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Bolaños P, Calderón JC. Excitation-contraction coupling in mammalian skeletal muscle: Blending old and last-decade research. Front Physiol 2022; 13:989796. [PMID: 36117698 PMCID: PMC9478590 DOI: 10.3389/fphys.2022.989796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The excitation–contraction coupling (ECC) in skeletal muscle refers to the Ca2+-mediated link between the membrane excitation and the mechanical contraction. The initiation and propagation of an action potential through the membranous system of the sarcolemma and the tubular network lead to the activation of the Ca2+-release units (CRU): tightly coupled dihydropyridine and ryanodine (RyR) receptors. The RyR gating allows a rapid, massive, and highly regulated release of Ca2+ from the sarcoplasmic reticulum (SR). The release from triadic places generates a sarcomeric gradient of Ca2+ concentrations ([Ca2+]) depending on the distance of a subcellular region from the CRU. Upon release, the diffusing Ca2+ has multiple fates: binds to troponin C thus activating the contractile machinery, binds to classical sarcoplasmic Ca2+ buffers such as parvalbumin, adenosine triphosphate and, experimentally, fluorescent dyes, enters the mitochondria and the SR, or is recycled through the Na+/Ca2+ exchanger and store-operated Ca2+ entry (SOCE) mechanisms. To commemorate the 7th decade after being coined, we comprehensively and critically reviewed “old”, historical landmarks and well-established concepts, and blended them with recent advances to have a complete, quantitative-focused landscape of the ECC. We discuss the: 1) elucidation of the CRU structures at near-atomic resolution and its implications for functional coupling; 2) reliable quantification of peak sarcoplasmic [Ca2+] using fast, low affinity Ca2+ dyes and the relative contributions of the Ca2+-binding mechanisms to the whole concert of Ca2+ fluxes inside the fibre; 3) articulation of this novel quantitative information with the unveiled structural details of the molecular machinery involved in mitochondrial Ca2+ handing to understand how and how much Ca2+ enters the mitochondria; 4) presence of the SOCE machinery and its different modes of activation, which awaits understanding of its magnitude and relevance in situ; 5) pharmacology of the ECC, and 6) emerging topics such as the use and potential applications of super-resolution and induced pluripotent stem cells (iPSC) in ECC. Blending the old with the new works better!
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Affiliation(s)
- Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
- *Correspondence: Juan C. Calderón,
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Elementary calcium release events in the skeletal muscle cells of the honey bee Apis mellifera. Sci Rep 2021; 11:16731. [PMID: 34408196 PMCID: PMC8373864 DOI: 10.1038/s41598-021-96028-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 08/04/2021] [Indexed: 11/28/2022] Open
Abstract
Calcium sparks are involved in major physiological and pathological processes in vertebrate muscles but have never been characterized in invertebrates. Here, dynamic confocal imaging on intact skeletal muscle cells isolated enzymatically from the adult honey bee legs allowed the first spatio-temporal characterization of subcellular calcium release events (CREs) in an insect species. The frequency of CREs, measured in x–y time lapse series, was higher than frequencies usually described in vertebrates. Honey bee CREs had a larger spatial spread at half maximum than their vertebrate counterparts and a slightly ellipsoidal shape, two characteristics that may be related to ultrastructural features specific to invertebrate cells. In line-scan experiments, the histogram of CREs’ duration followed a bimodal distribution, supporting the existence of both sparks and embers. Unlike in vertebrates, embers and sparks had similar amplitudes, a difference that could be related to genomic differences and/or excitation–contraction coupling specificities in honey bee skeletal muscle fibres. The first characterization of CREs from an arthropod which shows strong genomic, ultrastructural and physiological differences with vertebrates may help in improving the research field of sparkology and more generally the knowledge in invertebrates cell Ca2+ homeostasis, eventually leading to a better understanding of their roles and regulations in muscles but also the myotoxicity of new insecticides targeting ryanodine receptors.
