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Sun Z, Lu K, Kamla C, Kameritsch P, Seidel T, Dendorfer A. Synchronous force and Ca 2+ measurements for repeated characterization of excitation-contraction coupling in human myocardium. Commun Biol 2024; 7:220. [PMID: 38388802 PMCID: PMC10884022 DOI: 10.1038/s42003-024-05886-3] [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: 09/04/2023] [Accepted: 02/02/2024] [Indexed: 02/24/2024] Open
Abstract
Dysfunctional Ca2+ signaling affects the myocardial systole and diastole, may trigger arrhythmia and cause transcriptomic and proteomic modifications in heart failure. Thus, synchronous real-time measurement of Ca2+ and force is essential to investigate the relationship between contractility and Ca2+ signaling and the alteration of excitation-contraction coupling (ECC) in human failing myocardium. Here, we present a method for synchronized acquisition of intracellular Ca2+ and contraction force in long-term cultivated slices of human failing myocardium. Synchronous time series of contraction force and intracellular Ca2+ were used to calculate force-calcium loops and to analyze the dynamic alterations of ECC in response to various pacing frequencies, post-pause potentiation, high mechanical preload and pharmacological interventions in human failing myocardium. We provide an approach to simultaneously and repeatedly investigate alterations of contractility and Ca2+ signals in long-term cultured myocardium, which will allow detecting the effects of electrophysiological or pharmacological interventions on human myocardial ECC.
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Affiliation(s)
- Zhengwu Sun
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kun Lu
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany
| | - Christine Kamla
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Petra Kameritsch
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Dendorfer
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany.
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2
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Reisqs JB, Qu YS, Boutjdir M. Ion channel trafficking implications in heart failure. Front Cardiovasc Med 2024; 11:1351496. [PMID: 38420267 PMCID: PMC10899472 DOI: 10.3389/fcvm.2024.1351496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/25/2024] [Indexed: 03/02/2024] Open
Abstract
Heart failure (HF) is recognized as an epidemic in the contemporary world, impacting around 1%-2% of the adult population and affecting around 6 million Americans. HF remains a major cause of mortality, morbidity, and poor quality of life. Several therapies are used to treat HF and improve the survival of patients; however, despite these substantial improvements in treating HF, the incidence of HF is increasing rapidly, posing a significant burden to human health. The total cost of care for HF is USD 69.8 billion in 2023, warranting a better understanding of the mechanisms involved in HF. Among the most serious manifestations associated with HF is arrhythmia due to the electrophysiological changes within the cardiomyocyte. Among these electrophysiological changes, disruptions in sodium and potassium currents' function and trafficking, as well as calcium handling, all of which impact arrhythmia in HF. The mechanisms responsible for the trafficking, anchoring, organization, and recycling of ion channels at the plasma membrane seem to be significant contributors to ion channels dysfunction in HF. Variants, microtubule alterations, or disturbances of anchoring proteins lead to ion channel trafficking defects and the alteration of the cardiomyocyte's electrophysiology. Understanding the mechanisms of ion channels trafficking could provide new therapeutic approaches for the treatment of HF. This review provides an overview of the recent advances in ion channel trafficking in HF.
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Affiliation(s)
- Jean-Baptiste Reisqs
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
| | - Yongxia Sarah Qu
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Cardiology, New York Presbyterian Brooklyn Methodist Hospital, New York, NY, United States
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY, United States
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY, United States
- Department of Medicine, New York University Grossman School of Medicine, New York, NY, United States
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3
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Tsuji S, Otani C, Horie T, Watanabe S, Baba O, Sowa N, Ide Y, Kashiwa A, Makiyama T, Imai H, Nakashima Y, Yamasaki T, Xu S, Matsushita K, Suzuki K, Zou F, Kume E, Hasegawa K, Kimura T, Kakizuka A, Ono K. KUS121, a VCP modulator, has an ameliorating effect on acute and chronic heart failure without calcium loading via maintenance of intracellular ATP levels. Biomed Pharmacother 2024; 170:115850. [PMID: 38091636 DOI: 10.1016/j.biopha.2023.115850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/26/2023] [Accepted: 11/05/2023] [Indexed: 01/10/2024] Open
Abstract
AIMS As heart failure (HF) progresses, ATP levels in myocardial cells decrease, and myocardial contractility also decreases. Inotropic drugs improve myocardial contractility but increase ATP consumption, leading to poor prognosis. Kyoto University Substance 121 (KUS121) is known to selectively inhibit the ATPase activity of valosin-containing protein, maintain cellular ATP levels, and manifest cytoprotective effects in several pathological conditions. The aim of this study is to determine the therapeutic effect of KUS121 on HF models. METHODS AND RESULTS Cultured cell, mouse, and canine models of HF were used to examine the therapeutic effects of KUS121. The mechanism of action of KUS121 was also examined. Administration of KUS121 to a transverse aortic constriction (TAC)-induced mouse model of HF rapidly improved the left ventricular ejection fraction and improved the creatine phosphate/ATP ratio. In a canine model of high frequency-paced HF, administration of KUS121 also improved left ventricular contractility and decreased left ventricular end-diastolic pressure without increasing the heart rate. Long-term administration of KUS121 to a TAC-induced mouse model of HF suppressed cardiac hypertrophy and fibrosis. In H9C2 cells, KUS121 reduced ER stress. Finally, in experiments using primary cultured cardiomyocytes, KUS121 improved contractility and diastolic capacity without changing peak Ca2+ levels or contraction time. These effects were not accompanied by an increase in cyclic adenosine monophosphate or phosphorylation of phospholamban and ryanodine receptors. CONCLUSIONS KUS121 ameliorated HF by a mechanism totally different from that of conventional catecholamines. We propose that KUS121 is a promising new option for the treatment of HF.
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Affiliation(s)
- Shuhei Tsuji
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Chiharu Otani
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Takahiro Horie
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Shin Watanabe
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Osamu Baba
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan; Preemptive Medicine and Lifestyle Disease Research Center, Kyoto University Hospital Kyoto, 606-8507, Japan
| | - Naoya Sowa
- Division of Translational Research, National Hospital Organization, Kyoto Medical Center, 1-1 Fukakusa Mukaihata-cho, Fushimi-ku, Kyoto 612-8555, Japan
| | - Yuya Ide
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Asami Kashiwa
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Hirohiko Imai
- Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan
| | - Yasuhiro Nakashima
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Tomohiro Yamasaki
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Sijia Xu
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Kazuki Matsushita
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Keita Suzuki
- Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Fuquan Zou
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Eitaro Kume
- Department of Pediatrics, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Koji Hasegawa
- Preemptive Medicine and Lifestyle Disease Research Center, Kyoto University Hospital Kyoto, 606-8507, Japan
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Akira Kakizuka
- Laboratory of Functional Biology, Kyoto University Graduate School of Biostudies and Solution Oriented Research for Science and Technology, Kyoto 606-8501, Japan.
| | - Koh Ono
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
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4
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Chakraborty P, Azam MA, Massé S, Lai PF, Rose RA, Ibarra Moreno CA, Riazi S, Nanthakumar K. Uncoupling cytosolic calcium from membrane voltage by transient receptor potential melastatin 4 channel (TRPM4) modulation: A novel strategy to treat ventricular arrhythmias. Heart Rhythm O2 2023; 4:725-732. [PMID: 38034891 PMCID: PMC10685170 DOI: 10.1016/j.hroo.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023] Open
Abstract
The current antiarrhythmic paradigm is mainly centered around modulating membrane voltage. However, abnormal cytosolic calcium (Ca2+) signaling, which plays an important role in driving membrane voltage, has not been targeted for therapeutic purposes in arrhythmogenesis. There is clear evidence for bidirectional coupling between membrane voltage and intracellular Ca2+. Cytosolic Ca2+ regulates membrane voltage through Ca2+-sensitive membrane currents. As a component of Ca2+-sensitive currents, Ca2+-activated nonspecific cationic current through the TRPM4 (transient receptor potential melastatin 4) channel plays a significant role in Ca2+-driven changes in membrane electrophysiology. In myopathic and ischemic ventricles, upregulation and/or enhanced activity of this current is associated with the generation of afterdepolarization (both early and delayed), reduction of repolarization reserve, and increased propensity to ventricular arrhythmias. In this review, we describe a novel concept for the management of ventricular arrhythmias in the remodeled ventricle based on mechanistic concepts from experimental studies, by uncoupling the Ca2+-induced changes in membrane voltage by inhibition of this TRPM4-mediated current.
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Affiliation(s)
- Praloy Chakraborty
- Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Mohammed Ali Azam
- Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Stéphane Massé
- Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Patrick F.H. Lai
- Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Robert A. Rose
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Carlos A. Ibarra Moreno
- Malignant Hyperthermia Investigation Unit, Department of Anesthesiology and Pain Medicine, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Sheila Riazi
- Malignant Hyperthermia Investigation Unit, Department of Anesthesiology and Pain Medicine, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
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5
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Stokum JA, Shim B, Negoita S, Tsymbalyuk N, Tsymbalyuk O, Ivanova S, Keledjian K, Bryan J, Blaustein MP, Jha RM, Kahle KT, Gerzanich V, Simard JM. Cation flux through SUR1-TRPM4 and NCX1 in astrocyte endfeet induces water influx through AQP4 and brain swelling after ischemic stroke. Sci Signal 2023; 16:eadd6364. [PMID: 37279286 PMCID: PMC10369355 DOI: 10.1126/scisignal.add6364] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 05/10/2023] [Indexed: 06/08/2023]
Abstract
Brain swelling causes morbidity and mortality in various brain injuries and diseases but lacks effective treatments. Brain swelling is linked to the influx of water into perivascular astrocytes through channels called aquaporins. Water accumulation in astrocytes increases their volume, which contributes to brain swelling. Using a mouse model of severe ischemic stroke, we identified a potentially targetable mechanism that promoted the cell surface localization of aquaporin 4 (AQP4) in perivascular astrocytic endfeet, which completely ensheathe the brain's capillaries. Cerebral ischemia increased the abundance of the heteromeric cation channel SUR1-TRPM4 and of the Na+/Ca2+ exchanger NCX1 in the endfeet of perivascular astrocytes. The influx of Na+ through SUR1-TRPM4 induced Ca2+ transport into cells through NCX1 operating in reverse mode, thus raising the intra-endfoot concentration of Ca2+. This increase in Ca2+ stimulated calmodulin-dependent translocation of AQP4 to the plasma membrane and water influx, which led to cellular edema and brain swelling. Pharmacological inhibition or astrocyte-specific deletion of SUR1-TRPM4 or NCX1 reduced brain swelling and improved neurological function in mice to a similar extent as an AQP4 inhibitor and was independent of infarct size. Thus, channels in astrocyte endfeet could be targeted to reduce postischemic brain swelling in stroke patients.
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Affiliation(s)
- Jesse A Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Bosung Shim
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Serban Negoita
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Natalya Tsymbalyuk
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Orest Tsymbalyuk
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Svetlana Ivanova
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kaspar Keledjian
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph Bryan
- Pacific Northwest Diabetes Research Institute, Seattle, WA 98122, USA
| | - Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ruchira M Jha
- Department of Neurology, Barrow Neurological Institute and St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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6
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Nagy N, Tóth N, Nánási PP. Antiarrhythmic and Inotropic Effects of Selective Na +/Ca 2+ Exchanger Inhibition: What Can We Learn from the Pharmacological Studies? Int J Mol Sci 2022; 23:ijms232314651. [PMID: 36498977 PMCID: PMC9736231 DOI: 10.3390/ijms232314651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022] Open
Abstract
Life-long stable heart function requires a critical balance of intracellular Ca2+. Several ion channels and pumps cooperate in a complex machinery that controls the influx, release, and efflux of Ca2+. Probably one of the most interesting and most complex players of this crosstalk is the Na+/Ca2+ exchanger, which represents the main Ca2+ efflux mechanism; however, under some circumstances, it can also bring Ca2+ into the cell. Therefore, the inhibition of the Na+/Ca2+ exchanger has emerged as one of the most promising possible pharmacological targets to increase Ca2+ levels, to decrease arrhythmogenic depolarizations, and to reduce excessive Ca2+ influx. In line with this, as a response to increasing demand, several more or less selective Na+/Ca2+ exchanger inhibitor compounds have been developed. In the past 20 years, several results have been published regarding the effect of Na+/Ca2+ exchanger inhibition under various circumstances, e.g., species, inhibitor compounds, and experimental conditions; however, the results are often controversial. Does selective Na+/Ca2+ exchanger inhibition have any future in clinical pharmacological practice? In this review, the experimental results of Na+/Ca2+ exchanger inhibition are summarized focusing on the data obtained by novel highly selective inhibitors.
