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Sequeira V, Maack C, Reil GH, Reil JC. Exploring the Connection Between Relaxed Myosin States and the Anrep Effect. Circ Res 2024; 134:117-134. [PMID: 38175910 DOI: 10.1161/circresaha.123.323173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
The Anrep effect is an adaptive response that increases left ventricular contractility following an acute rise in afterload. Although the mechanistic origin remains undefined, recent findings suggest a two-phase activation of resting myosin for contraction, involving strain-sensitive and posttranslational phases. We propose that this mobilization represents a transition among the relaxed states of myosin-specifically, from the super-relaxed (SRX) to the disordered-relaxed (DRX)-with DRX myosin ready to participate in force generation. This hypothesis offers a unified explanation that connects myosin's SRX-DRX equilibrium and the Anrep effect as parts of a singular phenomenon. We underscore the significance of this equilibrium in modulating contractility, primarily studied in the context of hypertrophic cardiomyopathy, the most common inherited cardiomyopathy associated with diastolic dysfunction, hypercontractility, and left ventricular hypertrophy. As we posit that the cellular basis of the Anrep effect relies on a two-phased transition of myosin from the SRX to the contraction-ready DRX configuration, any dysregulation in this equilibrium may result in the pathological manifestation of the Anrep phenomenon. For instance, in hypertrophic cardiomyopathy, hypercontractility is linked to a considerable shift of myosin to the DRX state, implying a persistent activation of the Anrep effect. These valuable insights call for additional research to uncover a clinical Anrep fingerprint in pathological states. Here, we demonstrate through noninvasive echocardiographic pressure-volume measurements that this fingerprint is evident in 12 patients with hypertrophic obstructive cardiomyopathy before septal myocardial ablation. This unique signature is characterized by enhanced contractility, indicated by a leftward shift and steepening of the end-systolic pressure-volume relationship, and a prolonged systolic ejection time adjusted for heart rate, which reverses post-procedure. The clinical application of this concept has potential implications beyond hypertrophic cardiomyopathy, extending to other genetic cardiomyopathies and even noncongenital heart diseases with complex etiologies across a broad spectrum of left ventricular ejection fractions.
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Affiliation(s)
- Vasco Sequeira
- Department of Translational Science Universitätsklinikum, Deutsche Zentrum für Herzinsuffizienz (DZHI), Würzburg, Germany (V.S., C.M.)
| | - Christoph Maack
- Department of Translational Science Universitätsklinikum, Deutsche Zentrum für Herzinsuffizienz (DZHI), Würzburg, Germany (V.S., C.M.)
| | - Gert-Hinrich Reil
- Klinik für Kardiologie, Klinikum Oldenburg, Innere Medizin I, Germany (G.-H.R.)
| | - Jan-Christian Reil
- Klinik für Allgemeine und Interventionelle Kardiologie, Herz- und Diabetes-Zentrum Nordrhein-Westphalen, Germany (J.-C.R.)
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2
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Lookin O, Protsenko Y. The Slow Force Response and Simultaneous Changes in Ca2+ Transient in Healthy and Failing Rat Atrial and Ventricular Myocardium. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022070043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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3
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Zechini L, Camilleri-Brennan J, Walsh J, Beaven R, Moran O, Hartley PS, Diaz M, Denholm B. Piezo buffers mechanical stress via modulation of intracellular Ca 2+ handling in the Drosophila heart. Front Physiol 2022; 13:1003999. [PMID: 36187790 PMCID: PMC9515499 DOI: 10.3389/fphys.2022.1003999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Throughout its lifetime the heart is buffeted continuously by dynamic mechanical forces resulting from contraction of the heart muscle itself and fluctuations in haemodynamic load and pressure. These forces are in flux on a beat-by-beat basis, resulting from changes in posture, physical activity or emotional state, and over longer timescales due to altered physiology (e.g. pregnancy) or as a consequence of ageing or disease (e.g. hypertension). It has been known for over a century of the heart's ability to sense differences in haemodynamic load and adjust contractile force accordingly (Frank, Z. biology, 1895, 32, 370-447; Anrep, J. Physiol., 1912, 45 (5), 307-317; Patterson and Starling, J. Physiol., 1914, 48 (5), 357-79; Starling, The law of the heart (Linacre Lecture, given at Cambridge, 1915), 1918). These adaptive behaviours are important for cardiovascular homeostasis, but the mechanism(s) underpinning them are incompletely understood. Here we present evidence that the mechanically-activated ion channel, Piezo, is an important component of the Drosophila heart's ability to adapt to mechanical force. We find Piezo is a sarcoplasmic reticulum (SR)-resident channel and is part of a mechanism that regulates Ca2+ handling in cardiomyocytes in response to mechanical stress. Our data support a simple model in which Drosophila Piezo transduces mechanical force such as stretch into a Ca2+ signal, originating from the SR, that modulates cardiomyocyte contraction. We show that Piezo mutant hearts fail to buffer mechanical stress, have altered Ca2+ handling, become prone to arrhythmias and undergo pathological remodelling.
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Affiliation(s)
- Luigi Zechini
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
- Centre for Inflammation Research, Deanery of Clinical Sciences, Edinburgh Medical School, Edinburgh, United Kingtom
| | - Julian Camilleri-Brennan
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Jonathan Walsh
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Robin Beaven
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Oscar Moran
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche- CNR, Genoa, Italy
| | - Paul S. Hartley
- Department of Life and Environmental Science, Faculty of Science and Technology, Bournemouth University, Poole, United Kingtom
| | - Mary Diaz
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Barry Denholm
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
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4
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Kazemi-Lari MA, Shimkunas R, Jian Z, Hegyi B, Izu L, Shaw JA, Wineman AS, Chen-Izu Y. Modeling Cardiomyocyte Mechanics and Autoregulation of Contractility by Mechano-Chemo-Transduction Feedback. iScience 2022; 25:104667. [PMID: 35860762 PMCID: PMC9289640 DOI: 10.1016/j.isci.2022.104667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/22/2022] [Accepted: 06/20/2022] [Indexed: 11/30/2022] Open
Abstract
The heart pumps blood into circulation against vascular resistance and actively regulates the contractile force to compensate for mechanical load changes. Our experimental data show that cardiomyocytes have a mechano-chemo-transduction (MCT) mechanism that increases intracellular Ca2+ transient to enhance contractility in response to increased mechanical load. This study advances the cardiac excitation- Ca2+ signaling-contraction (E-C) coupling model on conceptual and technical fronts. First, we developed analytical and computational models to perform 3-dimensional mechanical analysis of cardiomyocytes contracting in a viscoelastic medium under mechanical load. Next, we proposed an MCT feedback loop in the E-C coupling dynamic system to shift the feedforward paradigm of cardiac E-C coupling to an autoregulation model. Our combined modeling and experimental studies reveal that MCT enables autoregulation of E-C coupling and contractility in single cardiomyocytes, which underlies the heart’s intrinsic autoregulation in compensatory response to load changes in order to maintain the stroke volume and cardiac output. Excitation-contraction (E-C) coupling has mechano-chemo-transduction (MCT) feedback MCT feedback enables autoregulation of E-C coupling when contracting under load Models for 3D mechanical analyses of cardiomyocytes contraction Shifts the paradigm of cardiac E-C coupling from feedforward to autoregulation model
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5
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Kamkin AG, Kamkina OV, Shim AL, Bilichenko A, Mitrokhin VM, Kazansky VE, Filatova TS, Abramochkin D, Mladenov MI. The role of activation of two different sGC binding sites by NO-dependent and NO-independent mechanisms in the regulation of SACs in rat ventricular cardiomyocytes. Physiol Rep 2022; 10:e15246. [PMID: 35384354 PMCID: PMC8981922 DOI: 10.14814/phy2.15246] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 03/09/2022] [Accepted: 03/09/2022] [Indexed: 04/18/2023] Open
Abstract
The mechanoelectrical feedback (MEF) mechanism in the heart that plays a significant role in the occurrence of arrhythmias, involves cation flux through cation nonselective stretch-activated channels (SACs). It is well known that nitric oxide (NO) can act as a regulator of MEF. Here we addressed the possibility of SAC's regulation along NO-dependent and NO-independent pathways, as well as the possibility of S-nitrosylation of SACs. In freshly isolated rat ventricular cardiomyocytes, using the patch-clamp method in whole-cell configuration, inward nonselective stretch-activated cation current ISAC was recorded through SACs, which occurs during dosed cell stretching. NO donor SNAP, α1-subunit of sGC activator BAY41-2272, sGC blocker ODQ, PKG blocker KT5823, PKG activator 8Br-cGMP, and S-nitrosylation blocker ascorbic acid, were employed. We concluded that the physiological concentration of NO in the cell is a necessary condition for the functioning of SACs. An increase in NO due to SNAP in an unstretched cell causes the appearance of a Gd3+ -sensitive nonselective cation current, an analog of ISAC , while in a stretched cell it eliminates ISAC . The NO-independent pathway of sGC activation of α subunit, triggered by BAY41-2272, is also important for the regulation of SACs. Since S-nitrosylation inhibitor completely abolishes ISAC , this mechanism occurs. The application of BAY41-2272 cannot induce ISAC in a nonstretched cell; however, the addition of SNAP on its background activates SACs, rather due to S-nitrosylation. ODQ eliminates ISAC , but SNAP added on the background of stretch increases ISAC in addition to ODQ. This may be a result of the lack of NO as a result of inhibition of NOS by metabolically modified ODQ. KT5823 reduces PKG activity and reduces SACs phosphorylation, leading to an increase in ISAC . 8Br-cGMP reduces ISAC by activating PKG and its phosphorylation. These results demonstrate a significant contribution of S-nitrosylation to the regulation of SACs.
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Affiliation(s)
- Andre G. Kamkin
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Olga V. Kamkina
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Andrey L. Shim
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Andrey Bilichenko
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Vadim M. Mitrokhin
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Viktor E. Kazansky
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
| | - Tatiana S. Filatova
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
- Department of Human and Animal PhysiologyLomonosov Moscow State UniversityMoscowRussia
| | - Denis V. Abramochkin
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
- Department of Human and Animal PhysiologyLomonosov Moscow State UniversityMoscowRussia
| | - Mitko I. Mladenov
- Department of PhysiologyPirogov Russian National Research Medical UniversityMoscowRussia
- Faculty of Natural Sciences and MathematicsInstitute of Biology, “Ss. Cyril and Methodius” UniversitySkopjeMacedonia
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6
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Wright PT, Gorelik J, Harding SE. Electrophysiological Remodeling: Cardiac T-Tubules and ß-Adrenoceptors. Cells 2021; 10:cells10092456. [PMID: 34572106 PMCID: PMC8468945 DOI: 10.3390/cells10092456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 01/09/2023] Open
Abstract
Beta-adrenoceptors (βAR) are often viewed as archetypal G-protein coupled receptors. Over the past fifteen years, investigations in cardiovascular biology have provided remarkable insights into this receptor family. These studies have shifted pharmacological dogma, from one which centralized the receptor to a new focus on structural micro-domains such as caveolae and t-tubules. Important studies have examined, separately, the structural compartmentation of ion channels and βAR. Despite links being assumed, relatively few studies have specifically examined the direct link between structural remodeling and electrical remodeling with a focus on βAR. In this review, we will examine the nature of receptor and ion channel dysfunction on a substrate of cardiomyocyte microdomain remodeling, as well as the likely ramifications for cardiac electrophysiology. We will then discuss the advances in methodologies in this area with a specific focus on super-resolution microscopy, fluorescent imaging, and new approaches involving microdomain specific, polymer-based agonists. The advent of powerful computational modelling approaches has allowed the science to shift from purely empirical work, and may allow future investigations based on prediction. Issues such as the cross-reactivity of receptors and cellular heterogeneity will also be discussed. Finally, we will speculate as to the potential developments within this field over the next ten years.