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Lamboley CRH, Kake Guena SA, Touré F, Hébert C, Yaddaden L, Nadeau S, Bouchard P, Wei-LaPierre L, Lainé J, Rousseau EC, Frenette J, Protasi F, Dirksen RT, Pape PC. New method for determining total calcium content in tissue applied to skeletal muscle with and without calsequestrin. ACTA ACUST UNITED AC 2015; 145:127-53. [PMID: 25624449 PMCID: PMC4306712 DOI: 10.1085/jgp.201411250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The concentration of total calcium in a skeletal muscle appears to be correlated with the muscle’s likely force requirements given by the ratio of body weight to muscle weight. We describe a new method for determining the concentration of total Ca in whole skeletal muscle samples ([CaT]WM in units of mmoles/kg wet weight) using the Ca-dependent UV absorbance spectra of the Ca chelator BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid). Muscle tissue was homogenized in a solution containing 0.15 mM BAPTA and 0.5% sodium dodecyl sulfate (to permeabilize membranes and denature proteins) and then centrifuged. The solution volume was adjusted so that BAPTA captured essentially all of the Ca. [CaT]WM was obtained with Beer’s law from the absorbance change produced by adding 1 mM EGTA to capture Ca from BAPTA. Results from mouse, rat, and frog muscles were reasonably consistent with results obtained using other methods for estimating total [Ca] in whole muscles and in single muscle fibers. Results with external Ca removed before determining [CaT]WM indicate that most of the Ca was intracellular, indicative of a lack of bound Ca in the extracellular space. In both fast-twitch (extensor digitorum longus, EDL) and slow-twitch (soleus) muscles from mice, [CaT]WM increased approximately linearly with decreasing muscle weight, increasing approximately twofold with a twofold decrease in muscle weight. This suggests that the Ca concentration of smaller muscles might be increased relative to that in larger muscles, thereby increasing the specific force to compensate for the smaller mass. Knocking out the high capacity Ca-binding protein calsequestrin (CSQ) did not significantly reduce [CaT]WM in mouse EDL or soleus muscle. However, in EDL muscles lacking CSQ, muscle weights were significantly lower than in wild-type (WT) muscles and the values of [CaT]WM were, on average, about half the expected WT values, taking into account the above [CaT]WM versus muscle weight relationship. Because greater reductions in [CaT]WM would be predicted in both muscle types, we hypothesize that there is a substantial increase in Ca bound to other sites in the CSQ knockout muscles.
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Affiliation(s)
- Cédric R H Lamboley
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria 8001, Australia
| | - Sandrine A Kake Guena
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Fatou Touré
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Camille Hébert
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Louiza Yaddaden
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Stephanie Nadeau
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Patrice Bouchard
- Département de Réadaptation, Université Laval, Québec G1K 7P4, Canada
| | - Lan Wei-LaPierre
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642
| | - Jean Lainé
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Eric C Rousseau
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | - Jérôme Frenette
- Département de Réadaptation, Université Laval, Québec G1K 7P4, Canada
| | - Feliciano Protasi
- Center for Research on Aging and Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, I-66100 Chieti, Italy
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642
| | - Paul C Pape
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médicine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
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Solis R, Carrillo ED, Hernández A, García MC, Sánchez JA. Parvalbumin is overexpressed in the late phase of pharmacological preconditioning in skeletal muscle. Can J Physiol Pharmacol 2013; 91:966-72. [PMID: 24117265 DOI: 10.1139/cjpp-2013-0113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pharmacological preconditioning (PPC) with mitochondrial ATP-sensitive K(+) channel openers such as diazoxide, provides protection against ischemia in cardiac muscle, skeletal muscle, and other tissues. Effects on Ca(2+) homeostasis during the late phase of PPC have been described in cardiomyocytes, but no information is available regarding intracellular Ca(2+) changes in skeletal muscle fibers during late PPC. Intracellular Ca(2+) signals were measured in single fibers of adult mouse skeletal muscle, with fluorescent probes, 48 h after the administration of diazoxide. Parvalbumin levels in the myofibers were quantitated by Western blot. Diazoxide induction of late PPC was confirmed by partial protection of muscles from peroxide-induced damage. Late PPC was associated with a significant decrease in the duration of Ca(2+) signals during single twitches and tetanus with no changes in peak values. This effect was prevented by the reactive oxygen species (ROS) scavenger tiron. Late PPC was accompanied by a 30% increase in parvalbumin levels, and this effect was also blocked by tiron. Our data show, for the first time, a role of parvalbumin in late PPC in skeletal muscle.
