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Kussauer S, Dilk P, Elleisy M, Michaelis C, Lichtwark S, Rimmbach C, David R, Jung J. Heart rhythm in vitro: measuring stem cell-derived pacemaker cells on microelectrode arrays. Front Cardiovasc Med 2024; 11:1200786. [PMID: 38450366 PMCID: PMC10915086 DOI: 10.3389/fcvm.2024.1200786] [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: 04/05/2023] [Accepted: 02/05/2024] [Indexed: 03/08/2024] Open
Abstract
Background Cardiac arrhythmias have markedly increased in recent decades, highlighting the urgent need for appropriate test systems to evaluate the efficacy and safety of new pharmaceuticals and the potential side effects of established drugs. Methods The Microelectrode Array (MEA) system may be a suitable option, as it provides both real-time and non-invasive monitoring of cellular networks of spontaneously active cells. However, there is currently no commercially available cell source to apply this technology in the context of the cardiac conduction system (CCS). In response to this problem, our group has previously developed a protocol for the generation of pure functional cardiac pacemaker cells from mouse embryonic stem cells (ESCs). In addition, we compared the hanging drop method, which was previously utilized, with spherical plate-derived embryoid bodies (EBs) and the pacemaker cells that are differentiated from these. Results We described the application of these pacemaker cells on the MEA platform, which required a number of crucial optimization steps in terms of coating, dissociation, and cell density. As a result, we were able to generate a monolayer of pure pacemaker cells on an MEA surface that is viable and electromechanically active for weeks. Furthermore, we introduced spherical plates as a convenient and scalable method to be applied for the production of induced sinoatrial bodies. Conclusion We provide a tool to transfer modeling and analysis of cardiac rhythm diseases to the cell culture dish. Our system allows answering CCS-related queries within a cellular network, both under baseline conditions and post-drug exposure in a reliable and affordable manner. Ultimately, our approach may provide valuable guidance not only for cardiac pacemaker cells but also for the generation of an MEA test platform using other sensitive non-proliferating cell types.
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Affiliation(s)
- Sophie Kussauer
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Patrick Dilk
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Moustafa Elleisy
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Claudia Michaelis
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Sarina Lichtwark
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Christian Rimmbach
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
| | - Julia Jung
- Department of Cardiac Surgery, Rostock University Medical Centre, Rostock, Germany
- Department of Life, Light, & Matter, University of Rostock, Rostock, Germany
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Shrestha N, Zorn-Pauly K, Mesirca P, Koyani CN, Wölkart G, Di Biase V, Torre E, Lang P, Gorischek A, Schreibmayer W, Arnold R, Maechler H, Mayer B, von Lewinski D, Torrente AG, Mangoni ME, Pelzmann B, Scheruebel S. Lipopolysaccharide-induced sepsis impairs M2R-GIRK signaling in the mouse sinoatrial node. Proc Natl Acad Sci U S A 2023; 120:e2210152120. [PMID: 37406102 PMCID: PMC10334783 DOI: 10.1073/pnas.2210152120] [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: 06/14/2022] [Accepted: 05/15/2023] [Indexed: 07/07/2023] Open
Abstract
Sepsis has emerged as a global health burden associated with multiple organ dysfunction and 20% mortality rate in patients. Numerous clinical studies over the past two decades have correlated the disease severity and mortality in septic patients with impaired heart rate variability (HRV), as a consequence of impaired chronotropic response of sinoatrial node (SAN) pacemaker activity to vagal/parasympathetic stimulation. However, the molecular mechanism(s) downstream to parasympathetic inputs have not been investigated yet in sepsis, particularly in the SAN. Based on electrocardiography, fluorescence Ca2+ imaging, electrophysiology, and protein assays from organ to subcellular level, we report that impaired muscarinic receptor subtype 2-G protein-activated inwardly-rectifying potassium channel (M2R-GIRK) signaling in a lipopolysaccharide-induced proxy septic mouse model plays a critical role in SAN pacemaking and HRV. The parasympathetic responses to a muscarinic agonist, namely IKACh activation in SAN cells, reduction in Ca2+ mobilization of SAN tissues, lowering of heart rate and increase in HRV, were profoundly attenuated upon lipopolysaccharide-induced sepsis. These functional alterations manifested as a direct consequence of reduced expression of key ion-channel components (GIRK1, GIRK4, and M2R) in the mouse SAN tissues and cells, which was further evident in the human right atrial appendages of septic patients and likely not mediated by the common proinflammatory cytokines elevated in sepsis.
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Affiliation(s)
- Niroj Shrestha
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Klaus Zorn-Pauly
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Chintan N. Koyani
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Gerald Wölkart
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Valentina Di Biase
- Institute of Pharmacology, Medical University of Innsbruck, 6020Innsbruck, Austria
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Petra Lang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Astrid Gorischek
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Wolfgang Schreibmayer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Robert Arnold
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Heinrich Maechler
- Division of Cardiac Surgery, Medical University of Graz, 8036Graz, Austria
| | - Bernd Mayer
- Department of Pharmacology and Toxicology, University of Graz, 8010Graz, Austria
| | - Dirk von Lewinski
- Division of Cardiology, Medical University of Graz, 8036Graz, Austria
| | - Angelo G. Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Matteo E. Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, 34094Montpellier, France
- Laboratory of Excellence in Ion Channels Science and Therapeutics, 34094Montpellier, France
| | - Brigitte Pelzmann
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
| | - Susanne Scheruebel
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Medical Physics and Biophysics, Medical University of Graz, 8010Graz, Austria
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3
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Butova X, Myachina T, Simonova R, Kochurova A, Bozhko Y, Arkhipov M, Solovyova O, Kopylova G, Shchepkin D, Khokhlova A. Peculiarities of the Acetylcholine Action on the Contractile Function of Cardiomyocytes from the Left and Right Atria in Rats. Cells 2022; 11:cells11233809. [PMID: 36497067 PMCID: PMC9737865 DOI: 10.3390/cells11233809] [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: 10/20/2022] [Revised: 11/18/2022] [Accepted: 11/25/2022] [Indexed: 11/30/2022] Open
Abstract
Acetylcholine (ACh) is the neurotransmitter of the parasympathetic nervous system that modulates cardiac function, and its high concentrations may induce atrial fibrillation. We compared the ACh action on the mechanical function of single cardiomyocytes from the left atria (LA) and the right atria (RA). We exposed single rat LA and RA cardiomyocytes to 1, 10, and 100 µM ACh for 10-15 min and measured the parameters of sarcomere shortening-relengthening and cytosolic calcium ([Ca2+]i) transients during cell contractions. We also studied the effects of ACh on cardiac myosin function using an in vitro motility assay and analyzed the phosphorylation level of sarcomeric proteins. In LA cardiomyocytes, ACh decreased the time to peak sarcomere shortening, time to 50% relengthening, and time to peak [Ca2+]i transients. In RA cardiomyocytes, ACh affected the time of shortening and relengthening only at 10 µM. In the in vitro motility assay, ACh reduced to a greater extent the sliding velocity of F-actin over myosin from LA cardiomyocytes, which was accompanied by a more pronounced decrease in phosphorylation of the myosin regulatory light chain (RLC) in LA cardiomyocytes than in RA cardiomyocytes. Our findings indicate that ACh plays an important role in modulating the contractile function of LA and RA, provoking more pronounced changes in the time course of sarcomere shortening-relengthening and the kinetics of actin-myosin interaction in LA cardiomyocytes.
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Affiliation(s)
- Xenia Butova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Tatiana Myachina
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Raisa Simonova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Anastasia Kochurova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Yakov Bozhko
- Department of Therapy, Ural State Medical University, Repina Str. 3, 620028 Yekaterinburg, Russia
| | - Michael Arkhipov
- Department of Therapy, Ural State Medical University, Repina Str. 3, 620028 Yekaterinburg, Russia
| | - Olga Solovyova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
| | - Galina Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Daniil Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
| | - Anastasia Khokhlova
- Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya Str. 106, 620049 Yekaterinburg, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University, Mira 19, 620002 Yekaterinburg, Russia
- Correspondence:
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Li J, Wiesinger A, Fokkert L, Boukens BJ, Verkerk AO, Christoffels VM, Boink GJ, Devalla HD. Molecular and electrophysiological evaluation of human cardiomyocyte subtypes to facilitate generation of composite cardiac models. J Tissue Eng 2022; 13:20417314221127908. [PMID: 36277058 PMCID: PMC9583221 DOI: 10.1177/20417314221127908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 09/06/2022] [Indexed: 11/06/2022] Open
Abstract
Paucity of physiologically relevant cardiac models has limited the widespread application of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes in drug development. Here, we performed comprehensive characterization of hiPSC-derived cardiomyocyte subtypes from 2D and 3D cultures and established a novel 3D model to study impulse initiation and propagation. Directed differentiation approaches were used to generate sinoatrial nodal (SANCM), atrial (ACM) and ventricular cardiomyocytes (VCM). Single cell RNA sequencing established that the protocols yield distinct cell populations in line with expected identities, which was also confirmed by electrophysiological characterization. In 3D EHT cultures of all subtypes, we observed prominent expression of stretch-responsive genes such as NPPA. Response to rate modulating drugs noradrenaline, carbachol and ivabradine were comparable in single cells and EHTs. Differences in the speed of impulse propagation between the subtypes were more pronounced in EHTs compared with 2D monolayers owing to a progressive increase in conduction velocities in atrial and ventricular cardiomyocytes, in line with a more mature phenotype. In a novel binary EHT model of pacemaker-atrial interface, the SANCM end of the tissue consistently paced the EHTs under baseline conditions, which was inhibited by ivabradine. Taken together, our data provide comprehensive insights into molecular and electrophysiological properties of hiPSC-derived cardiomyocyte subtypes, facilitating the creation of next generation composite cardiac models for drug discovery, disease modeling and cell-based regenerative therapies.
