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Sun Z, Lu K, Kamla C, Kameritsch P, Seidel T, Dendorfer A. Synchronous force and Ca 2+ measurements for repeated characterization of excitation-contraction coupling in human myocardium. Commun Biol 2024; 7:220. [PMID: 38388802 PMCID: PMC10884022 DOI: 10.1038/s42003-024-05886-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 02/02/2024] [Indexed: 02/24/2024] Open
Abstract
Dysfunctional Ca2+ signaling affects the myocardial systole and diastole, may trigger arrhythmia and cause transcriptomic and proteomic modifications in heart failure. Thus, synchronous real-time measurement of Ca2+ and force is essential to investigate the relationship between contractility and Ca2+ signaling and the alteration of excitation-contraction coupling (ECC) in human failing myocardium. Here, we present a method for synchronized acquisition of intracellular Ca2+ and contraction force in long-term cultivated slices of human failing myocardium. Synchronous time series of contraction force and intracellular Ca2+ were used to calculate force-calcium loops and to analyze the dynamic alterations of ECC in response to various pacing frequencies, post-pause potentiation, high mechanical preload and pharmacological interventions in human failing myocardium. We provide an approach to simultaneously and repeatedly investigate alterations of contractility and Ca2+ signals in long-term cultured myocardium, which will allow detecting the effects of electrophysiological or pharmacological interventions on human myocardial ECC.
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Affiliation(s)
- Zhengwu Sun
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kun Lu
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany
| | - Christine Kamla
- Department of Cardiac Surgery, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Petra Kameritsch
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Thomas Seidel
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Dendorfer
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
- DZHK (German Center for Cardiovascular Research), Partner site Munich Heart Alliance, Munich, Germany.
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Bibollet H, Kramer A, Bannister RA, Hernández-Ochoa EO. Advances in Ca V1.1 gating: New insights into permeation and voltage-sensing mechanisms. Channels (Austin) 2023; 17:2167569. [PMID: 36642864 PMCID: PMC9851209 DOI: 10.1080/19336950.2023.2167569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/09/2023] [Indexed: 01/17/2023] Open
Abstract
The CaV1.1 voltage-gated Ca2+ channel carries L-type Ca2+ current and is the voltage-sensor for excitation-contraction (EC) coupling in skeletal muscle. Significant breakthroughs in the EC coupling field have often been close on the heels of technological advancement. In particular, CaV1.1 was the first voltage-gated Ca2+ channel to be cloned, the first ion channel to have its gating current measured and the first ion channel to have an effectively null animal model. Though these innovations have provided invaluable information regarding how CaV1.1 detects changes in membrane potential and transmits intra- and inter-molecular signals which cause opening of the channel pore and support Ca2+ release from the sarcoplasmic reticulum remain elusive. Here, we review current perspectives on this topic including the recent application of functional site-directed fluorometry.
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Affiliation(s)
- Hugo Bibollet
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Audra Kramer
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Roger A. Bannister
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA
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3
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Campiglio M, Dyrda A, Tuinte WE, Török E. Ca V1.1 Calcium Channel Signaling Complexes in Excitation-Contraction Coupling: Insights from Channelopathies. Handb Exp Pharmacol 2023; 279:3-39. [PMID: 36592225 DOI: 10.1007/164_2022_627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In skeletal muscle, excitation-contraction (EC) coupling relies on the mechanical coupling between two ion channels: the L-type voltage-gated calcium channel (CaV1.1), located in the sarcolemma and functioning as the voltage sensor of EC coupling, and the ryanodine receptor 1 (RyR1), located on the sarcoplasmic reticulum serving as the calcium release channel. To this day, the molecular mechanism by which these two ion channels are linked remains elusive. However, recently, skeletal muscle EC coupling could be reconstituted in heterologous cells, revealing that only four proteins are essential for this process: CaV1.1, RyR1, and the cytosolic proteins CaVβ1a and STAC3. Due to the crucial role of these proteins in skeletal muscle EC coupling, any mutation that affects any one of these proteins can have devastating consequences, resulting in congenital myopathies and other pathologies.Here, we summarize the current knowledge concerning these four essential proteins and discuss the pathophysiology of the CaV1.1, RyR1, and STAC3-related skeletal muscle diseases with an emphasis on the molecular mechanisms. Being part of the same signalosome, mutations in different proteins often result in congenital myopathies with similar symptoms or even in the same disease.
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Affiliation(s)
- Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria.
| | - Agnieszka Dyrda
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Wietske E Tuinte
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Enikő Török
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
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Tuinte WE, Török E, Mahlknecht I, Tuluc P, Flucher BE, Campiglio M. STAC3 determines the slow activation kinetics of Ca V 1.1 currents and inhibits its voltage-dependent inactivation. J Cell Physiol 2022; 237:4197-4214. [PMID: 36161458 DOI: 10.1002/jcp.30870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 08/23/2022] [Indexed: 11/06/2022]
Abstract
The skeletal muscle CaV 1.1 channel functions as the voltage-sensor of excitation-contraction (EC) coupling. Recently, the adaptor protein STAC3 was found to be essential for both CaV 1.1 functional expression and EC coupling. Interestingly, STAC proteins were also reported to inhibit calcium-dependent inactivation (CDI) of L-type calcium channels (LTCC), an important negative feedback mechanism in calcium signaling. The same could not be demonstrated for CaV 1.1, as STAC3 is required for its functional expression. However, upon strong membrane depolarization, CaV 1.1 conducts calcium currents characterized by very slow kinetics of activation and inactivation. Therefore, we hypothesized that the negligible inactivation observed in CaV 1.1 currents reflects the inhibitory effect of STAC3. Here, we inserted a triple mutation in the linker region of STAC3 (ETLAAA), as the analogous mutation abolished the inhibitory effect of STAC2 on CDI of CaV 1.3 currents. When coexpressed in CaV 1.1/STAC3 double knockout myotubes, the mutant STAC3-ETLAAA failed to colocalize with CaV 1.1 in the sarcoplasmic reticulum/membrane junctions. However, combined patch-clamp and calcium recording experiments revealed that STAC3-ETLAAA supports CaV 1.1 functional expression and EC coupling, although at a reduced extent compared to wild-type STAC3. Importantly, STAC3-ETLAAA coexpression dramatically accelerated the kinetics of activation and inactivation of CaV 1.1 currents, suggesting that STAC3 determines the slow CaV 1.1 currents kinetics. To examine if STAC3 specifically inhibits the CDI of CaV 1.1 currents, we performed patch-clamp recordings using calcium and barium as charge carriers in HEK cells. While CaV 1.1 displayed negligible CDI with STAC3, this did not increase in the presence of STAC3-ETLAAA. On the contrary, our data demonstrate that STAC3 specifically inhibits the voltage-dependent inactivation (VDI) of CaV 1.1 currents. Altogether, these results designate STAC3 as a crucial determinant for the slow activation kinetics of CaV 1.1 currents and implicate STAC proteins as modulators of both components of inactivation of LTCC.
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Affiliation(s)
- Wietske E Tuinte
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Enikő Török
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Irene Mahlknecht
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
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Rincón OA, Milán AF, Calderón JC, Giraldo MA. Comprehensive Simulation of Ca 2+ Transients in the Continuum of Mouse Skeletal Muscle Fiber Types. Int J Mol Sci 2021; 22:12378. [PMID: 34830262 PMCID: PMC8624975 DOI: 10.3390/ijms222212378] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/01/2021] [Accepted: 10/12/2021] [Indexed: 01/19/2023] Open
Abstract
Mag-Fluo-4 has revealed differences in the kinetics of the Ca2+ transients of mammalian fiber types (I, IIA, IIX, and IIB). We simulated the changes in [Ca2+] through the sarcomere of these four fiber types, considering classical (troponin -Tn-, parvalbumin -Pv-, adenosine triphosphate -ATP-, sarcoplasmic reticulum Ca2+ pump -SERCA-, and dye) and new (mitochondria -MITO-, Na+/Ca2+ exchanger -NCX-, and store-operated calcium entry -SOCE-) Ca2+ binding sites, during single and tetanic stimulation. We found that during a single twitch, the sarcoplasmic peak [Ca2+] for fibers type IIB and IIX was around 16 µM, and for fibers type I and IIA reached 10-13 µM. The release rate in fibers type I, IIA, IIX, and IIB was 64.8, 153.6, 238.8, and 244.5 µM ms-1, respectively. Both the pattern of change and the peak concentrations of the Ca2+-bound species in the sarcoplasm (Tn, PV, ATP, and dye), the sarcolemma (NCX, SOCE), and the SR (SERCA) showed the order IIB ≥ IIX > IIA > I. The capacity of the NCX was 2.5, 1.3, 0.9, and 0.8% of the capacity of SERCA, for fibers type I, IIA, IIX, and IIB, respectively. MITO peak [Ca2+] ranged from 0.93 to 0.23 µM, in fibers type I and IIB, respectively, while intermediate values were obtained in fibers IIA and IIX. The latter numbers doubled during tetanic stimulation. In conclusion, we presented a comprehensive mathematical model of the excitation-contraction coupling that integrated most classical and novel Ca2+ handling mechanisms, overcoming the limitations of the fast- vs. slow-fibers dichotomy and the use of slow dyes.
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Affiliation(s)
- Oscar A. Rincón
- Biophysics Group, Institute of Physics, University of Antioquia, Medellín 050010, Colombia;
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín 050010, Colombia; (A.F.M.); (J.C.C.)
| | - Andrés F. Milán
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín 050010, Colombia; (A.F.M.); (J.C.C.)