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Affiliation(s)
- Norbert Nagy
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
- Correspondence: ; Tel.: +36-62-545-682; Fax: +36-62-545-680
| | - Noémi Tóth
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
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7
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Higher Na+-Ca2+ Exchanger Function and Triggered Activity Contribute to Male Predisposition to Atrial Fibrillation. Int J Mol Sci 2022; 23:ijms231810724. [PMID: 36142639 PMCID: PMC9501955 DOI: 10.3390/ijms231810724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022] Open
Abstract
Male sex is one of the most important risk factors of atrial fibrillation (AF), with the incidence in men being almost double that in women. However, the reasons for this sex difference are unknown. Accordingly, in this study, we sought to determine whether there are sex differences in intracellular Ca2+ homeostasis in mouse atrial myocytes that might help explain male predisposition to AF. AF susceptibility was assessed in male (M) and female (F) mice (4–5 months old) using programmed electrical stimulation (EPS) protocols. Males were 50% more likely to develop AF. The Ca2+ transient amplitude was 28% higher in male atrial myocytes. Spontaneous systolic and diastolic Ca2+ releases, which are known sources of triggered activity, were significantly more frequent in males than females. The time to 90% decay of Ca2+ transient was faster in males. Males had 54% higher Na+-Ca2+ exchanger (NCX1) current density, and its expression was also more abundant. L-type Ca2+ current (ICaL) was recorded with and without BAPTA, a Ca2+ chelator. ICaL density was lower in males only in the absence of BAPTA, suggesting stronger Ca2+-dependent inactivation in males. CaV1.2 expression was similar between sexes. This study reports major sex differences in Ca2+ homeostasis in mouse atria, with larger Ca2+ transients and enhanced NCX1 function and expression in males resulting in more spontaneous Ca2+ releases. These sex differences may contribute to male susceptibility to AF by promoting triggered activity.
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8
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Hegner P, Drzymalski M, Biedermann A, Memmel B, Durczok M, Wester M, Floerchinger B, Provaznik Z, Schmid C, Zausig Y, Maier LS, Wagner S. SAR296968, a Novel Selective Na+/Ca2+ Exchanger Inhibitor, Improves Ca2+ Handling and Contractile Function in Human Atrial Cardiomyocytes. Biomedicines 2022; 10:biomedicines10081932. [PMID: 36009478 PMCID: PMC9406204 DOI: 10.3390/biomedicines10081932] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 07/30/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
Background: In reverse-mode, cardiac sodium-calcium exchanger (NCX) can increase the cytoplasmic Ca2+ concentration in response to high intracellular Na+ levels, which may contribute to diastolic contractile dysfunction. Furthermore, increased spontaneous Ca2+ release from intracellular stores can activate forward mode NCX. The resulting transient inward current causes delayed afterdepolarization (DAD)-dependent arrhythmias. Moreover, recently, NCX has been associated with impaired relaxation and reduced cardiac function in heart failure with preserved ejection fraction (HFpEF). Since NCX is upregulated in human chronic atrial fibrillation (AF) as well as heart failure (HF), specific inhibition may have therapeutic potential. Objective: We tested the antiarrhythmic, lusitropic and inotropic effects of a novel selective NCX-inhibitor (SAR296968) in human atrial myocardium. Methods and Results: Right atrial appendage biopsies of 46 patients undergoing elective cardiac surgery in a predominant HFpEF cohort (n = 24/46) were investigated. In isolated human atrial cardiomyocytes, SAR296968 reduced the frequency of spontaneous SR Ca2+ release events and increased caffeine transient amplitude. In accordance, in isolated atrial trabeculae, SAR296968 enhanced the developed tension after a 30 s pause of electrical stimulation consistent with reduced diastolic sarcoplasmic reticulum (SR) Ca2+ leak. Moreover, compared to vehicle, SAR296968 decreased steady-state diastolic tension (at 1 Hz) without impairing developed systolic tension. Importantly, SAR296968 did not affect the safety parameters, such as resting membrane potential or action potential duration as measured by patch clamp. Conclusion: The novel selective NCX-inhibitor SAR296968 inhibits atrial pro-arrhythmic activity and improves diastolic and contractile function in human atrial myocardium, which may have therapeutic implications, especially for treatment of HFpEF.
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Affiliation(s)
- Philipp Hegner
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Marzena Drzymalski
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Alexander Biedermann
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Bernadette Memmel
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Melanie Durczok
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Michael Wester
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Bernhard Floerchinger
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Zdenek Provaznik
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Christof Schmid
- Department of Cardiothoracic Surgery, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - York Zausig
- Department of Anesthesiology, University Medical Center Regensburg, 93053 Regensburg, Germany
- Department of Anesthesiology and Operative Intensive Care Medicine, Aschaffenburg-Alzenau Hospital, 63739 Aschaffenburg, Germany
| | - Lars S. Maier
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
| | - Stefan Wagner
- Department of Internal Medicine II, University Medical Center Regensburg, 93053 Regensburg, Germany
- Correspondence: ; Tel.: +49-941-944-7206
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9
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Ismaili D, Gurr K, Horváth A, Yuan L, Lemoine MD, Schulz C, Sani J, Petersen J, Reichenspurner H, Kirchhof P, Jespersen T, Eschenhagen T, Hansen A, Koivumäki JT, Christ T. Regulation of APD and Force by the Na +/Ca 2+ Exchanger in Human-Induced Pluripotent Stem Cell-Derived Engineered Heart Tissue. Cells 2022; 11:cells11152424. [PMID: 35954268 PMCID: PMC9368200 DOI: 10.3390/cells11152424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/21/2022] [Accepted: 07/26/2022] [Indexed: 12/02/2022] Open
Abstract
The physiological importance of NCX in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is not well characterized but may depend on the relative strength of the current, compared to adult cardiomyocytes, and on the exact spatial arrangement of proteins involved in Ca2+ extrusion. Here, we determined NCX currents and its contribution to action potential and force in hiPSC-CMs cultured in engineered heart tissue (EHT). The results were compared with data from rat and human left ventricular tissue. The NCX currents in hiPSC-CMs were larger than in ventricular cardiomyocytes isolated from human left ventricles (1.3 ± 0.2 pA/pF and 3.2 ± 0.2 pA/pF for human ventricle and EHT, respectively, p < 0.05). SEA0400 (10 µM) markedly shortened the APD90 in EHT (by 26.6 ± 5%, p < 0.05) and, to a lesser extent, in rat ventricular tissue (by 10.7 ± 1.6%, p < 0.05). Shortening in human left ventricular preparations was small and not different from time-matched controls (TMCs; p > 0.05). Force was increased by the NCX block in rat ventricle (by 31 ± 5.4%, p < 0.05) and EHT (by 20.8 ± 3.9%, p < 0.05), but not in human left ventricular preparations. In conclusion, hiPSC-CMs possess NCX currents not smaller than human left ventricular tissue. Robust NCX block-induced APD shortening and inotropy makes EHT an attractive pharmacological model.
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Affiliation(s)
- Djemail Ismaili
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- Department of Cardiology, University Heart & Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Correspondence: (D.I.); (T.C.); Tel.: +49-40-7410-42414 (T.C.)
| | - Katrin Gurr
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - András Horváth
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Lei Yuan
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Marc D. Lemoine
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- Department of Cardiology, University Heart & Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Carl Schulz
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Jascha Sani
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Johannes Petersen
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Department of Cardiovascular Surgery, University Heart and Vascular Center, 20246 Hamburg, Germany
| | - Hermann Reichenspurner
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Department of Cardiovascular Surgery, University Heart and Vascular Center, 20246 Hamburg, Germany
| | - Paulus Kirchhof
- Department of Cardiology, University Heart & Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Thomas Jespersen
- Department of Cardiovascular Surgery, University Heart and Vascular Center, 20246 Hamburg, Germany
| | - Thomas Eschenhagen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Arne Hansen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Jussi T. Koivumäki
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
- Correspondence: (D.I.); (T.C.); Tel.: +49-40-7410-42414 (T.C.)
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10
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Horváth B, Szentandrássy N, Dienes C, Kovács ZM, Nánási PP, Chen-Izu Y, Izu LT, Banyasz T. Exploring the Coordination of Cardiac Ion Channels With Action Potential Clamp Technique. Front Physiol 2022; 13:864002. [PMID: 35370800 PMCID: PMC8966222 DOI: 10.3389/fphys.2022.864002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
The patch clamp technique underwent continual advancement and developed numerous variants in cardiac electrophysiology since its introduction in the late 1970s. In the beginning, the capability of the technique was limited to recording one single current from one cell stimulated with a rectangular command pulse. Since that time, the technique has been extended to record multiple currents under various command pulses including action potential. The current review summarizes the development of the patch clamp technique in cardiac electrophysiology with special focus on the potential applications in integrative physiology.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Norbert Szentandrássy
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Csaba Dienes
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | | | - Péter P. Nánási
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Leighton T. Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- *Correspondence: Tamas Banyasz,
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11
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Abstract
In mammalian cardiac myocytes, the plasma membrane includes the surface sarcolemma but also a network of membrane invaginations called transverse (t-) tubules. These structures carry the action potential deep into the cell interior, allowing efficient triggering of Ca2+ release and initiation of contraction. Once thought to serve as rather static enablers of excitation-contraction coupling, recent work has provided a newfound appreciation of the plasticity of the t-tubule network's structure and function. Indeed, t-tubules are now understood to support dynamic regulation of the heartbeat across a range of timescales, during all stages of life, in both health and disease. This review article aims to summarize these concepts, with consideration given to emerging t-tubule regulators and their targeting in future therapies.
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Affiliation(s)
- Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom;
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo Norway
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom;
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12
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Durak A, Akkus E, Canpolat AG, Tuncay E, Corapcioglu D, Turan B. Glucagon-like peptide-1 receptor agonist treatment of high carbohydrate intake-induced metabolic syndrome provides pleiotropic effects on cardiac dysfunction through alleviations in electrical and intracellular Ca 2+ abnormalities and mitochondrial dysfunction. Clin Exp Pharmacol Physiol 2021; 49:46-59. [PMID: 34519087 DOI: 10.1111/1440-1681.13590] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/07/2021] [Accepted: 09/10/2021] [Indexed: 02/06/2023]
Abstract
The pleiotropic effects of glucagon-like peptide-1 receptor (GLP-1R) agonists on the heart have been recognised in obese or diabetic patients. However, little is known regarding the molecular mechanisms of these agonists in cardioprotective actions under metabolic disturbances. We evaluated the effects of GLP-1R agonist liraglutide treatment on left ventricular cardiomyocytes from high-carbohydrate induced metabolic syndrome rats (MetS rats), characterised with insulin resistance and cardiac dysfunction with a long-QT. Liraglutide (0.3 mg/kg for 4 weeks) treatment of MetS rats significantly reversed long-QT, through a shortening the prolonged action potential duration and recovering inhibited K+ -currents. We also determined a significant recovery in the leaky sarcoplasmic reticulum (SR) and high cytosolic Ca2+ -level, which are confirmed with a full recovery in activated Na+ /Ca2+ -exchanger currents (INCX ). Moreover, the liraglutide treatment significantly reversed the depolarised mitochondrial membrane potential (MMP), increased production of oxidant markers, and cellular acidification together with the depressed ATP production. Our light microscopy analysis of isolated cardiomyocytes showed marked recoveries in the liraglutide-treated MetS group such as marked reverses in highly dilated T-tubules and SR-mitochondria junctions. Moreover, we determined a significant increase in depressed GLUT4 protein level in liraglutide-treated MetS group, possibly associated with recovery in casein kinase 2α. Overall, the study demonstrated a molecular mechanism of liraglutide-induced cardioprotection in MetS rats, at most, via its pleiotropic effects, such as alleviation in the electrical abnormalities, Ca2+ -homeostasis, and mitochondrial dysfunction in ventricular cardiomyocytes.