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Affiliation(s)
- Jiuru Li
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Alexandra Wiesinger
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Lianne Fokkert
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Bastiaan J. Boukens
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Arie O. Verkerk
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands,Department of Experimental Cardiology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Vincent M. Christoffels
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Gerard J.J. Boink
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands,Department of Cardiology, Amsterdam
University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands
| | - Harsha D. Devalla
- Department of Medical Biology,
Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The
Netherlands,Harsha D Devalla, Department of Medical
Biology, Amsterdam University Medical Centers, University of Amsterdam,
Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands.
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5
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Louradour J, Bortolotti O, Torre E, Bidaud I, Lamb N, Fernandez A, Le Guennec JY, Mangoni ME, Mesirca P. L-Type Cav1.3 Calcium Channels Are Required for Beta-Adrenergic Triggered Automaticity in Dormant Mouse Sinoatrial Pacemaker Cells. Cells 2022; 11:cells11071114. [PMID: 35406677 PMCID: PMC8997967 DOI: 10.3390/cells11071114] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/18/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Sinoatrial node cells (SANC) automaticity is generated by functional association between the activity of plasmalemmal ion channels and local diastolic intracellular Ca2+ release (LCR) from ryanodine receptors. Strikingly, most isolated SANC exhibit a “dormant” state, whereas only a fraction shows regular firing as observed in intact SAN. Recent studies showed that β-adrenergic stimulation can initiate spontaneous firing in dormant SANC, though this mechanism is not entirely understood. Methods: To investigate the role of L-type Cav1.3 Ca2+ channels in the adrenergic regulation of automaticity in dormant SANC, we used a knock-in mouse strain in which the sensitivity of L-type Cav1.2 α1 subunits to dihydropyridines (DHPs) was inactivated (Cav1.2DHP−/−), enabling the selective pharmacological inhibition of Cav1.3 by DHPs. Results: In dormant SANC, β-adrenergic stimulation with isoproterenol (ISO) induced spontaneous action potentials (AP) and Ca2+ transients, which were completely arrested with concomitant perfusion of the DHP nifedipine. In spontaneously firing SANC at baseline, Cav1.3 inhibition completely reversed the effect of β-adrenergic stimulation on AP and the frequency of Ca2+ transients. Confocal calcium imaging of SANC showed that the β-adrenergic-induced synchronization of LCRs is regulated by the activity of Cav1.3 channels. Conclusions: Our study shows a novel role of Cav1.3 channels in initiating and maintaining automaticity in dormant SANC upon β-adrenergic stimulation.
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Affiliation(s)
- Julien Louradour
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- PhyMedExp, Université de Montpellier, INSERM U1046, UMR CNRS, 34090 Montpellier, France;
| | - Olivier Bortolotti
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
| | - Ned Lamb
- Mammalian Stem Cell Biology Group, Institute of Human Genetics, Université de Montpellier, CNRS, 34090 Montpellier, France; (N.L.); (A.F.)
| | - Anne Fernandez
- Mammalian Stem Cell Biology Group, Institute of Human Genetics, Université de Montpellier, CNRS, 34090 Montpellier, France; (N.L.); (A.F.)
| | - Jean-Yves Le Guennec
- PhyMedExp, Université de Montpellier, INSERM U1046, UMR CNRS, 34090 Montpellier, France;
| | - Matteo E. Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- Correspondence: (M.E.M.); (P.M.)
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France; (J.L.); (O.B.); (E.T.); (I.B.)
- LabEx Ion Channels Science and Therapeutics (ICST), 34090 Montpellier, France
- Correspondence: (M.E.M.); (P.M.)
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Reddy GR, Ren L, Thai PN, Caldwell JL, Zaccolo M, Bossuyt J, Ripplinger CM, Xiang YK, Nieves-Cintrón M, Chiamvimonvat N, Navedo MF. Deciphering cellular signals in adult mouse sinoatrial node cells. iScience 2022; 25:103693. [PMID: 35036877 PMCID: PMC8749457 DOI: 10.1016/j.isci.2021.103693] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/30/2021] [Accepted: 12/22/2021] [Indexed: 01/27/2023] Open
Abstract
Sinoatrial node (SAN) cells are the pacemakers of the heart. This study describes a method for culturing and infection of adult mouse SAN cells with FRET-based biosensors that can be exploited to examine signaling events. SAN cells cultured in media with blebbistatin or (S)-nitro-blebbistatin retain their morphology, protein distribution, action potential (AP) waveform, and cAMP dynamics for at least 40 h. SAN cells expressing targeted cAMP sensors show distinct β-adrenergic-mediated cAMP pools. Cyclic GMP, protein kinase A, Ca2+/CaM kinase II, and protein kinase D in SAN cells also show unique dynamics to different stimuli. Heart failure SAN cells show a decrease in cAMP and cGMP levels. In summary, a reliable method for maintaining adult mouse SAN cells in culture is presented, which facilitates studies of signaling networks and regulatory mechanisms during physiological and pathological conditions.
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Affiliation(s)
- Gopireddy R. Reddy
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Lu Ren
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
| | - Phung N. Thai
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
| | - Jessica L. Caldwell
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Crystal M. Ripplinger
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Yang K. Xiang
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
- VA Northern California Healthcare System, 10535 Hospital Way, Mather, CA 95655, USA
| | - Madeline Nieves-Cintrón
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California Davis, 451 Health Science Drive, GBSF 6315, Davis, CA 95616, USA
- VA Northern California Healthcare System, 10535 Hospital Way, Mather, CA 95655, USA
| | - Manuel F. Navedo
- Department of Pharmacology, University of California Davis, One Shields Avenue MED: PHARM Tupper 242, Davis, CA 95616, USA
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Lu J, Wang X, Feng Z, Chen Y, Wen D, Liu Z. The protective effect of isoflurane pretreatment on liver IRI by suppressing noncanonical pyroptosis of liver macrophages. Int Immunopharmacol 2021; 99:107977. [PMID: 34332342 DOI: 10.1016/j.intimp.2021.107977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/24/2021] [Accepted: 07/08/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Liver ischaemia-reperfusion injury (IRI) is a major complication in the perioperative period and often leads to liver failure and even systemic inflammation. Sufficient evidence has demonstrated that isoflurane has anti-inflammatory effects. We aimed to determine whether isoflurane pretreatment protects against liver IRI and to investigate the mechanisms involved in this protection. METHODS Male C57BL/6 mice were pretreated with or without isoflurane and subjected to 90 min of 70% liver ischaemia, followed by reperfusion for 6 h. Liver tissues and serum were analysed to assess liver IRI. To probe the mechanisms, liver macrophages isolated from C57BL/6 mice were pretreated with or without emulsified isoflurane for 30 min before incubation with 1 µg/ml lipopolysaccharide (LPS) for 24 h. Inflammatory cytokine production, intracellular Ca2+ levels, caspase-11 expression, NF-κB transcription, and NLRP3 inflammasome activation were assessed by ELISA, an intracellular Ca2+ concentration assay, immunohistochemistry, or Western blotting. RESULTS Isoflurane preconditioning significantly relieved liver IRI in mice and LPS-induced inflammation in liver macrophages. Additionally, isoflurane pretreatment inhibited caspase-11 expression and noncanonical pyroptosis-related production of cytokines (IL-1β and IL-18). Interestingly, isoflurane preconditioning reduced intracellular Ca2+ levels, NF-κB translocation, and NLRP3 inflammasome activation in LPS-induced macrophages. Our results indicated that isoflurane preconditioning ameliorated liver IRI by suppressing noncanonical pyroptosis in liver macrophages. These findings suggest that isoflurane could be a pharmacological agent for liver IRI prevention and thus deserves more attention and further investigation.
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Affiliation(s)
- Jiao Lu
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China
| | - Xiaoying Wang
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China; The Third Affliated Hospital of Chongqing Medical University, Chongqing 40010, China
| | - Zhihao Feng
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China
| | - Yucheng Chen
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China
| | - Diguang Wen
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China
| | - Zuojin Liu
- Department of Hepatobiliary Surgery, Second Affiliated Hospital, Chongqing Medical University, Chongqing 40010, China.
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8
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Hoekstra M, van Ginneken ACG, Wilders R, Verkerk AO. HCN4 current during human sinoatrial node-like action potentials. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:105-118. [PMID: 34153331 DOI: 10.1016/j.pbiomolbio.2021.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/07/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND Despite the many studies carried out over the past 40 years, the contribution of the HCN4 encoded hyperpolarization-activated 'funny' current (If) to pacemaker activity in the mammalian sinoatrial node (SAN), and the human SAN in particular, is still controversial and not fully established. OBJECTIVE To study the contribution of If to diastolic depolarization of human SAN cells and its dependence on heart rate, cAMP levels, and atrial load. METHODS HCN4 channels were expressed in human cardiac myocyte progenitor cells (CMPCs) and HCN4 currents assessed using perforated patch-clamp in traditional voltage clamp mode and during action potential clamp with human SAN-like action potential waveforms with 500-1500 ms cycle length, in absence or presence of forskolin to mimic β-adrenergic stimulation and a -15 mV command potential offset to mimic atrial load. RESULTS Forskolin significantly increased the fully-activated HCN4 current density at -140 mV by 14% and shifted the steady-state activation curve by +7.4 mV without affecting its slope. In addition, forskolin significantly accelerated current activation but slowed deactivation. The HCN4 current did not completely deactivate before the subsequent diastolic depolarization during action potential clamp. The amplitude of HCN4 current increased with increasing cycle length, was significantly larger in the presence of forskolin at all cycle lengths, and was significantly increased upon the negative offset to the command potential. CONCLUSIONS If is active during a human SAN action potential waveform and its amplitude is modulated by heart rate, β-adrenergic stimulation, and diastolic voltage range, such that If is under delicate control.