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Affiliation(s)
- Rosario Solis
- Departamento de Farmacología. Centro de Investigación y de Estudios Avanzados del I.P.N., México, D.F. 07360
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Heyer WR, Heyer MM. Systematics, distribution, and bibliography of the frogLeptodactylus insularumBarbour, 1906 (Amphibia: Leptodactylidae). P BIOL SOC WASH 2013. [DOI: 10.2988/0006-324x-126.3.204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Biomechanics of the sarcolemma and costameres in single skeletal muscle fibers from normal and dystrophin-null mice. J Muscle Res Cell Motil 2011; 31:323-36. [PMID: 21312057 DOI: 10.1007/s10974-011-9238-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 01/11/2011] [Indexed: 01/01/2023]
Abstract
We studied the biomechanical properties of the sarcolemma and its links through costameres to the contractile apparatus in single mammalian myofibers of Extensor digitorum longus muscles isolated from wild (WT) and dystrophin-null (mdx) mice. Suction pressures (P) applied through a pipette to the sarcolemma generated a bleb, the height of which increased with increasing P. Larger increases in P broke the connections between the sarcolemma and myofibrils and eventually caused the sarcolemma to burst. We used the values of P at which these changes occurred to estimate the tensions and stiffness of the system and its individual elements. Tensions of the whole system and the sarcolemma, as well as the maximal tension sustained by the costameres, were all significantly lower (1.8-3.3 fold) in muscles of mdx mice compared to WT. Values of P at which separation and bursting occurred, as well as the stiffness of the whole system and of the isolated sarcolemma, were ~2-fold lower in mdx than in WT. Our results indicate that the absence of dystrophin reduces muscle stiffness, increases sarcolemmal deformability, and compromises the mechanical stability of costameres and their connections to nearby myofibrils.
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Estève E, Eltit JM, Bannister RA, Liu K, Pessah IN, Beam KG, Allen PD, López JR. A malignant hyperthermia-inducing mutation in RYR1 (R163C): alterations in Ca2+ entry, release, and retrograde signaling to the DHPR. ACTA ACUST UNITED AC 2010; 135:619-28. [PMID: 20479110 PMCID: PMC2888056 DOI: 10.1085/jgp.200910328] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bidirectional signaling between the sarcolemmal L-type Ca(2+) channel (1,4-dihydropyridine receptor [DHPR]) and the sarcoplasmic reticulum (SR) Ca(2+) release channel (type 1 ryanodine receptor [RYR1]) of skeletal muscle is essential for excitation-contraction coupling (ECC) and is a well-understood prototype of conformational coupling. Mutations in either channel alter coupling fidelity and with an added pharmacologic stimulus or stress can trigger malignant hyperthermia (MH). In this study, we measured the response of wild-type (WT), heterozygous (Het), or homozygous (Hom) RYR1-R163C knock-in mouse myotubes to maintained K(+) depolarization. The new findings are: (a) For all three genotypes, Ca(2+) transients decay during prolonged depolarization, and this decay is not a consequence of SR depletion or RYR1 inactivation. (b) The R163C mutation retards the decay rate with a rank order WT > Het > Hom. (c) The removal of external Ca(2+) or the addition of Ca(2+) entry blockers (nifedipine, SKF96365, and Ni(2+)) enhanced the rate of decay in all genotypes. (d) When Ca(2+) entry is blocked, the decay rates are slower for Hom and Het than WT, indicating that the rate of inactivation of ECC is affected by the R163C mutation and is genotype dependent (WT > Het > Hom). (e) Reduced ECC inactivation in Het and Hom myotubes was shown directly using two identical K(+) depolarizations separated by varying time intervals. These data suggest that conformational changes induced by the R163C MH mutation alter the retrograde signal that is sent from RYR1 to the DHPR, delaying the inactivation of the DHPR voltage sensor.