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Affiliation(s)
- Peter T. Wright
- School of Life & Health Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK;
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
| | - Julia Gorelik
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
| | - Sian E. Harding
- Cardiac Section, National Heart and Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK;
- Correspondence:
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7
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Reil JC, Reil GH, Kovács Á, Sequeira V, Waddingham MT, Lodi M, Herwig M, Ghaderi S, Kreusser MM, Papp Z, Voigt N, Dobrev D, Meyhöfer S, Langer HF, Maier LS, Linz D, Mügge A, Hohl M, Steendijk P, Hamdani N. CaMKII activity contributes to homeometric autoregulation of the heart: A novel mechanism for the Anrep effect. J Physiol 2020; 598:3129-3153. [PMID: 32394454 DOI: 10.1113/jp279607] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/04/2020] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS The Anrep effect represents the alteration of left ventricular (LV) contractility to acutely enhanced afterload in a few seconds, thereby preserving stroke volume (SV) at constant preload. As a result of the missing preload stretch in our model, the Anrep effect differs from the slow force response and has a different mechanism. The Anrep effect demonstrated two different phases. First, the sudden increased afterload was momentary equilibrated by the enhanced LV contractility as a result of higher power strokes of strongly-bound myosin cross-bridges. Second, the slightly delayed recovery of SV is perhaps dependent on Ca2+ /calmodulin-dependent protein kinase II activation caused by oxidation and myofilament phosphorylation (cardiac myosin-binding protein-C, myosin light chain 2), maximizing the recruitment of available strongly-bound myosin cross-bridges. Short-lived oxidative stress might present a new facet of subcellular signalling with respect to cardiovascular regulation. Relevance for human physiology was demonstrated by echocardiography disclosing the Anrep effect in humans during handgrip exercise. ABSTRACT The present study investigated whether oxidative stress and Ca2+ /calmodulin-dependent protein kinase II (CaMKII) activity are involved in triggering the Anrep effect. LV pressure-volume (PV) analyses of isolated, preload controlled working hearts were performed at two afterload levels (60 and 100 mmHg) in C57BL/6N wild-type (WT) and CaMKII-double knockout mice (DKOCaMKII ). In snap-frozen WT hearts, force-pCa relationship, H2 O2 generation, CaMKII oxidation and phosphorylation of myofilament and Ca2+ handling proteins were assessed. Acutely raised afterload showed significantly increased wall stress, H2 O2 generation and LV contractility in the PV diagram with an initial decrease and recovery of stroke volume, whereas end-diastolic pressure and volume, as well as heart rate, remained constant. Afterload induced increase in LV contractility was blunted in DKOCaMKII -hearts. Force development of single WT cardiomyocytes was greater with elevated afterload at submaximal Ca2+ concentration and associated with increases in CaMKII oxidation and phosphorylation of cardiac-myosin binding protein-C, myosin light chain and Ca2+ handling proteins. CaMKII activity is involved in the regulation of the Anrep effect and associates with stimulation of oxidative stress, presumably starting a cascade of CaMKII oxidation with downstream phosphorylation of myofilament and Ca2+ handling proteins. These mechanisms improve LV inotropy and preserve stroke volume within few seconds.
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Affiliation(s)
- Jan-Christian Reil
- Klinik für Innere Medizin II, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitäres Herzzentrum Lübeck, Universitätsklinikum Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
| | - Gert-Hinrich Reil
- Klinik für Kardiologie, Klinikum Oldenburg, Innere Medizin I, Oldenburg, Germany
| | - Árpád Kovács
- Institute of Physiology, Ruhr University Bochum, Bochum, Germany.,Department of Cardiology, St. Josef-Hospital, Ruhr University of Bochum, Bochum, Germany.,Molecular and Experimental Cardiology, Ruhr Universität Bochum, Bochum, Germany
| | - Vasco Sequeira
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Germany
| | - Mark T Waddingham
- Department of Physiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
| | - Maria Lodi
- Institute of Physiology, Ruhr University Bochum, Bochum, Germany.,Department of Cardiology, St. Josef-Hospital, Ruhr University of Bochum, Bochum, Germany.,Molecular and Experimental Cardiology, Ruhr Universität Bochum, Bochum, Germany
| | - Melissa Herwig
- Institute of Physiology, Ruhr University Bochum, Bochum, Germany.,Department of Cardiology, St. Josef-Hospital, Ruhr University of Bochum, Bochum, Germany.,Molecular and Experimental Cardiology, Ruhr Universität Bochum, Bochum, Germany
| | - Shahrooz Ghaderi
- Institute of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Michael M Kreusser
- Departments of Cardiology, University of Heidelberg, Heidelberg, Germany
| | - Zoltán Papp
- Division of Clinical Physiology, Department of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Niels Voigt
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.,Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Svenja Meyhöfer
- Institute for Endocrinology & Diabetes, University of Lübeck, Lübeck, Germany and German Center for Diabetes Research, Neuherberg, Germany
| | - Harald F Langer
- Klinik für Innere Medizin II, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitäres Herzzentrum Lübeck, Universitätsklinikum Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
| | - Lars S Maier
- Klinik und Poliklinik für innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany
| | - Dominik Linz
- Klinik für Innere Medizin III (Kardiologie, Angiologie, Internistische Intensivmedizin), Universitätsklinikum des Saarlandes, Homburg/Saar, Germany
| | - Andreas Mügge
- Department of Cardiology, St. Josef-Hospital, Ruhr University of Bochum, Bochum, Germany.,Molecular and Experimental Cardiology, Ruhr Universität Bochum, Bochum, Germany
| | - Mathias Hohl
- Klinik für Innere Medizin III (Kardiologie, Angiologie, Internistische Intensivmedizin), Universitätsklinikum des Saarlandes, Homburg/Saar, Germany
| | - Paul Steendijk
- Departments of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Nazha Hamdani
- Institute of Physiology, Ruhr University Bochum, Bochum, Germany.,Department of Cardiology, St. Josef-Hospital, Ruhr University of Bochum, Bochum, Germany.,Molecular and Experimental Cardiology, Ruhr Universität Bochum, Bochum, Germany.,Department Clinical Pharmacology, Ruhr University of Bochum, Bochum, Germany
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8
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Guidry ME, Nickerson DP, Crampin EJ, Nash MP, Loiselle DS, Tran K. Insights From Computational Modeling Into the Contribution of Mechano-Calcium Feedback on the Cardiac End-Systolic Force-Length Relationship. Front Physiol 2020; 11:587. [PMID: 32547426 PMCID: PMC7273927 DOI: 10.3389/fphys.2020.00587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 05/11/2020] [Indexed: 11/23/2022] Open
Abstract
In experimental studies on cardiac tissue, the end-systolic force-length relation (ESFLR) has been shown to depend on the mode of contraction: isometric or isotonic. The isometric ESFLR is derived from isometric contractions spanning a range of muscle lengths while the isotonic ESFLR is derived from shortening contractions across a range of afterloads. The ESFLR of isotonic contractions consistently lies below its isometric counterpart. Despite the passing of over a hundred years since the first insight by Otto Frank, the mechanism(s) underlying this protocol-dependent difference in the ESFLR remain incompletely explained. Here, we investigate the role of mechano-calcium feedback in accounting for the difference between these two ESFLRs. Previous studies have compared the dynamics of isotonic contractions to those of a single isometric contraction at a length that produces maximum force, without considering isometric contractions at shorter muscle lengths. We used a mathematical model of cardiac excitation-contraction to simulate isometric and force-length work-loop contractions (the latter being the 1D equivalent of the whole-heart pressure-volume loop), and compared Ca2+ transients produced under equivalent force conditions. We found that the duration of the simulated Ca2+ transient increases with decreasing sarcomere length for isometric contractions, and increases with decreasing afterload for work-loop contractions. At any given force, the Ca2+ transient for an isometric contraction is wider than that during a work-loop contraction. By driving simulated work-loops with wider Ca2+ transients generated from isometric contractions, we show that the duration of muscle shortening was prolonged, thereby shifting the work-loop ESFLR toward the isometric ESFLR. These observations are explained by an increase in the rate of binding of Ca2+ to troponin-C with increasing force. However, the leftward shift of the work-loop ESFLR does not superimpose on the isometric ESFLR, leading us to conclude that while mechano-calcium feedback does indeed contribute to the difference between the two ESFLRs, it does not completely account for it.
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Affiliation(s)
- Megan E Guidry
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - David P Nickerson
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Edmund J Crampin
- Systems Biology Laboratory, School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC, Australia.,ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, School of Chemical and Biomedical Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Martyn P Nash
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Engineering Science, The University of Auckland, Auckland, New Zealand
| | - Denis S Loiselle
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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9
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Izu LT, Kohl P, Boyden PA, Miura M, Banyasz T, Chiamvimonvat N, Trayanova N, Bers DM, Chen-Izu Y. Mechano-electric and mechano-chemo-transduction in cardiomyocytes. J Physiol 2020; 598:1285-1305. [PMID: 31789427 PMCID: PMC7127983 DOI: 10.1113/jp276494] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/21/2019] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction (E-C) coupling is influenced by (at least) three dynamic systems that couple and feedback to one another (see Abstract Figure). Here we review the mechanical effects on cardiomyocytes that include mechano-electro-transduction (commonly referred to as mechano-electric coupling, MEC) and mechano-chemo-transduction (MCT) mechanisms at cell and molecular levels which couple to Ca2+ -electro and E-C coupling reviewed elsewhere. These feedback loops from muscle contraction and mechano-transduction to the Ca2+ homeodynamics and to the electrical excitation are essential for understanding the E-C coupling dynamic system and arrhythmogenesis in mechanically loaded hearts. This white paper comprises two parts, each reflecting key aspects from the 2018 UC Davis symposium: MEC (how mechanical load influences electrical dynamics) and MCT (how mechanical load alters cell signalling and Ca2+ dynamics). Of course, such separation is artificial since Ca2+ dynamics profoundly affect ion channels and electrogenic transporters and vice versa. In time, these dynamic systems and their interactions must become fully integrated, and that should be a goal for a comprehensive understanding of how mechanical load influences cell signalling, Ca2+ homeodynamics and electrical dynamics. In this white paper we emphasize current understanding, consensus, controversies and the pressing issues for future investigations. Space constraints make it impossible to cover all relevant articles in the field, so we will focus on the topics discussed at the symposium.