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín 050010, Colombia; (A.F.M.); (J.C.C.)
| | - Marco A. Giraldo
- Biophysics Group, Institute of Physics, University of Antioquia, Medellín 050010, Colombia;
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Marchena M, Echebarria B. Influence of the tubular network on the characteristics of calcium transients in cardiac myocytes. PLoS One 2020; 15:e0231056. [PMID: 32302318 PMCID: PMC7164608 DOI: 10.1371/journal.pone.0231056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 03/14/2020] [Indexed: 01/09/2023] Open
Abstract
Transverse and axial tubules (TATS) are an essential ingredient of the excitation-contraction machinery that allow the effective coupling of L-type Calcium Channels (LCC) and ryanodine receptors (RyR2). They form a regular network in ventricular cells, while their presence in atrial myocytes is variable regionally and among animal species We have studied the effect of variations in the TAT network using a bidomain computational model of an atrial myocyte with variable density of tubules. At each z-line the t-tubule length is obtained from an exponential distribution, with a given mean penetration length. This gives rise to a distribution of t-tubules in the cell that is characterized by the fractional area (F.A.) occupied by the t-tubules. To obtain consistent results, we average over different realizations of the same mean penetration length. To this, in some simulations we add the effect of a network of axial tubules. Then we study global properties of calcium signaling, as well as regional heterogeneities and local properties of sparks and RyR2 openings. In agreement with recent experiments in detubulated ventricular and atrial cells, we find that detubulation reduces the calcium transient and synchronization in release. However, it does not affect sarcoplasmic reticulum (SR) load, so the decrease in SR calcium release is due to regional differences in Ca2+ release, that is restricted to the cell periphery in detubulated cells. Despite the decrease in release, the release gain is larger in detubulated cells, due to recruitment of orphaned RyR2s, i.e, those that are not confronting a cluster of LCCs. This probably provides a safeguard mechanism, allowing physiological values to be maintained upon small changes in the t-tubule density. Finally, we do not find any relevant change in spark properties between tubulated and detubulated cells, suggesting that the differences found in experiments could be due to differential properties of the RyR2s in the membrane and in the t-tubules, not incorporated in the present model. This work will help understand the effect of detubulation, that has been shown to occur in disease conditions such as heart failure (HF) in ventricular cells, or atrial fibrillation (AF) in atrial cells.
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Affiliation(s)
- Miquel Marchena
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona, Spain
| | - Blas Echebarria
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona, Spain
- * E-mail:
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7
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Kane C, Terracciano CM. Human Cardiac Fibroblasts Engage the Sarcoplasmic Reticulum in Induced Pluripotent Stem Cell-Derived Cardiomyocyte Excitation-Contraction Coupling. J Am Coll Cardiol 2019; 72:1061-1063. [PMID: 30139435 DOI: 10.1016/j.jacc.2018.06.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/30/2018] [Accepted: 06/10/2018] [Indexed: 11/30/2022]
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Flucher BE, Campiglio M. STAC proteins: The missing link in skeletal muscle EC coupling and new regulators of calcium channel function. Biochim Biophys Acta Mol Cell Res 2019; 1866:1101-1110. [PMID: 30543836 DOI: 10.1016/j.bbamcr.2018.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 01/19/2023]
Abstract
Excitation-contraction coupling is the signaling process by which action potentials control calcium release and consequently the force of muscle contraction. Until recently, three triad proteins were known to be essential for skeletal muscle EC coupling: the voltage-gated calcium channel CaV1.1 acting as voltage sensor, the SR calcium release channel RyR1 representing the only relevant calcium source, and the auxiliary CaV β1a subunit. Whether CaV1.1 and RyR1 are directly coupled or whether their interaction is mediated by another triad protein is still unknown. The recent identification of the adaptor protein STAC3 as fourth essential component of skeletal muscle EC coupling prompted vigorous research to reveal its role in this signaling process. Accumulating evidence supports its possible involvement in linking CaV1.1 and RyR1 in skeletal muscle EC coupling, but also indicates a second, much broader role of STAC proteins in the regulation of calcium/calmodulin-dependent feedback regulation of L-type calcium channels.
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Affiliation(s)
- Bernhard E Flucher
- Department of Physiology and Medical Physics, Medical University Innsbruck, Schöpfstraße 41, A6020 Innsbruck, Austria.
| | - Marta Campiglio
- Department of Physiology and Medical Physics, Medical University Innsbruck, Schöpfstraße 41, A6020 Innsbruck, Austria
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Bot CT, Juhasz K, Haeusermann F, Polonchuk L, Traebert M, Stoelzle-Feix S. Cross - site comparison of excitation-contraction coupling using impedance and field potential recordings in hiPSC cardiomyocytes. J Pharmacol Toxicol Methods 2018; 93:46-58. [PMID: 29940218 PMCID: PMC6146285 DOI: 10.1016/j.vascn.2018.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Since 2005 the S7B and E14 guidances from ICH and FDA have been in place to assess a potential drug candidate's ability to cause long QT syndrome. To refine these guidelines, the FDA proposed the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative, where the assessment of drug effects on cardiac repolarization was one subject of investigation. Within the myocyte validation study, effects of pharmaceutical compounds on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were assessed and this article will focus on the evaluation of the proarrhythmic potential of 23 blinded drugs in four hiPSC-CM cell lines. METHODS Experiments were performed on the CardioExcyte 96 at different sites. A combined readout of contractility (via impedance) and electrophysiology endpoints (field potentials) was performed. RESULTS Our data demonstrates that hERG blockers such as dofetilide and further high risk categorized compounds prolong the field potential duration. Arrhythmia were detected in both impedance as well as field potential recordings. Intermediate risk compounds induced arrhythmia in almost all cases at the highest dose. In the case of low risk compounds, either a decrease in FPDmax was observed, or not a significant change from pre-addition control values. DISCUSSION With exceptions, hiPSC-CMs are sensitive and exhibit at least 10% delayed or shortened repolarization from pre-addition values and arrhythmia after drug application and thus can provide predictive cardiac electrophysiology data. The baseline electrophysiological parameters vary between iPS cells from different sources, therefore positive and negative control recordings are recommended.
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Affiliation(s)
- Corina T Bot
- Nanion Technologies, Inc., 1 Naylon Place, Livingston, NJ 07039, USA
| | - Krisztina Juhasz
- Nanion Technologies GmbH, Ganghoferstrasse 70A, 80339 Munich, Germany; Institute for Nanoelectronics, Technische Universität München, Munich, Germany
| | - Fabian Haeusermann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Bldg. 73/R. 103b, Grenzacherstr. 124, CH-4070 Basel, Switzerland
| | - Liudmila Polonchuk
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Bldg. 73/R. 103b, Grenzacherstr. 124, CH-4070 Basel, Switzerland
| | - Martin Traebert
- Safety Pharmacology, Novartis Pharma AG, CH-4002 Basel, Switzerland
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Hernández‐Ochoa EO, Melville Z, Vanegas C, Varney KM, Wilder PT, Melzer W, Weber DJ, Schneider MF. Loss of S100A1 expression leads to Ca 2+ release potentiation in mutant mice with disrupted CaM and S100A1 binding to CaMBD2 of RyR1. Physiol Rep 2018; 6:e13822. [PMID: 30101473 PMCID: PMC6087734 DOI: 10.14814/phy2.13822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/24/2022] Open
Abstract
Calmodulin (CaM) and S100A1 fine-tune skeletal muscle Ca2+ release via opposite modulation of the ryanodine receptor type 1 (RyR1). Binding to and modulation of RyR1 by CaM and S100A1 occurs predominantly at the region ranging from amino acid residue 3614-3640 of RyR1 (here referred to as CaMBD2). Using synthetic peptides, it has been shown that CaM binds to two additional regions within the RyR1, specifically residues 1975-1999 and 4295-4325 (CaMBD1 and CaMBD3, respectively). Because S100A1 typically binds to similar motifs as CaM, we hypothesized that S100A1 could also bind to CaMBD1 and CaMBD3. Our goals were: (1) to establish whether S100A1 binds to synthetic peptides containing CaMBD1 and CaMBD3 using isothermal calorimetry (ITC), and (2) to identify whether S100A1 and CaM modulate RyR1 Ca2+ release activation via sites other than CaMBD2 in RyR1 in its native cellular context. We developed the mouse model (RyR1D-S100A1KO), which expresses point mutation RyR1-L3625D (RyR1D) that disrupts the modulation of RyR1 by CaM and S100A1 at CaMBD2 and also lacks S100A1 (S100A1KO). ITC assays revealed that S100A1 binds with different affinities to CaMBD1 and CaMBD3. Using high-speed Ca2+ imaging and a model for Ca2+ binding and transport, we show that the RyR1D-S100A1KO muscle fibers exhibit a modest but significant increase in myoplasmic Ca2+ transients and enhanced Ca2+ release flux following field stimulation when compared to fibers from RyR1D mice, which were used as controls to eliminate any effect of binding at CaMBD2, but with preserved S100A1 expression. Our results suggest that S100A1, similar to CaM, binds to CaMBD1 and CaMBD3 within the RyR1, but that CaMBD2 appears to be the primary site of RyR1 regulation by CaM and S100A1.
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Affiliation(s)
- Erick O. Hernández‐Ochoa
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
| | - Zephan Melville
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
| | - Camilo Vanegas
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
| | - Kristen M. Varney
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
- Center for Biomolecular Therapeutics (CBT)University of Maryland School of MedicineMaryland
| | - Paul T. Wilder
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
- Center for Biomolecular Therapeutics (CBT)University of Maryland School of MedicineMaryland
| | - Werner Melzer
- Institute of Applied PhysiologyUlm UniversityUlmGermany
| | - David J. Weber
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
- Center for Biomolecular Therapeutics (CBT)University of Maryland School of MedicineMaryland
| | - Martin F. Schneider
- Department of Biochemistry and Molecular BiologyUniversity of Maryland School of MedicineBaltimoreMaryland
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Hernández-Ochoa EO, Schneider MF. Voltage sensing mechanism in skeletal muscle excitation-contraction coupling: coming of age or midlife crisis? Skelet Muscle 2018; 8:22. [PMID: 30025545 PMCID: PMC6053751 DOI: 10.1186/s13395-018-0167-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/26/2018] [Indexed: 11/10/2022] Open
Abstract
The process by which muscle fiber electrical depolarization is linked to activation of muscle contraction is known as excitation-contraction coupling (ECC). Our understanding of ECC has increased enormously since the early scientific descriptions of the phenomenon of electrical activation of muscle contraction by Galvani that date back to the end of the eighteenth century. Major advances in electrical and optical measurements, including muscle fiber voltage clamp to reveal membrane electrical properties, in conjunction with the development of electron microscopy to unveil structural details provided an elegant view of ECC in skeletal muscle during the last century. This surge of knowledge on structural and biophysical aspects of the skeletal muscle was followed by breakthroughs in biochemistry and molecular biology, which allowed for the isolation, purification, and DNA sequencing of the muscle fiber membrane calcium channel/transverse tubule (TT) membrane voltage sensor (Cav1.1) for ECC and of the muscle ryanodine receptor/sarcoplasmic reticulum Ca2+ release channel (RyR1), two essential players of ECC in skeletal muscle. In regard to the process of voltage sensing for controlling calcium release, numerous studies support the concept that the TT Cav1.1 channel is the voltage sensor for ECC, as well as also being a Ca2+ channel in the TT membrane. In this review, we present early and recent findings that support and define the role of Cav1.1 as a voltage sensor for ECC.