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Affiliation(s)
- Eric Estève
- Department of Anesthesiology Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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Solares-Pérez A, Sánchez JA, Zentella-Dehesa A, García MC, Coral-Vázquez RM. Intracellular Ca2+ transients in delta-sarcoglycan knockout mouse skeletal muscle. Biochim Biophys Acta Gen Subj 2009; 1800:373-9. [PMID: 19931597 DOI: 10.1016/j.bbagen.2009.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 11/10/2009] [Accepted: 11/11/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND delta-Sarcoglycan (delta-SG) knockout (KO) mice develop skeletal muscle histopathological alterations similar to those in humans with limb muscular dystrophy. Membrane fragility and increased Ca(2+) permeability have been linked to muscle degeneration. However, little is known about the mechanisms by which genetic defects lead to disease. METHODS Isolated skeletal muscle fibers of wild-type and delta-SG KO mice were used to investigate whether the absence of delta-SG alters the increase in intracellular Ca(2+) during single twitches and tetani or during repeated stimulation. Immunolabeling, electrical field stimulation and Ca(2+) transient recording techniques with fluorescent indicators were used. RESULTS Ca(2+) transients during single twitches and tetani generated by muscle fibers of delta-SG KO mice are similar to those of wild-type mice, but their amplitude is greatly decreased during protracted stimulation in KO compared to wild-type fibers. This impairment is independent of extracellular Ca(2+) and is mimicked in wild-type fibers by blocking store-operated calcium channels with 2-aminoethoxydiphenyl borate (2-APB). Also, immunolabeling indicates the localization of a delta-SG isoform in the sarcoplasmic reticulum of the isolated skeletal muscle fibers of wild-type animals, which may be related to the functional differences between wild-type and KO muscles. CONCLUSIONS delta-SG has a role in calcium homeostasis in skeletal muscle fibers. GENERAL SIGNIFICANCE These results support a possible role of delta-SG on calcium homeostasis. The alterations caused by the absence of delta-SG may be related to the pathogenesis of muscular dystrophy.
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Affiliation(s)
- Alhondra Solares-Pérez
- Unidad de Investigación Médica en Genética Humana, Hospital de Pediatría, CMN Siglo XXI-IMSS, México, D.F., Mexico
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Yang T, Allen PD, Pessah IN, Lopez JR. Enhanced excitation-coupled calcium entry in myotubes is associated with expression of RyR1 malignant hyperthermia mutations. J Biol Chem 2007; 282:37471-8. [PMID: 17942409 DOI: 10.1074/jbc.m701379200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myotubes expressing wild type RyR1 (WT) or RyR1 with one of three malignant hyperthermia mutations R615C, R2163C, and T4826I (MH) were exposed sequentially to 60 mm KCl in Ca(2+)-replete and Ca(2+)-free external buffers (Ca+ and Ca-, respectively) with 3 min of rest between exposures. Although the maximal peak amplitude of the Ca(2+) transients during K(+) depolarization was similar for WT and MH in both external buffers, the rate of decay of the sustained phase of the transient during K(+) depolarization (decay rate) in Ca+ was 50% slower for MH. This difference was eliminated in Ca-, and the relative decay rates were faster for both genotypes than in Ca+. The integrated Ca(2+) transient in Ca-compared with Ca+ was reduced by 50-60% for MH and 20% for WT. The decay rate was not affected by [K(+)] x [Cl(-)] product or NiCl(2) (2 mm) supplementation of Ca-. The addition of La(2+) (0.1 mm), or SKF 96365 (20 microm) to Ca+ significantly accelerated decay rates for both WT and MH, but their effect was significantly greater in MH. Nifedipine (1 microm) had no effect, suggesting that the mechanism for this difference was not a reduction in L-type Ca(2+) channel Ca(2+) current. These data strongly suggest: 1) the decay rate in skeletal myotubes is related in part to Ca(2+) entry through the ECCE channel; 2) the MH mutations enhance ECCE compared with wild type; and 3) the increased Ca(2+) entry might play a significant role in the pathophysiology of MH.