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Affiliation(s)
- Leighton T. Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre, and Faculty of Medicine, University of Freiburg, D-79110, Germany
| | | | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
| | - Natalia Trayanova
- Department of Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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10
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Power A, Kaur S, Dyer C, Ward ML. Disruption of Transverse-Tubules Eliminates the Slow Force Response to Stretch in Isolated Rat Trabeculae. Front Physiol 2020; 11:193. [PMID: 32210837 PMCID: PMC7069251 DOI: 10.3389/fphys.2020.00193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/19/2020] [Indexed: 12/15/2022] Open
Abstract
Ventricular muscle has a biphasic response to stretch. There is an immediate increase in force that coincides with the stretch which is followed by a second phase that takes several minutes for force to develop to a new steady state. The initial increase in force is due to changes in myofilament properties, whereas the second, slower component of the stretch response (known as the “slow force response” or SFR) is accompanied by a steady increase in Ca2+ transient amplitude. Evidence shows stretch-dependent Ca2+ influx during the SFR occurs through some mechanism that is continuously active for several minutes following stretch. Many of the candidate ion channels are located primarily in the t-tubules, which are consequently lost in heart disease. Our aim, therefore, was to investigate the impact of t-tubule loss on the SFR in non-failing cardiac trabeculae in which expression of the different Ca2+ handling proteins was not altered by any disease process. For comparison, we also investigated the effect of formamide detubulation of trabeculae on β-adrenergic activation (1 μM isoproterenol), since this is another key regulator of cardiac force. Measurement of intracellular calcium ([Ca2+]i) and isometric stress were made in RV trabeculae from rat hearts before, during and after formamide treatment (1.5 M for 5 min), which on washout seals the surface sarcolemmal t-tubule openings. Results showed detubulation slowed the time course of Ca2+ transients and twitch force, with time-to-peak, maximum rate-of-rise, and relaxation prolonged in trabeculae at optimal length (Lo). Formamide treatment also prevented development of the SFR following a step change in length from 90 to 100% Lo, and blunted the response to β-adrenergic activation (1 μM isoproterenol).
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Affiliation(s)
- Amelia Power
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Sarbjot Kaur
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Cameron Dyer
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
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11
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Kaur S, Shen X, Power A, Ward ML. Stretch modulation of cardiac contractility: importance of myocyte calcium during the slow force response. Biophys Rev 2020; 12:135-142. [PMID: 31939110 DOI: 10.1007/s12551-020-00615-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/07/2020] [Indexed: 12/11/2022] Open
Abstract
The mechanical response of the heart to myocardial stretch has been understood since the work of muscle physiologists more than 100 years ago, whereby an increase in ventricular chamber filling during diastole increases the subsequent force of contraction. The stretch-induced increase in contraction is biphasic. There is an abrupt increase in the force that coincides with the stretch (the rapid response), which is then followed by a slower response that develops over several minutes (the slow force response, or SFR). The SFR is associated with a progressive increase in the magnitude of the Ca2+ transient, the event that initiates myocyte cross-bridge cycling and force development. However, the mechanisms underlying the stretch-dependent increase in the Ca2+ transient are still debated. This review outlines recent literature on the SFR and summarizes the different stretch-activated Ca2+ entry pathways. The SFR might result from a combination of several different cellular mechanisms initiated in response to activation of different cellular stretch sensors.
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Affiliation(s)
- Sarbjot Kaur
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G.Jebsen Center for Cardiac Research, Oslo, Norway
| | - Amelia Power
- Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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12
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Yeves AM, Ennis IL. Na +/H + exchanger and cardiac hypertrophy. HIPERTENSION Y RIESGO VASCULAR 2019; 37:22-32. [PMID: 31601481 DOI: 10.1016/j.hipert.2019.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/16/2019] [Accepted: 09/03/2019] [Indexed: 12/31/2022]
Abstract
Reactive cardiac hypertrophy (CH) is an increase in heart mass in response to hemodynamic overload. Exercise-induced CH emerges as an adaptive response with improved cardiac function, in contrast to pathological CH that represents a risk factor for cardiovascular health. The Na+/H+ exchanger (NHE-1) is a membrane transporter that not only regulates intracellular pH but also intracellular Na+ concentration. In the scenario of cardiovascular diseases, myocardial NHE-1 is activated by a variety of stimuli, such as neurohumoral factors and mechanical stress, leading to intracellular Na+ overload and activation of prohypertrophic cascades. NHE-1 hyperactivity is intimately linked to heart diseases, including ischemia-reperfusion injury, maladaptive CH and heart failure. In this review, we will present evidence to support that the NHE-1 hyperactivity constitutes a "switch on/off" for the pathological phenotype during CH development. We will also discuss some classical and novel strategies to avoid NHE-1 hyperactivity, and that are therefore worthwhile to improve cardiovascular health.
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Affiliation(s)
- A M Yeves
- Centro de Investigaciones Cardiovasculares "Horacio E. Cingolani", Facultad de Ciencias Médicas, Universidad Nacional de La Plata - CONICET, Calle 60 y 120, 1900 La Plata, Argentina
| | - I L Ennis
- Centro de Investigaciones Cardiovasculares "Horacio E. Cingolani", Facultad de Ciencias Médicas, Universidad Nacional de La Plata - CONICET, Calle 60 y 120, 1900 La Plata, Argentina.
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13
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Leite-Moreira AM, Almeida-Coelho J, Neves JS, Pires AL, Ferreira-Martins J, Castro-Ferreira R, Ladeiras-Lopes R, Conceição G, Miranda-Silva D, Rodrigues P, Hamdani N, Herwig M, Falcão-Pires I, Paulus WJ, Linke WA, Lourenço AP, Leite-Moreira AF. Stretch-induced compliance: a novel adaptive biological mechanism following acute cardiac load. Cardiovasc Res 2019; 114:656-667. [PMID: 29401264 DOI: 10.1093/cvr/cvy026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 01/30/2018] [Indexed: 01/09/2023] Open
Abstract
Aims The heart is constantly challenged with acute bouts of stretching or overload. Systolic adaptations to these challenges are known but adaptations in diastolic stiffness remain unknown. We evaluated adaptations in myocardial stiffness due to acute stretching and characterized the underlying mechanisms. Methods and results Left ventricles (LVs) of intact rat hearts, rabbit papillary muscles and myocardial strips from cardiac surgery patients were stretched. After stretching, there was a sustained >40% decrease in end-diastolic pressure (EDP) or passive tension (PT) for 15 min in all species and experimental preparations. Stretching by volume loading in volunteers and cardiac surgery patients resulted in E/E' and EDP decreases, respectively, after sustained stretching. Stretched samples had increased myocardial cGMP levels, increased phosphorylated vasodilator-stimulated phosphoprotein phosphorylation, as well as, increased titin phosphorylation, which was reduced by prior protein kinase G (PKG) inhibition (PKGi). Skinned cardiomyocytes from stretched and non-stretched myocardia were studied. Skinned cardiomyocytes from stretched hearts showed decreased PT, which was abrogated by protein phosphatase incubation; whereas those from non-stretched hearts decreased PT after PKG incubation. Pharmacological studies assessed the role of nitric oxide (NO) and natriuretic peptides (NPs). PT decay after stretching was significantly reduced by combined NP antagonism, NO synthase inhibition and NO scavenging, or by PKGi. Response to stretching was remarkably reduced in a rat model of LV hypertrophy, which also failed to increase titin phosphorylation. Conclusions We describe and translate to human physiology a novel adaptive mechanism, partly mediated by titin phosphorylation through cGMP-PKG signalling, whereby myocardial compliance increases in response to acute stretching. This mechanism may not function in the hypertrophic heart.
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Affiliation(s)
- André M Leite-Moreira
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Anaesthesiology, São João Hospital Centre, Porto, Portugal
| | - João Almeida-Coelho
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - João S Neves
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Ana L Pires
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - João Ferreira-Martins
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Ricardo Castro-Ferreira
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Ricardo Ladeiras-Lopes
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Glória Conceição
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Daniela Miranda-Silva
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Patrícia Rodrigues
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Nazha Hamdani
- Department of Cardiovascular Physiology, Ruhr University Bochum, Germany
| | - Melissa Herwig
- Department of Cardiovascular Physiology, Ruhr University Bochum, Germany
| | - Inês Falcão-Pires
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Walter J Paulus
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Centre, Amsterdam, The Netherlands
| | | | - André P Lourenço
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Anaesthesiology, São João Hospital Centre, Porto, Portugal
| | - Adelino F Leite-Moreira
- Department of Surgery and Physiology and Cardiovascular Research Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Cardiothoracic Surgery, São João Hospital Centre, Porto, Portugal
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Dowrick JM, Tran K, Loiselle DS, Nielsen PMF, Taberner AJ, Han J, Ward M. The slow force response to stretch: Controversy and contradictions. Acta Physiol (Oxf) 2019; 226:e13250. [PMID: 30614655 DOI: 10.1111/apha.13250] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/20/2018] [Accepted: 01/02/2019] [Indexed: 12/19/2022]
Abstract
When exposed to an abrupt stretch, cardiac muscle exhibits biphasic active force enhancement. The initial, instantaneous, force enhancement is well explained by the Frank-Starling mechanism. However, the cellular mechanisms associated with the second, slower phase remain contentious. This review explores hypotheses regarding this "slow force response" with the intention of clarifying some apparent contradictions in the literature. The review is partitioned into three sections. The first section considers pathways that modify the intracellular calcium handling to address the role of the sarcoplasmic reticulum in the mechanism underlying the slow force response. The second section focuses on extracellular calcium fluxes and explores the identity and contribution of the stretch-activated, non-specific, cation channels as well as signalling cascades associated with G-protein coupled receptors. The final section introduces promising candidates for the mechanosensor(s) responsible for detecting the stretch perturbation.
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Affiliation(s)
- Jarrah M. Dowrick
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Physiology University of Auckland Auckland New Zealand
| | - Poul M. F. Nielsen
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Engineering Science University of Auckland Auckland New Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Engineering Science University of Auckland Auckland New Zealand
| | - June‐Chiew Han
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Marie‐Louise Ward
- Department of Physiology University of Auckland Auckland New Zealand
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15
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Lookin O, Protsenko Y. The lack of slow force response in failing rat myocardium: role of stretch-induced modulation of Ca-TnC kinetics. J Physiol Sci 2019; 69:345-357. [PMID: 30560346 PMCID: PMC10717443 DOI: 10.1007/s12576-018-0651-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/08/2018] [Indexed: 10/27/2022]
Abstract
The slow force response (SFR) to stretch is an important adaptive mechanism of the heart. The SFR may result in ~ 20-30% extra force but it is substantially attenuated in heart failure. We investigated the relation of SFR magnitude with Ca2+ transient decay in healthy (CONT) and monocrotaline-treated rats with heart failure (MCT). Right ventricular trabeculae were stretched from 85 to 95% of optimal length and held stretched for 10 min at 30 °C and 1 Hz. Isometric twitches and Ca2+ transients were collected on 2, 4, 6, 8, 10 min after stretch. The changes in peak tension and Ca2+ transient decay characteristics during SFR were evaluated as a percentage of the value measured immediately after stretch. The amount of Ca2+ utilized by TnC was indirectly evaluated using the methods of Ca2+ transient "bump" and "difference curve." The muscles of CONT rats produced positive SFR and they showed prominent functional relation between SFR magnitude and the magnitude (amplitude, integral intensity) of Ca2+ transient "bump" and "difference curve." The myocardium of MCT rats showed negative SFR to stretch (force decreased in time) which was not correlated well with the characteristics of Ca2+ transient decay, evaluated by the methods of "bump" and "difference curve." We conclude that the intracellular mechanisms of Ca2+ balancing during stretch-induced slow adaptation of myocardial contractility are disrupted in failing rat myocardium. The potential significance of our findings is that the deficiency of slow force response in diseased myocardium may be diminished under augmented kinetics of Ca-TnC interaction.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation.