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Affiliation(s)
- Maaike Hoekstra
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Antoni C G van Ginneken
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
| | - Arie O Verkerk
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands; Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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9
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Tsutsui K, Florio MC, Yang A, Wirth AN, Yang D, Kim MS, Ziman BD, Bychkov R, Monfredi OJ, Maltsev VA, Lakatta EG. cAMP-Dependent Signaling Restores AP Firing in Dormant SA Node Cells via Enhancement of Surface Membrane Currents and Calcium Coupling. Front Physiol 2021; 12:596832. [PMID: 33897445 PMCID: PMC8063038 DOI: 10.3389/fphys.2021.596832] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 03/09/2021] [Indexed: 11/24/2022] Open
Abstract
Action potential (AP) firing rate and rhythm of sinoatrial nodal cells (SANC) are controlled by synergy between intracellular rhythmic local Ca2+ releases (LCRs) ("Ca2+ clock") and sarcolemmal electrogenic mechanisms ("membrane clock"). However, some SANC do not fire APs (dormant SANC). Prior studies have shown that β-adrenoceptor stimulation can restore AP firing in these cells. Here we tested whether this relates to improvement of synchronization of clock coupling. We characterized membrane potential, ion currents, Ca2+ dynamics, and phospholamban (PLB) phosphorylation, regulating Ca2+ pump in enzymatically isolated single guinea pig SANC prior to, during, and following β-adrenoceptor stimulation (isoproterenol) or application of cell-permeant cAMP (CPT-cAMP). Phosphorylation of PLB (Serine 16) was quantified in the same cells following Ca2+ measurement. In dormant SANC LCRs were small and disorganized at baseline, membrane potential was depolarized (-38 ± 1 mV, n = 46), and ICaL, If, and IK densities were smaller vs SANC firing APs. β-adrenoceptor stimulation or application of CPT-cAMP led to de novo spontaneous AP generation in 44 and 46% of dormant SANC, respectively. The initial response was an increase in size, rhythmicity and synchronization of LCRs, paralleled with membrane hyperpolarization and small amplitude APs (rate ∼1 Hz). During the transition to steady-state AP firing, LCR size further increased, while LCR period shortened. LCRs became more synchronized resulting in the growth of an ensemble LCR signal peaked in late diastole, culminating in AP ignition; the rate of diastolic depolarization, AP amplitude, and AP firing rate increased. ICaL, IK, and If amplitudes in dormant SANC increased in response to β-adrenoceptor stimulation. During washout, all changes reversed in order. Total PLB was higher, but the ratio of phosphorylated PLB (Serine 16) to total PLB was lower in dormant SANC. β-adrenoceptor stimulation increased this ratio in AP-firing cells. Thus, transition of dormant SANC to AP firing is linked to the increased functional coupling of membrane and Ca2+ clock proteins. The transition occurs via (i) an increase in cAMP-mediated phosphorylation of PLB accelerating Ca2+ pumping, (ii) increased spatiotemporal LCR synchronization, yielding a larger diastolic LCR ensemble signal resulting in an earlier increase in diastolic INCX; and (iii) increased current densities of If, ICaL, and IK.
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Affiliation(s)
- Kenta Tsutsui
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
- Department of Cardiovascular Medicine, Faculty of Medicine, Saitama Medical University International Medical Center, Saitama, Japan
| | - Maria Cristina Florio
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Annie Yang
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Ashley N. Wirth
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Mary S. Kim
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Bruce D. Ziman
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Rostislav Bychkov
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Oliver J. Monfredi
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
- Heart and Vascular Center, University of Virginia, Charlottesville, VA, United States
| | - Victor A. Maltsev
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, Biomedical Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, United States
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10
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Bidaud I, D'Souza A, Forte G, Torre E, Greuet D, Thirard S, Anderson C, Chung You Chong A, Torrente AG, Roussel J, Wickman K, Boyett MR, Mangoni ME, Mesirca P. Genetic Ablation of G Protein-Gated Inwardly Rectifying K + Channels Prevents Training-Induced Sinus Bradycardia. Front Physiol 2021; 11:519382. [PMID: 33551824 PMCID: PMC7857143 DOI: 10.3389/fphys.2020.519382] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/17/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Endurance athletes are prone to bradyarrhythmias, which in the long-term may underscore the increased incidence of pacemaker implantation reported in this population. Our previous work in rodent models has shown training-induced sinus bradycardia to be due to microRNA (miR)-mediated transcriptional remodeling of the HCN4 channel, leading to a reduction of the "funny" (I f) current in the sinoatrial node (SAN). Objective: To test if genetic ablation of G-protein-gated inwardly rectifying potassium channel, also known as I KACh channels prevents sinus bradycardia induced by intensive exercise training in mice. Methods: Control wild-type (WT) and mice lacking GIRK4 (Girk4 -/-), an integral subunit of I KACh were assigned to trained or sedentary groups. Mice in the trained group underwent 1-h exercise swimming twice a day for 28 days, 7 days per week. We performed electrocardiogram recordings and echocardiography in both groups at baseline, during and after the training period. At training cessation, mice were euthanized and SAN tissues were isolated for patch clamp recordings in isolated SAN cells and molecular profiling by quantitative PCR (qPCR) and western blotting. Results: At swimming cessation trained WT mice presented with a significantly lower resting HR that was reversible by acute I KACh block whereas Girk4 -/- mice failed to develop a training-induced sinus bradycardia. In line with HR reduction, action potential rate, density of I f, as well as of T- and L-type Ca2+ currents (I CaT and I CaL ) were significantly reduced only in SAN cells obtained from WT-trained mice. I f reduction in WT mice was concomitant with downregulation of HCN4 transcript and protein, attributable to increased expression of corresponding repressor microRNAs (miRs) whereas reduced I CaL in WT mice was associated with reduced Cav1.3 protein levels. Strikingly, I KACh ablation suppressed all training-induced molecular remodeling observed in WT mice. Conclusion: Genetic ablation of cardiac I KACh in mice prevents exercise-induced sinus bradycardia by suppressing training induced remodeling of inward currents I f, I CaT and I CaL due in part to the prevention of miR-mediated transcriptional remodeling of HCN4 and likely post transcriptional remodeling of Cav1.3. Strategies targeting cardiac I KACh may therefore represent an alternative to pacemaker implantation for bradyarrhythmias seen in some veteran athletes.
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Affiliation(s)
- Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Alicia D'Souza
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Gabriella Forte
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Denis Greuet
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Steeve Thirard
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cali Anderson
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Antony Chung You Chong
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Julien Roussel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Mark R Boyett
- Division of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx Ion Channels Science and Therapeutics, Montpellier, France
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11
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MacDonald EA, Rose RA, Quinn TA. Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans. Front Physiol 2020; 11:170. [PMID: 32194439 PMCID: PMC7063087 DOI: 10.3389/fphys.2020.00170] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/13/2020] [Indexed: 12/22/2022] Open
Abstract
The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.
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Affiliation(s)
- Eilidh A. MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Robert A. Rose
- Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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12
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Zhao M, Jia HH, Liu LZ, Bi XY, Xu M, Yu XJ, He X, Zang WJ. Acetylcholine attenuated TNF-α-induced intracellular Ca 2+ overload by inhibiting the formation of the NCX1-TRPC3-IP3R1 complex in human umbilical vein endothelial cells. J Mol Cell Cardiol 2017; 107:1-12. [PMID: 28395930 DOI: 10.1016/j.yjmcc.2017.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/16/2017] [Accepted: 04/06/2017] [Indexed: 12/21/2022]
Abstract
The endoplasmic reticulum (ER) forms discrete junctions with the plasma membrane (PM) that play a critical role in the regulation of Ca2+ signaling during cellular bioenergetics, apoptosis and autophagy. We have previously confirmed that acetylcholine can inhibit ER stress and apoptosis after inflammatory injury. However, limited research has focused on the effects of acetylcholine on ER-PM junctions. In this work, we evaluated the structure and function of the supramolecular sodium-calcium exchanger 1 (NCX1)-transient receptor potential canonical 3 (TRPC3)-inositol 1,4,5-trisphosphate receptor 1 (IP3R1) complex, which is involved in regulating Ca2+ homeostasis during inflammatory injury. The width of the ER-PM junctions of human umbilical vein endothelial cells (HUVECs) was measured in nanometres using transmission electron microscopy and a fluorescent probe for Ca2+. Protein-protein interactions were assessed by immunoprecipitation. Ca2+ concentration was measured using a confocal microscope. An siRNA assay was employed to silence specific proteins. Our results demonstrated that the peripheral ER was translocated to PM junction sites when induced by tumour necrosis factor-alpha (TNF-α) and that NCX1-TRPC3-IP3R1 complexes formed at these sites. After down-regulating the protein expression of NCX1 or IP3R1, we found that the NCX1-mediated inflow of Ca2+ and the release of intracellular Ca2+ stores were reduced in TNF-α-treated cells. We also observed that acetylcholine attenuated the formation of NCX1-TRPC3-IP3R1 complexes and maintained calcium homeostasis in cells treated with TNF-α. Interestingly, the positive effects of acetylcholine were abolished by the selective M3AChR antagonist darifenacin and by AMPK siRNAs. These results indicate that acetylcholine protects endothelial cells from TNF-alpha-induced injury, [Ca2+]cyt overload and ER-PM interactions, which depend on the muscarinic 3 receptor/AMPK pathway, and that acetylcholine may be a new inhibitor for suppressing [Ca2+]cyt overload.