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Affiliation(s)
- Tianzhong Yang
- Department of Anesthesiology Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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Zaldivar D, García MC, Sánchez JA. Ciliary neurotrophic factor promotes inactivation of muscle Ca2+ channels via PKC. Biochem Biophys Res Commun 2005; 338:1572-7. [PMID: 16274672 DOI: 10.1016/j.bbrc.2005.10.125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Accepted: 10/21/2005] [Indexed: 01/15/2023]
Abstract
The actions of the ciliary neurotrophic factor (CNTF) were assessed on adult mouse skeletal muscle L-type Ca2+ currents and on Ca2+ release from sarcoplasmic reticulum. Currents were measured with the whole cell patch clamp technique. Ca2+ signals in response to single action potentials were recorded with Fluo3-AM. CNTF (20 ng/ml) reversibly reduced the amplitude of Ca2+ channel currents by 50% within 15 min. In addition, CNTF greatly increased the rate of inactivation during depolarizing pulses and shifted the steady state inactivation curve by -12 mV. The effects of CNTF were mimicked by the PKC activator PMA and prevented by the PKC-inhibitor chelerythrine. In contrast to the effects on the Ca2+ conductance, charge movement and Ca2+ signals remained unaffected by CNTF. These results suggest that CNTF can rapidly decrease muscle Ca2+ channel currents by promoting inactivation, probably through an intracellular PKC-dependent mechanism.
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Affiliation(s)
- Daniel Zaldivar
- Departmento de Farmacología, Centro de Investigación y de Estudios Avanzados del I.P.N., México, DF 07360, Mexico
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11
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García MC, Carrillo E, Galindo JM, Hernández A, Copello JA, Fill M, Sánchez JA. Short-term regulation of excitation-contraction coupling by the beta1a subunit in adult mouse skeletal muscle. Biophys J 2005; 89:3976-84. [PMID: 16183888 PMCID: PMC1366963 DOI: 10.1529/biophysj.105.067116] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The beta1a subunit of the skeletal muscle voltage-gated Ca2+ channel plays a fundamental role in the targeting of the channel to the tubular system as well as in channel function. To determine whether this cytosolic auxiliary subunit is also a regulatory protein of Ca2+ release from the sarcoplasmic reticulum in vivo, we pressure-injected the beta1a subunit into intact adult mouse muscle fibers and recorded, with Fluo-3 AM, the intracellular Ca2+ signal induced by the action potential. We found that the beta1a subunit significantly increased, within minutes, the amplitude of Ca2+ release without major changes in its time course. beta1a subunits with the carboxy-terminus region deleted did not show an effect on Ca2+ release. The possibility that potentiation of Ca2+ release is due to a direct interaction between the beta1a subunit and the ryanodine receptor was ruled out by bilayer experiments of RyR1 single-channel currents and also by Ca2+ flux experiments. Our data suggest that the beta1a subunit is capable of regulating E-C coupling in the short term and that the integrity of the carboxy-terminus region is essential for its modulatory effect.
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Affiliation(s)
- María C García
- Departmento de Farmacología, Centro de Investigación y de Estudios Avanzados del I.P.N., Mexico, D.F. 07360, Mexico
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12
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Caputo C, Bolaños P, Gonzalez A. Inactivation of Ca2+ transients in amphibian and mammalian muscle fibres. J Muscle Res Cell Motil 2005; 25:315-28. [PMID: 15548860 DOI: 10.1007/s10974-004-4071-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
MagFluo-4 fluorescence (Ca2+) transients associated with action potentials were measured in intact muscle fibres, manually dissected from toads ( Leptodactylus insularis ) or enzymatically dissociated from mice. In toads, the decay phase of the Ca2+ transients is described by a single exponential with a time constant ( tau ) of about 7 ms. In mice, a double exponential function with tau 's of 1.5 and 15.5 ms, respectively gives a better fit. In both species the amplitude of Ca2+ transients diminished during repetitive stimulation: in amphibian muscle fibres, the decrease was about 20% with 1 Hz stimulation and 55% at 10 Hz. In mammalian fibres, repetitive stimulation causes a less conspicuous decrease of the transient amplitude: 10% at 1 Hz and 15% at 10 Hz. During tetanic stimulation at 100 Hz the transient amplitude decays to 20% in toad fibres and 40% in mouse fibres. This decrease could be associated with the phenomenon of inactivation of Ca2+ release, described by other authors. Recovery from inactivation, studied by a double stimuli protocol also indicates that in toad fibres the ability to release Ca2+ is abolished to a greater extent than in mouse fibres. In fact the ratio between the amplitudes of the second and first transient, when they are separated by a 10 ms interval, is 0.29 for toad and 0.58 for mouse fibres. In toad fibres, recovery from inactivation, to about 80 % of the initial value, occurs with a tau of 32 ms at 22 degrees C; while in mouse fibres recovery from inactivation is almost complete and occurs with a tau of 36 ms under the same conditions. The results indicate that Ca2+ release in enzymatically dissociated mammalian muscle fibres inactivates to a smaller extent than in intact amphibian muscle fibres.