- Ural Federal University, 19 Mira St., Yekaterinburg, 620002, Russian Federation.
| | - Yuri Protsenko
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation
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16
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Schönleitner P, Schotten U, Antoons G. Mechanosensitivity of microdomain calcium signalling in the heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28648626 DOI: 10.1016/j.pbiomolbio.2017.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In cardiac myocytes, calcium (Ca2+) signalling is tightly controlled in dedicated microdomains. At the dyad, i.e. the narrow cleft between t-tubules and junctional sarcoplasmic reticulum (SR), many signalling pathways combine to control Ca2+-induced Ca2+ release during contraction. Local Ca2+ gradients also exist in regions where SR and mitochondria are in close contact to regulate energetic demands. Loss of microdomain structures, or dysregulation of local Ca2+ fluxes in cardiac disease, is often associated with oxidative stress, contractile dysfunction and arrhythmias. Ca2+ signalling at these microdomains is highly mechanosensitive. Recent work has demonstrated that increasing mechanical load triggers rapid local Ca2+ releases that are not reflected by changes in global Ca2+. Key mechanisms involve rapid mechanotransduction with reactive oxygen species or nitric oxide as primary signalling molecules targeting SR or mitochondria microdomains depending on the nature of the mechanical stimulus. This review summarizes the most recent insights in rapid Ca2+ microdomain mechanosensitivity and re-evaluates its (patho)physiological significance in the context of historical data on the macroscopic role of Ca2+ in acute force adaptation and mechanically-induced arrhythmias. We distinguish between preload and afterload mediated effects on local Ca2+ release, and highlight differences between atrial and ventricular myocytes. Finally, we provide an outlook for further investigation in chronic models of abnormal mechanics (eg post-myocardial infarction, atrial fibrillation), to identify the clinical significance of disturbed Ca2+ mechanosensitivity for arrhythmogenesis.
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Affiliation(s)
- Patrick Schönleitner
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Uli Schotten
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Gudrun Antoons
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
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17
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Role of TRPC3 and TRPC6 channels in the myocardial response to stretch: Linking physiology and pathophysiology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28645743 DOI: 10.1016/j.pbiomolbio.2017.06.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transient receptor potential (TRP) channels constitute a large family of versatile multi-signal transducers. In particular, TRP canonical (TRPC) channels are known as receptor-operated, non-selective cation channels. TRPC3 and TRPC6, two members in the TRPC family, are highly expressed in the heart, and participate in the pathogenesis of cardiac hypertrophy and heart failure as a pathological response to chronic mechanical stress. In the pathological response, myocardial stretch increases intracellular Ca2+ levels and activates nuclear factor of activated T cells to induce cardiac hypertrophy. Recent studies have revealed that TRPC3 and TRPC6 also contribute to the physiological stretch-induced slow force response (SFR), a slow increase in the Ca2+ transient and twitch force during stretch. In the physiological response, a stretch-induced increase in intracellular Ca2+ mediated by TRPC3 and TRPC6 causes the SFR. We here overview experimental evidence of the involvement of TRPC3 and TRPC6 in cardiac physiology and pathophysiology in response to stretch.
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18
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Decher N, Kiper AK, Rinné S. Stretch-activated potassium currents in the heart: Focus on TREK-1 and arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:223-232. [PMID: 28526352 DOI: 10.1016/j.pbiomolbio.2017.05.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/09/2017] [Accepted: 05/15/2017] [Indexed: 12/26/2022]
Abstract
This review focuses on the role and the molecular candidates of the cardiac stretch-activated potassium current (SAK). The functional properties of the two-pore domain potassium (K2P) channel TREK-1, a major candidate for the cardiac SAK, are analyzed and the molecular mechanism of stretch-activation in K2P potassium channels is discussed. Furthermore, the functional modulation of TREK-1 by different cardiac interaction partners, as well as evidence for the functional role of the stretch-dependent TREK-1 and its putative subunits in the heart is reviewed. In addition, we summarize the recent evidence that TREK-1 is involved in the pathogenesis of human cardiac arrhythmias.
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Affiliation(s)
- Niels Decher
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany.
| | - Aytug K Kiper
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany
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19
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Chen-Izu Y, Izu LT. Mechano-chemo-transduction in cardiac myocytes. J Physiol 2017; 595:3949-3958. [PMID: 28098356 DOI: 10.1113/jp273101] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/15/2016] [Indexed: 12/31/2022] Open
Abstract
The heart has the ability to adjust to changing mechanical loads. The Frank-Starling law and the Anrep effect describe exquisite intrinsic mechanisms the heart has for autoregulating the force of contraction to maintain cardiac output under changes of preload and afterload. Although these mechanisms have been known for more than a century, their cellular and molecular underpinnings are still debated. How does the cardiac myocyte sense changes in preload or afterload? How does the myocyte adjust its response to compensate for such changes? In cardiac myocytes Ca2+ is a crucial regulator of contractile force and in this review we compare and contrast recent studies from different labs that address these two important questions. The 'dimensionality' of the mechanical milieu under which experiments are carried out provide important clues to the location of the mechanosensors and the kinds of mechanical forces they can sense and respond to. As a first approximation, sensors inside the myocyte appear to modulate reactive oxygen species while sensors on the cell surface appear to also modulate nitric oxide signalling; both signalling pathways affect Ca2+ handling. Undoubtedly, further studies will add layers to this simplified picture. Clarifying the intimate links from cellular mechanics to reactive oxygen species and nitric oxide signalling and to Ca2+ handling will deepen our understanding of the Frank-Starling law and the Anrep effect, and also provide a unified view on how arrhythmias may arise in seemingly disparate diseases that have in common altered myocyte mechanics.
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Affiliation(s)
- Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, CA, 95616, USA.,Department of Internal Medicine/Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Leighton T Izu
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
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20
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Abstract
Mechanical forces will have been omnipresent since the origin of life, and living organisms have evolved mechanisms to sense, interpret, and respond to mechanical stimuli. The cardiovascular system in general, and the heart in particular, is exposed to constantly changing mechanical signals, including stretch, compression, bending, and shear. The heart adjusts its performance to the mechanical environment, modifying electrical, mechanical, metabolic, and structural properties over a range of time scales. Many of the underlying regulatory processes are encoded intracardially and are, thus, maintained even in heart transplant recipients. Although mechanosensitivity of heart rhythm has been described in the medical literature for over a century, its molecular mechanisms are incompletely understood. Thanks to modern biophysical and molecular technologies, the roles of mechanical forces in cardiac biology are being explored in more detail, and detailed mechanisms of mechanotransduction have started to emerge. Mechano-gated ion channels are cardiac mechanoreceptors. They give rise to mechano-electric feedback, thought to contribute to normal function, disease development, and, potentially, therapeutic interventions. In this review, we focus on acute mechanical effects on cardiac electrophysiology, explore molecular candidates underlying observed responses, and discuss their pharmaceutical regulation. From this, we identify open research questions and highlight emerging technologies that may help in addressing them.
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Affiliation(s)
- Rémi Peyronnet
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.)
| | - Jeanne M Nerbonne
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.)
| | - Peter Kohl
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.).
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21
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Chorro FJ, Canto ID, Brines L, Such-Miquel L, Calvo C, Soler C, Zarzoso M, Trapero I, Tormos Á, Such L. Estudio experimental de los efectos de EIPA, losartán y BQ-123 sobre las modificaciones electrofisiológicas inducidas por el estiramiento miocárdico. Rev Esp Cardiol 2015. [DOI: 10.1016/j.recesp.2014.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Chorro FJ, Canto ID, Brines L, Such-Miquel L, Calvo C, Soler C, Zarzoso M, Trapero I, Tormos Á, Such L. Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch. ACTA ACUST UNITED AC 2015; 68:1101-10. [PMID: 25985899 DOI: 10.1016/j.rec.2014.12.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/12/2014] [Indexed: 11/26/2022]
Abstract
INTRODUCTION AND OBJECTIVES Mechanical response to myocardial stretch has been explained by various mechanisms, which include Na(+)/H(+) exchanger activation by autocrine-paracrine system activity. Drug-induced changes were analyzed to investigate the role of these mechanisms in the electrophysiological responses to acute myocardial stretch. METHODS Multiple epicardial electrodes and mapping techniques were used to analyze changes in ventricular fibrillation induced by acute myocardial stretch in isolated perfused rabbit hearts. Four series were studied: control (n = 9); during perfusion with the angiotensin receptor blocker losartan (1 μM, n = 8); during perfusion with the endothelin A receptor blocker BQ-123 (0.1 μM, n = 9), and during perfusion with the Na(+)/H(+) exchanger inhibitor EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 μM, n = 9). RESULTS EIPA attenuated the increase in the dominant frequency of stretch-induced fibrillation (control=40.4%; losartan=36% [not significant]; BQ-123=46% [not significant]; and EIPA=22% [P<.001]). During stretch, the activation maps were less complex (P<.0001) and the spectral concentration of the arrhythmia was greater (greater regularity) in the EIPA series: control=18 (3%); EIPA = 26 (9%) (P < .02); losartan=18 (5%) (not significant); and BQ-123=18 (4%) (not significant). CONCLUSIONS The Na(+)/H(+) exchanger inhibitor EIPA attenuated the electrophysiological effects responsible for the acceleration and increased complexity of ventricular fibrillation induced by acute myocardial stretch. The angiotensin II receptor antagonist losartan and the endothelin A receptor blocker BQ-123 did not modify these effects.
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Affiliation(s)
- Francisco J Chorro
- Servicio de Cardiología, Hospital Clínico Universitario de Valencia, INCLIVA, Valencia, Spain; Departamento de Medicina, Universidad de Valencia-Estudi General, Valencia, Spain.