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Affiliation(s)
- Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201 USA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201 USA
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12
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Denniss A, Dulhunty AF, Beard NA. Ryanodine receptor Ca 2+ release channel post-translational modification: Central player in cardiac and skeletal muscle disease. Int J Biochem Cell Biol 2018; 101:49-53. [PMID: 29775742 DOI: 10.1016/j.biocel.2018.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/10/2018] [Accepted: 05/13/2018] [Indexed: 12/21/2022]
Abstract
Calcium release from internal stores is a quintessential event in excitation-contraction coupling in cardiac and skeletal muscle. The ryanodine receptor Ca2+ release channel is embedded in the internal sarcoplasmic reticulum Ca2+ store, which releases Ca2+ into the cytoplasm, enabling contraction. Ryanodine receptors form the hub of a macromolecular complex extending from the extracellular space to the sarcoplasmic reticulum lumen. Ryanodine receptor activity is influenced by the integrated effects of associated co-proteins, ions, and post-translational phosphor and redox modifications. In healthy muscle, ryanodine receptors are phosphorylated and redox modified to basal levels, to support cellular function. A pathological increase in the degree of both post-translational modifications disturbs intracellular Ca2+ signalling, and is implicated in various cardiac and skeletal disorders. This review summarises our current understanding of the mechanisms linking ryanodine receptor post-translational modification to heart failure and skeletal myopathy and highlights the challenges and controversies within the field.
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Affiliation(s)
- Amanda Denniss
- Health Research Institute, Faculty of Science and Technology, University of Canberra, Bruce, ACT, Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia
| | - Nicole A Beard
- Health Research Institute, Faculty of Science and Technology, University of Canberra, Bruce, ACT, Australia.
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13
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Mora MT, Ferrero JM, Romero L, Trenor B. Sensitivity analysis revealing the effect of modulating ionic mechanisms on calcium dynamics in simulated human heart failure. PLoS One 2017; 12:e0187739. [PMID: 29117223 PMCID: PMC5678731 DOI: 10.1371/journal.pone.0187739] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Abnormal intracellular Ca2+ handling is the major contributor to the depressed cardiac contractility observed in heart failure. The electrophysiological remodeling associated with this pathology alters both the action potential and the Ca2+ dynamics, leading to a defective excitation-contraction coupling that ends in mechanical dysfunction. The importance of maintaining a correct intracellular Ca2+ concentration requires a better understanding of its regulation by ionic mechanisms. To study the electrical activity and ionic homeostasis of failing myocytes, a modified version of the O’Hara et al. human action potential model was used, including electrophysiological remodeling. The impact of the main ionic transport mechanisms was analyzed using single-parameter sensitivity analyses, the first of which explored the modulation of electrophysiological characteristics related to Ca2+ exerted by the remodeled parameters. The second sensitivity analysis compared the potential consequences of modulating individual channel conductivities, as one of the main effects of potential drugs, on Ca2+ dynamic properties under both normal conditions and in heart failure. The first analysis revealed the important contribution of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) dysfunction to the altered Ca2+ homeostasis, with the Na+/Ca2+ exchanger (NCX) and other Ca2+ cycling proteins also playing a significant role. Our results highlight the importance of improving the SR uptake function to increase Ca2+ content and restore Ca2+ homeostasis and contractility. The second sensitivity analysis highlights the different response of the failing myocyte versus the healthy myocyte to potential pharmacological actions on single channels. The result of modifying the conductances of the remodeled proteins such as SERCA and NCX in heart failure has less impact on Ca2+ modulation. These differences should be taken into account when designing drug therapies.
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Affiliation(s)
- Maria T. Mora
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Jose M. Ferrero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Lucia Romero
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centro de Investigación e Innovación en Bioingeniería, Universitat Politècnica de València, Valencia, Spain
- * E-mail:
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14
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Santulli G, Lewis DR, Marks AR. Physiology and pathophysiology of excitation-contraction coupling: the functional role of ryanodine receptor. J Muscle Res Cell Motil 2017; 38:37-45. [PMID: 28653141 PMCID: PMC5813681 DOI: 10.1007/s10974-017-9470-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/06/2017] [Indexed: 12/21/2022]
Abstract
Calcium (Ca2+) release from intracellular stores plays a key role in the regulation of skeletal muscle contraction. The type 1 ryanodine receptors (RyR1) is the major Ca2+ release channel on the sarcoplasmic reticulum (SR) of myocytes in skeletal muscle and is required for excitation-contraction (E-C) coupling. This article explores the role of RyR1 in skeletal muscle physiology and pathophysiology.
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Affiliation(s)
- Gaetano Santulli
- The Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University Medical Center, Columbia University, New York, NY, USA
| | - Daniel R Lewis
- The Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University Medical Center, Columbia University, New York, NY, USA
| | - Andrew R Marks
- The Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA.
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University Medical Center, Columbia University, New York, NY, USA.
- Department of Medicine, Columbia University, New York, NY, USA.
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15
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Pasqualini FS, Nesmith AP, Horton RE, Sheehy SP, Parker KK. Mechanotransduction and Metabolism in Cardiomyocyte Microdomains. Biomed Res Int 2016; 2016:4081638. [PMID: 28044126 PMCID: PMC5164897 DOI: 10.1155/2016/4081638] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 01/11/2023]
Abstract
Efficient contractions of the left ventricle are ensured by the continuous transfer of adenosine triphosphate (ATP) from energy production sites, the mitochondria, to energy utilization sites, such as ionic pumps and the force-generating sarcomeres. To minimize the impact of intracellular ATP trafficking, sarcomeres and mitochondria are closely packed together and in proximity with other ultrastructures involved in excitation-contraction coupling, such as t-tubules and sarcoplasmic reticulum junctions. This complex microdomain has been referred to as the intracellular energetic unit. Here, we review the literature in support of the notion that cardiac homeostasis and disease are emergent properties of the hierarchical organization of these units. Specifically, we will focus on pathological alterations of this microdomain that result in cardiac diseases through energy imbalance and posttranslational modifications of the cytoskeletal proteins involved in mechanosensing and transduction.
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Affiliation(s)
- Francesco S. Pasqualini
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering and Applied Sciences, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
- Institute for Regenerative Medicine (IREM), Wyss Translational Center, University and ETH Zurich, Zurich, Switzerland
| | - Alexander P. Nesmith
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering and Applied Sciences, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Renita E. Horton
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering and Applied Sciences, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
- James Worth Bagley College of Engineering and College of Agriculture and Life Sciences, Mississippi State University, Starkville, MS, USA
| | - Sean P. Sheehy
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering and Applied Sciences, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Kevin Kit Parker
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, School of Engineering and Applied Sciences, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
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16
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A nanoscale view of junctophilin-2 and ryanodine receptors. J Cell Sci 2016; 129:e2303. [PMID: 27909078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
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17
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Falisse A, Van Rossom S, Jonkers I, De Groote F. EMG-Driven Optimal Estimation of Subject-SPECIFIC Hill Model Muscle-Tendon Parameters of the Knee Joint Actuators. IEEE Trans Biomed Eng 2016; 64:2253-2262. [PMID: 27875132 DOI: 10.1109/tbme.2016.2630009] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE the purpose of this paper is to propose an optimal control problem formulation to estimate subject-specific Hill model muscle-tendon (MT-) parameters of the knee joint actuators by optimizing the fit between experimental and model-based knee moments. Additionally, this paper aims at determining which sets of functional motions contain the necessary information to identify the MT-parameters. METHODS the optimal control and parameter estimation problem underlying the MT-parameter estimation is solved for subject-specific MT-parameters via direct collocation using an electromyography-driven musculoskeletal model. The sets of motions containing sufficient information to identify the MT-parameters are determined by evaluating knee moments simulated based on subject-specific MT-parameters against experimental moments. RESULTS the MT-parameter estimation problem was solved in about 30 CPU minutes. MT-parameters could be identified from only seven of the 62 investigated sets of motions, underlining the importance of the experimental protocol. Using subject-specific MT-parameters instead of more common linearly scaled MT-parameters improved the fit between inverse dynamics moments and simulated moments by about 30% in terms of the coefficient of determination (from [Formula: see text] to [Formula: see text]) and by about 26% in terms of the root mean square error (from [Formula: see text] to [Formula: see text] ). In particular, subject-specific MT-parameters of the knee flexors were very different from linearly scaled MT-parameters. CONCLUSION we introduced a computationally efficient optimal control problem formulation and provided guidelines for designing an experimental protocol to estimate subject-specific MT-parameters improving the accuracy of motion simulations. SIGNIFICANCE the proposed formulation opens new perspectives for subject-specific musculoskeletal modeling, which might be beneficial for simulating and understanding pathological motions.
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Downey RJ, Merad M, Gonzalez EJ, Dixon WE. The Time-Varying Nature of Electromechanical Delay and Muscle Control Effectiveness in Response to Stimulation-Induced Fatigue. IEEE Trans Neural Syst Rehabil Eng 2016; 25:1397-1408. [PMID: 27845664 DOI: 10.1109/tnsre.2016.2626471] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Neuromuscular electrical stimulation (NMES) and Functional Electrical Stimulation (FES) are commonly prescribed rehabilitative therapies. Closed-loop NMES holds the promise to yield more accurate limb control, which could enable new rehabilitative procedures. However, NMES/FES can rapidly fatigue muscle, which limits potential treatments and presents several control challenges. Specifically, the stimulation intensity-force relation changes as the muscle fatigues. Additionally, the delayed response between the application of stimulation and muscle force production, termed electromechanical delay (EMD), may increase with fatigue. This paper quantifies these effects. Specifically, open-loop fatiguing protocols were applied to the quadriceps femoris muscle group of able-bodied individuals under isometric conditions, and the resulting torque was recorded. Short pulse trains were used to measure EMD with a thresholding method while long duration pulse trains were used to induce fatigue, measure EMD with a cross-correlation method, and construct recruitment curves. EMD was found to increase significantly with fatigue, and the control effectiveness (i.e., the linear slope of the recruitment curve) decreased with fatigue. Outcomes of these experiments indicate an opportunity for improved closed-loop NMES/FES control development by considering EMD to be time-varying and by considering the muscle recruitment curve to be a nonlinear, time-varying function of the stimulation input.