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Affiliation(s)
- Aysegul Durak
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey
| | - Erman Akkus
- Faculty of Medicine, Department of Internal Medicine, Ankara University, Ankara, Turkey
| | - Asena Gokcay Canpolat
- Faculty of Medicine, Department of Endocrinology and Metabolism, Ankara University, Ankara, Turkey
| | - Erkan Tuncay
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey
| | - Demet Corapcioglu
- Faculty of Medicine, Department of Endocrinology and Metabolism, Ankara University, Ankara, Turkey
| | - Belma Turan
- Faculty of Medicine, Department of Biophysics, Ankara University, Ankara, Turkey.,Faculty of Medicine, Department of Biophysics, Lokman Hekim University, Ankara, Turkey
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13
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Zhao R, Liu X, Qi Z, Yao X, Tsang SY. TRPV1 channels regulate the automaticity of embryonic stem cell-derived cardiomyocytes through stimulating the Na + /Ca 2+ exchanger current. J Cell Physiol 2021; 236:6806-6823. [PMID: 33782967 DOI: 10.1002/jcp.30369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/25/2021] [Accepted: 03/09/2021] [Indexed: 12/16/2022]
Abstract
Calcium controls the excitation-contraction coupling in cardiomyocytes. Embryonic stem cell-derived cardiomyocytes (ESC-CMs) are an important cardiomyocyte source for regenerative medicine and drug screening. Transient receptor potential vanilloid 1 (TRPV1) channels are nonselective cation channels that permeate sodium and calcium. This study aimed to investigate whether TRPV1 channels regulate the electrophysiological characteristics of ESC-CMs. If yes, what is the mechanism behind? By immunostaining and subcellular fractionation, followed by western blotting, TRPV1 was found to locate intracellularly. The staining pattern of TRPV1 was found to largely overlap with that of the sarco/endoplasmic reticulum Ca2+ -ATPase, the sarcoplasmic reticulum (SR) marker. By electrophysiology and calcium imaging, pharmacological blocker of TRPV1 and the molecular tool TRPV1β (which could functionally knockdown TRPV1) were found to decrease the rate and diastolic depolarization slope of spontaneous action potentials, and the amplitude and frequency of global calcium transients. By calcium imaging, in the absence of external calcium, TRPV1-specific opener increased intracellular calcium; this increase was abolished by preincubation with caffeine, which could deplete SR calcium store. The results suggest that TRPV1 controls calcium release from the SR. By electrophysiology, TRPV1 blockade and functional knockdown of TRPV1 decreased the Na+ /Ca2+ exchanger (NCX) currents from both the forward and reverse modes, suggesting that sodium and calcium through TRPV1 stimulate the NCX activity. Our novel findings suggest that TRPV1 activity is important for regulating the spontaneous activity of ESC-CMs and reveal a novel interplay between TRPV1 and NCX in regulating the physiological functions of ESC-CMs.
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Affiliation(s)
- Rui Zhao
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Xianji Liu
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Zenghua Qi
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiaoqiang Yao
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Suk Ying Tsang
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China.,State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.,Key Laboratory for Regenerative Medicine, Ministry of Education, The Chinese University of Hong Kong, Hong Kong, China
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14
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Moreira Souza AC, Grabe-Guimarães A, Cruz JDS, Santos-Miranda A, Farah C, Teixeira Oliveira L, Lucas A, Aimond F, Sicard P, Mosqueira VCF, Richard S. Mechanisms of artemether toxicity on single cardiomyocytes and protective effect of nanoencapsulation. Br J Pharmacol 2020; 177:4448-4463. [PMID: 32608017 DOI: 10.1111/bph.15186] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/11/2020] [Accepted: 06/15/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE The artemisinin derivative, artemether, has antimalarial activity with potential neurotoxic and cardiotoxic effects. Artemether in nanocapsules (NC-ATM) is more efficient than free artemether for reducing parasitaemia and increasing survival of Plasmodium berghei-infected mice. NCs also prevent prolongation of the QT interval of the ECG. Here, we assessed cellular cardiotoxicity of artemether and how this toxicity was prevented by nanoencapsulation. EXPERIMENTAL APPROACH Mice were treated with NC-ATM orally (120 mg·kg-1 twice daily) for 4 days. Other mice received free artemether, blank NCs, and vehicle for comparison. We measured single-cell contraction, intracellular Ca2+ transient using fluorescent Indo-1AM Ca2+ dye, and electrical activity using the patch-clamp technique in freshly isolated left ventricular myocytes. The acute effect of free artemether was also tested on cardiomyocytes of untreated animals. KEY RESULTS Artemether prolonged action potentials (AP) upon acute exposure (at 0.1, 1, and 10 μM) of cardiomyocytes from untreated mice or after in vivo treatment. This prolongation was unrelated to blockade of K+ currents, increased Ca2+ currents or promotion of a sustained Na+ current. AP lengthening was abolished by the NCX inhibitor SEA-0400. Artemether promoted irregular Ca2+ transients during pacing and spontaneous Ca2+ events during resting periods. NC-ATM prevented all effects. Blank NCs had no effects compared with vehicle. CONCLUSION AND IMPLICATIONS Artemether induced NCX-dependent AP lengthening (explaining QTc prolongation) and disrupted Ca2+ handling, both effects increasing pro-arrhythmogenic risks. NCs prevented these adverse effects, providing a safe alternative to the use of artemether alone, especially to treat malaria.
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Affiliation(s)
- Ana Carolina Moreira Souza
- Pharmaceutical Sciences Graduate Program (CiPharma), Pharmacy School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil.,Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Andrea Grabe-Guimarães
- Pharmaceutical Sciences Graduate Program (CiPharma), Pharmacy School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Jader Dos Santos Cruz
- Department of Immunology and Biochemistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Artur Santos-Miranda
- Department of Immunology and Biochemistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Charlotte Farah
- Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Liliam Teixeira Oliveira
- Pharmaceutical Sciences Graduate Program (CiPharma), Pharmacy School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil.,Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Alexandre Lucas
- Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), Inserm/Université Paul Sabatier UMR1048, Toulouse, France
| | - Franck Aimond
- Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Pierre Sicard
- Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Vanessa Carla Furtado Mosqueira
- Pharmaceutical Sciences Graduate Program (CiPharma), Pharmacy School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Sylvain Richard
- Physiologie et Médecine Expérimentale du Cœur et des Muscles (PhyMedExp), Université de Montpellier, CNRS, Inserm, Montpellier, France
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15
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Olgar Y, Tuncay E, Degirmenci S, Billur D, Dhingra R, Kirshenbaum L, Turan B. Ageing-associated increase in SGLT2 disrupts mitochondrial/sarcoplasmic reticulum Ca 2+ homeostasis and promotes cardiac dysfunction. J Cell Mol Med 2020; 24:8567-8578. [PMID: 32652890 PMCID: PMC7412693 DOI: 10.1111/jcmm.15483] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/30/2020] [Accepted: 05/24/2020] [Indexed: 12/12/2022] Open
Abstract
The prevalence of death from cardiovascular disease is significantly higher in elderly populations; the underlying factors that contribute to the age‐associated decline in cardiac performance are poorly understood. Herein, we identify the involvement of sodium/glucose co‐transporter gene (SGLT2) in disrupted cellular Ca2+‐homeostasis, and mitochondrial dysfunction in age‐associated cardiac dysfunction. In contrast to younger rats (6‐month of age), older rats (24‐month of age) exhibited severe cardiac ultrastructural defects, including deformed, fragmented mitochondria with high electron densities. Cardiomyocytes isolated from aged rats demonstrated increased reactive oxygen species (ROS), loss of mitochondrial membrane potential and altered mitochondrial dynamics, compared with younger controls. Moreover, mitochondrial defects were accompanied by mitochondrial and cytosolic Ca2+ ([Ca2+]i) overload, indicative of disrupted cellular Ca2+‐homeostasis. Interestingly, increased [Ca2+]i coincided with decreased phosphorylation of phospholamban (PLB) and contractility. Aged‐cardiomyocytes also displayed high Na+/Ca2+‐exchanger (NCX) activity and blood glucose levels compared with young‐controls. Interestingly, the protein level of SGLT2 was dramatically increased in the aged cardiomyocytes. Moreover, SGLT2 inhibition was sufficient to restore age‐associated defects in [Ca2+]i‐homeostasis, PLB phosphorylation, NCX activity and mitochondrial Ca2+‐loading. Hence, the present data suggest that deregulated SGLT2 during ageing disrupts mitochondrial function and cardiac contractility through a mechanism that impinges upon [Ca2+]i‐homeostasis. Our studies support the notion that interventions that modulate SGLT2‐activity can provide benefits in maintaining [Ca2+]i and cardiac function with advanced age.
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Affiliation(s)
- Yusuf Olgar
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Erkan Tuncay
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Sinan Degirmenci
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Deniz Billur
- Departments of Histology-Embriyology, Ankara University Faculty of Medicine, Ankara, Turkey
| | - Rimpy Dhingra
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Lorrie Kirshenbaum
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Belma Turan
- Departments of Biophysics, Ankara University Faculty of Medicine, Ankara, Turkey
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16
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Feric NT, Pallotta I, Singh R, Bogdanowicz DR, Gustilo M, Chaudhary K, Willette RN, Chendrimada T, Xu X, Graziano MP, Aschar-Sobbi R. Engineered Cardiac Tissues Generated in the Biowire™ II: A Platform for Human-Based Drug Discovery. Toxicol Sci 2019; 172:89-97. [PMID: 31385592 PMCID: PMC6813749 DOI: 10.1093/toxsci/kfz168] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/01/2019] [Accepted: 07/14/2019] [Indexed: 01/14/2023] Open
Abstract
Recent advances in techniques to differentiate human induced pluripotent stem cells (hiPSCs) hold the promise of an unlimited supply of human derived cardiac cells from both healthy and disease populations. That promise has been tempered by the observation that hiPSC-derived cardiomyocytes (hiPSC-CMs) typically retain a fetal-like phenotype, raising concern about the translatability of the in vitro data obtained to drug safety, discovery and development studies. The Biowire™ II platform was used to generate 3D engineered cardiac tissues (ECTs) from hiPSC-CMs and cardiac fibroblasts. Long term electrical stimulation was employed to obtain ECTs that possess a phenotype like that of adult human myocardium including a lack of spontaneous beating, the presence of a positive force-frequency response from 1-4Hz and prominent post-rest potentiation. Pharmacology studies were performed in the ECTs to confirm the presence and functionality of pathways that modulate cardiac contractility in humans. Canonical responses were observed for compounds that act via the β-adrenergic/cAMP-mediated pathway, e.g. isoproterenol and milrinone; the L-type calcium channel, e.g. FPL64176 and nifedipine; and indirectly effect intracellular Ca2+ concentrations, e.g. digoxin. Expected positive inotropic responses were observed for compounds that modulate proteins of the cardiac sarcomere, e.g. omecamtiv mecarbil and levosimendan. ECTs generated in the BiowireTM II platform display adult-like properties and have canonical responses to cardiotherapeutic and cardiotoxic agents that affect contractility in humans via a variety of mechanisms. These data demonstrate that this human-based model can be used to assess the effects of novel compounds on contractility early in the drug discovery and development process.
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17
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Davargaon RS, Sambe AD, Muthangi V V S. Toxic effect of high glucose on cardiomyocytes, H9c2 cells: Induction of oxidative stress and ameliorative effect of trolox. J Biochem Mol Toxicol 2018; 33:e22272. [PMID: 30512247 DOI: 10.1002/jbt.22272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/11/2018] [Accepted: 10/26/2018] [Indexed: 12/15/2022]
Abstract
Oxidative stress (OS) has been implicated in a variety of pathological conditions, including diabetes mellitus, characterized by hyperglycemia. In the present study, OS induced by hyperglycemia and the effect of trolox, a vitamin E analog, were studied in cardiomyocytes and H9c2 cells exposed to 15 to 33 mM glucose (HG) for 24 to 72 hours in Dulbecco modified Eagle medium. Cells treated wirh 24 or 33 mM glucose for 24 hours or above showed decreased viability and adenosine triphosphate (ATP) content with a concomitant increase in radicals of oxygen species, calcium (Ca2+ ), mitochondrial permeability transition, and oxidative markers, confirming that the cells were under stress. However, upon exposure to 15 mM glucose for 24 hours, H9c2 cells maintained homeostasis and ATP generation. Pretreatment of cells with trolox reduced HG-induced OS to control levels. Here, we report that the toxic effect of HG is highly regulated and that OS induction can be prevented with Trolox, a potential inhibitor of membrane damage.
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Affiliation(s)
| | - Asha Devi Sambe
- Department of Zoology, Laboratory of Gerontology, J.B. Campus, Bangalore University, Bangalore, India
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18
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Mora MT, Ferrero JM, Gomez JF, Sobie EA, Trenor B. Ca 2+ Cycling Impairment in Heart Failure Is Exacerbated by Fibrosis: Insights Gained From Mechanistic Simulations. Front Physiol 2018; 9:1194. [PMID: 30190684 PMCID: PMC6116328 DOI: 10.3389/fphys.2018.01194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/08/2018] [Indexed: 12/28/2022] Open
Abstract
Heart failure (HF) is characterized by altered Ca2+ cycling, resulting in cardiac contractile dysfunction. Failing myocytes undergo electrophysiological remodeling, which is known to be the main cause of abnormal Ca2+ homeostasis. However, structural remodeling, specifically proliferating fibroblasts coupled to myocytes in the failing heart, could also contribute to Ca2+ cycling impairment. The goal of the present study was to systematically analyze the mechanisms by which myocyte–fibroblast coupling could affect Ca2+ dynamics in normal conditions and in HF. Simulations of healthy and failing human myocytes were performed using established mathematical models, and cells were either isolated or coupled to fibroblasts. Univariate and multivariate sensitivity analyses were performed to quantify effects of ion transport pathways on biomarkers computed from intracellular [Ca2+] waveforms. Variability in ion channels and pumps was imposed and populations of models were analyzed to determine effects on Ca2+ dynamics. Our results suggest that both univariate and multivariate sensitivity analyses are valuable methodologies to shed light into the ionic mechanisms underlying Ca2+ impairment in HF, although differences between the two methodologies are observed at high parameter variability. These can result from either the fact that multivariate analyses take into account ion channels or non-linear effects of ion transport pathways on Ca2+ dynamics. Coupling either healthy or failing myocytes to fibroblasts decreased Ca2+ transients due to an indirect sink effect on action potential (AP) and thus on Ca2+ related currents. Simulations that investigated restoration of normal physiology in failing myocytes showed that Ca2+ cycling can be normalized by increasing SERCA and L-type Ca2+ current activity while decreasing Na+–Ca2+ exchange and SR Ca2+ leak. Changes required to normalize APs in failing myocytes depended on whether myocytes were coupled to fibroblasts. In conclusion, univariate and multivariate sensitivity analyses are helpful tools to understand how Ca2+ cycling is impaired in HF and how this can be exacerbated by coupling of myocytes to fibroblasts. The design of pharmacological actions to restore normal activity should take into account the degree of fibrosis in the failing heart.