| | - Irene Del Canto
- Departamento de Medicina, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Laia Brines
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Luis Such-Miquel
- Departamento de Fisioterapia, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Conrado Calvo
- Departamento de Electrónica, Universidad Politécnica de Valencia, Valencia, Spain
| | - Carlos Soler
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Manuel Zarzoso
- Departamento de Fisioterapia, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Isabel Trapero
- Departamento de Enfermería, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Álvaro Tormos
- Departamento de Electrónica, Universidad Politécnica de Valencia, Valencia, Spain
| | - Luis Such
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
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Villa-Abrille MC, Pérez NG, Cingolani HE. Letter by Villa Abrille et al regarding article, "hyperactive adverse mechanical stress responses in dystrophic heart are coupled to transient receptor potential canonical 6 and blocked by cGMP-protein kinase G modulation". Circ Res 2015; 116:e11. [PMID: 25552698 DOI: 10.1161/circresaha.114.305543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- María Celeste Villa-Abrille
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas de La Plata, UNLP-CONICET, Argentina
| | - Néstor Gustavo Pérez
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas de La Plata, UNLP-CONICET, Argentina
| | - Horacio Eugenio Cingolani
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas de La Plata, UNLP-CONICET, Argentina
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Ismail HM, Dorchies OM, Perozzo R, Strosova MK, Scapozza L, Ruegg UT. Inhibition of iPLA2 β and of stretch-activated channels by doxorubicin alters dystrophic muscle function. Br J Pharmacol 2014; 169:1537-50. [PMID: 23849042 DOI: 10.1111/bph.12188] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/28/2013] [Accepted: 03/15/2013] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Chronic elevation in intracellular Ca(2+) concentration participates in death of skeletal muscle from mdx mice, a model for Duchenne muscular dystrophy (DMD). Candidate pathways mediating this Ca(2+) overload involve store-operated channels (SOCs) and stretch-activated channels (SACs), which are modulated by the Ca(2+) -independent form of PL A2 (iPLA2 ). We investigated the effect of doxorubicin (Dox), a chemotherapeutic agent reported to inhibit iPLA2 in other systems, on the activity of this enzyme and on the consequences on Ca(2+) handling and muscle function in mdx mice. EXPERIMENTAL APPROACH Effects of Dox on iPLA2 activity, reactive oxygen species production and on Ca(2+) influx were investigated in C2C12 and mdx myotubes. The mechanism of Dox-mediated iPLA2 inhibition was evaluated using purified 6x histidine-tagged enzyme. Aequorin technology was used to assess Ca(2+) concentrations underneath the plasma membrane. Isolated muscles were exposed to fatigue protocols and eccentric contractions to evaluate the effects of Dox on muscle function. KEY RESULTS Dox at 1-30 μM inhibited iPLA2 activity in cells and in the purified enzyme. Dox also inhibited SAC- but not SOC-mediated Ca(2+) influx in myotubes. Stimulated elevations of Ca(2+) concentrations below the plasmalemma were also blocked. Exposure of excised muscle to Dox was not deleterious to force production and promoted recovery from eccentric contractions. CONCLUSIONS AND IMPLICATIONS Dox showed efficacy against targets known to play a role in the pathology of DMD, namely iPLA2 and SAC. The potent SAC inhibitory effect of Dox is a novel finding that can explain partly the cardiomyopathy seen in chronic anthracycline treatment.
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Affiliation(s)
- H M Ismail
- Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva and University of Lausanne, Geneva, Switzerland
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25
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Benoist D, Stones R, Benson AP, Fowler ED, Drinkhill MJ, Hardy MEL, Saint DA, Cazorla O, Bernus O, White E. Systems approach to the study of stretch and arrhythmias in right ventricular failure induced in rats by monocrotaline. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:162-72. [PMID: 25016242 PMCID: PMC4210667 DOI: 10.1016/j.pbiomolbio.2014.06.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 06/27/2014] [Indexed: 02/05/2023]
Abstract
We demonstrate the synergistic benefits of using multiple technologies to investigate complex multi-scale biological responses. The combination of reductionist and integrative methodologies can reveal novel insights into mechanisms of action by tracking changes of in vivo phenomena to alterations in protein activity (or vice versa). We have applied this approach to electrical and mechanical remodelling in right ventricular failure caused by monocrotaline-induced pulmonary artery hypertension in rats. We show arrhythmogenic T-wave alternans in the ECG of conscious heart failure animals. Optical mapping of isolated hearts revealed discordant action potential duration (APD) alternans. Potential causes of the arrhythmic substrate; structural remodelling and/or steep APD restitution and dispersion were observed, with specific remodelling of the Right Ventricular Outflow Tract. At the myocyte level, [Ca(2+)]i transient alternans were observed together with decreased activity, gene and protein expression of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA). Computer simulations of the electrical and structural remodelling suggest both contribute to a less stable substrate. Echocardiography was used to estimate increased wall stress in failure, in vivo. Stretch of intact and skinned single myocytes revealed no effect on the Frank-Starling mechanism in failing myocytes. In isolated hearts acute stretch-induced arrhythmias occurred in all preparations. Significant shortening of the early APD was seen in control but not failing hearts. These observations may be linked to changes in the gene expression of candidate mechanosensitive ion channels (MSCs) TREK-1 and TRPC1/6. Computer simulations incorporating MSCs and changes in ion channels with failure, based on altered gene expression, largely reproduced experimental observations.
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Affiliation(s)
- David Benoist
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK; L'Institut de Rythmologie et Modelisation Cardiaque, INSERM U1045, Université de Bordeaux, France
| | - Rachel Stones
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK
| | - Alan P Benson
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK
| | - Ewan D Fowler
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK
| | - Mark J Drinkhill
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK
| | - Matthew E L Hardy
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK; Faculty of Life Sciences, University of Manchester, UK
| | - David A Saint
- School of Medical Sciences, University of Adelaide, Australia
| | - Olivier Cazorla
- INSERM U1046, Université Montpellier 1, Université Montpellier 2, France
| | - Olivier Bernus
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK; L'Institut de Rythmologie et Modelisation Cardiaque, INSERM U1045, Université de Bordeaux, France
| | - Ed White
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, UK.
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26
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Ward ML, Shen X, Greenwood DR. Use of liquid chromatography-mass spectrometry (LC-MS) to detect substances of nanomolar concentration in the coronary effluent of isolated perfused hearts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:270-8. [DOI: 10.1016/j.pbiomolbio.2014.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 01/29/2023]
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Seo K, Inagaki M, Hidaka I, Fukano H, Sugimachi M, Hisada T, Nishimura S, Sugiura S. Relevance of cardiomyocyte mechano-electric coupling to stretch-induced arrhythmias: optical voltage/calcium measurement in mechanically stimulated cells, tissues and organs. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:129-39. [PMID: 25084395 DOI: 10.1016/j.pbiomolbio.2014.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/19/2014] [Indexed: 12/27/2022]
Abstract
Stretch-induced arrhythmias are multi-scale phenomena in which alterations in channel activities and/or calcium handling lead to the organ level derangement of the heart rhythm. To understand how cellular mechano-electric coupling (MEC) leads to stretch-induced arrhythmias at the organ level, we developed stretching devices and optical voltage/calcium measurement techniques optimized to each cardiac level. This review introduces these experimental techniques of (1) optical voltage measurement coupled with a carbon-fiber technique for single isolated cardiomyocytes, (2) optical voltage mapping combined with motion tracking technique for myocardial tissue/whole heart preparations and (3) real-time calcium imaging coupled with a laser optical trap technique for cardiomyocytes. Following the overview of each methodology, results are presented. We conclude that individual MEC in cardiomyocytes can be heterogeneous at the ventricular level, especially when moderate amplitude mechanical stretches are applied to the heart, and that this heterogeneous MEC can evoke focal excitation that develops into re-entrant arrhythmias.
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Affiliation(s)
- Kinya Seo
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.
| | - Masashi Inagaki
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan.
| | - Ichiro Hidaka
- Division of Physical and Health Education, Graduate School of Education, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Hana Fukano
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan.
| | - Toshiaki Hisada
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
| | - Satoshi Nishimura
- Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan; Department of Cardiovascular Medicine, Translational Systems Biology and Medicine Initiative, The University of Tokyo, Tokyo 113-8655, Japan.
| | - Seiryo Sugiura
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
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Glucagon-like peptide-1 (7-36) but not (9-36) augments cardiac output during myocardial ischemia via a Frank-Starling mechanism. Basic Res Cardiol 2014; 109:426. [PMID: 25005062 DOI: 10.1007/s00395-014-0426-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 06/30/2014] [Accepted: 07/03/2014] [Indexed: 12/17/2022]
Abstract
This study examined the cardiovascular effects of GLP-1 (7-36) or (9-36) on myocardial oxygen consumption, function and systemic hemodynamics in vivo during normal perfusion and during acute, regional myocardial ischemia. Lean Ossabaw swine received systemic infusions of saline vehicle or GLP-1 (7-36 or 9-36) at 1.5, 3.0, and 10.0 pmol/kg/min in sequence for 30 min at each dose, followed by ligation of the left circumflex artery during continued infusion at 10.0 pmol/kg/min. Systemic GLP-1 (9-36) had no effect on coronary flow, blood pressure, heart rate or indices of cardiac function before or during regional myocardial ischemia. Systemic GLP-1 (7-36) exerted no cardiometabolic or hemodynamic effects prior to ischemia. During ischemia, GLP-1 (7-36) increased cardiac output by approximately 2 L/min relative to vehicle-controls (p = 0.003). This response was not diminished by treatment with the non-depolarizing ganglionic blocker hexamethonium. Left ventricular pressure-volume loops measured during steady-state conditions with graded occlusion of the inferior vena cava to assess load-independent contractility revealed that GLP-1 (7-36) produced marked increases in end-diastolic volume (74 ± 1 to 92 ± 5 ml; p = 0.03) and volume axis intercept (8 ± 2 to 26 ± 8; p = 0.05), without any change in the slope of the end-systolic pressure-volume relationship vs. vehicle during regional ischemia. GLP-1 (9-36) produced no changes in any of these parameters compared to vehicle. These findings indicate that short-term systemic treatment with GLP-1 (7-36) but not GLP-1 (9-36) significantly augments cardiac output during regional myocardial ischemia, via increases in ventricular preload without changes in cardiac inotropy.
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29
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Ennis IL, Aiello EA, Cingolani HE, Perez NG. The autocrine/paracrine loop after myocardial stretch: mineralocorticoid receptor activation. Curr Cardiol Rev 2014; 9:230-40. [PMID: 23909633 PMCID: PMC3780348 DOI: 10.2174/1573403x113099990034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 12/13/2012] [Indexed: 01/13/2023] Open
Abstract
The stretch of cardiac muscle increases developed force in two phases. The first phase, which occurs rapidly, constitutes the well-known Frank-Starling mechanism and it is generally attributed to enhanced myofilament responsiveness to Ca(2+). The second phase or slow force response (SFR) occurs gradually and is due to an increase in the calcium transient amplitude as a result of a stretch-triggered autocrine/paracrine mechanism. We previously showed that Ca(2+) entry through reverse Na(+)/Ca(2+) exchange underlies the SFR, as the final step of an autocrine/paracrine cascade involving release of angiotensin II/endothelin, and a Na(+)/H(+) exchanger (NHE-1) activation-mediated rise in Na+. In the present review we mainly focus on our three latest contributions to the understanding of this signalling pathway triggered by myocardial stretch: 1) The finding that an increased production of reactive oxygen species (ROS) from mitochondrial origin is critical in the activation of the NHE-1 and therefore in the genesis of the SFR; 2) the demonstration of a key role played by the transactivation of the epidermal growth factor receptor; and 3) the involvement of mineralocorticoid receptors (MR) activation in the stretch-triggered cascade leading to the SFR. Among these novel contributions, the critical role played by the MR is perhaps the most important one. This finding may conceivably provide a mechanistic explanation to the recently discovered strikingly beneficial effects of MR antagonism in humans with cardiac hypertrophy and failure.