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Affiliation(s)
- Ming Zhao
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Hang-Huan Jia
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Long-Zhu Liu
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Xue-Yuan Bi
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Man Xu
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Xiao-Jiang Yu
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Xi He
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China
| | - Wei-Jin Zang
- Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an 710061, PR China.
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13
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Devalla HD, Gélinas R, Aburawi EH, Beqqali A, Goyette P, Freund C, Chaix MA, Tadros R, Jiang H, Le Béchec A, Monshouwer-Kloots JJ, Zwetsloot T, Kosmidis G, Latour F, Alikashani A, Hoekstra M, Schlaepfer J, Mummery CL, Stevenson B, Kutalik Z, de Vries AA, Rivard L, Wilde AA, Talajic M, Verkerk AO, Al-Gazali L, Rioux JD, Bhuiyan ZA, Passier R. TECRL, a new life-threatening inherited arrhythmia gene associated with overlapping clinical features of both LQTS and CPVT. EMBO Mol Med 2016; 8:1390-1408. [PMID: 27861123 PMCID: PMC5167130 DOI: 10.15252/emmm.201505719] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Genetic causes of many familial arrhythmia syndromes remain elusive. In this study, whole‐exome sequencing (WES) was carried out on patients from three different families that presented with life‐threatening arrhythmias and high risk of sudden cardiac death (SCD). Two French Canadian probands carried identical homozygous rare variant in TECRL gene (p.Arg196Gln), which encodes the trans‐2,3‐enoyl‐CoA reductase‐like protein. Both patients had cardiac arrest, stress‐induced atrial and ventricular tachycardia, and QT prolongation on adrenergic stimulation. A third patient from a consanguineous Sudanese family diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT) had a homozygous splice site mutation (c.331+1G>A) in TECRL. Analysis of intracellular calcium ([Ca2+]i) dynamics in human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) generated from this individual (TECRLHom‐hiPSCs), his heterozygous but clinically asymptomatic father (TECRLHet‐hiPSCs), and a healthy individual (CTRL‐hiPSCs) from the same Sudanese family, revealed smaller [Ca2+]i transient amplitudes as well as elevated diastolic [Ca2+]i in TECRLHom‐hiPSC‐CMs compared with CTRL‐hiPSC‐CMs. The [Ca2+]i transient also rose markedly slower and contained lower sarcoplasmic reticulum (SR) calcium stores, evidenced by the decreased magnitude of caffeine‐induced [Ca2+]i transients. In addition, the decay phase of the [Ca2+]i transient was slower in TECRLHom‐hiPSC‐CMs due to decreased SERCA and NCX activities. Furthermore, TECRLHom‐hiPSC‐CMs showed prolonged action potentials (APs) compared with CTRL‐hiPSC‐CMs. TECRL knockdown in control human embryonic stem cell‐derived CMs (hESC‐CMs) also resulted in significantly longer APs. Moreover, stimulation by noradrenaline (NA) significantly increased the propensity for triggered activity based on delayed afterdepolarizations (DADs) in TECRLHom‐hiPSC‐CMs and treatment with flecainide, a class Ic antiarrhythmic drug, significantly reduced the triggered activity in these cells. In summary, we report that mutations in TECRL are associated with inherited arrhythmias characterized by clinical features of both LQTS and CPVT. Patient‐specific hiPSC‐CMs recapitulated salient features of the clinical phenotype and provide a platform for drug screening evidenced by initial identification of flecainide as a potential therapeutic. These findings have implications for diagnosis and treatment of inherited cardiac arrhythmias.
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Affiliation(s)
- Harsha D Devalla
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Roselle Gélinas
- Montreal Heart Institute, Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Elhadi H Aburawi
- Department of Pediatrics, College of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates
| | - Abdelaziz Beqqali
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Christian Freund
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden University Medical Center hiPSC Core Facility, Leiden, The Netherlands
| | - Marie-A Chaix
- Montreal Heart Institute, Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Rafik Tadros
- Montreal Heart Institute, Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada.,Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Hui Jiang
- Beijing Genomics Institute, Shenzhen, China.,Shenzhen Key Laboratory of Genomics, Shenzhen, China.,The Guangdong Enterprise Key Laboratory of Human Disease Genomics, Shenzhen, China
| | - Antony Le Béchec
- Vital-IT group, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Tom Zwetsloot
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Georgios Kosmidis
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | - Maaike Hoekstra
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jurg Schlaepfer
- Service de Cardiologie, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Christine L Mummery
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands
| | - Brian Stevenson
- Vital-IT group, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Zoltan Kutalik
- Vital-IT group, Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Institute of Social and Preventive Medicine, University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
| | - Antoine Af de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.,ICIN-Netherlands Heart Institute, Utrecht, The Netherlands
| | - Léna Rivard
- Montreal Heart Institute, Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Arthur Am Wilde
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Saudi Arabia
| | - Mario Talajic
- Montreal Heart Institute, Montreal, QC, Canada.,Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Arie O Verkerk
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Lihadh Al-Gazali
- Department of Pediatrics, College of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates
| | - John D Rioux
- Montreal Heart Institute, Montreal, QC, Canada .,Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Zahurul A Bhuiyan
- Laboratoire Génétiqué Moléculaire, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland
| | - Robert Passier
- Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands .,Department of Applied Stem Cell Technologies, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
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14
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Behar J, Ganesan A, Zhang J, Yaniv Y. The Autonomic Nervous System Regulates the Heart Rate through cAMP-PKA Dependent and Independent Coupled-Clock Pacemaker Cell Mechanisms. Front Physiol 2016; 7:419. [PMID: 27729868 PMCID: PMC5037226 DOI: 10.3389/fphys.2016.00419] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/05/2016] [Indexed: 12/19/2022] Open
Abstract
Sinoatrial nodal cells (SANCs) generate spontaneous action potentials (APs) that control the cardiac rate. The brain modulates SANC automaticity, via the autonomic nervous system, by stimulating membrane receptors that activate (adrenergic) or inactivate (cholinergic) adenylyl cyclase (AC). However, these opposing afferents are not simply additive. We showed that activation of adrenergic signaling increases AC-cAMP/PKA signaling, which mediates the increase in the SANC AP firing rate (i.e., positive chronotropic modulation). However, there is a limited understanding of the underlying internal pacemaker mechanisms involved in the crosstalk between cholinergic receptors and the decrease in the SANC AP firing rate (i.e., negative chronotropic modulation). We hypothesize that changes in AC-cAMP/PKA activity are crucial for mediating either decrease or increase in the AP firing rate and that the change in rate is due to both internal and membrane mechanisms. In cultured adult rabbit pacemaker cells infected with an adenovirus expressing the FRET sensor AKAR3, PKA activity and AP firing rate were tightly linked in response to either adrenergic receptor stimulation (by isoproterenol, ISO) or cholinergic stimulation (by carbachol, CCh). To identify the main molecular targets that mediate between PKA signaling and pacemaker function, we developed a mechanistic computational model. The model includes a description of autonomic-nervous receptors, post- translation signaling cascades, membrane molecules, and internal pacemaker mechanisms. Yielding results similar to those of the experiments, the model simulations faithfully reproduce the changes in AP firing rate in response to CCh or ISO or a combination of both (i.e., accentuated antagonism). Eliminating AC-cAMP-PKA signaling abolished the core effect of autonomic receptor stimulation on the AP firing rate. Specifically, disabling the phospholamban modulation of the SERCA activity resulted in a significantly reduced effect of CCh and a failure to increase the AP firing rate under ISO stimulation. Directly activating internal pacemaker mechanisms led to a similar extent of changes in the AP firing rate with respect to brain receptor stimulation. Thus, Ca2+ and cAMP/PKA-dependent phosphorylation limits the rate and magnitude of chronotropic changes in the spontaneous AP firing rate.
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Affiliation(s)
- Joachim Behar
- Laboratory of Bioenergetic and Bioelectric Systems, Biomedical Engineering Faculty, Technion-IIT Haifa, Israel
| | - Ambhighainath Ganesan
- Department of Biomedical Engineering, The Johns Hopkins University of Medicine Baltimore, MD, USA
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego San Diego, CA, USA
| | - Yael Yaniv
- Laboratory of Bioenergetic and Bioelectric Systems, Biomedical Engineering Faculty, Technion-IIT Haifa, Israel
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15
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Torrente AG, Mesirca P, Neco P, Rizzetto R, Dubel S, Barrere C, Sinegger-Brauns M, Striessnig J, Richard S, Nargeot J, Gomez AM, Mangoni ME. L-type Cav1.3 channels regulate ryanodine receptor-dependent Ca2+ release during sino-atrial node pacemaker activity. Cardiovasc Res 2016; 109:451-61. [PMID: 26786159 DOI: 10.1093/cvr/cvw006] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 01/07/2016] [Indexed: 11/13/2022] Open
Abstract
AIMS Sino-atrial node (SAN) automaticity is an essential mechanism of heart rate generation that is still not completely understood. Recent studies highlighted the importance of intracellular Ca(2+) ([Ca(2+)]i) dynamics during SAN pacemaker activity. Nevertheless, the functional role of voltage-dependent L-type Ca(2+) channels in controlling SAN [Ca(2+)]i release is largely unexplored. Since Cav1.3 is the predominant L-type Ca(2+) channel isoform in SAN cells, we studied [Ca(2+)]i dynamics in isolated cells and ex vivo SAN preparations explanted from wild-type (WT) and Cav1.3 knockout (KO) mice (Cav1.3(-/-)). METHODS AND RESULTS We found that Cav1.3 deficiency strongly impaired [Ca(2+)]i dynamics, reducing the frequency of local [Ca(2+)]i release events and preventing their synchronization. This impairment inhibited the generation of Ca(2+) transients and delayed spontaneous activity. We also used action potentials recorded in WT SAN cells as voltage-clamp commands for Cav1.3(-/-) cells. Although these experiments showed abolished Ca(2+) entry through L-type Ca(2+) channels in the diastolic depolarization range of KO SAN cells, their sarcoplasmic reticulum Ca(2+) load remained normal. β-Adrenergic stimulation enhanced pacemaking of both genotypes, though, Cav1.3(-/-) SAN cells remained slower than WT. Conversely, we rescued pacemaker activity in Cav1.3(-/-) SAN cells and intact tissues through caffeine-mediated stimulation of Ca(2+)-induced Ca(2+) release. CONCLUSIONS Cav1.3 channels play a critical role in the regulation of [Ca(2+)]i dynamics, providing an unanticipated mechanism for triggering local [Ca(2+)]i releases and thereby controlling pacemaker activity. Our study also provides an additional pathophysiological mechanism for congenital SAN dysfunction and heart block linked to Cav1.3 loss of function in humans.