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Affiliation(s)
- Carlo Caputo
- Centro de Biofisica y Bioquimica, Instituto Venezolano de Investigaciones Cientificas IVIC, Apartado 21827, Caracas, Venezuela.
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Kerrick WGL, Xu Y. Inorganic phosphate affects the pCa-force relationship more than the pCa-ATPase by increasing the rate of dissociation of force generating cross-bridges in skinned fibers from both EDL and soleus muscles of the rat. J Muscle Res Cell Motil 2005; 25:107-17. [PMID: 15360126 DOI: 10.1023/b:jure.0000035841.04314.16] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of inorganic phosphate (Pi) on Ca2+ -activation of actomyosin ATPase activity and force in permeabilized (skinned) single extensor digitorum longus (EDL) and soleus muscle fibers of the rat were investigated. Increasing concentrations of Pi decreased force more than ATPase rate at all Ca2+ concentrations and this effect was more pronounced at submaximal Ca2+ -activation. Increasing Pi caused both the normalized pCa-ATPase and pCa-force relationship to be shifted to a higher Ca2+ concentration. At all Ca2+ concentrations ATPase was activated at a lower concentration of Ca2+ than force and this difference in Ca2+ concentration required for the activation of ATPase and force was greater in fast-twitch (EDL) than in slow twitch (soleus) muscle. Soleus muscle pCa-ATPase and pCa-force curves were more sensitive to Ca2+ (pCa50 = 5.97 and 5.89, respectively) than EDL (pCa50 = 5.68 and 5.54, respectively). Finally the shape of the pCa-ATPase and pCa-force curves was similar and not affected by Pi. Analysis shows that Pi increases the rate of dissociation of force generating myosin cross-bridges (ratio of ATPase/force (g(app at all Ca2+ concentration, especially at submaximal Ca2+ -activation levels. Pi effects on g(app) are discussed in terms Pi interacting with the isomerization high force AM*ADP states to form high force transitional AM*ADP*Pi* states which facilitate the dissociation of ADP from AM*ADP. Increasing Ca2+ during Ca2+ -activation of the fibers is associated with a progressive decrease in rate of dissociation of force generating myosin cross-bridges g(app).
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Affiliation(s)
- W Glenn L Kerrick
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, FL 33101, USA.