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Affiliation(s)
- Maria T Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Juan F Gomez
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Eric A Sobie
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
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19
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de Godoy CMG, Vasques ÊR, Caricati-Neto A, Tavares JGP, Alves BJ, Duarte J, Miranda-Ferreira R, Lima MA, Nader HB, Tersariol ILDS. Heparin Oligosaccharides Have Antiarrhythmic Effect by Accelerating the Sodium-Calcium Exchanger. Front Cardiovasc Med 2018; 5:67. [PMID: 29930947 PMCID: PMC5999778 DOI: 10.3389/fcvm.2018.00067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 05/17/2018] [Indexed: 01/15/2023] Open
Abstract
Background: Blockage of the Na+/Ca2+ exchanger (NCX) is used to determine the role of NCX in arrhythmogenesis. Trisulfated heparin disaccharide (TD) and Low Molecular Weight Heparins (LMWHs) can directly interact with the NCX and accelerate its activity. Objective: In this work, we investigated the antiarrhythmic effect of heparin oligosaccharides related to the NCX activity. Methods: The effects of heparin oligosaccharides were tested on the NCX current (patch clamping) and intracellular calcium transient in rat cardiomyocytes. The effects of heparin oligosaccharides were further investigated in arrhythmia induced in isolated rat atria and rats in vivo. Results: The intracellular Ca2+ concentration decreases upon treatment with either enoxaparin or ardeparin. These drugs abolished arrhythmia induction in isolated atria. The NCX antagonist KB-R7943 abolished the enoxaparin or ardeparin antiarrhythmic effects in isolated atria. In the in vivo measurements, injection of TD 15 min both before coronary occlusion or immediately after reperfusion, significantly prevented the occurrence of reperfusion-induced arrhythmias (ventricular arrhythmia and total AV block) and reduced the lethality rate. The patch clamping experiments showed that, mechanistically, TD increases the forward mode NCX current. Conclusion: Together, the data shows that heparin oligosaccharides may constitute a new class of antiarrhythmic drug that acts by accelerating the forward mode NCX under calcium overload.
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Affiliation(s)
- Carlos M G de Godoy
- Institute of Science and Technology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ênio R Vasques
- Department of Gastroenterology (LIM 37), Medical School, University of São Paulo, São Paulo, Brazil.,Núcleo de Pesquisas Tecnológicas, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
| | - Afonso Caricati-Neto
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - José G P Tavares
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Beatriz J Alves
- Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juliana Duarte
- Núcleo de Pesquisas Tecnológicas, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
| | | | - Marcelo A Lima
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Helena B Nader
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ivarne L Dos Santos Tersariol
- Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, Brazil.,Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil
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20
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Inotropic effect of NCX inhibition depends on the relative activity of the reverse NCX assessed by a novel inhibitor ORM-10962 on canine ventricular myocytes. Eur J Pharmacol 2018; 818:278-286. [DOI: 10.1016/j.ejphar.2017.10.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 01/25/2023]
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21
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Mora MT, Ferrero JM, Romero L, Trenor B. Sensitivity analysis revealing the effect of modulating ionic mechanisms on calcium dynamics in simulated human heart failure. PLoS One 2017; 12:e0187739. [PMID: 29117223 PMCID: PMC5678731 DOI: 10.1371/journal.pone.0187739] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Abnormal intracellular Ca2+ handling is the major contributor to the depressed cardiac contractility observed in heart failure. The electrophysiological remodeling associated with this pathology alters both the action potential and the Ca2+ dynamics, leading to a defective excitation-contraction coupling that ends in mechanical dysfunction. The importance of maintaining a correct intracellular Ca2+ concentration requires a better understanding of its regulation by ionic mechanisms. To study the electrical activity and ionic homeostasis of failing myocytes, a modified version of the O’Hara et al. human action potential model was used, including electrophysiological remodeling. The impact of the main ionic transport mechanisms was analyzed using single-parameter sensitivity analyses, the first of which explored the modulation of electrophysiological characteristics related to Ca2+ exerted by the remodeled parameters. The second sensitivity analysis compared the potential consequences of modulating individual channel conductivities, as one of the main effects of potential drugs, on Ca2+ dynamic properties under both normal conditions and in heart failure. The first analysis revealed the important contribution of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) dysfunction to the altered Ca2+ homeostasis, with the Na+/Ca2+ exchanger (NCX) and other Ca2+ cycling proteins also playing a significant role. Our results highlight the importance of improving the SR uptake function to increase Ca2+ content and restore Ca2+ homeostasis and contractility. The second sensitivity analysis highlights the different response of the failing myocyte versus the healthy myocyte to potential pharmacological actions on single channels. The result of modifying the conductances of the remodeled proteins such as SERCA and NCX in heart failure has less impact on Ca2+ modulation. These differences should be taken into account when designing drug therapies.
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Affiliation(s)
- Maria T. Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M. Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
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22
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Bögeholz N, Schulte JS, Kaese S, Bauer BK, Pauls P, Dechering DG, Frommeyer G, Goldhaber JI, Kirchhefer U, Eckardt L, Pott C, Müller FU. The Effects of SEA0400 on Ca 2+ Transient Amplitude and Proarrhythmia Depend on the Na +/Ca 2+ Exchanger Expression Level in Murine Models. Front Pharmacol 2017; 8:649. [PMID: 28983248 PMCID: PMC5613119 DOI: 10.3389/fphar.2017.00649] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/01/2017] [Indexed: 11/13/2022] Open
Abstract
Background/Objective: The cardiac Na+/Ca2+ exchanger (NCX) has been identified as a promising target to counter arrhythmia in previous studies investigating the benefit of NCX inhibition. However, the consequences of NCX inhibition have not been investigated in the setting of altered NCX expression and function, which is essential, since major cardiac diseases (heart failure/atrial fibrillation) exhibit NCX upregulation. Thus, we here investigated the effects of the NCX inhibitor SEA0400 on the Ca2+ transient amplitude and on proarrhythmia in homozygous NCX overexpressor (OE) and heterozygous NCX knockout (hetKO) mice compared to corresponding wild-types (WTOE/WThetKO). Methods/Results: Ca2+ transients of field-stimulated isolated ventricular cardiomyocytes were recorded with fluo-4-AM or indo-1-AM. SEA0400 (1 μM) significantly reduced NCX forward mode function in all mouse lines. SEA0400 (1 μM) significantly increased the amplitude of field-stimulated Ca2+ transients in WTOE, WThetKO, and hetKO, but not in OE (% of basal; OE = 98.7 ± 5.0; WTOE = 137.8 ± 5.2*; WThetKO = 126.3 ± 6.0*; hetKO = 140.6 ± 12.8*; *p < 0.05 vs. basal). SEA0400 (1 μM) significantly reduced the number of proarrhythmic spontaneous Ca2+ transients (sCR) in OE, but increased it in WTOE, WThetKO and hetKO (sCR per cell; basal/+SEA0400; OE = 12.5/3.7; WTOE = 0.2/2.4; WThetKO = 1.3/8.8; hetKO = 0.2/5.5) and induced Ca2+ overload with subsequent cell death in hetKO. Conclusion: The effects of SEA0400 on Ca2+ transient amplitude and the occurrence of spontaneous Ca2+ transients as a proxy measure for inotropy and cellular proarrhythmia depend on the NCX expression level. The antiarrhythmic effect of SEA0400 in conditions of increased NCX expression promotes the therapeutic concept of NCX inhibition in heart failure/atrial fibrillation. Conversely, in conditions of reduced NCX expression, SEA0400 suppressed the NCX function below a critical level leading to adverse Ca2+ accumulation as reflected by an increase in Ca2+ transient amplitude, proarrhythmia and cell death. Thus, the remaining NCX function under inhibition may be a critical factor determining the inotropic and antiarrhythmic efficacy of SEA0400.
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Affiliation(s)
- Nils Bögeholz
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - Jan S Schulte
- Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Sven Kaese
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - B Klemens Bauer
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany.,Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Paul Pauls
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany.,Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Dirk G Dechering
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - Gerrit Frommeyer
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - Joshua I Goldhaber
- Cedars-Sinai Medical Center, Heart InstituteLos Angeles, CA, United States
| | - Uwe Kirchhefer
- Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Lars Eckardt
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - Christian Pott
- Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital MünsterMünster, Germany
| | - Frank U Müller
- Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
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23
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Mechanisms contributing to cardiac remodelling. Clin Sci (Lond) 2017; 131:2319-2345. [PMID: 28842527 DOI: 10.1042/cs20171167] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/26/2017] [Accepted: 07/31/2017] [Indexed: 12/14/2022]
Abstract
Cardiac remodelling is classified as physiological (in response to growth, exercise and pregnancy) or pathological (in response to inflammation, ischaemia, ischaemia/reperfusion (I/R) injury, biomechanical stress, excess neurohormonal activation and excess afterload). Physiological remodelling of the heart is characterized by a fine-tuned and orchestrated process of beneficial adaptations. Pathological cardiac remodelling is the process of structural and functional changes in the left ventricle (LV) in response to internal or external cardiovascular damage or influence by pathogenic risk factors, and is a precursor of clinical heart failure (HF). Pathological remodelling is associated with fibrosis, inflammation and cellular dysfunction (e.g. abnormal cardiomyocyte/non-cardiomyocyte interactions, oxidative stress, endoplasmic reticulum (ER) stress, autophagy alterations, impairment of metabolism and signalling pathways), leading to HF. This review describes the key molecular and cellular responses involved in pathological cardiac remodelling.
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24
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Identification of Na+/K+-ATPase inhibition-independent proarrhythmic ionic mechanisms of cardiac glycosides. Sci Rep 2017; 7:2465. [PMID: 28550304 PMCID: PMC5446409 DOI: 10.1038/s41598-017-02496-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 04/13/2017] [Indexed: 12/17/2022] Open
Abstract
The current study explored the Na+/K+-ATPase (NKA) inhibition-independent proarrhythmic mechanisms of cardiac glycosides (CGs) which are well-known NKA inhibitors. With the cytosolic Ca2+ chelated by EGTA and BAPTA or extracellular Ca2+ replaced by Ba2+, effects of bufadienolides (bufalin (BF) and cinobufagin (CBG)) and cardenolides (ouabain (Oua) and pecilocerin A (PEA)) on the L-type calcium current (ICa,L) were recorded in heterologous expression Cav1.2-CHO cells and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). BF and CBG demonstrated a concentration-dependent (0.1 to 100 µM) ICa,L inhibition (maximal ≥50%) without and with the NKA activity blocked by 10 µM Oua. BF significantly shortened the action potential duration at 1.0 µM and shortened the extracellular field potential duration at 0.01~1.0 µM. On the other hand, BF and CBG at 100 µM demonstrated a strong inhibition (≥40%) of the rapidly activating component of the delayed rectifier K+ current (IKr) in heterologous expression HEK293 cells and prolonged the APD of the heart of day-3 Zebrafish larva with disrupted rhythmic contractions. Moreover, hESC-CMs treated with BF (10 nM) for 24 hours showed moderate yet significant prolongation in APD90. In conclusion, our data indicate that CGs particularly bufadienolides possess cytosolic [Ca2+]i- and NKA inhibition- independent proarrhythmic potential through ICa,L and IKr inhibitions.