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Affiliation(s)
- Angelo Giovanni Torrente
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Pietro Mesirca
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Patricia Neco
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France Department of Pharmacology and Toxicology, Institute of Pharmacy
| | - Riccardo Rizzetto
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Stefan Dubel
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Christian Barrere
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Martina Sinegger-Brauns
- Department of Pharmacology and Toxicology, Institute of Pharmacy Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Joerg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Sylvain Richard
- INSERM, U1046, Montpellier, France CNRS UMR 9214, PhyMedExp, University of Montpellier, France
| | - Joël Nargeot
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
| | - Ana Maria Gomez
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France Department of Pharmacology and Toxicology, Institute of Pharmacy
| | - Matteo Elia Mangoni
- Département de Physiologie, CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier F-34000, France INSERM, U1191, Montpellier F-34000, France Université de Montpellier, UMR-5203, Montpellier F-34000, France
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Zhang H, Sun AY, Kim JJ, Graham V, Finch EA, Nepliouev I, Zhao G, Li T, Lederer WJ, Stiber JA, Pitt GS, Bursac N, Rosenberg PB. STIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node. Proc Natl Acad Sci U S A 2015; 112:E5618-27. [PMID: 26424448 PMCID: PMC4611639 DOI: 10.1073/pnas.1503847112] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiac pacemaking is governed by specialized cardiomyocytes located in the sinoatrial node (SAN). SAN cells (SANCs) integrate voltage-gated currents from channels on the membrane surface (membrane clock) with rhythmic Ca(2+) release from internal Ca(2+) stores (Ca(2+) clock) to adjust heart rate to meet hemodynamic demand. Here, we report that stromal interaction molecule 1 (STIM1) and Orai1 channels, key components of store-operated Ca(2+) entry, are selectively expressed in SANCs. Cardiac-specific deletion of STIM1 in mice resulted in depletion of sarcoplasmic reticulum (SR) Ca(2+) stores of SANCs and led to SAN dysfunction, as was evident by a reduction in heart rate, sinus arrest, and an exaggerated autonomic response to cholinergic signaling. Moreover, STIM1 influenced SAN function by regulating ionic fluxes in SANCs, including activation of a store-operated Ca(2+) current, a reduction in L-type Ca(2+) current, and enhancing the activities of Na(+)/Ca(2+) exchanger. In conclusion, these studies reveal that STIM1 is a multifunctional regulator of Ca(2+) dynamics in SANCs that links SR Ca(2+) store content with electrical events occurring in the plasma membrane, thereby contributing to automaticity of the SAN.
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Affiliation(s)
- Hengtao Zhang
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Albert Y Sun
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Jong J Kim
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Victoria Graham
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Elizabeth A Finch
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Igor Nepliouev
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Guiling Zhao
- Department of Physiology, Center for BioMedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Tianyu Li
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - W J Lederer
- Department of Physiology, Center for BioMedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Jonathan A Stiber
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Geoffrey S Pitt
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Paul B Rosenberg
- Department of Medicine, Duke University School of Medicine, Durham, NC 27704;
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Capel RA, Terrar DA. The importance of Ca(2+)-dependent mechanisms for the initiation of the heartbeat. Front Physiol 2015; 6:80. [PMID: 25859219 PMCID: PMC4373508 DOI: 10.3389/fphys.2015.00080] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 03/02/2015] [Indexed: 01/01/2023] Open
Abstract
Mechanisms underlying pacemaker activity in the sinus node remain controversial, with some ascribing a dominant role to timing events in the surface membrane (“membrane clock”) and others to uptake and release of calcium from the sarcoplasmic reticulum (SR) (“calcium clock”). Here we discuss recent evidence on mechanisms underlying pacemaker activity with a particular emphasis on the many roles of calcium. There are particular areas of controversy concerning the contribution of calcium spark-like events and the importance of I(f) to spontaneous diastolic depolarisation, though it will be suggested that neither of these is essential for pacemaking. Sodium-calcium exchange (NCX) is most often considered in the context of mediating membrane depolarisation after spark-like events. We present evidence for a broader role of this electrogenic exchanger which need not always depend upon these spark-like events. Short (milliseconds or seconds) and long (minutes) term influences of calcium are discussed including direct regulation of ion channels and NCX, and control of the activity of calcium-dependent enzymes (including CaMKII, AC1, and AC8). The balance between the many contributory factors to pacemaker activity may well alter with experimental and clinical conditions, and potentially redundant mechanisms are desirable to ensure the regular spontaneous heart rate that is essential for life. This review presents evidence that calcium is central to the normal control of pacemaking across a range of temporal scales and seeks to broaden the accepted description of the “calcium clock” to cover these important influences.
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Affiliation(s)
- Rebecca A Capel
- British Heart Foundation Centre of Research Excellence, Department of Pharmacology, University of Oxford Oxford, UK
| | - Derek A Terrar
- British Heart Foundation Centre of Research Excellence, Department of Pharmacology, University of Oxford Oxford, UK
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Verkerk AO, van Borren MMGJ, van Ginneken ACG, Wilders R. Ca(2+) cycling properties are conserved despite bradycardic effects of heart failure in sinoatrial node cells. Front Physiol 2015; 6:18. [PMID: 25698973 PMCID: PMC4313601 DOI: 10.3389/fphys.2015.00018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 01/12/2015] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In animal models of heart failure (HF), heart rate decreases due to an increase in intrinsic cycle length (CL) of the sinoatrial node (SAN). Pacemaker activity of SAN cells is complex and modulated by the membrane clock, i.e., the ensemble of voltage gated ion channels and electrogenic pumps and exchangers, and the Ca(2+) clock, i.e., the ensemble of intracellular Ca(2+) ([Ca(2+)]i) dependent processes. HF in SAN cells results in remodeling of the membrane clock, but few studies have examined its effects on [Ca(2+)]i homeostasis. METHODS SAN cells were isolated from control rabbits and rabbits with volume and pressure overload-induced HF. [Ca(2+)]i concentrations, and action potentials (APs) and Na(+)-Ca(2+) exchange current (INCX) were measured using indo-1 and patch-clamp methodology, respectively. RESULTS The frequency of spontaneous [Ca(2+)]i transients was significantly lower in HF SAN cells (3.0 ± 0.1 (n = 40) vs. 3.4 ± 0.1 Hz (n = 45); mean ± SEM), indicating that intrinsic CL was prolonged. HF slowed the [Ca(2+)]i transient decay, which could be explained by the slower frequency and reduced sarcoplasmic reticulum (SR) dependent rate of Ca(2+) uptake. Other [Ca(2+)]i transient parameters, SR Ca(2+) content, INCX density, and INCX-[Ca(2+)]i relationship were all unaffected by HF. Combined AP and [Ca(2+)]i recordings demonstrated that the slower [Ca(2+)]i transient decay in HF SAN cells may result in increased INCX during the diastolic depolarization, but that this effect is likely counteracted by the HF-induced increase in intracellular Na(+). β-adrenergic and muscarinic stimulation were not changed in HF SAN cells, except that late diastolic [Ca(2+)]i rise, a prominent feature of the Ca(2+) clock, is lower during β-adrenergic stimulation. CONCLUSIONS HF SAN cells have a slower [Ca(2+)]i transient decay with limited effects on pacemaker activity. Reduced late diastolic [Ca(2+)]i rise during β-adrenergic stimulation may contribute to an impaired increase in intrinsic frequency in HF SAN cells.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Marcel M G J van Borren
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands ; Laboratory of Clinical Chemistry and Haematology, Rijnstate Hospital Arnhem, Netherlands
| | - Antoni C G van Ginneken
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
| | - Ronald Wilders
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
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Maltsev VA, Yaniv Y, Maltsev AV, Stern MD, Lakatta EG. Modern perspectives on numerical modeling of cardiac pacemaker cell. J Pharmacol Sci 2014; 125:6-38. [PMID: 24748434 DOI: 10.1254/jphs.13r04cr] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Cardiac pacemaking is a complex phenomenon that is still not completely understood. Together with experimental studies, numerical modeling has been traditionally used to acquire mechanistic insights in this research area. This review summarizes the present state of numerical modeling of the cardiac pacemaker, including approaches to resolve present paradoxes and controversies. Specifically we discuss the requirement for realistic modeling to consider symmetrical importance of both intracellular and cell membrane processes (within a recent "coupled-clock" theory). Promising future developments of the complex pacemaker system models include the introduction of local calcium control, mitochondria function, and biochemical regulation of protein phosphorylation and cAMP production. Modern numerical and theoretical methods such as multi-parameter sensitivity analyses within extended populations of models and bifurcation analyses are also important for the definition of the most realistic parameters that describe a robust, yet simultaneously flexible operation of the coupled-clock pacemaker cell system. The systems approach to exploring cardiac pacemaker function will guide development of new therapies such as biological pacemakers for treating insufficient cardiac pacemaker function that becomes especially prevalent with advancing age.