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Affiliation(s)
- Irene L Ennis
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Medicas, Universidad Nacional de La Plata, Argentina
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Shen X, Cannell MB, Ward ML. Effect of SR load and pH regulatory mechanisms on stretch-dependent Ca(2+) entry during the slow force response. J Mol Cell Cardiol 2013; 63:37-46. [PMID: 23880608 DOI: 10.1016/j.yjmcc.2013.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 06/11/2013] [Accepted: 07/11/2013] [Indexed: 12/22/2022]
Abstract
When cardiac muscle is stretched, there is an initial inotropic response that coincides with the stretch followed by a slower increase in twitch force that develops over several minutes (the "slow force response", or SFR). Unlike the initial response to stretch, the SFR is produced by an increase in Ca(2+) transient amplitude, but the cellular mechanisms that give rise to the increased transients are still debated. We have examined the relationship between the SFR, intracellular [Ca(2+)] and the inotropic state of right ventricular trabeculae from rat hearts at 37°C. The magnitude of the SFR varied with [Ca(2+)]o and stimulation frequency, so that the SFR was greatest for conditions associated with a reduced SR Ca(2+) content. The SFR was not blocked by the AT1 receptor blocker losartan, but was reduced by SN-6, an inhibitor of reverse mode Na(+)/Ca(2+)-exchange (NCX). The Na(+)/H(+)-exchange (NHE) inhibitor HOE642 had no effect in HCO3(-)-buffered solutions, but blocked 50% of the SFR in HCO3(-)-free solution. Inhibition of HCO3(-) transport by DIDS increased the SFR and made it sensitive to HOE642. The addition of cross-bridge cycle inhibitors (20mM BDM or 20μM blebbistatin) to the superfusate reduced the SFR as monitored by changes in Ca(2+). In HCO3(-)-free conditions, the SFR was associated with a slow acidification that was inhibited by BDM, and by stopping electrical stimulation. These results can be explained by stretch increasing metabolic demand and stimulating Na(+) entry via both NHE and the Na(+)/HCO3(-) transporters. This mechanism provides a novel link between inotropic state and stretch, as well as a way for the cell to compensate for increased acid load. The feedback mechanism between force and Ca(2+) transient amplitude that we describe is also limited by the degree of SR Ca(2+) load.
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Affiliation(s)
- Xin Shen
- Department of Physiology, University of Auckland, Auckland 1023, New Zealand
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31
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Vargas LA, Díaz RG, Swenson ER, Pérez NG, Álvarez BV. Inhibition of carbonic anhydrase prevents the Na(+)/H(+) exchanger 1-dependent slow force response to rat myocardial stretch. Am J Physiol Heart Circ Physiol 2013; 305:H228-37. [PMID: 23709596 DOI: 10.1152/ajpheart.00055.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Myocardial stretch is an established signal that leads to hypertrophy. Myocardial stretch induces a first immediate force increase followed by a slow force response (SFR), which is a consequence of an increased Ca(2+) transient that follows the NHE1 Na(+)/H(+) exchanger activation. Carbonic anhydrase II (CAII) binds to the extreme COOH terminus of NHE1 and regulates its transport activity. We aimed to test the role of CAII bound to NHE1 in the SFR. The SFR and changes in intracellular pH (pHi) were evaluated in rat papillary muscle bathed with CO2/HCO3(-) buffer and stretched from 92% to 98% of the muscle maximal force development length for 10 min in the presence of the CA inhibitor 6-ethoxzolamide (ETZ, 100 μM). SFR control was 120 ± 3% (n = 8) of the rapid initial phase and was fully blocked by ETZ (99 ± 4%, n = 6). The SFR corresponded to a maximal increase in pHi of 0.18 ± 0.02 pH units (n = 4), and pHi changes were blocked by ETZ (0.04 ± 0.04, n = 6), as monitored by epifluorescence. NHE1/CAII physical association was examined in the SFR by coimmunoprecipitation, using muscle lysates. CAII immunoprecipitated with an anti-NHE1 antibody and the CAII immunoprecipitated protein levels increased 58 ± 9% (n = 6) upon stretch of muscles, assessed by immunoblots. The p90(RSK) kinase inhibitor SL0101-1 (10 μM) blocked the SFR of heart muscles after stretch 102 ± 2% (n = 4) and reduced the binding of CAII to NHE1, suggesting that the stretch-induced phosphorylation of NHE1 increases its binding to CAII. CAII/NHE1 interaction constitutes a component of the SFR to heart muscle stretch, which potentiates NHE1-mediated H(+) transport in the myocardium.
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Affiliation(s)
- Lorena A Vargas
- Centro de Investigaciones Cardiovasculares, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
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Prosser BL, Khairallah RJ, Ziman AP, Ward CW, Lederer WJ. X-ROS signaling in the heart and skeletal muscle: stretch-dependent local ROS regulates [Ca²⁺]i. J Mol Cell Cardiol 2012; 58:172-81. [PMID: 23220288 DOI: 10.1016/j.yjmcc.2012.11.011] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 10/23/2012] [Accepted: 11/22/2012] [Indexed: 02/02/2023]
Abstract
X-ROS signaling is a novel redox signaling pathway that links mechanical stress to changes in [Ca(2+)]i. This pathway is activated rapidly and locally within a muscle cell under physiological conditions, but can also contribute to Ca(2+)-dependent arrhythmia in the heart and to the dystrophic phenotype in the heart and skeletal muscle. Upon physiologic cellular stretch, microtubules serve as mechanotransducers to activate NADPH oxidase 2 in the transverse tubules and sarcolemmal membranes to produce reactive oxygen species (ROS). In the heart, the ROS acts locally to activate ryanodine receptor Ca(2+) release channels in the junctional sarcoplasmic reticulum, increasing the Ca(2+) spark rate and "tuning" excitation-contraction coupling. In the skeletal muscle, where Ca(2+) sparks are not normally observed, the X-ROS signaling process is muted. However in muscular dystrophies, such as Duchenne Muscular Dystrophy and dysferlinopathy, X-ROS signaling operates at a high level and contributes to myopathy. Importantly, Ca(2+) permeable stretch-activated channels are activated by X-ROS and contribute to skeletal muscle pathology. Here we review X-ROS signaling and mechanotransduction in striated muscle, and highlight important questions to drive future work on stretch-dependent signaling. We conclude that X-ROS provides an exciting mechanism for the mechanical control of redox and Ca(2+) signaling, but much work is needed to establish its contribution to physiologic and pathophysiologic processes in diverse cell systems.
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Affiliation(s)
- Benjamin L Prosser
- Department of Physiology, Center for Biomedical Engineering and Technology (BioMET), University of Maryland School of Medicine, Baltimore, MD, USA
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Abstract
Myocardial stretch elicits a rapid increase in developed force, which is mainly caused by an increase in myofilament calcium sensitivity (Frank-Starling mechanism). Over the ensuing 10-15 min, a second gradual increase in force takes place. This slow force response to stretch is known to be the result of an increase in the calcium transient amplitude and constitutes the in vitro equivalent of the Anrep effect described 100 years ago in the intact heart. In the present review, we will update and discuss what is known about the Anrep effect as the mechanical counterpart of autocrine/paracrine mechanisms involved in its genesis. The chain of events triggered by myocardial stretch comprises 1) release of angiotensin II, 2) release of endothelin, 3) activation of the mineralocorticoid receptor, 4) transactivation of the epidermal growth factor receptor, 5) increased formation of mitochondria reactive oxygen species, 6) activation of redox-sensitive kinases upstream myocardial Na(+)/H(+) exchanger (NHE1), 7) NHE1 activation, 8) increase in intracellular Na(+) concentration, and 9) increase in Ca(2+) transient amplitude through the Na(+)/Ca(2+) exchanger. We will present the experimental evidence supporting each of the signaling steps leading to the Anrep effect and its blunting by silencing NHE1 expression with a specific small hairpin interference RNA injected into the ventricular wall.
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Affiliation(s)
- Horacio E Cingolani
- Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, La Plata, Argentina.
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Markhasin VS, Balakin AA, Katsnelson LB, Konovalov P, Lookin ON, Protsenko Y, Solovyova O. Slow force response and auto-regulation of contractility in heterogeneous myocardium. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:305-18. [DOI: 10.1016/j.pbiomolbio.2012.08.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/09/2012] [Indexed: 11/25/2022]
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The zebrafish as a novel animal model to study the molecular mechanisms of mechano-electrical feedback in the heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:154-65. [PMID: 22835662 DOI: 10.1016/j.pbiomolbio.2012.07.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 02/07/2023]
Abstract
Altered mechanical loading of the heart leads to hypertrophy, decompensated heart failure and fatal arrhythmias. However, the molecular mechanisms that link mechanical and electrical dysfunction remain poorly understood. Growing evidence suggest that ventricular electrical remodeling (VER) is a process that can be induced by altered mechanical stress, creating persistent electrophysiological changes that predispose the heart to life-threatening arrhythmias. While VER is clearly a physiological property of the human heart, as evidenced by "T wave memory", it is also thought to occur in a variety of pathological states associated with altered ventricular activation such as bundle branch block, myocardial infarction, and cardiac pacing. Animal models that are currently being used for investigating stretch-induced VER have significant limitations. The zebrafish has recently emerged as an attractive animal model for studying cardiovascular disease and could overcome some of these limitations. Owing to its extensively sequenced genome, high conservation of gene function, and the comprehensive genetic resources that are available in this model, the zebrafish may provide new insights into the molecular mechanisms that drive detrimental electrical remodeling in response to stretch. Here, we have established a zebrafish model to study mechano-electrical feedback in the heart, which combines efficient genetic manipulation with high-precision stretch and high-resolution electrophysiology. In this model, only 90 min of ventricular stretch caused VER and recapitulated key features of VER found previously in the mammalian heart. Our data suggest that the zebrafish model is a powerful platform for investigating the molecular mechanisms underlying mechano-electrical feedback and VER in the heart.
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Wignall F, Shiels HA. Contractile properties of the axolotl ventricle at 17 and 21°C. J Therm Biol 2012. [DOI: 10.1016/j.jtherbio.2012.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Iribe G, Jin H, Naruse K. Role of sarcolemmal BK(Ca) channels in stretch-induced extrasystoles in isolated chick hearts. Circ J 2011; 75:2552-8. [PMID: 21914957 DOI: 10.1253/circj.cj-11-0486] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND It remains unclear whether sarcolemmal BK(Ca) channels in post-hatch chick ventricular myocytes contribute to stretch-induced extrasystoles (SIE), and whether they are stretch-activated BK(Ca) (SAK(Ca)) channels or a non-stretch-sensitive BK(Ca) variant. METHODS AND RESULTS To determine the role of sarcolemmal BK(Ca) channels in SIE and their stretch sensitivity, an isolated 2-week-old Langendorff-perfused chick heart and mathematical simulation were used. The ventricular wall was rapidly stretched by application of a volume change pulse. As the speed of the stretch increased, the probability of SIE also significantly increased, significantly shortening the delay between SIE and the initiation of the stretch. Application of 100 nmol/L of Grammostola spatulata mechanotoxin 4, a cation-selective stretch-activated channel (SAC) blocker, significantly decreased the probability of SIE. The application of Iberiotoxin, however, a BK(Ca) channel blocker, significantly increased the probability of SIE, suggesting that a K(+) efflux via a sarcolemmal BK(Ca) channel reduces SIE by balancing out stretch-induced cation influx via SACs. The simulation using a cardiomyocyte model combined with a new stretch sensitivity model that considers viscoelastic intracellular force transmission showed that stretch sensitivity in BK(Ca) channels is required to reproduce the present wet experimental results. CONCLUSIONS Sarcolemmal BK(Ca) channels in post-hatch chick ventricular myocytes are SAK(Ca) channels, and they have a suppressive effect on SIE.