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Kuroda Y, Yuasa S, Watanabe Y, Ito S, Egashira T, Seki T, Hattori T, Ohno S, Kodaira M, Suzuki T, Hashimoto H, Okata S, Tanaka A, Aizawa Y, Murata M, Aiba T, Makita N, Furukawa T, Shimizu W, Kodama I, Ogawa S, Kokubun N, Horigome H, Horie M, Kamiya K, Fukuda K. Flecainide ameliorates arrhythmogenicity through NCX flux in Andersen-Tawil syndrome-iPS cell-derived cardiomyocytes. Biochem Biophys Rep 2017; 9:245-256. [PMID: 28956012 PMCID: PMC5614591 DOI: 10.1016/j.bbrep.2017.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 12/09/2016] [Accepted: 01/10/2017] [Indexed: 12/15/2022] Open
Abstract
Andersen-Tawil syndrome (ATS) is a rare inherited channelopathy. The cardiac phenotype in ATS is typified by a prominent U wave and ventricular arrhythmia. An effective treatment for this disease remains to be established. We reprogrammed somatic cells from three ATS patients to generate induced pluripotent stem cells (iPSCs). Multi-electrode arrays (MEAs) were used to record extracellular electrograms of iPSC-derived cardiomyocytes, revealing strong arrhythmic events in the ATS-iPSC-derived cardiomyocytes. Ca2+ imaging of cells loaded with the Ca2+ indicator Fluo-4 enabled us to examine intracellular Ca2+ handling properties, and we found a significantly higher incidence of irregular Ca2+ release in the ATS-iPSC-derived cardiomyocytes than in control-iPSC-derived cardiomyocytes. Drug testing using ATS-iPSC-derived cardiomyocytes further revealed that antiarrhythmic agent, flecainide, but not the sodium channel blocker, pilsicainide, significantly suppressed these irregular Ca2+ release and arrhythmic events, suggesting that flecainide's effect in these cardiac cells was not via sodium channels blocking. A reverse-mode Na+/Ca2+exchanger (NCX) inhibitor, KB-R7943, was also found to suppress the irregular Ca2+ release, and whole-cell voltage clamping of isolated guinea-pig cardiac ventricular myocytes confirmed that flecainide could directly affect the NCX current (INCX). ATS-iPSC-derived cardiomyocytes recapitulate abnormal electrophysiological phenotypes and flecainide suppresses the arrhythmic events through the modulation of INCX. iPS cells are generated from three patients with ATS. ATS-iPS cell-derived cardiomyocytes show abnormal electrophysiological phenotypes. Flecainide suppresses abnormal electrophysiological phenotypes in ATS-iPS cell-derived cardiomyocytes.
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Affiliation(s)
- Yusuke Kuroda
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.,Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan.,Department of Cardiology, Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Shinsuke Yuasa
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Yasuhide Watanabe
- Division of Pharmacological Science, Department of Health Science, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Shogo Ito
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Toru Egashira
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Tomohisa Seki
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Tetsuhisa Hattori
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Seiko Ohno
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan.,Center for Epidemiologic Research in Asia, Shiga University of Medical Science, Shiga, Japan
| | - Masaki Kodaira
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Tomoyuki Suzuki
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.,Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan.,Department of Cardiology, Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Hisayuki Hashimoto
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Shinichiro Okata
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Atsushi Tanaka
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Yoshiyasu Aizawa
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Mitsushige Murata
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.,Department of Laboratory Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Takeshi Aiba
- Division of Arrhythmia and Electrophysiology, Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Naomasa Makita
- Department of Molecular Pathophysiology-1, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Tetsushi Furukawa
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Itsuo Kodama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan
| | - Satoshi Ogawa
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
| | - Norito Kokubun
- Department of Neurology, Dokkyo Medical University, Tochigi, Japan
| | - Hitoshi Horigome
- Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Minoru Horie
- Department of Cardiovascular Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Aichi, Japan
| | - Keiichi Fukuda
- Department of Cardiology, Keio University School of Medicine, Tokyo, Japan
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26
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Kohajda Z, Farkas-Morvay N, Jost N, Nagy N, Geramipour A, Horváth A, Varga RS, Hornyik T, Corici C, Acsai K, Horváth B, Prorok J, Ördög B, Déri S, Tóth D, Levijoki J, Pollesello P, Koskelainen T, Otsomaa L, Tóth A, Baczkó I, Leprán I, Nánási PP, Papp JG, Varró A, Virág L. The Effect of a Novel Highly Selective Inhibitor of the Sodium/Calcium Exchanger (NCX) on Cardiac Arrhythmias in In Vitro and In Vivo Experiments. PLoS One 2016; 11:e0166041. [PMID: 27832106 PMCID: PMC5104402 DOI: 10.1371/journal.pone.0166041] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 10/21/2016] [Indexed: 11/18/2022] Open
Abstract
Background In this study the effects of a new, highly selective sodium-calcium exchanger (NCX) inhibitor, ORM-10962 were investigated on cardiac NCX current, Ca2+ transients, cell shortening and in experimental arrhythmias. The level of selectivity of the novel inhibitor on several major transmembrane ion currents (L-type Ca2+ current, major repolarizing K+ currents, late Na+ current, Na+/K+ pump current) was also determined. Methods Ion currents in single dog ventricular cells (cardiac myocytes; CM), and action potentials in dog cardiac multicellular preparations were recorded utilizing the whole-cell patch clamp and standard microelectrode techniques, respectively. Ca2+ transients and cell shortening were measured in fluorescent dye loaded isolated dog myocytes. Antiarrhythmic effects of ORM-10962 were studied in anesthetized ouabain (10 μg/kg/min i.v.) pretreated guinea pigs and in ischemia-reperfusion models (I/R) of anesthetized coronary artery occluded rats and Langendorff perfused guinea pigs hearts. Results ORM-10962 significantly reduced the inward/outward NCX currents with estimated EC50 values of 55/67 nM, respectively. The compound, even at a high concentration of 1 μM, did not modify significantly the magnitude of ICaL in CMs, neither had any apparent influence on the inward rectifier, transient outward, the rapid and slow components of the delayed rectifier potassium currents, the late and peak sodium and Na+/K+ pump currents. NCX inhibition exerted moderate positive inotropic effect under normal condition, negative inotropy when reverse, and further positive inotropic effect when forward mode was facilitated. In dog Purkinje fibres 1 μM ORM-10962 decreased the amplitude of digoxin induced delayed afterdepolarizations (DADs). Pre-treatment with 0.3 mg/kg ORM-10962 (i.v.) 10 min before starting ouabain infusion significantly delayed the development and recurrence of ventricular extrasystoles (by about 50%) or ventricular tachycardia (by about 30%) in anesthetized guinea pigs. On the contrary, ORM-10962 pre-treatment had no apparent influence on the time of onset or the severity of I/R induced arrhythmias in anesthetized rats and in Langendorff perfused guinea-pig hearts. Conclusions The present study provides strong evidence for a high efficacy and selectivity of the NCX-inhibitory effect of ORM-10962. Selective NCX inhibition can exert positive as well as negative inotropic effect depending on the actual operation mode of NCX. Selective NCX blockade may contribute to the prevention of DAD based arrhythmogenesis, in vivo, however, its effect on I/R induced arrhythmias is still uncertain.
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Affiliation(s)
- Zsófia Kohajda
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Nikolett Farkas-Morvay
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Norbert Jost
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
- Department of Pathophysiology, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania
| | - Norbert Nagy
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Amir Geramipour
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - András Horváth
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Richárd S. Varga
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Claudia Corici
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Károly Acsai
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Prorok
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Balázs Ördög
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Szilvia Déri
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Dániel Tóth
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | | | | | | | | | - András Tóth
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- Department of Pathophysiology, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania
| | - István Leprán
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Julius Gy Papp
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
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27
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Yamashita K, Watanabe Y, Kita S, Iwamoto T, Kimura J. Inhibitory effect of YM-244769, a novel Na +/Ca 2+ exchanger inhibitor on Na +/Ca 2+ exchange current in guinea pig cardiac ventricular myocytes. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:1205-1214. [PMID: 27480939 DOI: 10.1007/s00210-016-1282-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/21/2016] [Indexed: 11/28/2022]
Abstract
Recently, YM-244769 (N-(3-aminobenzyl)-6-{4-[(3-fluorobenzyl)oxy]phenoxy} nicotinamide) has been reported as a new potent and selective Na+/Ca2+ exchange (NCX) inhibitor by using various cells transfected with NCX using the 45Ca2+ fluorescent technique. However, the electrophysiological study of YM-244769 on NCX had not been performed in the mammalian heart. We examined the effects of YM-244769 on NCX current (INCX) in single cardiac ventricular myocytes of guinea pigs by using the whole-cell voltage clamp technique. YM-244769 suppressed the bidirectional INCX in a concentration-dependent manner. The IC50 values of YM-244769 for the bidirectional outward and inward INCX were both about 0.1 μM. YM-244769 suppressed the unidirectional outward INCX (Ca2+ entry mode) with an IC50 value of 0.05 μM. The effect on the unidirectional inward INCX (Ca2+ exit mode) was less potent, with 10 μM of YM-244769 resulting in the inhibition of only about 50 %. At 5 mM intracellular Na+ concentration, YM-244769 suppressed INCX more potently than it did at 0 mM [Na+]i. Intracellular application of trypsin via the pipette solution did not change the blocking effect of YM-244769. In conclusion, YM-244769 inhibits the Ca2+ entry mode of NCX more potently than the Ca2+ exit mode, and inhibition by YM-244769 is [Na+]i-dependent and trypsin-insensitive. These characteristics are similar to those of other benzyloxyphenyl derivative NCX inhibitors such as KB-R7943, SEA0400, and SN-6. The potency of YM-244769 as an NCX1 inhibitor is higher than those of KB-R7943 and SN-6 and is similar to that of SEA0400.
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Affiliation(s)
- Kanna Yamashita
- Division of Pharmacological Science, Department of Health Science, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasuhide Watanabe
- Division of Pharmacological Science, Department of Health Science, Hamamatsu University School of Medicine, Hamamatsu, Japan.
| | - Satomi Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Takahiro Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Junko Kimura
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Fukushima, Japan
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28
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Acsai K, Ördög B, Varró A, Nánási PP. Role of the dysfunctional ryanodine receptor - Na(+)-Ca(2+)exchanger axis in progression of cardiovascular diseases: What we can learn from pharmacological studies? Eur J Pharmacol 2016; 779:91-101. [PMID: 26970182 DOI: 10.1016/j.ejphar.2016.03.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 03/04/2016] [Accepted: 03/07/2016] [Indexed: 12/28/2022]
Abstract
Abnormal Ca(2+)homeostasis is often associated with chronic cardiovascular diseases, such as hypertension, heart failure or cardiac arrhythmias, and typically contributes to the basic ethiology of the disease. Pharmacological targeting of cardiac Ca(2+)handling has great therapeutic potential offering invaluable options for the prevention, slowing down the progression or suppression of the harmful outcomes like life threatening cardiac arrhythmias. In this review we outline the existing knowledge on the involvement of malfunction of the ryanodine receptor and the Na(+)-Ca(2+)exchanger in disturbances of Ca(2+)homeostasis and discuss important proof of concept pharmacological studies targeting these mechanisms in context of hypertension, heart failure, atrial fibrillation and ventricular arrhythmias. We emphasize the promising results of preclinical studies underpinning the potential benefits of the therapeutic strategies based on ryanodine receptor or Na(+)-Ca(2+)exchanger inhibition.
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Affiliation(s)
- Károly Acsai
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Balázs Ördög
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Faculty of Medicine, Szeged, Hungary
| | - András Varró
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, University of Szeged, Faculty of Medicine, Szeged, Hungary
| | - Péter P Nánási
- Department of Physiology, University of Debrecen, Debrecen, Hungary; Department of Dentistry, University of Debrecen, Debrecen, Hungary.
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29
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Lookin ON, Protsenko YL. The kinetics of cytosolic calcium in the right ventricular myocardium of guinea pigs and rats. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916010140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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30
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Abstract
Na(+)/Ca(2+) exchangers (NCXs) have traditionally been viewed principally as a means of Ca(2+) removal from non-excitable cells. However there has recently been increasing interest in the operation of NCXs in reverse mode acting as a means of eliciting Ca(2+) entry into these cells. Reverse mode exchange requires a significant change in the normal resting transmembrane ion gradients and membrane potential, which has been suggested to occur principally via the coupling of NCXs to localised Na(+) entry through non-selective cation channels such as canonical transient receptor potential (TRPC) channels. Here we review evidence for functional or physical coupling of NCXs to non-selective cation channels, and how this affects NCX activity in non-excitable cells. In particular we focus on the potential role of nanojunctions, where the close apposition of plasma and intracellular membranes may help create the conditions needed for the generation of localised rises in Na(+) concentration that would be required to trigger reverse mode exchange.
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Shattock MJ, Ottolia M, Bers DM, Blaustein MP, Boguslavskyi A, Bossuyt J, Bridge JHB, Chen-Izu Y, Clancy CE, Edwards A, Goldhaber J, Kaplan J, Lingrel JB, Pavlovic D, Philipson K, Sipido KR, Xie ZJ. Na+/Ca2+ exchange and Na+/K+-ATPase in the heart. J Physiol 2015; 593:1361-82. [PMID: 25772291 PMCID: PMC4376416 DOI: 10.1113/jphysiol.2014.282319] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/30/2014] [Indexed: 12/17/2022] Open
Abstract
This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field.