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Affiliation(s)
- Victor A Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, USA
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Chen HX, Jin ZL, Zhang LM, Xue R, Xu XD, Zhao N, Qiu ZK, Wang XW, Zhang YZ, Yang RF, Li YF. Antidepressant-like activity of YL-0919: a novel combined selective serotonin reuptake inhibitor and 5-HT1A receptor agonist. PLoS One 2013; 8:e83271. [PMID: 24367588 PMCID: PMC3867442 DOI: 10.1371/journal.pone.0083271] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 11/10/2013] [Indexed: 11/19/2022] Open
Abstract
It has been suggested that drugs combining activities of selective serotonin reuptake inhibitor and 5-HT1A receptor agonist may form a novel strategy for higher therapeutic efficacy of antidepressant. The present study aimed to examine the pharmacology of YL-0919, a novel synthetic compound with combined high affinity and selectivity for serotonin transporter and 5-HT1A receptors. We performed in vitro binding and function assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of YL-0919. YL-0919 displayed high affinity in vitro to both 5-HT1A receptor and 5-HT transporter prepared from rat cortical tissue. It exerted an inhibitory effect on forskolin-stimulated cAMP formation and potently inhibited 5-HT uptake in both rat cortical synaptosomes and recombinant cells. After acute p.o. administration, very low doses of YL-0919 reduced the immobility time in tail suspension test and forced swimming test in mice and rats, with no significant effect on locomotor activity in open field test. Furthermore, WAY-100635 (a selective 5-HT1A receptor antagonist, 0.3 mg/kg) significantly blocked the effect of YL-0919 in tail suspension test and forced swimming test. In addition, chronic YL-0919 treatment significantly reversed the depressive-like behaviors in chronically stressed rats. These findings suggest that YL-0919, a novel structure compound, exerts dual effect on the serotonergic system, as both 5-HT1A receptor agonist and 5-HT uptake blocker, showing remarkable antidepressant effects in animal models. Therefore, YL-0919 may be used as a new option for the treatment of major depressive disorder.
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Affiliation(s)
- Hong-xia Chen
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Zeng-liang Jin
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
- Department of Pharmacology, School of Basic Medical Scieneces, Capital Medical University, Beijing, P. R. of China
| | - Li-ming Zhang
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Rui Xue
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Xiao-dan Xu
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Nan Zhao
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Zhi-kun Qiu
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Xian-wang Wang
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
- Department of Anesthesiology, Chinese PLA 309 Hospital, Beijing, P. R. of China
| | - You-zhi Zhang
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Ri-fang Yang
- Department of Medicinal Chemistry, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
| | - Yun-feng Li
- Department of New Drug Evaluation, Beijing Institute of Pharmacology and Toxicology, Beijing, P. R. of China
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Zefirov TL, Ziyatdinova NI, Zefirov AL. Age-related peculiarities of inotropic response of rat myocardium to selective block of M1-cholinoreceptors. Bull Exp Biol Med 2013; 155:708-10. [PMID: 24288746 DOI: 10.1007/s10517-013-2232-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In vitro effect of M1-cholinoreceptor blockade on the cardiac inotropic function was examined in rats aging 1, 3, 6, 8, and 20 weeks. In 1- and 3-week old rat pups, the sympathetic control of the heart has not developed, the age of 7-8 weeks being pubertal. Adult 20-week rats were used as the controls. In rats of all age groups, preliminary blockade of M1-cholinoreceptors did not prevent the inhibitory effect of carbacholine on contractility of the atrial and ventricular myocardium. The inhibitory effect of pirenzepine on the contractile force of ventricular myocardium was revealed in 6-week rats.
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Affiliation(s)
- T L Zefirov
- Department of Anatomy, Physiology, and Human Health Protection, Kazan Volga Riverside Federal University; Department of Normal Physiology, Kazan Federal Medical University, Russia.
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Mesirca P, Marger L, Toyoda F, Rizzetto R, Audoubert M, Dubel S, Torrente AG, Difrancesco ML, Muller JC, Leoni AL, Couette B, Nargeot J, Clapham DE, Wickman K, Mangoni ME. The G-protein-gated K+ channel, IKACh, is required for regulation of pacemaker activity and recovery of resting heart rate after sympathetic stimulation. ACTA ACUST UNITED AC 2013; 142:113-26. [PMID: 23858001 PMCID: PMC3727310 DOI: 10.1085/jgp.201310996] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein–activated K+ current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4−/− mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4−/− mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4−/− animals. Although the relative extent of heart rate regulation of Girk4−/− mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological β-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4−/− animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct β-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation.
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Affiliation(s)
- Pietro Mesirca
- Centre National de la Recherche Scientifique UMR 5203, Institut de Génomique Fonctionnelle, Département de Physiologie, Laboratoire d'Excellence Canaux Ioniques d'Intérêt Thérapeutique, 34094 Montpellier, France
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Hyperpolarization-activated current, If, in mathematical models of rabbit sinoatrial node pacemaker cells. BIOMED RESEARCH INTERNATIONAL 2013; 2013:872454. [PMID: 23936852 PMCID: PMC3722861 DOI: 10.1155/2013/872454] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 05/31/2013] [Indexed: 01/01/2023]
Abstract
A typical feature of sinoatrial (SA) node pacemaker cells is the presence of an ionic current that activates upon hyperpolarization. The role of this hyperpolarization-activated current, If, which is also known as the “funny current” or “pacemaker current,” in the spontaneous pacemaker activity of SA nodal cells remains a matter of intense debate. Whereas some conclude that If plays a fundamental role in the generation of pacemaker activity and its rate control, others conclude that the role of If is limited to a modest contribution to rate control. The ongoing debate is often accompanied with arguments from computer simulations, either to support one's personal view or to invalidate that of the antagonist. In the present paper, we review the various mathematical descriptions of If that have been used in computer simulations and compare their strikingly different characteristics with our experimental data. We identify caveats and propose a novel model for If based on our experimental data.
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Calcium transient and sodium-calcium exchange current in human versus rabbit sinoatrial node pacemaker cells. ScientificWorldJournal 2013; 2013:507872. [PMID: 23606816 PMCID: PMC3621208 DOI: 10.1155/2013/507872] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/07/2013] [Indexed: 01/01/2023] Open
Abstract
There is an ongoing debate on the mechanism underlying the pacemaker activity of sinoatrial node (SAN) cells, focusing on the relative importance of the “membrane clock” and the “Ca2+ clock” in the generation of the small net membrane current that depolarizes the cell towards the action potential threshold. Specifically, the debate centers around the question whether the membrane clock-driven hyperpolarization-activated current, If, which is also known as the “funny current” or “pacemaker current,” or the Ca2+ clock-driven sodium-calcium exchange current, INaCa, is the main contributor to diastolic depolarization. In our contribution to this journal's “Special Issue on Cardiac Electrophysiology,” we present a numerical reconstruction of If and
INaCa in isolated rabbit and human SAN pacemaker cells based on experimental data on action potentials, If, and intracellular calcium concentration ([Ca2+]i) that we have acquired from these cells. The human SAN pacemaker cells have a smaller If, a weaker [Ca2+]i transient, and a smaller INaCa than the rabbit cells. However, when compared to the diastolic net membrane current, INaCa is of similar size in human and rabbit SAN pacemaker cells, whereas If is smaller in human than in rabbit cells.
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Time-Resolved Förster Resonance Energy Transfer-Based Technologies to Investigate G Protein-Coupled Receptor Machinery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 113:275-312. [DOI: 10.1016/b978-0-12-386932-6.00007-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Ziyatdinova NI, Sergeeva AM, Dementieva RE, Zefirov TL. Peculiar Effects of Muscarinic M1, M2, and M3 Receptor Blockers on Cardiac Chronotropic Function in Neonatal Rats. Bull Exp Biol Med 2012; 154:1-2. [DOI: 10.1007/s10517-012-1859-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Verkerk AO, Geuzebroek GSC, Veldkamp MW, Wilders R. Effects of acetylcholine and noradrenalin on action potentials of isolated rabbit sinoatrial and atrial myocytes. Front Physiol 2012; 3:174. [PMID: 22754533 PMCID: PMC3385584 DOI: 10.3389/fphys.2012.00174] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/12/2012] [Indexed: 01/07/2023] Open
Abstract
The autonomic nervous system controls heart rate and contractility through sympathetic and parasympathetic inputs to the cardiac tissue, with acetylcholine (ACh) and noradrenalin (NA) as the chemical transmitters. In recent years, it has become clear that specific Regulators of G protein Signaling proteins (RGS proteins) suppress muscarinic sensitivity and parasympathetic tone, identifying RGS proteins as intriguing potential therapeutic targets. In the present study, we have identified the effects of 1 μM ACh and 1 μM NA on the intrinsic action potentials of sinoatrial (SA) nodal and atrial myocytes. Single cells were enzymatically isolated from the SA node or from the left atrium of rabbit hearts. Action potentials were recorded using the amphotericin-perforated patch-clamp technique in the absence and presence of ACh, NA, or a combination of both. In SA nodal myocytes, ACh increased cycle length and decreased diastolic depolarization rate, whereas NA decreased cycle length and increased diastolic depolarization rate. Both ACh and NA increased maximum upstroke velocity. Furthermore, ACh hyperpolarized the maximum diastolic potential. In atrial myocytes stimulated at 2 Hz, both ACh and NA hyperpolarized the maximum diastolic potential, increased the action potential amplitude, and increased the maximum upstroke velocity. Action potential duration at 50 and 90% repolarization was decreased by ACh, but increased by NA. The effects of both ACh and NA on action potential duration showed a dose dependence in the range of 1-1000 nM, while a clear-cut frequency dependence in the range of 1-4 Hz was absent. Intermediate results were obtained in the combined presence of ACh and NA in both SA nodal and atrial myocytes. Our data uncover the extent to which SA nodal and atrial action potentials are intrinsically dependent on ACh, NA, or a combination of both and may thus guide further experiments with RGS proteins.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam Amsterdam, Netherlands
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Yoon SY, Choe C, Kim EJ, Kim CW, Han J, Kang D. Acetylcholine controls mouse oocyte maturation via downregulation of cAMP. Clin Exp Pharmacol Physiol 2011; 38:435-7. [PMID: 21545631 DOI: 10.1111/j.1440-1681.2011.05533.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. In mice, acetylcholine (ACh) plays an important role in oocyte activation and embryonic development. However, the role of ACh in mouse oocyte maturation has not been investigated. 2. In the present study, the effects of 100 μmol/L and 1 mmol/L ACh on maturation processes of murine germinal vesicle (GV) intact oocytes (GV oocytes) exposed to 10 and 100 μmol/L 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of cyclic nucleotide phosphodiesterase, were evaluated morphologically and immunologically. It has been shown that IBMX inhibits the resumption of meiosis by preventing cAMP breakdown. 3. In the present study, at the start of in vitro culture 100% of oocytes were at the GV stage. After 18 h culture, 95 ± 3, 0 and 85.8 ± 10.2% of oocytes had passed the GV stage in the control, IBMX and IBMX + ACh groups, respectively. The IBMX-induced inhibition of the maturation process was significantly attenuated by approximately 90% by ACh in groups treated with 10 μmol/L IBMX + 100 μmol/L ACh and 100 μmol/L IBMX + 1 mmol/L ACh. Although cAMP levels were high in oocytes treated with 100 μmol/L IBMX, levels were reduced in groups treated simultaneously with 100 μmol/L ACh. Furthermore, compared with mature oocytes, ACh-treated GV oocytes exhibited significantly lower (by approximately 2.3-fold) or absent Ca(2+) peaks. 4. The results of the present study indicate that maturation of GV oocytes, arrested by IBMX treatment, is resumed following ACh treatment and that this effect is due to downregulation of cAMP rather than changes in intracellular Ca(2+) levels.