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Chawla S, Skepper JN, Huang CLH. Differential effects of sarcoplasmic reticular Ca(2+)-ATPase inhibition on charge movements and calcium transients in intact amphibian skeletal muscle fibres. J Physiol 2002; 539:869-82. [PMID: 11897856 PMCID: PMC2290190 DOI: 10.1113/jphysiol.2001.013095] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A hypothesis in which intramembrane charge reflects a voltage sensing process allosterically coupled to transitions in ryanodine receptor (RyR)-Ca(2+) release channels as opposed to one driven by release of intracellularly stored Ca(2+) would predict that such charging phenomena should persist in skeletal muscle fibres unable to release stored Ca(2+). Charge movement components were accordingly investigated in intact voltage-clamped amphibian fibres treated with known sarcoplasmic reticular (SR) Ca(2+)-ATPase inhibitors. Cyclopiazonic acid (CPA) pretreatment abolished Ca(2+) transients in fluo-3-loaded fibres following even prolonged applications of caffeine (10 mM) or K(+) (122 mM). Both CPA and thapsigargin (TG) transformed charge movements that included delayed (q(gamma)) "hump" components into simpler decays. However, steady-state charge-voltage characteristics were conserved to values (maximum charge, Q(max) approximately equal to 20-25 nC microF(-1); transition voltage, V* approximately equal to -40 to-50 mV; steepness factor, k approximately equal to 6-9 mV; holding voltage -90 mV) indicating persistent q(gamma) charge. The features of charge inactivation similarly suggested persistent q(beta) and q(gamma) charge contributions in CPA-treated fibres. Perchlorate (8.0 mM) restored the delayed kinetics shown by "on" q(gamma) charge movements, prolonged their "off" decays, conserved both Q(max) and k, yet failed to restore the capacity of such CPA-treated fibres for Ca(2+) release. Introduction of perchlorate (8.0 mM) or caffeine (0.2 mM) to tetracaine (2.0 mM)-treated fibres, also known to restore q(gamma) charge, similarly failed to restore Ca(2+) transients. Steady-state intramembrane q(gamma) charge thus persists with modified kinetics that can be restored to its normally complex waveform by perchlorate, even in intact muscle fibres unable to release Ca(2+). It is thus unlikely that q(gamma) charge movement is a consequence of SR Ca(2+) release rather than changes in tubular membrane potential.
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Affiliation(s)
- Sangeeta Chawla
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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Caputo C, Bolaños P, Escobar AL. Fast calcium removal during single twitches in amphibian skeletal muscle fibres. J Muscle Res Cell Motil 1999; 20:555-67. [PMID: 10555074 DOI: 10.1023/a:1005526202747] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Fluorescence signals from the calcium sensitive dyes Fluo-3 or Rhod-2 were obtained simultaneously with isometric tension in single fibres isolated from the anterior tibialis muscle of Leptodactylus insularis (20-22 degrees C). Fluo-3 fluorescence signals were transformed into [Ca2+]i transients as previously described. Most of the decay phase of single twitch transient is well fitted by a single exponential (tau of about 10 ms), followed by a slower declining component lasting tens of milliseconds. During short periods, 10 to 20 s, of low frequency stimulation, between 0.2 and 5 Hz, the basal [Ca2+]i increased slowly from 0.1 to about 0.4 microM, with only minor changes in the exponentially decaying phase. In fibres poisoned with thapsigargin or cyclopiazonic acid (1-2 microM) the tau of decay of fluorescence or Ca2+ transients of single twitches was very similar to that observed in non-poisoned fibres. Nevertheless, in poisoned fibres challenged with repetitive stimulation. the tau of Ca2+ transients decay increased from about 10 ms to >40 ms, while the basal [Ca2+]i increased from 0.1 to 2 microM. Short rest periods (about 5 min) could reverse these effects, indicating that they were not a direct consequence of SR Ca 2+ -ATPase inhibition. The correlation coefficient between tau of decay and basal [Ca2+]i was >0.8 (P<0.0001). Qualitatively similar results were obtained measuring Rhod-2 fluorescence signals. A lumped, two-compartment model could account for these results. Loading the fibres with EGTA-AM, diminished the effects of prolonged stimulation observed in poisoned fibres. Moreover, we show that the Na+ - Ca2+ exchange mechanism does not participate appreciably in fast Ca2+ removal.