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Affiliation(s)
- Michael J Shattock
- King's College London BHF Centre of Excellence, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, UK
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Voigt N, Heijman J, Dobrev D. New antiarrhythmic targets in atrial fibrillation. Future Cardiol 2015; 11:645-54. [PMID: 26609872 DOI: 10.2217/fca.15.67] [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: 12/17/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia in developed countries. AF is associated with increased mortality and morbidity due to thromboembolism, stroke and worsening of pre-existing heart failure. Currently available pharmacological therapies for AF suffer from unsatisfying efficacy and/or are associated with major side effects such as bleeding complications or proarrhythmia. These limitations largely result from the fact that most of the currently available drugs were developed on an empirical basis, without precise knowledge of the molecular mechanisms underlying the arrhythmia. During the last decade substantial progress has been made in understanding the molecular mechanisms contributing to the initiation and maintenance of AF. This knowledge is expected to stimulate the development of safer and more effective drugs. Here, we review new antiarrhythmic drug targets, which have emerged based on this increasing knowledge about the molecular mechanisms of AF.
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Affiliation(s)
- Niels Voigt
- Faculty of Medicine, Institute of Pharmacology, University Duisburg-Essen, Hufelandstr 55, 45122 Essen, Germany
| | - Jordi Heijman
- Faculty of Medicine, Institute of Pharmacology, University Duisburg-Essen, Hufelandstr 55, 45122 Essen, Germany
| | - Dobromir Dobrev
- Faculty of Medicine, Institute of Pharmacology, University Duisburg-Essen, Hufelandstr 55, 45122 Essen, Germany
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Antoons G, Johnson DM, Dries E, Santiago DJ, Ozdemir S, Lenaerts I, Beekman JDM, Houtman MJC, Sipido KR, Vos MA. Calcium release near L-type calcium channels promotes beat-to-beat variability in ventricular myocytes from the chronic AV block dog. J Mol Cell Cardiol 2015; 89:326-34. [PMID: 26454162 DOI: 10.1016/j.yjmcc.2015.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 09/08/2015] [Accepted: 10/06/2015] [Indexed: 11/25/2022]
Abstract
Beat-to-beat variability of ventricular repolarization (BVR) has been proposed as a strong predictor of Torsades de Pointes (TdP). BVR is also observed at the myocyte level, and a number of studies have shown the importance of calcium handling in influencing this parameter. The chronic AV block (CAVB) dog is a model of TdP arrhythmia in cardiac hypertrophy, and myocytes from these animals show extensive remodeling, including of Ca(2+) handling. This remodeling process also leads to increased BVR. We aimed to determine the role that (local) Ca(2+) handling plays in BVR. In isolated LV myocytes an exponential relationship was observed between BVR magnitude and action potential duration (APD) at baseline. Inhibition of Ca(2+) release from sarcoplasmic reticulum (SR) with thapsigargin resulted in a reduction of [Ca(2+)]i, and of both BVR and APD. Increasing ICaL in the presence of thapsigargin restored APD but BVR remained low. In contrast, increasing ICaL with preserved Ca(2+) release increased both APD and BVR. Inhibition of Ca(2+) release with caffeine, as with thapsigargin, reduced BVR despite maintained APD. Simultaneous inhibition of Na(+)/Ca(2+) exchange and ICaL decreased APD and BVR to similar degrees, whilst increasing diastolic Ca(2+). Buffering of Ca(2+) transients with BAPTA reduced BVR for a given APD to a greater extent than buffering with EGTA, suggesting subsarcolemmal Ca(2+) transients modulated BVR to a larger extent than the cytosolic Ca(2+) transient. In conclusion, BVR in hypertrophied dog myocytes, at any APD, is strongly dependent on SR Ca(2+) release, which may act through modulation of the l-type Ca(2+) current in a subsarcolemmal microdomain.
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Affiliation(s)
- Gudrun Antoons
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium; Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands; Department of Physiology, Maastricht University, Maastricht, The Netherlands
| | - Daniel M Johnson
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Eef Dries
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Demetrio J Santiago
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Semir Ozdemir
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium; Department of Biophysics, Akdeniz University, Antalya, Turkey
| | - Ilse Lenaerts
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium
| | - Jet D M Beekman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Karin R Sipido
- Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
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Roe AT, Frisk M, Louch WE. Targeting cardiomyocyte Ca2+ homeostasis in heart failure. Curr Pharm Des 2015; 21:431-48. [PMID: 25483944 PMCID: PMC4475738 DOI: 10.2174/138161282104141204124129] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 08/06/2014] [Indexed: 12/19/2022]
Abstract
Improved treatments for heart failure patients will require the development of novel therapeutic strategies that target basal disease
mechanisms. Disrupted cardiomyocyte Ca2+ homeostasis is recognized as a major contributor to the heart failure phenotype, as it
plays a key role in systolic and diastolic dysfunction, arrhythmogenesis, and hypertrophy and apoptosis signaling. In this review, we outline
existing knowledge of the involvement of Ca2+ homeostasis in these deficits, and identify four promising targets for therapeutic intervention:
the sarcoplasmic reticulum Ca2+ ATPase, the Na+-Ca2+ exchanger, the ryanodine receptor, and t-tubule structure. We discuss
experimental data indicating the applicability of these targets that has led to recent and ongoing clinical trials, and suggest future therapeutic
approaches.
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Affiliation(s)
| | | | - William E Louch
- Institute for Experimental Medical Research, Kirkeveien 166, 4.etg. Bygg 7, Oslo University Hospital Ullevål, 0407 Oslo, Norway.
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Bito V, Sipido KR, Macquaide N. Assessing Ca²⁺-removal pathways in cardiac myocytes. Cold Spring Harb Protoc 2015; 2015:498-503. [PMID: 25934931 DOI: 10.1101/pdb.prot076992] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The decline of an intracellular calcium ([Ca(2+)]i) transient during a single excitation-contraction coupling (ECC) cycle reflects the combined activity of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) pump and the sarcolemmal Na(+)-Ca(2+) exchanger (NCX), along with minor contributions of the plasma membrane Ca(2+)-ATPase and mitochondrial Ca(2+) uniporter, in removing Ca(2+) from the cytosol. A traditional approach for assessing the individual components is to fit the decline of the [Ca(2+)]i transient evoked during electrical stimulation with an exponential. This reflects mostly the SERCA-dependent rate of uptake, which can be properly deduced after correcting for a component of NCX removal. As NCX function is an important determinant of the membrane potential as well as the Ca(2+) balance, we present here several detailed protocols for assessing NCX function. As the reversal potential and the amplitudes of the current are highly dependent on the prevailing concentrations of Na(+) and Ca(2+), we show how NCX function can be assessed under highly controlled conditions, with Ca(2+) and Na(+) clamped, as well as under more physiological conditions, with freely changing Ca(2+) and Na(+).
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Affiliation(s)
- Virginie Bito
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Karin R Sipido
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
| | - Niall Macquaide
- Division of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Belgium
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Ferrantini C, Coppini R, Sacconi L, Tosi B, Zhang ML, Wang GL, de Vries E, Hoppenbrouwers E, Pavone F, Cerbai E, Tesi C, Poggesi C, ter Keurs HEDJ. Impact of detubulation on force and kinetics of cardiac muscle contraction. ACTA ACUST UNITED AC 2014; 143:783-97. [PMID: 24863933 PMCID: PMC4035744 DOI: 10.1085/jgp.201311125] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
T-tubule uncoupling from the plasma membrane leads to myocardial contractile abnormalities. Action potential–driven Ca2+ currents from the transverse tubules (t-tubules) trigger synchronous Ca2+ release from the sarcoplasmic reticulum of cardiomyocytes. Loss of t-tubules has been reported in cardiac diseases, including heart failure, but the effect of uncoupling t-tubules from the sarcolemma on cardiac muscle mechanics remains largely unknown. We dissected intact rat right ventricular trabeculae and compared force, sarcomere length, and intracellular Ca2+ in control trabeculae with trabeculae in which the t-tubules were uncoupled from the plasma membrane by formamide-induced osmotic shock (detubulation). We verified disconnection of a consistent fraction of t-tubules from the sarcolemma by two-photon fluorescence imaging of FM4-64–labeled membranes and by the absence of tubular action potential, which was recorded by random access multiphoton microscopy in combination with a voltage-sensitive dye (Di-4-AN(F)EPPTEA). Detubulation reduced the amplitude and prolonged the duration of Ca2+ transients, leading to slower kinetics of force generation and relaxation and reduced twitch tension (1 Hz, 30°C, 1.5 mM [Ca2+]o). No mechanical changes were observed in rat left atrial trabeculae after formamide shock, consistent with the lack of t-tubules in rodent atrial myocytes. Detubulation diminished the rate-dependent increase of Ca2+-transient amplitude and twitch force. However, maximal twitch tension at high [Ca2+]o or in post-rest potentiated beats was unaffected, although contraction kinetics were slower. The ryanodine receptor (RyR)2 Ca-sensitizing agent caffeine (200 µM), which increases the velocity of transverse Ca2+ release propagation in detubulated cardiomyocytes, rescued the depressed contractile force and the slower twitch kinetics of detubulated trabeculae, with negligible effects in controls. We conclude that partial loss of t-tubules leads to myocardial contractile abnormalities that can be rescued by enhancing and accelerating the propagation of Ca2+-induced Ca2+ release to orphan RyR2 clusters.
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Affiliation(s)
- Cecilia Ferrantini
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Raffaele Coppini
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Leonardo Sacconi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy National Institute of Optics, National Research Council, 50019 Sesto Fiorentino, Italy
| | - Benedetta Tosi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Mei Luo Zhang
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Guo Liang Wang
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Ewout de Vries
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Ernst Hoppenbrouwers
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Francesco Pavone
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy National Institute of Optics, National Research Council, 50019 Sesto Fiorentino, Italy
| | - Elisabetta Cerbai
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Chiara Tesi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Corrado Poggesi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Henk E D J ter Keurs
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Wanichawan P, Hafver TL, Hodne K, Aronsen JM, Lunde IG, Dalhus B, Lunde M, Kvaløy H, Louch WE, Tønnessen T, Sjaastad I, Sejersted OM, Carlson CR. Molecular basis of calpain cleavage and inactivation of the sodium-calcium exchanger 1 in heart failure. J Biol Chem 2014; 289:33984-98. [PMID: 25336645 DOI: 10.1074/jbc.m114.602581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cardiac sodium (Na(+))-calcium (Ca(2+)) exchanger 1 (NCX1) is central to the maintenance of normal Ca(2+) homeostasis and contraction. Studies indicate that the Ca(2+)-activated protease calpain cleaves NCX1. We hypothesized that calpain is an important regulator of NCX1 in response to pressure overload and aimed to identify molecular mechanisms and functional consequences of calpain binding and cleavage of NCX1 in the heart. NCX1 full-length protein and a 75-kDa NCX1 fragment along with calpain were up-regulated in aortic stenosis patients and rats with heart failure. Patients with coronary artery disease and sham-operated rats were used as controls. Calpain co-localized, co-fractionated, and co-immunoprecipitated with NCX1 in rat cardiomyocytes and left ventricle lysate. Immunoprecipitations, pull-down experiments, and extensive use of peptide arrays indicated that calpain domain III anchored to the first Ca(2+) binding domain in NCX1, whereas the calpain catalytic region bound to the catenin-like domain in NCX1. The use of bioinformatics, mutational analyses, a substrate competitor peptide, and a specific NCX1-Met(369) antibody identified a novel calpain cleavage site at Met(369). Engineering NCX1-Met(369) into a tobacco etch virus protease cleavage site revealed that specific cleavage at Met(369) inhibited NCX1 activity (both forward and reverse mode). Finally, a short peptide fragment containing the NCX1-Met(369) cleavage site was modeled into the narrow active cleft of human calpain. Inhibition of NCX1 activity, such as we have observed here following calpain-induced NCX1 cleavage, might be beneficial in pathophysiological conditions where increased NCX1 activity contributes to cardiac dysfunction.