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Himeno Y, Asakura K, Cha CY, Memida H, Powell T, Amano A, Noma A. A human ventricular myocyte model with a refined representation of excitation-contraction coupling. Biophys J 2016. [PMID: 26200878 DOI: 10.1016/j.bpj.2015.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cardiac Ca(2+)-induced Ca(2+) release (CICR) occurs by a regenerative activation of ryanodine receptors (RyRs) within each Ca(2+)-releasing unit, triggered by the activation of L-type Ca(2+) channels (LCCs). CICR is then terminated, most probably by depletion of Ca(2+) in the junctional sarcoplasmic reticulum (SR). Hinch et al. previously developed a tightly coupled LCC-RyR mathematical model, known as the Hinch model, that enables simulations to deal with a variety of functional states of whole-cell populations of a Ca(2+)-releasing unit using a personal computer. In this study, we developed a membrane excitation-contraction model of the human ventricular myocyte, which we call the human ventricular cell (HuVEC) model. This model is a hybrid of the most recent HuVEC models and the Hinch model. We modified the Hinch model to reproduce the regenerative activation and termination of CICR. In particular, we removed the inactivated RyR state and separated the single step of RyR activation by LCCs into triggering and regenerative steps. More importantly, we included the experimental measurement of a transient rise in Ca(2+) concentrations ([Ca(2+)], 10-15 μM) during CICR in the vicinity of Ca(2+)-releasing sites, and thereby calculated the effects of the local Ca(2+) gradient on CICR as well as membrane excitation. This HuVEC model successfully reconstructed both membrane excitation and key properties of CICR. The time course of CICR evoked by an action potential was accounted for by autonomous changes in an instantaneous equilibrium open probability of couplons. This autonomous time course was driven by a core feedback loop including the pivotal local [Ca(2+)], influenced by a time-dependent decay in the SR Ca(2+) content during CICR.
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Affiliation(s)
- Yukiko Himeno
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Keiichi Asakura
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan; Nippon Shinyaku Co., Ltd., Kyoto, Japan
| | - Chae Young Cha
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan; Oxford Centre for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Hiraku Memida
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Trevor Powell
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Akira Amano
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Akinori Noma
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan.
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Yamamoto D, Imai T, Tsuda E, Hozuki T, Yamauchi R, Hisahara S, Kawamata J, Shimohama S. Impaired post-tetanic potentiation of muscle twitch in myasthenia gravis. Clin Neurophysiol 2015; 127:1689-1693. [PMID: 26547355 DOI: 10.1016/j.clinph.2015.10.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/06/2015] [Accepted: 10/10/2015] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate post-tetanic potentiation of muscle twitch in myasthenia gravis (MG). METHODS Post-tetanic potentiation was evaluated by recording the compound muscle action potential (CMAP) of abductor pollicis brevis and movement-related potential (MRP) of the thumb using an accelerometer after tetanic stimulation of the median nerve at the wrist. After baseline recording, tetanic stimulation was delivered to the median nerve at a frequency of 10 Hz for 10s. The CMAP and MRP were successively recorded at baseline and at 5, 10, 30, 60, 90 and 120 s after tetanic stimulation. The chronological changes of CMAPs and MRPs were recorded bilaterally in 11 patients with MG, 9 patients with myopathies (disease controls), and 25 healthy control subjects. RESULTS Maximal acceleration of MRP was significantly elevated during 10s after tetanic stimulation without any CMAP changes in all groups. However, statistical analysis detected a significant decrease in post-tetanic potentiation of maximal acceleration of MRP in MG patients only compared to healthy controls, but not in myopathy patients, which may imply impairment of excitation-contraction coupling in MG. CONCLUSIONS Post-tetanic potentiation of muscle twitch is significantly diminished in MG, suggesting impaired excitation-contraction coupling. SIGNIFICANCE Measurement of post-tetanic potentiation using an accelerometer is a simple and sensitive method to detect impairment of excitation-contraction coupling in MG.
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Affiliation(s)
- Daisuke Yamamoto
- Department of Neurology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Tomihiro Imai
- Department of Occupational Therapy, Sapporo Medical University School of Health Sciences, Sapporo, Japan.
| | - Emiko Tsuda
- Department of Neurology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | | | - Rika Yamauchi
- Department of Neurology, Sunagawa City Medical Center, Sunagawa, Japan
| | - Shin Hisahara
- Department of Neurology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Jun Kawamata
- Department of Neurology, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Shun Shimohama
- Department of Neurology, Sapporo Medical University School of Medicine, Sapporo, Japan
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21
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Haustein M, Hannes T, Trieschmann J, Verhaegh R, Köster A, Hescheler J, Brockmeier K, Adelmann R, Khalil M. Excitation-contraction coupling in zebrafish ventricular myocardium is regulated by trans-sarcolemmal Ca2+ influx and sarcoplasmic reticulum Ca2+ release. PLoS One 2015; 10:e0125654. [PMID: 25938412 PMCID: PMC4418605 DOI: 10.1371/journal.pone.0125654] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 03/17/2015] [Indexed: 01/19/2023] Open
Abstract
Zebrafish (Danio rerio) have become a popular model in cardiovascular research mainly due to identification of a large number of mutants with structural defects. In recent years, cardiomyopathies and other diseases influencing contractility of the heart have been studied in zebrafish mutants. However, little is known about the regulation of contractility of the zebrafish heart on a tissue level. The aim of the present study was to elucidate the role of trans-sarcolemmal Ca2+-flux and sarcoplasmic reticulum Ca2+-release in zebrafish myocardium. Using isometric force measurements of fresh heart slices, we characterised the effects of changes of the extracellular Ca2+-concentration, trans-sarcolemmal Ca2+-flux via L-type Ca2+-channels and Na+-Ca2+-exchanger, and Ca2+-release from the sarcoplasmic reticulum as well as beating frequency and β-adrenergic stimulation on contractility of adult zebrafish myocardium. We found an overall negative force-frequency relationship (FFR). Inhibition of L-type Ca2+-channels by verapamil (1 μM) decreased force of contraction to 22±7% compared to baseline (n=4, p<0.05). Ni2+ was the only substance to prolong relaxation (5 mM, time after peak to 50% relaxation: 73±3 ms vs. 101±8 ms, n=5, p<0.05). Surprisingly though, inhibition of the sarcoplasmic Ca2+-release decreased force development to 54±3% in ventricular (n=13, p<0.05) and to 52±8% in atrial myocardium (n=5, p<0.05) suggesting a substantial role of SR Ca2+-release in force generation. In line with this finding, we observed significant post pause potentiation after pauses of 5 s (169±7% force compared to baseline, n=8, p<0.05) and 10 s (198±9% force compared to baseline, n=5, p<0.05) and mildly positive lusitropy after β-adrenergic stimulation. In conclusion, force development in adult zebrafish ventricular myocardium requires not only trans-sarcolemmal Ca2+-flux, but also intact sarcoplasmic reticulum Ca2+-cycling. In contrast to mammals, FFR is strongly negative in the zebrafish heart. These aspects need to be considered when using zebrafish to model human diseases of myocardial contractility.
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Affiliation(s)
- Moritz Haustein
- Department of Paediatric Cardiology, Cologne Heart Centre, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Tobias Hannes
- Department of Paediatric Cardiology, Cologne Heart Centre, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
- Institute for Neurophysiology, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
- * E-mail:
| | - Jan Trieschmann
- Institute for Neurophysiology, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Rabea Verhaegh
- Institute of Physiological Chemistry, University Hospital Essen, Essen, North Rhine-Westphalia, Germany
| | - Annette Köster
- Institute for Neurophysiology, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Jürgen Hescheler
- Institute for Neurophysiology, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Konrad Brockmeier
- Department of Paediatric Cardiology, Cologne Heart Centre, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Roland Adelmann
- Department of Paediatric Cardiology, Cologne Heart Centre, Medical Faculty, University of Cologne, Cologne, North Rhine-Westphalia, Germany
| | - Markus Khalil
- Department of Paediatric Cardiology, University Hospital of Giessen and Marburg, University of Giessen and Marburg, Giessen, Hessen, Germany
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Kamide T, Okumura S, Ghosh S, Shinoda Y, Mototani Y, Ohnuki Y, Jin H, Cai W, Suita K, Sato I, Umemura M, Fujita T, Yokoyama U, Sato M, Furutani K, Kitano H, Ishikawa Y. Oscillation of cAMP and Ca(2+) in cardiac myocytes: a systems biology approach. J Physiol Sci 2015; 65:195-200. [PMID: 25585963 PMCID: PMC10717207 DOI: 10.1007/s12576-014-0354-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 12/18/2014] [Indexed: 12/19/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) and Ca(2+) levels may oscillate in harmony within excitable cells; a mathematical oscillation loop model, the Cooper model, of these oscillations was developed two decades ago. However, in that model all adenylyl cyclase (AC) isoforms were assumed to be inhibited by Ca(2+), and it is now known that the heart expresses multiple AC isoforms, among which the type 5/6 isoforms are Ca(2+)-inhibitable whereas the other five (AC2, 3, 4, 7, and 9) are not. We used a computational systems biology approach with CellDesigner simulation software to develop a comprehensive graphical map and oscillation loop model for cAMP and Ca(2+). This model indicated that Ca(2+)-mediated inhibition of AC is essential to create oscillations of Ca(2+) and cAMP, and the oscillations were not altered by incorporation of phosphodiesterase-mediated cAMP hydrolysis or PKA-mediated inhibition of AC into the model. More importantly, they were created but faded out immediately in the co-presence of Ca(2+)-noninhibitable AC isoforms. Because the subcellular locations of AC isoforms are different, spontaneous cAMP and Ca(2+) oscillations may occur within microdomains containing only Ca(2+)-inhibitable isoforms in cardiac myocytes, which might be necessary for fine tuning of excitation-contraction coupling.