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Affiliation(s)
- Gentaro Iribe
- Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
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Pérez NG, Nolly MB, Roldan MC, Villa-Abrille MC, Cingolani E, Portiansky EL, Álvarez BV, Ennis IL, Cingolani HE. Silencing of NHE-1 blunts the slow force response to myocardial stretch. J Appl Physiol (1985) 2011; 111:874-80. [DOI: 10.1152/japplphysiol.01344.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Myocardial stretch induces a biphasic force response: a first abrupt increase followed by a slow force response (SFR), believed to be the in vitro manifestation of the Anrep effect. The SFR is due to an increase in Ca2+ transient of unclear mechanism. We proposed that Na+/H+ exchanger (NHE-1) activation is a key factor in determining the contractile response, but recent reports challenged our findings. We aimed to specifically test the role of the NHE-1 in the SFR. To this purpose small hairpin interference RNA capable of mediating specific NHE-1 knockdown was incorporated into a lentiviral vector (l-shNHE1) and injected into the left ventricular wall of Wistar rats. Injection of a lentiviral vector expressing a nonsilencing sequence (scramble) served as control. Myocardial NHE-1 protein expression and function (the latter evaluated by the recovery of pHi after an acidic load and the SFR) were evaluated. Animals transduced with l-shNHE1 showed reduced NHE-1 expression (45 ± 8% of controls; P < 0.05), and the presence of the lentivirus in the left ventricular myocardium, far from the site of injection, was evidenced by confocal microscopy. These findings correlated with depressed basal pHi recovery after acidosis [maxdpHi/d t 0.055 ± 0.008 (scramble) vs. 0.009 ± 0.004 (l-shNHE1) pH units/min, P < 0.05], leftward shift of the relationship between JH+ (H+ efflux corrected by the intrinsic buffer capacity), and abolishment of SFR (124 ± 2 vs. 101 ± 2% of rapid phase; P < 0.05) despite preserved ERK1/2 phosphorylation [247 ± 12 (stretch) and 263 ± 23 (stretch l-shNHE1) % of control; P < 0.05 vs. nonstretched control], well-known NHE-1 activators. Our results provide strong evidence to propose NHE-1 activation as key factor in determining the SFR to stretch.
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Affiliation(s)
- Néstor G. Pérez
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Mariela B. Nolly
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Mirian C. Roldan
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - María C. Villa-Abrille
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Eugenio Cingolani
- Cedars Sinai Heart Institute, Cedars Sinai Medical Center, Los Angeles, California; and
| | - Enrique L. Portiansky
- Instituto de Patología. Facultad de Cs. Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina
| | - Bernardo V. Álvarez
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Irene L. Ennis
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Horacio E. Cingolani
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
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Patrick SM, White E, Shiels HA. Rainbow trout myocardium does not exhibit a slow inotropic response to stretch. J Exp Biol 2011; 214:1118-22. [DOI: 10.1242/jeb.048546] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
SUMMARY
Mammalian myocardial studies reveal a biphasic increase in the force of contraction due to stretch. The first rapid response, known as the Frank-Starling response, occurs within one heartbeat of stretch. A second positive inotropic response occurs over the minutes following the initial stretch and is known as the slow force response (SFR). The SFR has been observed in mammalian isolated whole hearts, muscle preparations and individual myocytes. We present the first direct study into the SFR in the heart of a non-mammalian vertebrate, the rainbow trout (Oncorhynchus mykiss). We stretched ventricular trabecular muscle preparations from 88% to 98% of their optimal length and individual ventricular myocytes by 7% of their slack sarcomere length (SL). Stretch caused an immediate increase in force in both preparations, indicative of the Frank-Starling response. However, we found no significant effect of prolonged stretch on the force of contraction in either the ventricular trabecular preparations or the single myocytes. This indicates that rainbow trout ventricular myocardium does not exhibit a SFR and that, in contrast to mammals, the piscine Frank-Starling response may not be associated with the SFR. We speculate that this is due to the fish myocardium modulating cardiac output via changes in stroke volume to a larger extent than heart rate.
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Affiliation(s)
- Simon M. Patrick
- Faculty of Life Sciences, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
| | - Ed White
- Institute of Membrane and Systems Biology, and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK
| | - Holly A. Shiels
- Faculty of Life Sciences, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
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Pong T, Adams WJ, Bray MA, Feinberg AW, Sheehy SP, Werdich AA, Parker KK. Hierarchical architecture influences calcium dynamics in engineered cardiac muscle. Exp Biol Med (Maywood) 2011; 236:366-73. [PMID: 21330361 DOI: 10.1258/ebm.2010.010239] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Changes in myocyte cell shape and tissue structure are concurrent with changes in electromechanical function in both the developing and diseased heart. While the anisotropic architecture of cardiac tissue is known to influence the propagation of the action potential, the influence of tissue architecture and its potential role in regulating excitation-contraction coupling (ECC) are less well defined. We hypothesized that changes in the shape and the orientation of cardiac myocytes induced by spatial arrangement of the extracellular matrix (ECM) affects ECC. To test this hypothesis, we isolated and cultured neonatal rat ventricular cardiac myocytes on various micropatterns of fibronectin where they self-organized into tissues with varying degrees of anisotropy. We then measured the morphological features of these engineered myocardial tissues across several hierarchical dimensions by measuring cellular aspect ratio, myocyte area, nuclear density and the degree of cytoskeletal F-actin alignment. We found that when compared with isotropic tissues, anisotropic tissues have increased cellular aspect ratios, increased nuclear densities, decreased myocyte cell areas and smaller variances in actin alignment. To understand how tissue architecture influences cardiac function, we studied the role of anisotropy on intracellular calcium ([Ca(2+)](i)) dynamics by characterizing the [Ca(2+)](i)-frequency relationship of electrically paced tissues. When compared with isotropic tissues, anisotropic tissues displayed significant differences in [Ca(2+)](i) transients, decreased diastolic baseline [Ca(2+)](i) levels and greater [Ca(2+)](i) influx per cardiac cycle. These results suggest that ECM cues influence tissue structure at cellular and subcellular levels and regulate ECC.
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Affiliation(s)
- Terrence Pong
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Cingolani HE, Ennis IL, Aiello EA, Pérez NG. Role of autocrine/paracrine mechanisms in response to myocardial strain. Pflugers Arch 2011; 462:29-38. [DOI: 10.1007/s00424-011-0930-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/19/2011] [Accepted: 01/19/2011] [Indexed: 10/18/2022]
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42
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Miura M, Nishio T, Hattori T, Murai N, Stuyvers BD, Shindoh C, Boyden PA. Effect of nonuniform muscle contraction on sustainability and frequency of triggered arrhythmias in rat cardiac muscle. Circulation 2010; 121:2711-7. [PMID: 20547931 DOI: 10.1161/circulationaha.109.907717] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Arrhythmias are benign or lethal, depending on their sustainability and frequency. To determine why lethal arrhythmias are prone to occur in diseased hearts, usually characterized by nonuniform muscle contraction, we investigated the effect of nonuniformity on sustainability and frequency of triggered arrhythmias. METHODS AND RESULTS Force, membrane potential, and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured in 51 rat ventricular trabeculae. Nonuniform contraction was produced by exposing a restricted region of muscle to a jet of 20 mmol/L 2,3-butanedione monoxime (BDM) or 20 mumol/L blebbistatin. Sustained arrhythmias (>10 seconds) could be induced by stimulus trains for 7.5 seconds only with the BDM or blebbistatin jet (100 nmol/L isoproterenol, 1.0 mmol/L [Ca(2+)](o), 24 degrees C). During sustained arrhythmias, Ca(2+) surges preceded synchronous increases in [Ca(2+)](i), whereas the stoppage of the BDM jet made the Ca(2+) surges unclear and arrested sustained arrhythmias (n=6). With 200 nmol/L isoproterenol, 2.5 mmol/L [Ca(2+)](o), and the BDM jet, lengthening or shortening of the muscle during sustained arrhythmias accelerated or decelerated their cycle in both the absence (n=10) and presence (n=10) of 100 mumol/L streptomycin, a stretch-activated channel blocker, respectively. The maximum rate of force relaxation correlated inversely with the change in cycle lengths (n=14; P<0.01). Sustained arrhythmias with the BDM jet were significantly accelerated by 30 mumol/L SCH00013, a Ca(2+) sensitizer of myofilaments (n=10). CONCLUSIONS These results suggest that nonuniformity of muscle contraction is an important determinant of the sustainability and frequency of triggered arrhythmias caused by the surge of Ca(2+) dissociated from myofilaments in cardiac muscle.
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Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Iribe G, Jin H, Kaihara K, Naruse K. Effects of axial stretch on sarcolemmal BKCachannels in post-hatch chick ventricular myocytes. Exp Physiol 2010; 95:699-711. [DOI: 10.1113/expphysiol.2009.051896] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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von Lewinski D, Kockskämper J, Zhu D, Post H, Elgner A, Pieske B. Reduced stretch-induced force response in failing human myocardium caused by impaired Na(+)-contraction coupling. Circ Heart Fail 2009; 2:47-55. [PMID: 19808315 DOI: 10.1161/circheartfailure.108.794065] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Stretch elicits an immediate, followed by a delayed, inotropic response in various animal models and failing human myocardium. This study aimed to characterize functional differences in the stretch response between failing and nonfailing human myocardium. METHODS AND RESULTS Experiments were performed in muscle tissue from 86 failing and 16 nonfailing human hearts. Muscles were stretched from 88% to 98% of optimal length. Resulting immediate (Frank-Starling mechanism [FSM]) and delayed (slow-force response [SFR]) increases in twitch force were assessed before and after blockade of nitric oxide synthase, phosphatidylinositol-3-kinase, or reverse-mode Na(+)/Ca(2+) exchange. Stretch-induced changes in [Na(+)](i) were measured using fluorescent indicator sodium-binding benzofuran isophthalate-AM. Nitric oxide synthase isoform expression was quantified by Western blot analysis. FSM was comparable between nonfailing (227+/-8%) and failing (222+/-9%) myocardium, whereas the additional increase during SFR (approximately 5 minutes) was larger in nonfailing myocardium (to 126+/-3% versus 119+/-2% of force of FSM, respectively; P<0.05). Basal [Na(+)](i) and stretch-induced increase in [Na(+)](i) were lower in nonfailing myocardium. Inhibition of the Na(+)/H(+) exchange largely reduced the increase in [Na(+)](i) and significantly blocked the SFR. In both groups, SFR was almost completely prevented by reverse-mode Na(+)/Ca(+)-exchanger inhibition. Although neuronal and inducible nitric oxide synthase expression were significantly upregulated in failing myocardium, inhibition of nitric oxide synthase and phosphatidylinositol-3-kinase had no effect on FSM or SFR. CONCLUSIONS These data demonstrate a Na(+)-independent FSM and a Na(+)-dependent SFR in both nonfailing and failing human myocardium. The larger stretch-dependent increase in [Na(+)](i) in failing myocardium was associated with a blunted functional response, indicating impaired Na(+)-contraction coupling in the failing human heart.