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Han SY, Bolter CP. The muscarinic-activated potassium channel always participates in vagal slowing of the guinea-pig sinoatrial pacemaker. Auton Neurosci 2011; 164:96-100. [PMID: 21684818 DOI: 10.1016/j.autneu.2011.05.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 05/23/2011] [Accepted: 05/26/2011] [Indexed: 10/18/2022]
Abstract
UNLABELLED Controversy persists regarding participation of the muscarinic-activated potassium current (c(KACh)) in small and moderate vagal bradycardia. We investigated this by (i) critical examination of earlier experimental data for mechanisms proposed to operate in modest vagal bradycardia (modulation of I(f) and inhibition of a junctional Na(+) current) and (ii) experiments performed on isolated vagally-innervated guinea-pig atria. In 8 superperfused preparations, 10-s trains of vagal stimulation (1 to 20Hz) produced a bradycardia that ranged from 1 to 80%. Hyperpolarisation of sinoatrial cells accompanied bradycardia in 65/67 observations (linear correlation between bradycardia and increase in maximum diastolic potential (mV)=0.076x%; R(2)=0.57; P<0.001). In bath-mounted preparations single supramaximal stimuli to the vagus immediately and briefly increased pacemaker cycle length in 7 of 18 preparations. This response was eliminated by 300nM tertiapin-Q. Trains of 10 single supramaximal vagal stimuli applied at 1-s intervals caused progressive increase in overall cycle length during the train; immediate and brief increases in cycle length occurred following some stimuli. Immediate brief responses and part of the slower response to the stimulus train were removed by 300nM tertiapin-Q. SUMMARY experimental data shows that small and modest vagal bradycardia is accompanied by hyperpolarisation of the pacemaker cell which is severely attenuated by tertiapin-Q. These observations support the idea that activation of I(KACh) occurs at all levels of vagal bradycardia. Contradictory conclusions from earlier studies may be attributed to the nature of experimental models and experimental design.
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Affiliation(s)
- Su Young Han
- Department of Physiology and the Centre for Neuroscience, University of Otago, Dunedin, New Zealand
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Yaniv Y, Juhaszova M, Lyashkov AE, Spurgeon HA, Sollott SJ, Lakatta EG. Ca2+-regulated-cAMP/PKA signaling in cardiac pacemaker cells links ATP supply to demand. J Mol Cell Cardiol 2011; 51:740-8. [PMID: 21835182 DOI: 10.1016/j.yjmcc.2011.07.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 07/12/2011] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
Abstract
RATIONALE In sinoatrial node cells (SANC), Ca(2+) activates adenylate cyclase (AC) to generate a high basal level of cAMP-mediated/protein kinase A (PKA)-dependent phosphorylation of Ca(2+) cycling proteins. These result in spontaneous sarcoplasmic-reticulum (SR) generated rhythmic Ca(2+) oscillations during diastolic depolarization, that not only trigger the surface membrane to generate rhythmic action potentials (APs), but, in a feed-forward manner, also activate AC/PKA signaling. ATP is consumed to pump Ca(2+) to the SR, to produce cAMP, to support contraction and to maintain cell ionic homeostasis. OBJECTIVE Since feedback mechanisms link ATP-demand to ATP production, we hypothesized that (1) both basal ATP supply and demand in SANC would be Ca(2+)-cAMP/PKA dependent; and (2) due to its feed-forward nature, a decrease in flux through the Ca(2+)-cAMP/PKA signaling axis will reduce the basal ATP production rate. METHODS AND RESULTS O(2) consumption in spontaneous beating SANC was comparable to ventricular myocytes (VM) stimulated at 3 Hz. Graded reduction of basal Ca(2+)-cAMP/PKA signaling to reduce ATP demand in rabbit SANC produced graded ATP depletion (r(2)=0.96), and reduced O(2) consumption and flavoprotein fluorescence. Neither inhibition of glycolysis, selectively blocking contraction nor specific inhibition of mitochondrial Ca(2+) flux reduced the ATP level. CONCLUSIONS Feed-forward basal Ca(2+)-cAMP/PKA signaling both consumes ATP to drive spontaneous APs in SANC and is tightly linked to mitochondrial ATP production. Interfering with Ca(2+)-cAMP/PKA signaling not only slows the firing rate and reduces ATP consumption, but also appears to reduce ATP production so that ATP levels fall. This distinctly differs from VM, which lack this feed-forward basal cAMP/PKA signaling, and in which ATP level remains constant when the demand changes.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, NIH, Baltimore, Maryland 21224-6825, USA
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Kaumann AJ. Phosphodiesterases reduce spontaneous sinoatrial beating but not the 'fight or flight' tachycardia elicited by agonists through Gs-protein-coupled receptors. Trends Pharmacol Sci 2011; 32:377-83. [PMID: 21481950 DOI: 10.1016/j.tips.2011.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 03/07/2011] [Accepted: 03/09/2011] [Indexed: 01/01/2023]
Abstract
Cyclic AMP (cAMP) steers the generation of basal heart beat in the sinoatrial node. It also induces sinoatrial tachycardia and increased cardiac force, elicited through activation of Gs-protein-coupled receptors (GsPCRs). Phosphodiesterases (PDEs) hydrolyse cAMP. In the heart mainly PDE3 and PDE4 would be expected to limit those functions, and the PDE isoenzymes do indeed reduce basal sinoatrial beating rate and blunt the positive inotropic effects of agonists, mediated by GsPCRs. By contrast, recent evidence shows that GsPCR-mediated sinoatrial tachycardia is not controlled by PDE1-5. A PDE-resistant cAMP pool in sinoatrial cells, generated through activation of GsPCRs, including β(1)- and β(2)-adrenoceptors, appears to guarantee unrestrained tachycardia during fight or flight stress.
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Affiliation(s)
- Alberto J Kaumann
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
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Nimura A, Sato N, Sakuragi H, Koyama S, Maruyama J, Talib AK, Nakagawa N, Sakamoto N, Ota H, Tanabe Y, Takeuchi T, Kawamura Y, Hasebe N. Recovery of advanced atrioventricular block by cilostazol. Intern Med 2011; 50:1957-61. [PMID: 21921376 DOI: 10.2169/internalmedicine.50.5228] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We describe a case of advanced atrioventricular (AV) block, in which treatment with cilostazol was effective in recovering the AV conduction. The patient was referred to our hospital for close examination of the advanced AV block and permanent pacemaker implantation. Although the patient had experienced third-degree AV block with occasional AV synchrony for more than two days, the AV conduction completely recovered after treatment with oral cilostazol at 200 mg/day. Here we discuss the possible mechanism of the improvement in the AV conduction by cilostazol.
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Affiliation(s)
- Asami Nimura
- Cardiovascular Respiratory and Neurology Division, Department of Internal Medicine, Asahikawa Medical College, Japan
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Discrepant electrophysiological characteristics and calcium homeostasis of left atrial anterior and posterior myocytes. Basic Res Cardiol 2010; 106:65-74. [PMID: 21072524 DOI: 10.1007/s00395-010-0132-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 10/13/2010] [Accepted: 10/22/2010] [Indexed: 10/18/2022]
Abstract
The left atrial (LA) posterior wall has been demonstrated to have regional electrophysiological differences with a higher arrhythmogenic potential leading to atrial fibrillation (AF). However, the ionic characteristics and calcium regulation in the LA anterior and posterior myocytes have not been fully elucidated. The purpose of this study was to investigate the electrical characteristics of the LA anterior and posterior myocytes. Whole-cell patch-clamp techniques and the indo-1 fluorimetric ratio technique were used to investigate the characteristics of the ionic currents, action potentials, and intracellular calcium in single isolated rabbit myocytes in the LA anterior and posterior walls. The expression of the Na(+)-Ca(2+) exchanger (NCX) and ryanodine receptor (RyR) were evaluated by a Western blot. The LA posterior myocytes (n = 15) had a higher incidence (53 vs. 19%, P < 0.05) of delayed afterdepolarizations than the LA anterior myocytes (n = 16). The LA posterior myocytes had larger sodium currents and late sodium currents, but smaller inward rectifier potassium currents than the LA anterior myocytes. The LA posterior myocytes had larger intracellular Ca(2+) transient and sarcoplasmic reticulum Ca(2+) contents as compared with the LA anterior myocytes. However, the NCX currents in the LA posterior myocytes were smaller than those in the LA anterior myocytes. The LA posterior myocytes had a smaller protein expression of NCX, but a larger protein expression of RyR than the LA anterior myocytes. In conclusion, LA posterior myocytes contain a high arrhythmogenic potential and distinctive electrophysiological characteristics, which may contribute to the pathophysiology of AF.