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Affiliation(s)
- Takehisa Kamide
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Satoshi Okumura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
- Department of Physiology, Tsurumi University School of Dental Medicine, 2-1-2 Tsurumi, Tsurumi-ku, Yokohama, 230-8501 Japan
| | - Samik Ghosh
- The Systems Biology Institute, Minato, Tokyo, 108-0071 Japan
| | - Yoko Shinoda
- Department of Physiology, Tsurumi University School of Dental Medicine, 2-1-2 Tsurumi, Tsurumi-ku, Yokohama, 230-8501 Japan
| | - Yasumasa Mototani
- Department of Physiology, Tsurumi University School of Dental Medicine, 2-1-2 Tsurumi, Tsurumi-ku, Yokohama, 230-8501 Japan
| | - Yoshiki Ohnuki
- Department of Physiology, Tsurumi University School of Dental Medicine, 2-1-2 Tsurumi, Tsurumi-ku, Yokohama, 230-8501 Japan
| | - Huiling Jin
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Wenqian Cai
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Kenji Suita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Itaru Sato
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Masanari Umemura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Takayuki Fujita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
| | - Motohiko Sato
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
- Department of Physiology, Aichi Medical University, Nagakute, Aichi 480-1195 Japan
| | - Kazuharu Furutani
- Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, 565-0871 Japan
- Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, 565-0871 Japan
| | - Hiroaki Kitano
- The Systems Biology Institute, Minato, Tokyo, 108-0071 Japan
- Okinawa Institute of Science and Technology Graduate School, Onna-Son, Okinawa, 904-0412 Japan
- Laboratory for Disease Systems Modeling, Riken Center for Integrative Medical Sciences, Yokohama, 230-0045 Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004 Japan
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23
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Radszuweit M, Alvarez-Lacalle E, Bär M, Echebarria B. Cardiac contraction induces discordant alternans and localized block. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:022703. [PMID: 25768527 DOI: 10.1103/physreve.91.022703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Indexed: 06/04/2023]
Abstract
In this paper we use a simplified model of cardiac excitation-contraction coupling to study the effect of tissue deformation on the dynamics of alternans, i.e., alternations in the duration of the cardiac action potential, that occur at fast pacing rates and are known to be proarrhythmic. We show that small stretch-activated currents can produce large effects and cause a transition from in-phase to off-phase alternations (i.e., from concordant to discordant alternans) and to conduction blocks. We demonstrate numerically and analytically that this effect is the result of a generic change in the slope of the conduction velocity restitution curve due to electromechanical coupling. Thus, excitation-contraction coupling can potentially play a relevant role in the transition to reentry and fibrillation.
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Affiliation(s)
- M Radszuweit
- Weierstrass Institute for Applied Analysis and Stochastics Mohrenstrasse 39, 10117 Berlin, Germany
| | - E Alvarez-Lacalle
- Departament de Física Aplicada, Universitat Politècnica de Catalunya.BarcelonaTech, Av. Dr. Marañón 44-50, E-08028, Barcelona, Spain
| | - M Bär
- Physikalisch-Technische Bundesanstalt, 10587 Berlin, Germany
| | - B Echebarria
- Departament de Física Aplicada, Universitat Politècnica de Catalunya.BarcelonaTech, Av. Dr. Marañón 44-50, E-08028, Barcelona, Spain
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Veklich TO, Mazur II, Kosterin SO. [Mg2+, ATP-dependent plasma membrane calcium pump of smooth muscle cells. I. Structural organization and properties]. Ukr Biochem J 2015; 87:5-20. [PMID: 26036127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
Tight control of cytoplasm Ca2+ concentration is essential in cell functioning. Changing of Ca2+ concentration is thorough in smooth muscle cells, because it determines relaxation/constraint process. One of key proteins which control Ca2+ concentration in cytoplasm is Mg2+, ATP-dependent plasma membrane calcium pump. Thus, it is important to find compoumds which allowed one to change Mg2+, ATP-dependent plasma membrane calcium pump activity, as long as this topic is of current interest in biochemical research which regards energy and pharmacomechanical coupling mechanism of muscle excitation and contraction. In this article we generalized literatute and own data about properties of smooth muscle cell plasma membrane Ca(2+)-pump. Stuctural oganization, kinetical properties and molecular biology are considered.
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25
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Pfeiffer ER, Tangney JR, Omens JH, McCulloch AD. Biomechanics of cardiac electromechanical coupling and mechanoelectric feedback. J Biomech Eng 2014; 136:021007. [PMID: 24337452 DOI: 10.1115/1.4026221] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 12/12/2013] [Indexed: 11/08/2022]
Abstract
Cardiac mechanical contraction is triggered by electrical activation via an intracellular calcium-dependent process known as excitation-contraction coupling. Dysregulation of cardiac myocyte intracellular calcium handling is a common feature of heart failure. At the organ scale, electrical dyssynchrony leads to mechanical alterations and exacerbates pump dysfunction in heart failure. A reverse coupling between cardiac mechanics and electrophysiology is also well established. It is commonly referred as cardiac mechanoelectric feedback and thought to be an important contributor to the increased risk of arrhythmia during pathological conditions that alter regional cardiac wall mechanics, including heart failure. At the cellular scale, most investigations of myocyte mechanoelectric feedback have focused on the roles of stretch-activated ion channels, though mechanisms that are independent of ionic currents have also been described. Here we review excitation-contraction coupling and mechanoelectric feedback at the cellular and organ scales, and we identify the need for new multicellular tissue-scale model systems and experiments that can help us to obtain a better understanding of how interactions between electrophysiological and mechanical processes at the cell scale affect ventricular electromechanical interactions at the organ scale in the normal and diseased heart.
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26
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Galie PA, Byfield FJ, Chen CS, Kresh JY, Janmey PA. Mechanically stimulated contraction of engineered cardiac constructs using a microcantilever. IEEE Trans Biomed Eng 2014; 62:438-42. [PMID: 25248171 DOI: 10.1109/tbme.2014.2357778] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The beating heart undergoes cyclic mechanical and electrical activity during systole and diastole. The interaction between mechanical stimulation and propagation of the depolarization wavefront is important for understanding not just normal sinus rhythm, but also mechanically induced cardiac arrhythmia. This study presents a new platform to study mechanoelectrical coupling in a 3-D in vitro model of the myocardium. Cardiomyocytes and cardiac fibroblasts are seeded within extracellular matrix proteins and form constructs constrained by microfabricated tissue gauges that provide in situ measurement of contractile function. The microcantilever of an atomic force microscope is indented into the construct at varying magnitudes and frequencies to cause a coordinated contraction. The results indicate that changes in indentation depth and frequency do not significantly affect the magnitude of contraction, but increasing indentation frequency significantly increases the contractile velocity. Overall, this study demonstrates the validity of this platform as a means to study mechanoelectrical coupling in a 3-D setting, and to investigate the mechanism underlying mechanically stimulated contraction.
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Affiliation(s)
- Peter Kohl
- National Heart and Lung Institute, Imperial College London, UK; Department of Computer Science, University of Oxford, UK.
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Canada
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28
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Solovyova O, Katsnelson LB, Konovalov PV, Kursanov AG, Vikulova NA, Kohl P, Markhasin VS. The cardiac muscle duplex as a method to study myocardial heterogeneity. Prog Biophys Mol Biol 2014; 115:115-28. [PMID: 25106702 PMCID: PMC4210666 DOI: 10.1016/j.pbiomolbio.2014.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 07/25/2014] [Indexed: 12/14/2022]
Abstract
This paper reviews the development and application of paired muscle preparations, called duplex, for the investigation of mechanisms and consequences of intra-myocardial electro-mechanical heterogeneity. We illustrate the utility of the underlying combined experimental and computational approach for conceptual development and integration of basic science insight with clinically relevant settings, using previously published and new data. Directions for further study are identified.
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Affiliation(s)
- O Solovyova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia.
| | - L B Katsnelson
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P V Konovalov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - A G Kursanov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
| | - N A Vikulova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P Kohl
- National Heart and Lung Institute, Imperial College of London, Heart Science Centre, Harefield Hospital, Hill End Road, Harefield UB9 6JH, UK; Department of Computer Sciences, University of Oxford, UK
| | - V S Markhasin
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
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29
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Dias P, Desplantez T, El-Harasis MA, Chowdhury RA, Ullrich ND, Cabestrero de Diego A, Peters NS, Severs NJ, MacLeod KT, Dupont E. Characterisation of connexin expression and electrophysiological properties in stable clones of the HL-1 myocyte cell line. PLoS One 2014; 9:e90266. [PMID: 24587307 PMCID: PMC3938655 DOI: 10.1371/journal.pone.0090266] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 01/26/2014] [Indexed: 11/18/2022] Open
Abstract
The HL-1 atrial line contains cells blocked at various developmental stages. To obtain homogeneous sub-clones and correlate changes in gene expression with functional alterations, individual clones were obtained and characterised for parameters involved in conduction and excitation-contraction coupling. Northern blots for mRNAs coding for connexins 40, 43 and 45 and calcium handling proteins (sodium/calcium exchanger, L- and T-type calcium channels, ryanodine receptor 2 and sarco-endoplasmic reticulum calcium ATPase 2) were performed. Connexin expression was further characterised by western blots and immunofluorescence. Inward currents were characterised by voltage clamp and conduction velocities measured using microelectrode arrays. The HL-1 clones had similar sodium and calcium inward currents with the exception of clone 2 which had a significantly smaller calcium current density. All the clones displayed homogenous propagation of electrical activity across the monolayer correlating with the levels of connexin expression. Conduction velocities were also more sensitive to inhibition of junctional coupling by carbenoxolone (∼ 80%) compared to inhibition of the sodium current by lidocaine (∼ 20%). Electrical coupling by gap junctions was the major determinant of conduction velocities in HL-1 cell lines. In summary we have isolated homogenous and stable HL-1 clones that display characteristics distinct from the heterogeneous properties of the original cell line.
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Affiliation(s)
- Priyanthi Dias
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Thomas Desplantez
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Majd A. El-Harasis
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Rasheda A. Chowdhury
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Nina D. Ullrich
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Alberto Cabestrero de Diego
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Nicholas S. Peters
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Nicholas J. Severs
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kenneth T. MacLeod
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Emmanuel Dupont
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, United Kingdom
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30
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Costet A, Provost J, Gambhir A, Bobkov Y, Danilo P, Boink GJ, Rosen MR, Konofagou E. Electromechanical wave imaging of biologically and electrically paced canine hearts in vivo. Ultrasound Med Biol 2014; 40:177-187. [PMID: 24239363 PMCID: PMC3897195 DOI: 10.1016/j.ultrasmedbio.2013.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 08/20/2013] [Accepted: 08/26/2013] [Indexed: 06/02/2023]
Abstract
Electromechanical wave imaging (EWI) has been show capable of directly and entirely non-invasively mapping the trans mural electromechanical activation in all four cardiac chambers in vivo. In this study, we assessed EWI repeatability and reproducibility, as well as its capability of localizing electronic and, for the first time, biological pacing locations in closed-chest, conscious canines. Electromechanical activation was obtained in six conscious animals during normal sinus rhythm (NSR) and idioventricular rhythms occurring in dogs with complete heart block instrumented with electronic and biologic pacemakers (EPM and BPM respectively). After atrioventricular node ablation, dogs were implanted with an EPM in the right ventricular (RV) endocardial apex (n = 4) and two additionally received a BPM at the left ventricular (LV) epicardial base (n = 2). EWI was performed trans thoracically during NSR, BPM and EPM pacing, in conscious dogs, using an unfocused transmit sequence at 2000 frames/s. During NSR, the EW originated at the right atrium (RA), propagated to the left atrium (LA) and emerged from multiple sources in both ventricles. During EPM, the EW originated at the RV apex and propagated throughout both ventricles. During BPM, the EW originated from the LV basal lateral wall and subsequently propagated throughout the ventricles. EWI differentiated BPM from EPM and NSR and identified the distinct pacing origins. Isochrone comparison indicated that EWI was repeatable and reliable. These findings thus indicate the potential for EWI to serve as a simple, non-invasive and direct imaging technology for mapping and characterizing arrhythmias as well as the treatments thereof.