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45
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Differential expression of TRPC channels in the left ventricle of spontaneously hypertensive rats. Mol Biol Rep 2009; 37:2645-51. [PMID: 19757180 DOI: 10.1007/s11033-009-9792-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2008] [Accepted: 09/02/2009] [Indexed: 10/20/2022]
Abstract
This study was designed to identify the differential expression of the canonical transient receptor potential (TRPC) channels in the left ventricle of spontaneously hypertensive rats (SHR). Echocardiography studies were performed to compare the left ventricular function in SHR vs. Wistar-Kyoto rats (WKY), and the mRNA level of the TRPC channels was determined by quantitative real-time RT-PCR (qRT-PCR). Western blots were performed to examine whether the mRNA expression corresponded with the protein expression. Compared with the WKY, the mRNA expression of TRPC4 and TRPC5 was significantly increased in the 10-week-old SHR (P = 0.032 for TRPC4 and P = 0.043 for TRPC5), so did the TRPC4/5 protein content. The midwall fractional shortening (mFS) of SHR was lower than WKY (P = 0.016). Furthermore, increased expression of TRPC4/5 was correlated with both increased blood pressure and decreased mFS. These findings suggest that TRPC4 and 5 seem to be the main subtypes expressed in the heart of the SHR at the beginning period of hypertension. Theses channels may participate in the development of left ventricular systolic dysfunction.
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Zhang YH, Dingle L, Hall R, Casadei B. The role of nitric oxide and reactive oxygen species in the positive inotropic response to mechanical stretch in the mammalian myocardium. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:811-7. [PMID: 19361482 PMCID: PMC2791851 DOI: 10.1016/j.bbabio.2009.03.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 03/28/2009] [Accepted: 03/31/2009] [Indexed: 11/13/2022]
Abstract
The endothelial nitric oxide synthase (eNOS) has been implicated in the rapid (Frank–Starling) and slow (Anrep) cardiac response to stretch. Our work and that of others have demonstrated that a neuronal nitric oxide synthase (nNOS) localized to the myocardium plays an important role in the regulation of cardiac function and calcium handling. However, the effect of nNOS on the myocardial response to stretch has yet to be investigated. Recent evidence suggests that the stretch-induced release of angiotensin II (Ang II) and endothelin 1 (ET-1) stimulates myocardial superoxide production from NADPH oxidases which, in turn, contributes to the Anrep effect. nNOS has also been shown to regulate the production of myocardial superoxide, suggesting that this isoform may influence the cardiac response to stretch or ET-1 by altering the NO-redox balance in the myocardium. Here we show that the increase in left ventricular (LV) myocyte shortening in response to the application of ET-1 (10 nM, 5 min) did not differ between nNOS−/− mice and their wild type littermates (nNOS+/+). Pre-incubating LV myocytes with the NADPH oxidase inhibitor, apocynin (100 μM, 30 min), reduced cell shortening in nNOS−/− myocytes only but prevented the positive inotropic effects of ET-1 in both groups. Superoxide production (O2−) was enhanced in nNOS−/− myocytes compared to nNOS+/+; however, this difference was abolished by pre-incubation with apocynin. There was no detectable increase in O2− production in ET-1 pre-treated LV myocytes. Inhibition of protein kinase C (chelerythrine, 1 μM) did not affect cell shortening in either group, however, protein kinase A inhibitor, PKI (2 μM), significantly reduced the positive inotropic effects of ET-1 in both nNOS+/+ and nNOS−/− myocytes. Taken together, our findings show that the positive inotropic effect of ET-1 in murine LV myocytes is independent of nNOS but requires NADPH oxidases and protein kinase A (PKA)-dependent signaling. These results may further our understanding of the signaling pathways involved in the myocardial inotropic response to stretch.
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Affiliation(s)
- Yin Hua Zhang
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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Iribe G, Ward CW, Camelliti P, Bollensdorff C, Mason F, Burton RAB, Garny A, Morphew MK, Hoenger A, Lederer WJ, Kohl P. Axial stretch of rat single ventricular cardiomyocytes causes an acute and transient increase in Ca2+ spark rate. Circ Res 2009; 104:787-95. [PMID: 19197074 PMCID: PMC3522525 DOI: 10.1161/circresaha.108.193334] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigate acute effects of axial stretch, applied by carbon fibers (CFs), on diastolic Ca2+ spark rate in rat isolated cardiomyocytes. CFs were attached either to both cell ends (to maximize the stretched region), or to the center and one end of the cell (to compare responses in stretched and nonstretched half-cells). Sarcomere length was increased by 8.01+/-0.94% in the stretched cell fraction, and time series of XY confocal images were recorded to monitor diastolic Ca2+ spark frequency and dynamics. Whole-cell stretch causes an acute increase of Ca2+ spark rate (to 130.7+/-6.4%) within 5 seconds, followed by a return to near background levels (to 104.4+/-5.1%) within 1 minute of sustained distension. Spark rate increased only in the stretched cell region, without significant differences in spark amplitude, time to peak, and decay time constants of sparks in stretched and nonstretched areas. Block of stretch-activated ion channels (2 micromol/L GsMTx-4), perfusion with Na+/Ca2+-free solution, and block of nitric oxide synthesis (1 mmol/L L-NAME) all had no effect on the stretch-induced acute increase in Ca2+ spark rate. Conversely, interference with cytoskeletal integrity (2 hours of 10 micromol/L colchicine) abolished the response. Subsequent electron microscopic tomography confirmed the close approximation of microtubules with the T-tubular-sarcoplasmic reticulum complex (to within approximately 10(-8)m). In conclusion, axial stretch of rat cardiomyocytes acutely and transiently increases sarcoplasmic reticulum Ca2+ spark rate via a mechanism that is independent of sarcolemmal stretch-activated ion channels, nitric oxide synthesis, or availability of extracellular calcium but that requires cytoskeletal integrity. The potential of microtubule-mediated modulation of ryanodine receptor function warrants further investigation.
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Affiliation(s)
- Gentaro Iribe
- University of Oxford, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, United Kingdom
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Affiliation(s)
- Mark B. Cannell
- From the Department of Physiology, School of Medicine and Health Sciences, University of Auckland, New Zealand
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Consolini AE, Bonazzola P. Energetics of Ca2+ homeostasis during ischemia–reperfusion on neonatal rat hearts under high-[K+] cardioplegia. Can J Physiol Pharmacol 2008; 86:866-79. [DOI: 10.1139/y08-095] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanocalorimetric consequences and mechanisms involved in Ca2+ homeostasis during ischemia–reperfusion (I/R) as well as the protective role of cardioplegic pretreatment with high [K+] (25 mmol/L) and low or near-normal [Ca2+] (0.5 or 2 mmol/L) were evaluated in a model of neonatal rat heart. Beating hearts from 10–12-day-old rats were perfused with Krebs solution (2 mmol/L Ca2+) under both isotonic and isometric conditions. During pretreatment, hearts were exposed for 20 min to either Krebs (control) or cardioplegia (CPG) before 15 min ischemia and 45 min reperfusion while being continuously measured for either contractility or total heat rate (Ht) in a flow calorimeter. Contractile recovery after reperfusion in hearts exposed to ischemia only (control) was higher in the isometric hearts under optimal length (87.9% ± 8.1%) than in the isotonic hearts (57.3% ± 10.6%). This same behavior was found in hearts pretreated with CPG-0.5 mmol/L Ca2+. Ht in controls was reduced from 11.5 ± 0.8 mW/g in the initial beating condition to 1.11 ± 0.33 mW/g during ischemia and was increased to 13.02 ± 0.93 mW/g (113.8% ± 5.0% of preischemic) after reperfusion. Hearts pretreated with CPG-0.5 mmol/L Ca2+ showed the same behavior. However, when extracellular calcium ([Ca]o) was increased to 2 mmol/L under CPG, isotonic hearts, but not isometric hearts, significantly increased the contractile recovery to a maximum of 88.7% ± 10.8% of preischemic levels. Ht was recovered to 92.1% ± 4.3% of preischemic, suggesting that contractile recovery was less energetically expensive after CPG-2 mmol/L Ca2+ than it was in postischemic hearts exposed to control or CPG-0.5 mmol/L Ca2+. The role of the sarcoplasmic reticulum store was evaluated by pretreating hearts with 10 mmol/L caffeine, which reduced contractile recovery only under isometric conditions or after increasing [Ca]o in CPG under isotonic conditions, suggesting that the contribution of the sarcoplasmic reticulum was dependent on the fibre length or the [Ca]o. The inhibition of the reverse mode of the sarcolemmal Na/Ca exchanger (NCX) and the mitochondrial Ca uniporter (CaU) by KB-R7943 (KBR) at 5 µmol/L in CPG-0.5 mmol/L Ca2+ improved contractile recovery of isotonic hearts, whereas it decreased Ht at the start of reperfusion, suggesting that mitochondria could uptake Ca2+ vía the mitochondrial CaU. Neither the positive inotropism nor Ht were changed by inhibiting the mitochondrial NCX with 10 µmol/L clonazepam in CPG-0.5 mmol/L Ca2+ + 5 µmol/L KBR, which suggests that the mitochondrial NCX does not have a role. Finally, the role of the forward mode of the sarcolemmal NCX was evidenced by the fall in contractile recovery with increased Ht when KBR was increased to 20 µmol/L and added to CPG-2 mmol/L Ca2+ + 10 mmol/L caffeine before I/R. Thus the sarcolemmal NCX was essential for removing the diastolic Ca2+ during the periods of CPG and I/R. In summary, Ca2+ homeostasis during I/R of neonatal rat hearts is different from that of adult rats. High-[K+] CPG protected neonatal hearts only under isotonic conditions, at a near-normal [Ca]o, or by exposure to KBR. Mitochondria were able to uptake Ca2+ via the mitochondrial CaU and reduce the Ca2+ available for contractile recovery. Nevertheless, after increasing [Ca]o in CPG, the sarcoplasmic reticulum had a main role in restoring contractility during reperfusion, as it does in adults. Thus, the degree of maturation of the heart must be taken into account to evaluate the effects of CPG and drugs on I/R.
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Affiliation(s)
- Alicia E. Consolini
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115 (1900) La Plata, Argentina
- Cátedra de Biofísica, Facultad de Odontología e Instituto de Investigaciones Cardiológicas (CONICET, Facultad de Medicina), Universidad de Buenos Aires, (1122) Buenos Aires, Argentina
| | - Patricia Bonazzola
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 47 y 115 (1900) La Plata, Argentina
- Cátedra de Biofísica, Facultad de Odontología e Instituto de Investigaciones Cardiológicas (CONICET, Facultad de Medicina), Universidad de Buenos Aires, (1122) Buenos Aires, Argentina
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Abstract
SUMMARY
The Frank–Starling law of the heart applies to all classes of vertebrates. It describes how stretch of cardiac muscle, up to an optimum length, increases contractility thereby linking cardiac ejection to cardiac filling. The cellular mechanisms underlying the Frank–Starling response include an increase in myofilament sensitivity for Ca2+, decreased myofilament lattice spacing and increased thin filament cooperativity. Stretching of mammalian, amphibian and fish cardiac myocytes reveal that the functional peak of the sarcomere length (SL)–tension relationship occurs at longer SL in the non-mammalian classes. These findings correlate with in vivo cardiac function as non-mammalian vertebrates, such as fish,vary stroke volume to a relatively larger extent than mammals. Thus, it seems the length-dependent properties of individual myocytes are modified to accommodate differences in organ function, and the high extensibility of certain hearts is matched by the extensibility of their myocytes. Reasons for the differences between classes are still to be elucidated, however, the structure of mammalian ventricular myocytes, with larger widths and higher levels of passive stiffness than those from other vertebrate classes may be implicated.
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Affiliation(s)
- Holly A. Shiels
- Faculty of Life Sciences, Core Technology Facility, 46 Grafton Street,University of Manchester, Manchester M13 9NT, UK
| | - Ed White
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT,UK
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