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Affiliation(s)
- Pimthanya Wanichawan
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Tandekile Lubelwana Hafver
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Kjetil Hodne
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Jan Magnus Aronsen
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, Bjorknes College, 0456 Oslo, Norway
| | - Ida Gjervold Lunde
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway, the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Bjørn Dalhus
- the Departments of Microbiology and Medical Biochemistry, Oslo University Hospital, Rikshospitalet, 0372 Oslo, Norway, and
| | - Marianne Lunde
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Heidi Kvaløy
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - William Edward Louch
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Theis Tønnessen
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the Department of Cardiothoracic Surgery, Oslo University Hospital, Ullevål, 0407 Oslo, Norway
| | - Ivar Sjaastad
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Ole Mathias Sejersted
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway
| | - Cathrine Rein Carlson
- From the Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0407 Oslo, Norway, the KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, 0318 Oslo, Norway,
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Gandhi A, Siedlecka U, Shah AP, Navaratnarajah M, Yacoub MH, Terracciano CM. The effect of SN-6, a novel sodium-calcium exchange inhibitor, on contractility and calcium handling in isolated failing rat ventricular myocytes. Cardiovasc Ther 2014; 31:e115-24. [PMID: 24106913 DOI: 10.1111/1755-5922.12045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Specific Na(+) /Ca(2+) exchanger (NCX) inhibition is a potential strategy to correct reduced contractility and depleted sarcoplasmic reticulum (SR) Ca(2+) content in heart failure (HF). SN-6, a benzyloxyphenyl derivative and proposed selective NCX inhibitor, could be used for this purpose. This study aimed to evaluate the effects of SN-6 on contractility and Ca(2+) handling in normal and failing rat cardiomyocytes. EXPERIMENTAL APPROACH HF was induced in rats by coronary artery ligation. Left ventricular myocytes were isolated and superfused with increasing concentrations of SN-6. KEY RESULTS Sarcomere shortening, induced by field-stimulation, was reduced in amplitude with increasing concentrations of SN-6 compared with control solution. This effect was greater in failing cells. Kinetics of contractility (time to 90% peak and time to 50% relaxation) were significantly faster. Despite this, intracellular Ca(2+) transients demonstrated no change in the peak amplitude at low concentrations of SN-6, suggesting that SN-6 may affect myofilament sensitivity to Ca(2+) . Ten micro molar SN-6 significantly reduced peak Ca(2+) amplitude by 61.57% and 64.73% in normal and failing cells, respectively. Diastolic Ca(2+) was significantly increased at 1 μM SN-6. SR Ca(2+) content, assessed by rapid application of caffeine, was reduced in failing cells with 1 μM SN-6. Peak ICa , measured by whole-cell patch clamping, was significantly reduced in normal and failing myocytes at 1 μM SN-6. CONCLUSIONS AND IMPLICATIONS Our data suggest that SN-6 is not a selective inhibitor of NCX and impairs contractility and Ca(2+) handling. Its use, together with similar putative NCX blockers, in correcting the contractile abnormalities of heart failure requires further studies.
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Affiliation(s)
- Ajay Gandhi
- Cell Electrophysiology, Heart Science Centre, NHLI, Imperial College London, London, UK
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39
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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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40
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Wang J, Song J, Gao E, Zhang XQ, Gu T, Yu D, Koch WJ, Feldman AM, Cheung JY. Induced overexpression of phospholemman S68E mutant improves cardiac contractility and mortality after ischemia-reperfusion. Am J Physiol Heart Circ Physiol 2014; 306:H1066-77. [PMID: 24486513 DOI: 10.1152/ajpheart.00861.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phospholemman (PLM), when phosphorylated at Ser(68), inhibits cardiac Na+ / Ca2+ exchanger 1 (NCX1) and relieves its inhibition on Na+ -K+ -ATPase. We have engineered mice in which expression of the phosphomimetic PLM S68E mutant was induced when dietary doxycycline was removed at 5 wk. At 8-10 wk, compared with noninduced or wild-type hearts, S68E expression in induced hearts was ∼35-75% that of endogenous PLM, but protein levels of sarco(endo)plasmic reticulum Ca2+ -ATPase, α1- and α2-subunits of Na+ -K+ -ATPase, α1c-subunit of L-type Ca2+ channel, and phosphorylated ryanodine receptor were unchanged. The NCX1 protein level was increased by ∼47% but the NCX1 current was depressed by ∼34% in induced hearts. Isoproterenol had no effect on NCX1 currents but stimulated Na+ -K+ -ATPase currents equally in induced and noninduced myocytes. At baseline, systolic intracellular Ca2+ concentrations ([Ca2+]i), sarcoplasmic reticulum Ca2+ contents, and [Ca(2+)]i transient and contraction amplitudes were similar between induced and noninduced myocytes. Isoproterenol stimulation resulted in much higher systolic [Ca2+]i, sarcoplasmic reticulum Ca2+ content, and [Ca2+]i transient and contraction amplitudes in induced myocytes. Echocardiography and in vivo close-chest catheterization demonstrated similar baseline myocardial function, but isoproterenol induced a significantly higher +dP/dt in induced compared with noninduced hearts. In contrast to the 50% mortality observed in mice constitutively overexpressing the S68E mutant, induced mice had similar survival as wild-type and noninduced mice. After ischemia-reperfusion, despite similar areas at risk and left ventricular infarct sizes, induced mice had significantly higher +dP/dt and -dP/dt and lower perioperative mortality compared with noninduced mice. We propose that phosphorylated PLM may be a novel therapeutic target in ischemic heart disease.
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Affiliation(s)
- JuFang Wang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
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41
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Signore S, Sorrentino A, Ferreira-Martins J, Kannappan R, Shafaie M, Del Ben F, Isobe K, Arranto C, Wybieralska E, Webster A, Sanada F, Ogórek B, Zheng H, Liu X, Del Monte F, D'Alessandro DA, Wunimenghe O, Michler RE, Hosoda T, Goichberg P, Leri A, Kajstura J, Anversa P, Rota M. Inositol 1, 4, 5-trisphosphate receptors and human left ventricular myocytes. Circulation 2013; 128:1286-97. [PMID: 23983250 DOI: 10.1161/circulationaha.113.002764] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Little is known about the function of inositol 1,4,5-trisphosphate receptors (IP3Rs) in the adult heart experimentally. Moreover, whether these Ca(2+) release channels are present and play a critical role in human cardiomyocytes remains to be defined. IP3Rs may be activated after Gαq-protein-coupled receptor stimulation, affecting Ca(2+) cycling, enhancing myocyte performance, and potentially favoring an increase in the incidence of arrhythmias. METHODS AND RESULTS IP3R function was determined in human left ventricular myocytes, and this analysis was integrated with assays in mouse myocytes to identify the mechanisms by which IP3Rs influence the electric and mechanical properties of the myocardium. We report that IP3Rs are expressed and operative in human left ventricular myocytes. After Gαq-protein-coupled receptor activation, Ca(2+) mobilized from the sarcoplasmic reticulum via IP3Rs contributes to the decrease in resting membrane potential, prolongation of the action potential, and occurrence of early afterdepolarizations. Ca(2+) transient amplitude and cell shortening are enhanced, and extrasystolic and dysregulated Ca(2+) elevations and contractions become apparent. These alterations in the electromechanical behavior of human cardiomyocytes are coupled with increased isometric twitch of the myocardium and arrhythmic events, suggesting that Gαq-protein-coupled receptor activation provides inotropic reserve, which is hampered by electric instability and contractile abnormalities. Additionally, our findings support the notion that increases in Ca(2+) load by IP3Rs promote Ca(2+) extrusion by forward-mode Na(+)/Ca(2+) exchange, an important mechanism of arrhythmic events. CONCLUSIONS The Gαq-protein/coupled receptor/IP3R axis modulates the electromechanical properties of the human myocardium and its propensity to develop arrhythmias.
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Affiliation(s)
- Sergio Signore
- Departments of Anesthesia and Medicine and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (S.S., A.S., J.F.-M., R.K., M.S., F.D.B., K.I., C.A., E.W., A.W., F.S., B.O., H.Z., X.L., T.H., P.G., A.L., J.K., P.A., M.R.); Cardiovascular Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (F.d.M.); and Department of Cardiovascular and Thoracic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY (D.A.D., O.W., R.E.M.)
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42
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DeSantiago J, Bare DJ, Ke Y, Sheehan KA, Solaro RJ, Banach K. Functional integrity of the T-tubular system in cardiomyocytes depends on p21-activated kinase 1. J Mol Cell Cardiol 2013; 60:121-8. [PMID: 23612118 PMCID: PMC3679655 DOI: 10.1016/j.yjmcc.2013.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 03/06/2013] [Accepted: 04/12/2013] [Indexed: 12/30/2022]
Abstract
p21-activated kinase (Pak1), a serine-threonine protein kinase, regulates cytoskeletal dynamics and cell motility. Recent experiments further demonstrate that loss of Pak1 results in exaggerated hypertrophic growth in response to pathophysiological stimuli. Calcium (Ca) signaling plays an important role in the regulation of transcription factors involved in hypertrophic remodeling. Here we aimed to determine the role of Pak1 in cardiac excitation-contraction coupling (ECC). Ca transients were recorded in isolated, ventricular myocytes (VMs) from WT and Pak1(-/-) mice. Pak1(-/-) Ca transients had a decreased amplitude, prolonged rise time and delayed recovery time. Di-8-ANNEPS staining revealed a decreased T-tubular density in Pak1(-/-) VMs that coincided with decreased cell capacitance and increased dis-synchrony of Ca induced Ca release (CICR) at individual release units. These changes were not observed in atrial myocytes of Pak1(-/-) mice where the T-tubular system is only sparsely developed. Experiments in cultured rabbit VMs supported a role of Pak1 in the maintenance of the T-tubular structure. T-tubular density in rabbit VMs significantly decreased within 24h of culture. This was accompanied by a decrease of the Ca transient amplitude and a prolongation of its rise time. However, overexpression of constitutively active Pak1 in VMs attenuated the structural remodeling as well as changes in ECC. The results provide significant support for a prominent role of Pak1 activity not only in the functional regulation of ECC but for the structural maintenance of the T-tubular system whose remodeling is an integral feature of hypertrophic remodeling.
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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
- Dept. 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
- Dept. of Medicine, Section of Cardiology, 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
- Dept. of Physiology and Biophysics, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
| | - Katherine A. Sheehan
- Center for Cardiovascular Research, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
- Dept. 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
- Dept. 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
- Dept. of Medicine, Section of Cardiology, University of Illinois at Chicago, 840 S. Wood Street, Chicago, IL 60612, USA
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Ottolia M, Torres N, Bridge JHB, Philipson KD, Goldhaber JI. Na/Ca exchange and contraction of the heart. J Mol Cell Cardiol 2013; 61:28-33. [PMID: 23770352 DOI: 10.1016/j.yjmcc.2013.06.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 05/30/2013] [Accepted: 06/04/2013] [Indexed: 12/19/2022]
Abstract
Sodium-calcium exchange (NCX) is the major calcium (Ca) efflux mechanism of ventricular cardiomyocytes. Consequently the exchanger plays a critical role in the regulation of cellular Ca content and hence contractility. Reductions in Ca efflux by the exchanger, such as those produced by elevated intracellular sodium (Na) in response to cardiac glycosides, raise sarcoplasmic reticulum (SR) Ca stores. The result is an increased Ca transient and cardiac contractility. Enhanced Ca efflux activity by the exchanger, for example during heart failure, may reduce diadic cleft Ca and excitation-contraction (EC) coupling gain. This aggravates the impaired contractility associated with SR Ca ATPase dysfunction and reduced SR Ca load in failing heart muscle. Recent data from our laboratories indicate that NCX can also impact the efficiency of EC coupling and contractility independent of SR Ca load through diadic cleft priming with Ca during the upstroke of the action potential. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
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Affiliation(s)
- Michela Ottolia
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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44
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Wang J, Gao E, Chan TO, Zhang XQ, Song J, Shang X, Koch WJ, Feldman AM, Cheung JY. Induced overexpression of Na(+)/Ca(2+) exchanger does not aggravate myocardial dysfunction induced by transverse aortic constriction. J Card Fail 2013; 19:60-70. [PMID: 23273595 DOI: 10.1016/j.cardfail.2012.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/06/2012] [Accepted: 11/08/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND Alterations in expression and activity of cardiac Na(+)/Ca(2+) exchanger (NCX1) have been implicated in the pathogenesis of heart failure. METHODS AND RESULTS Using transgenic mice in which expression of rat NCX1 was induced at 5 weeks of age, we performed transverse aortic constriction (TAC) at 8 weeks and examined cardiac and myocyte function at 15-18 weeks after TAC (age 23-26 weeks). TAC induced left ventricular (LV) and myocyte hypertrophy and increased myocardial fibrosis in both wild-type (WT) and NCX1-overexpressed mice. NCX1 and phosphorylated ryanodine receptor expression was increased by TAC, whereas sarco(endo)plasmic reticulum Ca(2+)-ATPase levels were decreased by TAC. Action potential duration was prolonged by TAC, but to a greater extent in NCX1 myocytes. Na(+)/Ca(2+) exchange current was similar between WT-TAC and WT-sham myocytes, but was higher in NCX1-TAC myocytes. Both myocyte contraction and [Ca(2+)](i) transient amplitudes were reduced in WT-TAC myocytes, but restored to WT-sham levels in NCX1-TAC myocytes. Despite improvement in single myocyte contractility and Ca(2+) dynamics, induced NCX1 overexpression in TAC animals did not ameliorate LV hypertrophy, increase ejection fraction, or enhance inotropic (maximal first derivative of LV pressure rise, +dP/dt) responses to isoproterenol. CONCLUSIONS In pressure-overload hypertrophy, induced overexpression of NCX1 corrected myocyte contractile and [Ca(2+)](i) transient abnormalities but did not aggravate or improve myocardial dysfunction.