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Affiliation(s)
- Alexandre Costet
- Department of Biomedical Engineering, Columbia University, New York, NY, 10027, USA
| | - Jean Provost
- Department of Biomedical Engineering, Columbia University, New York, NY, 10027, USA
| | - Alok Gambhir
- Department of Medicine-Cardiology, Columbia University, New York, NY, 10032, USA
| | - Yevgeniy Bobkov
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA
| | - Peter Danilo
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA
| | - Gerard J.J. Boink
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA
- Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, the Netherlands
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Michael R. Rosen
- Department of Pharmacology, Columbia University, New York, NY, 10032, USA
| | - Elisa Konofagou
- Department of Biomedical Engineering, Columbia University, New York, NY, 10027, USA
- Department of Radiology, Columbia University, New York, NY, 10032, USA
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31
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Abstract
In ratchet-based models describing actomyosin contraction the activity is usually associated with actin binding potential while the power-stroke mechanism, residing inside myosin heads, is viewed as passive. To show that contraction can be propelled directly through a conformational change, we propose an alternative model where the power stroke is the only active mechanism. The asymmetry, ensuring directional motion, resides in steric interaction between the externally driven power-stroke element and the passive nonpolar actin filament. The proposed model can reproduce all four discrete states of the minimal actomyosin catalytic cycle even though it is formulated in terms of continuous Langevin dynamics. We build a conceptual bridge between processive and nonprocessive molecular motors by demonstrating that not only the former but also the latter can use structural transformation as the main driving force.
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Affiliation(s)
- R Sheshka
- LMS, CNRS-UMR 7649, École Polytechnique, Route de Saclay, 91128 Palaiseau, France and LITEN, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
| | - L Truskinovsky
- LMS, CNRS-UMR 7649, École Polytechnique, Route de Saclay, 91128 Palaiseau, France
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32
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Szpala A, Rutkowska-Kucharska A, Drapala J. Electromechanical delay of abdominal muscles is modified by low back pain prevention exercise. Acta Bioeng Biomech 2014; 16:95-102. [PMID: 25307027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The objective of the research was to assess the effect of a 4-week-long training program on selected parameters: electromechanical delay (EMD) and amplitude of electromyographic signal (EMG). Fourteen female students of the University School of Physical Education participated in the study. Torques and surface electromyography were evaluated under static conditions. Surface electrodes were glued to both sides of the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles. The 4-week-long program was aimed at strengthening the abdominal muscles and resulted in increased EMD during maximum torque production by flexors of the trunk, increased amplitudes of the signals of the erector spinae ( p = 0.005), and increased EMG amplitude asymmetry of the lower ( p = 0.013) and upper part ( p = 0.006) of the rectus abdominis muscle. In a training program composed of a large number of repetitions of strength exercises, in which the training person uses their own weight as the load (like in exercises such as curl-ups), the process of recruitment of motor units is similar to that found during fatiguing exercises and plyometric training.
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Affiliation(s)
- Agnieszka Szpala
- Department of Biomechanics, University School of Physical Education in Wrocław, Wrocław, Poland
| | | | - Jaroslaw Drapala
- Department of Computer Science and Management, Wrocław University of Technology, Wrocław, Poland
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33
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Wang F, Cong XF, Chen X. [Developmental changes of excitation-contraction coupling in the postnatal mammalian heart]. Sheng Li Ke Xue Jin Zhan 2013; 44:227-232. [PMID: 24027833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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34
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Stawicki TM, Takayanagi-Kiya S, Zhou K, Jin Y. Neuropeptides function in a homeostatic manner to modulate excitation-inhibition imbalance in C. elegans. PLoS Genet 2013; 9:e1003472. [PMID: 23658528 PMCID: PMC3642046 DOI: 10.1371/journal.pgen.1003472] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 03/07/2013] [Indexed: 11/18/2022] Open
Abstract
Neuropeptides play crucial roles in modulating neuronal networks, including changing intrinsic properties of neurons and synaptic efficacy. We previously reported a Caenorhabditis elegans mutant, acr-2(gf), that displays spontaneous convulsions as the result of a gain-of-function mutation in a neuronal nicotinic acetylcholine receptor subunit. The ACR-2 channel is expressed in the cholinergic motor neurons, and acr-2(gf) causes cholinergic overexcitation accompanied by reduced GABAergic inhibition in the locomotor circuit. Here we show that neuropeptides play a homeostatic role that compensates for this excitation-inhibition imbalance in the locomotor circuit. Loss of function in genes required for neuropeptide processing or release of dense core vesicles specifically modulate the convulsion frequency of acr-2(gf). The proprotein convertase EGL-3 is required in the cholinergic motor neurons to restrain convulsions. Electrophysiological recordings of neuromuscular junctions show that loss of egl-3 in acr-2(gf) causes a further reduction of GABAergic inhibition. We identify two neuropeptide encoding genes, flp-1 and flp-18, that together counteract the excitation-inhibition imbalance in acr-2(gf) mutants. We further find that acr-2(gf) causes an increased expression of flp-18 in the ventral cord cholinergic motor neurons and that overexpression of flp-18 reduces the convulsion of acr-2(gf) mutants. The effects of these peptides are in part mediated by two G-protein coupled receptors, NPR-1 and NPR-5. Our data suggest that the chronic overexcitation of the cholinergic motor neurons imposed by acr-2(gf) leads to an increased production of FMRFamide neuropeptides, which act to decrease the activity level of the locomotor circuit, thereby homeostatically modulating the excitation and inhibition imbalance. Imbalanced neuronal circuit activity is considered a major underlying cause in many neurological disorders, such as epilepsy and autism. Neuropeptides are small polypeptides that are released from neurons. They are widely known to provide neuromodulatory functions and have diverse roles in the nervous system. By investigating a C. elegans mutant that exhibits convulsions as the result of an imbalanced excitation and inhibition in the locomotor circuit, we have identified a homeostatic mechanism involving two distinct neuropeptide genes. We find that the expression of the neuropeptides is up-regulated in response to over-excitation and that, in turn, they act to increase inhibitory transmission. While current treatment strategies for epilepsy have focused on targeting fast synaptic transmission, this work supports the general notion that manipulating slow neuropeptide neurotransmission can strongly influence neural excitation and inhibition imbalance.
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Affiliation(s)
- Tamara M. Stawicki
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
| | - Seika Takayanagi-Kiya
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
| | - Keming Zhou
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
| | - Yishi Jin
- Division of Biological Sciences, Section of Neurobiology, University of California San Diego, La Jolla, California, United States of America
- Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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35
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Hollingworth S, Baylor SM. Comparison of myoplasmic calcium movements during excitation-contraction coupling in frog twitch and mouse fast-twitch muscle fibers. J Gen Physiol 2013; 141:567-83. [PMID: 23630340 PMCID: PMC3639574 DOI: 10.1085/jgp.201310961] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/25/2013] [Indexed: 01/26/2023] Open
Abstract
Single twitch fibers from frog leg muscles were isolated by dissection and micro-injected with furaptra, a rapidly responding fluorescent Ca(2+) indicator. Indicator resting fluorescence (FR) and the change evoked by an action potential (ΔF) were measured at long sarcomere length (16°C); ΔF/FR was scaled to units of ΔfCaD, the change in fraction of the indicator in the Ca(2+)-bound form. ΔfCaD was simulated with a multicompartment model of the underlying myoplasmic Ca(2+) movements, and the results were compared with previous measurements and analyses in mouse fast-twitch fibers. In frog fibers, sarcoplasmic reticulum (SR) Ca(2+) release evoked by an action potential appears to be the sum of two components. The time course of the first component is similar to that of the entire Ca(2+) release waveform in mouse fibers, whereas that of the second component is severalfold slower; the fractional release amounts are ~0.8 (first component) and ~0.2 (second component). Similar results were obtained in frog simulations with a modified model that permitted competition between Mg(2+) and Ca(2+) for occupancy of the regulatory sites on troponin. An anatomical basis for two release components in frog fibers is the presence of both junctional and parajunctional SR Ca(2+) release channels (ryanodine receptors [RyRs]), whereas mouse fibers (usually) have only junctional RyRs. Also, frog fibers have two RyR isoforms, RyRα and RyRβ, whereas the mouse fibers (usually) have only one, RyR1. Our simulations suggest that the second release component in frog fibers functions to supply extra Ca(2+) to activate troponin, which, in mouse fibers, is not needed because of the more favorable location of their triadic junctions (near the middle of the thin filament). We speculate that, in general, parajunctional RyRs permit increased myofilament activation in fibers whose triadic junctions are located at the z-line.
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Affiliation(s)
- Stephen Hollingworth
- Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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36
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Okuda S, Yano M. [Excitation-Contraction coupling and intracellular calcium cycling in failing hearts]. Clin Calcium 2013; 23:471-480. [PMID: 23545736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Alterations in Excitation-Contraction coupling have recently been shown to play a crucial role in the pathogenesis of heart failure (HF). In failing hearts, abnormalities of neurohormonal mechanisms, which were included chronic activation of the sympathetic nervous system or of the renin-angiotensin system result in structural and functional changes in the calcium (Ca(2 +) ) regulatory proteins. These changes include the decreased sarcoplasmic reticulum (SR) load, which could be caused by reduced SR Ca(2 +) -ATPase (SERCA2A) function and increased SR Ca(2 +) leak via cardiac ryanodine receptor (RyR2) , a functional defect in L-type Ca(2 +) channel and activation of the reversal mode of Na (+) /Ca(2 +) exchanger. The abnormal regulation of intracellular Ca(2 +) affects troponin C binding and actin-myosin cross bridging and modulates post signaling pathway, which in turn contributes to the contractile dysfunction of hearts and hence to the progression of HF. Moreover, diastolic Ca(2 +) leak may develop delayed after depolarization and triggered activity as a substrate for lethal arrhythmia and sudden cardiac death. In this review, we focus on the underlying mechanism of defective Ca(2 +) regulation in HF and on the possibility of proceeding to clinical application as a new treatment for HF by targeting Ca(2 +) regulatory proteins.
