Affiliation(s)
- Sabine Lotteau
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Rui Zhang
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Adina Hazan
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Christina Grabar
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | - Devina Gonzalez
- Smidt Heart Institute Cedars-Sinai Medical Center Los Angeles CA
| | | | - Kenneth D Philipson
- Department of Physiology David Geffen School of Medicine at UCLA Los Angeles CA
| | - Michela Ottolia
- Division of Molecular Medicine Department of Anesthesiology and Perioperative Medicine David Geffen School of Medicine at UCLA Los Angeles CA
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Geramipour A, Kohajda Z, Corici C, Prorok J, Szakonyi Z, Oravecz K, Márton Z, Nagy N, Tóth A, Acsai K, Virág L, Varró A, Jost N. The investigation of the cellular electrophysiological and antiarrhythmic effects of a novel selective sodium-calcium exchanger inhibitor, GYKB-6635, in canine and guinea-pig hearts. Can J Physiol Pharmacol 2016; 94:1090-1101. [PMID: 27508313 DOI: 10.1139/cjpp-2015-0566] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The sodium-calcium exchanger (NCX) is considered as the major transmembrane transport mechanism that controls Ca2+ homeostasis. Its contribution to the cardiac repolarization has not yet been directly studied due to lack of specific inhibitors, so that an urgent need for more selective compounds. In this study, the electrophysiological effects of GYKB-6635, a novel NCX inhibitor, on the NCX, L-type calcium, and main repolarizing potassium currents as well as action potential (AP) parameters were investigated. Ion currents and AP recordings were investigated by applying the whole-cell patch clamp and standard microelectrode techniques in canine heart at 37 °C. Effects of GYKB-6635 were studied in ouabain-induced arrhythmias in isolated guinea-pig hearts. At a concentration of 1 μmol/L, GYKB significantly reduced both the inward and outward NCX currents (57% and 58%, respectively). Even at a high concentration (10 μmol/L), GYKB-6635 did not change the ICaL, the maximum rate of depolarization (dV/dtmax), the main repolarizing K+ currents, and the main AP parameters. GYKB-6635 pre-treatment significantly delayed the time to the development of ventricular fibrillation (by about 18%). It is concluded that GYKB-6635 is a potent and highly selective inhibitor of the cardiac NCX and, in addition, it is suggested to also contribute to the prevention of DAD-based arrhythmias.
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Affiliation(s)
- Amir Geramipour
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary
| | - Zsófia Kohajda
- b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Claudia Corici
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary
| | - János Prorok
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary
| | - Zsolt Szakonyi
- c Institute of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Szeged, H-6720 Szeged, Hungary
| | - Kinga Oravecz
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary
| | - Zoltán Márton
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary
| | - Norbert Nagy
- b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - András Tóth
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary.,b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Károly Acsai
- b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - László Virág
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary.,b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - András Varró
- a Department of Pharmacology & Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary.,b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Norbert Jost
- b MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary.,d "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania
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Chu R, Ge Y, Yang M. KB-R7943 Increases Glucose-Stimulated Insulin Secretion from INS-1E Cells through an NCX1-Independent Pathway. INT J PHARMACOL 2015. [DOI: 10.3923/ijp.2015.291.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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