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Affiliation(s)
- Jufang Wang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Ozturk N, Yaras N, Ozmen A, Ozdemir S. Long-term administration of rosuvastatin prevents contractile and electrical remodelling of diabetic rat heart. J Bioenerg Biomembr 2013; 45:343-52. [PMID: 23640692 DOI: 10.1007/s10863-013-9514-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 04/19/2013] [Indexed: 01/09/2023]
Abstract
In recent years, many findings have been presented about the potential benefit of statin therapy on diabetes-induced cardiovascular complications. Cardioprotective effects of statins were suggested to be mediated at least in part through inhibition of small GTPases, particularly those of the Rho family. The present study was designed to examine whether rosuvastatin can improve electrical remodeling and contractile dysfunction in type 1 diabetic rat heart via modulation of RhoA pathway. Type 1 diabetes was induced by single dose injection of STZ (50 mg/kg). One week after injection rosuvastatin (10 mg/kg/day) and sham treatment was given for 5 weeks in the diabetic rats, as well as in control groups. Shortening and Ca²⁺ transients were recorded in myocytes loaded with Fura2-AM. Membrane currents and Ca²⁺ transients were measured synchronously via whole-cell patch clamping. In untreated diabetic rats, relaxation of shortening and decay of the matched Ca²⁺ transients were prolonged. Fractional shortening and Ca²⁺ transients were also decreased. Rosuvastatin treatment reversed those changes. I(CaL) density did not change in either group but rosuvastatin recovered the loss of sarcoplasmic reticulum Ca²⁺ and Na⁺/Ca²⁺ exchange as evidenced from amplitude and decay of caffeine-induced Ca²⁺ transients, peak INCX and calculated sarcoplasmic reticulum Ca²⁺ content. Diabetes-induced attenuation of I(to) and I(sus) was also reversed, whilst I(K1) was unchanged in diabetes and unaffected by treatment. Rosuvastatin prevented the diabetes-induced increase in RhoA expression. Plasma cholesterol and triglyceride levels were higher in diabetic rats, but rosuvastatin reduced only the latter. In conclusion, HMG-CoA reductase inhibitor rosuvastatin can prevent diabetes-induced electrical and functional remodeling of heart due to inhibition of RhoA signalling rather than reduction of cholesterol level.
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Affiliation(s)
- Nihal Ozturk
- Department of Biophysics, Akdeniz University Faculty of Medicine, Antalya, Turkey
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46
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Bourgonje VJA, Vos MA, Ozdemir S, Doisne N, Acsai K, Varro A, Sztojkov-Ivanov A, Zupko I, Rauch E, Kattner L, Bito V, Houtman M, van der Nagel R, Beekman JD, van Veen TAB, Sipido KR, Antoons G. Combined Na(+)/Ca(2+) exchanger and L-type calcium channel block as a potential strategy to suppress arrhythmias and maintain ventricular function. Circ Arrhythm Electrophysiol 2013; 6:371-9. [PMID: 23515266 DOI: 10.1161/circep.113.000322] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND L-type calcium channel (LTCC) and Na(+)/Ca(2+) exchanger (NCX) have been implicated in repolarization-dependent arrhythmias, but also modulate calcium and contractility. Although LTCC inhibition is negative inotropic, NCX inhibition has the opposite effect. Combined block may, therefore, offer an advantage for hemodynamics and antiarrhythmic efficiency, particularly in diseased hearts. In a model of proarrhythmia, the dog with chronic atrioventricular block, we investigated whether combined inhibition of NCX and LTCC with SEA-0400 is effective against dofetilide-induced torsade de pointes arrhythmias (TdP), while maintaining calcium homeostasis and hemodynamics. METHODS AND RESULTS Left ventricular pressure (LVP) and ECG were monitored during infusion of SEA-0400 and verapamil in anesthetized dogs. Different doses were tested against dofetilide-induced TdP in chronic atrioventricular block dogs. In ventricular myocytes, effects of SEA-0400 were tested on action potentials, calcium transients, and early afterdepolarizations. In cardiomyocytes, SEA-0400 (1 μmol/L) blocked 66±3% of outward NCX, 50±2% of inward NCX, and 33±9% of LTCC current. SEA-0400 had no effect on systolic calcium, but slowed relaxation, despite action potential shortening, and increased diastolic calcium. SEA-0400 stabilized dofetilide-induced lability of repolarization and suppressed early afterdepolarizations. In vivo, SEA-0400 (0.4 and 0.8 mg/kg) had no effect on left ventricular pressure and suppressed dofetilide-induced TdPs dose dependently. Verapamil (0.3 mg/kg) also inhibited TdP, but caused a 15±8% drop of left ventricular pressure. A lower dose of verapamil without effects on left ventricular pressure (0.06 mg/kg) was not antiarrhythmic. CONCLUSIONS In chronic atrioventricular block dogs, SEA-0400 treatment is effective against TdP. Unlike specific inhibition of LTCC, combined NCX and LTCC inhibition has no negative effects on cardiac hemodynamics.
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Affiliation(s)
- Vincent J A Bourgonje
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
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Louch WE, Stokke MK, Sjaastad I, Christensen G, Sejersted OM. No rest for the weary: diastolic calcium homeostasis in the normal and failing myocardium. Physiology (Bethesda) 2013; 27:308-23. [PMID: 23026754 DOI: 10.1152/physiol.00021.2012] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Following contraction of the heart, efficient relaxation (diastole) is essential for refilling the ventricles with blood. This review describes how ventricular relaxation is controlled by Ca(2+) homeostasis in cardiac muscle cells and how alterations in Ca(2+) cycling affect diastolic function in the normal and failing heart. These discussions illustrate that the diastolic phase is not simply a period of rest but rather involves highly regulated and dynamic Ca(2+) fluxes.
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Affiliation(s)
- William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.
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Sacherer M, Sedej S, Wakuła P, Wallner M, Vos MA, Kockskämper J, Stiegler P, Sereinigg M, von Lewinski D, Antoons G, Pieske BM, Heinzel FR. JTV519 (K201) reduces sarcoplasmic reticulum Ca²⁺ leak and improves diastolic function in vitro in murine and human non-failing myocardium. Br J Pharmacol 2013; 167:493-504. [PMID: 22509897 DOI: 10.1111/j.1476-5381.2012.01995.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca²⁺ leak from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyR2s) contributes to cardiomyocyte dysfunction. RyR2 Ca²⁺ leak has been related to RyR2 phosphorylation. In these conditions, JTV519 (K201), a 1,4-benzothiazepine derivative and multi-channel blocker, stabilizes RyR2s and decrease SR Ca²⁺ leak. We investigated whether JTV519 stabilizes RyR2s without increasing RyR2 phosphorylation in mice and in non-failing human myocardium and explored underlying mechanisms. EXPERIMENTAL APPROACH SR Ca²⁺ leak was induced by ouabain in murine cardiomyocytes. [Ca²⁺]-transients, SR Ca²⁺ load and RyR2-mediated Ca²⁺ leak (sparks/waves) were quantified, with or without JTV519 (1 µmol·L⁻¹). Contribution of Ca²⁺ -/calmodulin-dependent kinase II (CaMKII) was assessed by KN-93 and Western blot (RyR2-Ser(2814) phosphorylation). Effects of JTV519 on contractile force were investigated in non-failing human ventricular trabeculae. KEY RESULTS Ouabain increased systolic and diastolic cytosolic [Ca²⁺](i) , SR [Ca²⁺], and SR Ca²⁺ leak (Ca²⁺ spark (SparkF) and Ca²⁺ wave frequency), independently of CaMKII and RyR-Ser(2814) phosphorylation. JTV519 decreased SparkF but also SR Ca²⁺ load. At matched SR [Ca²⁺], Ca²⁺ leak was significantly reduced by JTV519, but it had no effect on fractional Ca²⁺ release or Ca²⁺ wave propagation velocity. In human muscle, JTV519 was negatively inotropic at baseline but significantly enhanced ouabain-induced force and reduced its deleterious effects on diastolic function. CONCLUSIONS AND IMPLICATIONS JTV519 was effective in reducing SR Ca²⁺ leak by specifically regulating RyR2 opening at diastolic [Ca²⁺](i) in the absence of increased RyR2 phosphorylation at Ser(2814) , extending the potential use of JTV519 to conditions of acute cellular Ca²⁺ overload.
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Affiliation(s)
- M Sacherer
- Division of Cardiology, Medical University of Graz, Austria
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Menick DR, Li MS, Chernysh O, Renaud L, Kimbrough D, Kasiganesan H, Mani SK. Transcriptional pathways and potential therapeutic targets in the regulation of Ncx1 expression in cardiac hypertrophy and failure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:125-35. [PMID: 23224875 PMCID: PMC3624972 DOI: 10.1007/978-1-4614-4756-6_11] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Changes in cardiac gene expression contribute to the progression of heart failure by affecting cardiomyocyte growth, function, and survival. The Na(+)-Ca(2+) exchanger gene (Ncx1) is upregulated in hypertrophy and is often found elevated in end-stage heart failure. Studies have shown that the change in its expression contributes to contractile dysfunction. Several transcriptional pathways mediate Ncx1 expression in pathological cardiac remodeling. Both α-adrenergic receptor (α-AR) and β-adrenergic receptor (β-AR) signaling can play a role in the regulation of calcium homeostasis in the cardiomyocyte, but chronic activation in periods of cardiac stress contributes to heart failure by mechanisms which include Ncx1 upregulation. Our studies have even demonstrated that NCX1 can directly act as a regulator of "activity-dependent signal transduction" mediating changes in its own expression. Finally, we present evidence that histone deacetylases (HDACs) and histone acetyltransferases (HATs) act as master regulators of Ncx1 expression. We show that many of the transcription factors regulating Ncx1 expression are important in cardiac development and also in the regulation of many other genes in the so-called fetal gene program, which are activated by pathological stimuli. Importantly, studies have revealed that the transcriptional network regulating Ncx1 expression is also mediating many of the other changes in genetic remodeling contributing to the development of cardiac dysfunction and revealed potential therapeutic targets for the treatment of hypertrophy and failure.
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Aydemir M, Ozturk N, Dogan S, Aslan M, Olgar Y, Ozdemir S. Sodium tungstate administration ameliorated diabetes-induced electrical and contractile remodeling of rat heart without normalization of hyperglycemia. Biol Trace Elem Res 2012; 148:216-23. [PMID: 22351103 DOI: 10.1007/s12011-012-9350-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 01/26/2012] [Indexed: 01/01/2023]
Abstract
Recently, sodium tungstate was suggested to improve cardiac performance of diabetic rats in perfused hearts based on its insulinomimetic activity. In this study, we aimed to investigate the cellular and molecular mechanisms underlying this beneficial effect of sodium tungstate. Tungstate was administered (100 mg/kg/day) to diabetic and control rats intragastrically for 6 weeks. Blood glucose levels increased, whereas body weight, heart weight and plasma insulin levels decreased significantly in diabetic animals. Interestingly, none of these parameters was changed by tungstate treatment. On the other hand, fractional shortening and accompanying intracellular Ca(2+) [Ca(2+)](i) transients of isolated ventricular myocytes were measured, and sodium tungstate was found to improve the peak shortening and the amplitude of [Ca(2+)](i) transients in diabetic cardiomyocytes. Potassium and L-type Ca(2+) currents were also recorded in isolated ventricular cells. Significant restoration of suppressed I (to) and I (ss) was achieved by tungstate administration. Nevertheless, L-type calcium currents did not change either in untreated or treated diabetic rats. Tissue biochemical parameters including TBARS, protein carbonyl content, xanthine oxidase (XO) and xanthine dehydogenase (XDH) were also determined, and diabetes revealed a marked increase in TBARS and carbonyl content which were decreased significantly by tungstate treatment. Conversely, although XO and XDH activities didn't change in untreated diabetic rats, a remarkable but insignificant decrease was detected in treated animals. In conclusion, tungstate treatment improved diabetes-induced contractile abnormalities via restoration of dysregulated [Ca(2+)](i) and altered ionic currents. This beneficial effect is due to antioxidant property of sodium tungstate rather than normalization of hyperglycemia.
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Affiliation(s)
- Mustafa Aydemir
- Faculty of Medicine, Department of Biophysics, Akdeniz University, Antalya, Turkey
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