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Affiliation(s)
- Shinichi Okuda
- Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, Japan
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37
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Abstract
Myosin VI is an ATP driven molecular motor that normally takes forward and processive steps on actin filaments, but also on occasion stochastic backward steps. While a number of models have attempted to explain the backwards steps, none offer an acceptable mechanism for their existence. We therefore performed single molecule imaging of myosin VI and calculated the stepping rates of forward and backward steps at the single molecule level. The forward stepping rate was proportional to the ATP concentration, whereas the backward stepping rate was independent. Using these data, we proposed that spontaneous detachment of the leading head is uncoupled from ATP binding and is responsible for the backward steps of myosin VI.
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Affiliation(s)
- Keigo Ikezaki
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
- Quantitative Biology Center (QBiC), RIKEN, Suita, Osaka, Japan
| | - Tomotaka Komori
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
- Quantitative Biology Center (QBiC), RIKEN, Suita, Osaka, Japan
- * E-mail: (TK); (TY)
| | - Toshio Yanagida
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
- Quantitative Biology Center (QBiC), RIKEN, Suita, Osaka, Japan
- Center for Information and Neural Networks (CiNet), Suita, Osaka, Japan
- Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan
- * E-mail: (TK); (TY)
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38
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Zhang GX, Obata K, Takeshita D, Mitsuyama S, Nakashima T, Kikuta A, Hirabayashi M, Tomita K, Vetter R, Dillmann WH, Takaki M. Evaluation of left ventricular mechanical work and energetics of normal hearts in SERCA2a transgenic rats. J Physiol Sci 2012; 62:221-31. [PMID: 22383047 PMCID: PMC10717940 DOI: 10.1007/s12576-012-0200-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 02/09/2012] [Indexed: 10/28/2022]
Abstract
Cardiac sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a) is responsible for most of the Ca(2+) removal during diastole and a larger Ca(2+) handling energy consumer in excitation-contraction (E-C) coupling. To understand the cardiac performance under long-term SERCA2a overexpression conditions, we established SERCA2a transgenic (TG) Wistar rats to analyze cardiac mechanical work and energetics in normal hearts during pacing at 300 beats/min. SERCA2a protein expression was increased in TGI and TGII rats (F2 and F3 of the same father and different mothers). Mean left ventricular (LV) end-systolic pressure (ESP) and systolic pressure-volume area (PVA; a total mechanical energy per beat) at midrange LV volume (mLVV) were significantly larger in TGI rats and were unchanged in TGII rats, compared to those in non-TG [wildtype (WT)] littermates. Mean myocardial oxygen consumption per minute for E-C coupling was significantly increased, and the mean slope of myocardial oxygen consumption per beat (VO(2))-PVA (systolic PVA) linear relation was smaller, but the overall O(2) cost of LV contractility for Ca(2+) is unchanged in all TG rats. Mean Ca(2+) concentration exerting maximal ESP(mLVV) in TGII rats was significantly higher than that in WT rats. The Ca(2+) overloading protocol did not elicit mitochondrial swelling in TGII rats. Tolerance to higher Ca(2+) concentrations may support the possibility for enhanced SERCA2a activity in TGII rats. In conclusion, long-term SERCA2a overexpression enhanced or maintained LV mechanics, improved contractile efficiency under higher energy expenditure for Ca(2+) handling, and improved Ca(2+) tolerance, but it did not change the overall O(2) cost of LV contractility for Ca(2+) in normal hearts of TG rats.
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Affiliation(s)
- Guo-Xing Zhang
- Department of Physiology II, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521 Japan
- Department of Physiology, Medical College of Soochow University, Dushu Lake Campus, Suzhou Industrial Park, Suzhou, 215123 People’s Republic of China
| | - Koji Obata
- Department of Physiology II, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521 Japan
| | - Daisuke Takeshita
- Department of Physiology II, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521 Japan
| | - Shinichi Mitsuyama
- Department of Physiology II, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521 Japan
| | - Tamiji Nakashima
- Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555 Japan
| | - Akio Kikuta
- Department of Anatomy, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555 Japan
| | - Masumi Hirabayashi
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8787 Japan
| | - Koichi Tomita
- National Institute for Physiological Sciences, Okazaki, Aichi 444-8787 Japan
| | - Roland Vetter
- Institut für Klinische Pharmakologie und Toxikologie, Charité-Universitätsmedizin Berlin, Charité Campus Mitte, Hufelandweg 9, 10117 Berlin, Germany
| | | | - Miyako Takaki
- Department of Physiology II, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8521 Japan
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Abstract
Ca(2+) signaling plays an essential role in several functions of cardiac myocytes. Transient rises and reductions of cytosolic Ca(2+), permitted by the sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) and other proteins, control each cycle of contraction and relaxation. Here we provide a practical method for isolation of neonatal rat cardiac myocytes and measurement of Ca(2+) transients in cultured cardiac myocytes, yielding information on kinetic resolution of the transients, variations of cytosolic Ca(2+) concentrations, and adequacy of intracellular Ca(2+) stores. We also provide examples of experimental perturbations that can be used to assess the contribution of SERCA2 to Ca(2+) signaling.
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Affiliation(s)
- Anand Mohan Prasad
- California Pacific Medical Center Research Institute, San Francisco, CA, USA
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Stanishevs'ka TI, Soboliev VI. [Characterization of the latent periods of excitation and shortening of anterior tibial muscle of white rats depending on the blood level of triiodothyronine]. Fiziol Zh (1994) 2012; 58:68-75. [PMID: 22590740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In experiments in situ it was shown an expressed negative correlation between the duration of latent periods of excitation and contraction of the anterior tibial muscle of white rats and the blood level of free triiodothyronine. The difference in mean values of latent periods at starting and final points of scale of physiological fluctuations of triiodothyronine level amounted 15.5% and 37.0% respectively. In parallel with lengthening of latent period of anterior tibial muscle excitation it was found an increase in latent period of this muscle contraction. Interestingly, at high values of the latent periods of excitation such dependence disappeared.
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Abstract
Can human muscle be highly efficient in vivo? Animal muscles typically show contraction-coupling efficiencies <50% in vitro but a recent study reports that the human first dorsal interosseous (FDI) muscle of the hand has an efficiency value in vivo of 68%. We examine two key factors that could account for this apparently high efficiency value: (1) transfer of cross-bridge work into mechanical work and (2) the use of elastic energy to do external work. Our analysis supports a high contractile efficiency reflective of nearly complete transfer of muscular to mechanical work with no contribution by recycling of elastic energy to mechanical work. Our survey of reported contraction-coupling efficiency values puts the FDI value higher than typical values found in small animals in vitro but within the range of values for human muscle in vivo. These high efficiency values support recent studies that suggest lower Ca(2+) cycling costs in working contractions and a decline in cost during repeated contractions. In the end, our analysis indicates that the FDI muscle may be exceptional in having an efficiency value on the higher end of that reported for human muscle. Thus, the FDI muscle may be an exception both in contraction-coupling efficiency and in Ca(2+) cycling costs, which makes it an ideal muscle model system offering prime conditions for studying the energetics of muscle contraction in vivo.
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Abstract
The heart has complex mechanisms that facilitate the maintenance of an oxygen supply-demand balance necessary for its contractile function in response to physiological fluctuations in workload as well as in response to chronic stresses such as hypoxia, ischemia, and overload. Redox-sensitive signaling pathways are centrally involved in many of these homeostatic and stress-response mechanisms. Here, we review the main redox-regulated pathways that are involved in cardiac myocyte excitation-contraction coupling, differentiation, hypertrophy, and stress responses. We discuss specific sources of endogenously generated reactive oxygen species (e.g., mitochondria and NADPH oxidases of the Nox family), the particular pathways and processes that they affect, the role of modulators such as thioredoxin, and the specific molecular mechanisms that are involved-where this knowledge is available. A better understanding of this complex regulatory system may allow the development of more specific therapeutic strategies for heart diseases.
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Key Words
- aif, apoptosis-inducing factor
- arc, apoptosis repressor with caspase recruitment domain
- camkii, calmodulin kinase ii
- ctgf, connective tissue growth factor
- eb, embryoid body
- ecc, excitation–contraction coupling
- er, endoplasmic reticulum
- es, embryonic stem
- etc, electron transport chain
- g6pdh, glucose-6-phosphate dehydrogenase
- gpcr, g-protein-coupled receptor
- hdac, histone deacetylase
- hif, hypoxia-inducible factor
- mao-a, monoamine oxidase-a
- mi, myocardial infarction
- mmp, matrix metalloproteinase
- mptp, mitochondrial permeability transition pore
- mtdna, mitochondrial dna
- ncx, na/ca exchanger
- nos, nitric oxide synthase
- phd, prolyl hydroxylase dioxygenase
- pka, protein kinase a
- pkc, protein kinase c
- pkg, protein kinase g
- ros, reactive oxygen species
- ryr, ryanodine receptor
- serca, sarcoplasmic reticulum calcium atpase
- sr, sarcoplasmic reticulum
- trx1, thioredoxin1
- tnfα, tumor necrosis factor-α
- vegf, vascular endothelial growth factor
- cardiac myocyte
- reactive oxygen species
- redox signaling
- hypertrophy
- heart failure
- nadph oxidase
- mitochondria
- free radicals
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Briston SJ, Caldwell JL, Horn MA, Clarke JD, Richards MA, Greensmith DJ, Graham HK, Hall MCS, Eisner DA, Dibb KM, Trafford AW. Impaired β-adrenergic responsiveness accentuates dysfunctional excitation-contraction coupling in an ovine model of tachypacing-induced heart failure. J Physiol 2011; 589:1367-82. [PMID: 21242250 PMCID: PMC3082097 DOI: 10.1113/jphysiol.2010.203984] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 01/10/2011] [Indexed: 01/08/2023] Open
Abstract
Reduced inotropic responsiveness is characteristic of heart failure (HF). This study determined the cellular Ca2+ homeostatic and molecular mechanisms causing the blunted β-adrenergic (β-AR) response in HF.We induced HF by tachypacing in sheep; intracellular Ca2+ concentration was measured in voltage-clamped ventricular myocytes. In HF, Ca2+ transient amplitude and peak L-type Ca2+ current (ICa-L) were reduced (to 70 ± 11% and 50 ± 3.7% of control, respectively, P <0.05) whereas sarcoplasmic reticulum (SR) Ca2+ content was unchanged. β-AR stimulation with isoprenaline (ISO) increased Ca2+ transient amplitude, ICa-L and SRCa2+ content in both cell types; however, the response of HF cells was markedly diminished (P <0.05).Western blotting revealed an increase in protein phosphatase levels (PP1, 158 ± 17% and PP2A, 188 ± 34% of control, P <0.05) and reduced phosphorylation of phospholamban in HF (Ser16, 30 ± 10% and Thr17, 41 ± 15% of control, P <0.05). The β-AR receptor kinase GRK-2 was also increased in HF (173 ± 38% of control, P <0.05). In HF, activation of adenylyl cyclase with forskolin rescued the Ca2+ transient, SR Ca2+ content and SR Ca2+ uptake rate to the same levels as control cells in ISO. In conclusion, the reduced responsiveness of the myocardium to β-AR agonists in HF probably arises as a consequence of impaired phosphorylation of key intracellular proteins responsible for regulating the SR Ca2+ content and therefore failure of the systolic Ca2+ transient to increase appropriately during β-AR stimulation.