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Vassalle M, Nett MP, Catanzaro JN, Rota M. Novel oscillatory mechanisms in the cholinergic control of Guinea pig sino-atrial node discharge. J Cardiovasc Electrophysiol 2010; 22:71-80. [PMID: 20662981 DOI: 10.1111/j.1540-8167.2010.01839.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UNLABELLED Oscillatory Mechanisms in Sinus Node Cholinergic Control. INTRODUCTION The role of the oscillatory after-potential V(os) and pre-potential ThV(os) in cholinergic control of discharge was studied in sino-atrial node (SAN). METHODS AND RESULTS A microelectrode technique was used in isolated guinea-pig SAN superfused in vitro in high [K(+) ](o) to visualize V(os) and ThV(os) . The cholinergic agonist carbachol (CCh) decreased the amplitude and slope of V(os) and ThV(os) at a time when there was no increase in maximum diastolic potential. The slowing in SAN rate was due to slower and smaller ThV(os) that missed intermittently the threshold and occurred gradually later in diastole, but not to a decrease in the intrinsic rate of ThV(os) . Eventually, quiescence followed. Larger CCh concentrations quickly induced a hyperpolarization that altogether prevented the occurrence of oscillatory potentials. During CCh washout, ThV(os) reappeared and consistently reinitiated discharge. Lower [Ca(2+) ](o) also decreased slopes and amplitude of V(os) and ThV(os) , thereby slowing and stopping SAN discharge, as CCh did. Overdrive temporarily offset the negative chronotropic effects of CCh and of low [Ca(2+) ](o.) Cesium (a blocker of hyperpolarization-activated current I(f) ) did not abolish CCh inhibitory effects on oscillatory potentials. CONCLUSIONS The cholinergic agonist CCh: (1) slows SAN discharge by decreasing the amplitude of V(os) and ThV(os) , but not the rate of ThV(os) ; (2) can cause hyperpolarization that altogether suppresses the oscillatory potentials; (3) is mimicked in its effects by low [Ca(2+) ](o) ; (4) is antagonized by procedures that increase cellular calcium; and (5) modifies the oscillatory potentials independently of I(f) .
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Affiliation(s)
- Mario Vassalle
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, USA.
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Han S, Wilson SJ, Bolter CP. Tertiapin-Q removes a mechanosensitive component of muscarinic control of the sinoatrial pacemaker in the rat. Clin Exp Pharmacol Physiol 2010; 37:900-4. [PMID: 20497420 DOI: 10.1111/j.1440-1681.2010.05408.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. In an isolated right atrial preparation, an increase in right atrial pressure (RAP) produces an increase in atrial rate. This rate response is larger and occurs faster when there is background vagal or muscarinic stimulation. 2. We hypothesized that in the latter situation, an increase in RAP antagonizes the effect of muscarinic stimulation through stretch inactivation of the mechanosensitive muscarinic potassium current I(K,ACh). 3. In two groups of bath-mounted right atria isolated from male Wistar rats (control n = 12; 300 nmol/L tertiapin-Q treated (to block I(K,ACh)) n = 10), we examined the change in atrial rate when RAP was raised from 2 to 8 mmHg; oxotremorine-M (oxo-M; from 10 to 500 nmol/L) was added to incrementally activate muscarinic receptors. 4. In both control and tertiapin-Q-treated groups, oxo-M reduced atrial rate, but its effect was less ( approximately 40-50%) in the latter group (P < 0.001). In control preparations, responses to an increase in RAP became progressively larger and quicker as the concentration of oxo-M was increased, whereas in tertiapin-Q treated preparations oxo-M did not affect either the amplitude or the speed of the response (P < 0.0001 for both). 5. The results support the hypothesis that atrial stretch antagonizes muscarinic slowing by its effect on I(K,ACh). We suggest that through this mechanism, parasympathetic control of heart rate may be modulated continuously by RAP.
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Affiliation(s)
- SuYoung Han
- Department of Physiology and The Centre for Neuroscience, University of Otago, Dunedin, New Zealand
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Maltsev VA, Lakatta EG. A novel quantitative explanation for the autonomic modulation of cardiac pacemaker cell automaticity via a dynamic system of sarcolemmal and intracellular proteins. Am J Physiol Heart Circ Physiol 2010; 298:H2010-23. [PMID: 20228256 DOI: 10.1152/ajpheart.00783.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Classical numerical models have attributed the regulation of normal cardiac automaticity in sinoatrial node cells (SANCs) largely to G protein-coupled receptor (GPCR) modulation of sarcolemmal ion currents. More recent experimental evidence, however, has indicated that GPCR modulation of SANCs automaticity involves spontaneous, rhythmic, local Ca(2+) releases (LCRs) from the sarcoplasmic reticulum (SR). We explored the GPCR rate modulation of SANCs using a unique and novel numerical model of SANCs in which Ca(2+)-release characteristics are graded by variations in the SR Ca(2+) pumping capability, mimicking the modulation by phospholamban regulated by cAMP-mediated, PKA-activated signaling. The model faithfully predicted the entire range of physiological chronotropic modulation of SANCs by the activation of beta-adrenergic receptors or cholinergic receptors only when experimentally documented changes of sarcolemmal ion channels are combined with a simultaneous increase/decrease in SR Ca(2+) pumping capability. The novel numerical mechanism of GPCR rate modulation is based on numerous complex synergistic interactions between sarcolemmal and intracellular processes via membrane voltage and Ca(2+). Major interactions include changes of diastolic Na(+)/Ca(2+) exchanger current that couple earlier/later diastolic Ca(2+) releases (predicting the experimentally defined LCR period shift) of increased/decreased amplitude (predicting changes in LCR signal mass, i.e., the product of LCR spatial size, amplitude, and number per cycle) to the diastolic depolarization and ultimately to the spontaneous action potential firing rate. Concomitantly, larger/smaller and more/less frequent activation of L-type Ca(2+) current shifts the cellular Ca(2+) balance to support the respective Ca(2+) cycling changes. In conclusion, our model simulations corroborate recent experimental results in rabbit SANCs pointing to a new paradigm for GPCR heart rate modulation by a complex system of dynamically coupled sarcolemmal and intracellular proteins.
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Affiliation(s)
- Victor A Maltsev
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224-6825, USA
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Lakatta EG, Maltsev VA, Vinogradova TM. A coupled SYSTEM of intracellular Ca2+ clocks and surface membrane voltage clocks controls the timekeeping mechanism of the heart's pacemaker. Circ Res 2010; 106:659-73. [PMID: 20203315 PMCID: PMC2837285 DOI: 10.1161/circresaha.109.206078] [Citation(s) in RCA: 453] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ion channels on the surface membrane of sinoatrial nodal pacemaker cells (SANCs) are the proximal cause of an action potential. Each individual channel type has been thoroughly characterized under voltage clamp, and the ensemble of the ion channel currents reconstructed in silico generates rhythmic action potentials. Thus, this ensemble can be envisioned as a surface "membrane clock" (M clock). Localized subsarcolemmal Ca(2+) releases are generated by the sarcoplasmic reticulum via ryanodine receptors during late diastolic depolarization and are referred to as an intracellular "Ca(2+) clock," because their spontaneous occurrence is periodic during voltage clamp or in detergent-permeabilized SANCs, and in silico as well. In spontaneously firing SANCs, the M and Ca(2+) clocks do not operate in isolation but work together via numerous interactions modulated by membrane voltage, subsarcolemmal Ca(2+), and protein kinase A and CaMKII-dependent protein phosphorylation. Through these interactions, the 2 subsystem clocks become mutually entrained to form a robust, stable, coupled-clock system that drives normal cardiac pacemaker cell automaticity. G protein-coupled receptors signaling creates pacemaker flexibility, ie, effects changes in the rhythmic action potential firing rate, by impacting on these very same factors that regulate robust basal coupled-clock system function. This review examines evidence that forms the basis of this coupled-clock system concept in cardiac SANCs.
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Affiliation(s)
- Edward G Lakatta
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging/NIH, 5600 Nathan Shock Dr., Baltimore, MD 21224-6825, USA.
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Funny current provides a relatively modest contribution to spontaneous beating rate regulation of human and rabbit sinoatrial node cells. J Mol Cell Cardiol 2009; 48:804-6. [PMID: 20036245 DOI: 10.1016/j.yjmcc.2009.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 12/04/2009] [Accepted: 12/10/2009] [Indexed: 11/22/2022]
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Lakatta EG. A paradigm shift for the heart's pacemaker. Heart Rhythm 2009; 7:559-64. [PMID: 20156611 DOI: 10.1016/j.hrthm.2009.12.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 12/12/2009] [Indexed: 01/01/2023]
Affiliation(s)
- Edward G Lakatta
- Laboratory of Cardiovascular Science, Gerontology Research Center, NIA Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224-6825, USA.
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