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Affiliation(s)
- Sarah J Briston
- Unit of Cardiac Physiology, Manchester Academic Health Sciences Centre, University of Manchester, Manchester M13 9NT, UK
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Crossman DJ, Ruygrok PR, Soeller C, Cannell MB. Changes in the organization of excitation-contraction coupling structures in failing human heart. PLoS One 2011; 6:e17901. [PMID: 21408028 PMCID: PMC3052389 DOI: 10.1371/journal.pone.0017901] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/14/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The cardiac myocyte t-tubular system ensures rapid, uniform cell activation and several experimental lines of evidence suggest changes in the t-tubular system and associated excitation-contraction coupling proteins may occur in heart failure. METHODS AND RESULTS The organization of t-tubules, L-type calcium channels (DHPRs), ryanodine receptors (RyRs) and contractile machinery were examined in fixed ventricular tissue samples from both normal and failing hearts (idiopathic (non-ischemic) dilated cardiomyopathy) using high resolution fluorescent imaging. Wheat germ agglutinin (WGA), Na-Ca exchanger, DHPR and caveolin-3 labels revealed a shift from a predominantly transverse orientation to oblique and axial directions in failing myocytes. In failure, dilation of peripheral t-tubules occurred and a change in the extent of protein glycosylation was evident. There was no change in the fractional area occupied by myofilaments (labeled with phalloidin) but there was a small reduction in the number of RyR clusters per unit area. The general relationship between DHPRs and RyR was not changed and RyR labeling overlapped with 51±3% of DHPR labeling in normal hearts. In longitudinal (but not transverse) sections there was an ∼30% reduction in the degree of colocalization between DHPRs and RyRs as measured by Pearson's correlation coefficient in failing hearts. CONCLUSIONS The results show that extensive remodelling of the t-tubular network and associated excitation-contraction coupling proteins occurs in failing human heart. These changes may contribute to abnormal calcium handling in heart failure. The general organization of the t-system and changes observed in failure samples have subtle differences to some animal models although the general direction of changes are generally similar.
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Affiliation(s)
- David J. Crossman
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Peter R. Ruygrok
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
- Auckland City Hospital, Auckland, New Zealand
| | - Christian Soeller
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mark B. Cannell
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
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Pirone A, Schredelseker J, Tuluc P, Gravino E, Fortunato G, Flucher BE, Carsana A, Salvatore F, Grabner M. Identification and functional characterization of malignant hyperthermia mutation T1354S in the outer pore of the Cavalpha1S-subunit. Am J Physiol Cell Physiol 2010; 299:C1345-54. [PMID: 20861472 PMCID: PMC3006335 DOI: 10.1152/ajpcell.00008.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 09/16/2010] [Indexed: 11/22/2022]
Abstract
To identify the genetic locus responsible for malignant hyperthermia susceptibility (MHS) in an Italian family, we performed linkage analysis to recognized MHS loci. All MHS individuals showed cosegregation of informative markers close to the voltage-dependent Ca(2+) channel (Ca(V)) α(1S)-subunit gene (CACNA1S) with logarithm of odds (LOD)-score values that matched or approached the maximal possible value for this family. This is particularly interesting, because so far MHS was mapped to >178 different positions on the ryanodine receptor (RYR1) gene but only to two on CACNA1S. Sequence analysis of CACNA1S revealed a c.4060A>T transversion resulting in amino acid exchange T1354S in the IVS5-S6 extracellular pore-loop region of Ca(V)α(1S) in all MHS subjects of the family but not in 268 control subjects. To investigate the impact of mutation T1354S on the assembly and function of the excitation-contraction coupling apparatus, we expressed GFP-tagged α(1S)T1354S in dysgenic (α(1S)-null) myotubes. Whole cell patch-clamp analysis revealed that α(1S)T1354S produced significantly faster activation of L-type Ca(2+) currents upon 200-ms depolarizing test pulses compared with wild-type GFP-α(1S) (α(1S)WT). In addition, α(1S)T1354S-expressing myotubes showed a tendency to increased sensitivity for caffeine-induced Ca(2+) release and to larger action-potential-induced intracellular Ca(2+) transients under low (≤ 2 mM) caffeine concentrations compared with α(1S)WT. Thus our data suggest that an additional influx of Ca(2+) due to faster activation of the α(1S)T1354S L-type Ca(2+) current, in concert with higher caffeine sensitivity of Ca(2+) release, leads to elevated muscle contraction under pharmacological trigger, which might be sufficient to explain the MHS phenotype.
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Affiliation(s)
- Antonella Pirone
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, Innsbruck, Austria
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Affiliation(s)
- Lars S Maier
- Department of Cardiology & Pneumology/Heart Center, Georg-August-University Göttingen, Germany.
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Abstract
One of the main outcomes of aerobic endurance exercise training is the improved maximal oxygen uptake, and this is pivotal to the improved work capacity that follows the exercise training. Improved maximal oxygen uptake in turn is at least partly achieved because exercise training increases the ability of the myocardium to produce a greater cardiac output. In healthy subjects, this has been demonstrated repeatedly over many decades. It has recently emerged that this scenario may also be true under conditions of an initial myocardial dysfunction. For instance, myocardial improvements may still be observed after exercise training in post-myocardial infarction heart failure. In both health and disease, it is the changes that occur in the individual cardiomyocytes with respect to their ability to contract that by and large drive the exercise training-induced adaptation to the heart. Here, we review the evidence and the mechanisms by which exercise training induces beneficial changes in the mammalian myocardium, as obtained by means of experimental and clinical studies, and argue that these changes ultimately alter the function of the whole heart and contribute to the changes in whole-body function.
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Affiliation(s)
- O J Kemi
- Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
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Tuluc P, Molenda N, Schlick B, Obermair GJ, Flucher BE, Jurkat-Rott K. A CaV1.1 Ca2+ channel splice variant with high conductance and voltage-sensitivity alters EC coupling in developing skeletal muscle. Biophys J 2010; 96:35-44. [PMID: 19134469 DOI: 10.1016/j.bpj.2008.09.027] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Accepted: 09/22/2008] [Indexed: 11/17/2022] Open
Abstract
The Ca(2+) channel alpha(1S) subunit (Ca(V)1.1) is the voltage sensor in skeletal muscle excitation-contraction (EC) coupling. Upon membrane depolarization, this sensor rapidly triggers Ca(2+) release from internal stores and conducts a slowly activating Ca(2+) current. However, this Ca(2+) current is not essential for skeletal muscle EC coupling. Here, we identified a Ca(V)1.1 splice variant with greatly distinct current properties. The variant of the CACNA1S gene lacking exon 29 was expressed at low levels in differentiated human and mouse muscle, and up to 80% in myotubes. To test its biophysical properties, we deleted exon 29 in a green fluorescent protein (GFP)-tagged alpha(1S) subunit and expressed it in dysgenic (alpha(1S)-null) myotubes. GFP-alpha(1S)Delta 29 was correctly targeted into triads and supported skeletal muscle EC coupling. However, the Ca(2+) currents through GFP-alpha(1S)Delta 29 showed a 30-mV left-shifted voltage dependence of activation and a substantially increased open probability, giving rise to an eightfold increased current density. This robust Ca(2+) influx contributed substantially to the depolarization-induced Ca(2+) transient that triggers contraction. Moreover, deletion of exon 29 accelerated current kinetics independent of the auxiliary alpha(2)delta-1 subunit. Thus, characterizing the Ca(V)1.1 Delta 29 splice variant revealed the structural bases underlying the specific gating properties of skeletal muscle Ca(2+) channels, and it suggests the existence of a distinct mode of EC coupling in developing muscle.
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Affiliation(s)
- Petronel Tuluc
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria
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50
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Ziman AP, Gómez-Viquez NL, Bloch RJ, Lederer WJ. Excitation-contraction coupling changes during postnatal cardiac development. J Mol Cell Cardiol 2010; 48:379-86. [PMID: 19818794 PMCID: PMC3097073 DOI: 10.1016/j.yjmcc.2009.09.016] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 09/14/2009] [Accepted: 09/26/2009] [Indexed: 01/09/2023]
Abstract
Cardiac contraction is initiated by the release of Ca(2+) from intracellular stores in response to an action potential, in a process known as "excitation-contraction coupling" (ECC). Here we investigate the maturation of ECC in the rat heart during postnatal development. We provide new information on how proteins of the sarcoplasmic reticulum (SR) and the t-tubules (TTs) assemble to form the structures that support EC coupling during postnatal development. We show that the surface membrane protein, caveolin-3 (Cav3), is a good protein marker for TTs in ventricular myocytes and compared it quantitatively to junctophilin-2 (JP2), a protein found on the SR at sites of SR-TT junctions, or couplons. Although JP2 and Cav3 associate primarily with the SR and TTs, respectively, we found that they occupy the appropriate sites at maturing structures in synchrony, as visualized with high resolution, quantitative 3-dimensional imaging. We also found the surprising result that while both ryanodine receptor type 2, (RyR2) and JP2 proteins are localized to the same membrane and sub-compartments, they assume their positions at very different rates: RyR2 moves to the SR membrane at the Z-disc very early in development while JP2 only appears in the SR membrane as the TTs mature. Our data suggest that, although RyR2 appears to be prepositioned at the sites ultimately occupied by dyad junctions, JP2 arrives at these sites in synchrony with the development of the TTs at the Z-discs. Finally, we report that EC coupling efficiency changes with development, in concert with these structural changes. Thus we provide the first well-integrated information that links the developing organization of proteins underlying EC coupling (RyR2, DHPR, Cav3 and JP2) to the developing efficacy of EC coupling.
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Affiliation(s)
- Andrew P Ziman
- Medical Biotechnology Center, University of Maryland Biotechnology Institute, 725 West Lombard St Baltimore, MD 21201, USA
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