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Affiliation(s)
- C Caputo
- Laboratorio de Biofísica del Músculo, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, IVIC, Caracas, Venezuela
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Murrant CL, Andrade FH, Reid MB. Exogenous reactive oxygen and nitric oxide alter intracellular oxidant status of skeletal muscle fibres. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 166:111-21. [PMID: 10383490 DOI: 10.1046/j.1365-201x.1999.00555.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To test whether exogenous oxidants alter intracellular oxidant levels in skeletal muscle fibres, we exposed rat diaphragm to donors of nitric oxide (NOx), reactive oxygen species (ROS) or hyperoxia, and monitored intracellular oxidant levels using a fluorescent probe. Fibre bundles were dissected from the diaphragm and loaded with 2', 7'-dichlorodihydrofluorescein (DCFH); emissions were monitored using a fluorescence microscope. DCFH-loaded muscles were exposed to either a NOx donor (1 mM S-nitroso-N-acetyl penicillamine, SNAP; 1 mM sodium nitroprusside, SNP; 400 microM 1-hydroxy-2-oxo-3-(N-3-methyl-aminopropyl)-3-methyl-1-triazen, NOC-7), an ROS donor (100 microM hydrogen peroxide, H2O2; 100 microM tert-butyl hydroperoxide; 1 mM hypoxanthine plus 0.01 U mL-1 xanthine oxidase, HXXO) or a range of PO2s (25, 60 or 95% O2 oxygenating Krebs-Ringer solution) for 40 min; time-matched control bundles remained in Krebs-Ringer solution. Control muscles oxidized DCFH at a rate of 0.32 +/- 0.1 greyscale units min-1. SNAP (766%), SNP (1244%), NOC-7 (851%), H2O2 (543%), and HXXO (541%) increased DCFH oxidation from control levels. The increase in emissions caused by NOC-7 and SNP were blunted by the NOx scavenger haemoglobin (1 microM). DCFH oxidation by HXXO was unaffected by 1000 U mL-1 superoxide dismutase but was significantly decreased by 1000 U mL-1 catalase and 1 mM salicylate. PO2 had no effect on intracellular oxidant levels. Therefore, extracellular NOx and ROS can alter intracellular oxidant status in skeletal muscle fibres. These observations suggest that intrafibre oxidant levels could be the result of both intracellular and extracellular oxidant production.
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Affiliation(s)
- C L Murrant
- Pulmonary and Critical Care Section, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
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Yamaguchi I, Ichikawa K. A novel method of estimating real [Ca2+]i dynamics from fluorescence signals. Neurosci Res 1998; 30:91-8. [PMID: 9572584 DOI: 10.1016/s0168-0102(97)00122-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To detect changes in the concentration of intracellular calcium ions ([Ca2+]i), fluorescence measurement techniques are used in experimental studies. When the calcium concentration is calculated from fluorescence signals, an equilibrium between calcium ions and the fluorescent dye is assumed in conventional methods. However, using this assumption, calculated calcium concentrations would not be an accurate representation of [Ca2+]i if the dynamics of [Ca2+]i are so fast that the reaction between calcium ions and the dye cannot reach equilibrium. In this report, we propose a new method of estimating [Ca2+]i in dye-free conditions from fluorescence signals of the dye using differential equations expressing reactions between calcium ions and the dye without assuming equilibrium. We compared our method with a conventional method with respect to calculations of [Ca2+]i using a model of a dendritic spine. Simulation results showed that our method gave a better estimation of the changes in [Ca2+]i than did the conventional method.
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Affiliation(s)
- I Yamaguchi
- Foundation Research Laboratory, Corporate Research Laboratories, Fuji Xerox Co. Ltd., Kanagawa, Japan
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Même W, Huchet-Cadiou C, Léoty C. Cyclopiazonic acid-induced changes in the contraction and Ca2+ transient of frog fast-twitch skeletal muscle. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:C253-61. [PMID: 9458735 DOI: 10.1152/ajpcell.1998.274.1.c253] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The effects of cyclopiazonic acid (CPA) were investigated on isolated skeletal muscle fibers of frog semitendinosus muscle. CPA (0.5-10 microM) enhanced isometric twitch but produced little change in resting tension. At higher concentrations (10-50 microM), CPA depressed twitch and induced sustained contracture without affecting resting and action potentials. In Triton-skinned fibers, CPA had no significant effect on myofibrillar Ca2+ sensitivity but decreased maximal activated force at concentrations > 5 microM. In intact cells loaded with the Ca2+ fluorescence indicator indo 1, CPA (2 microM) induced an increase in Ca(2+)-transient amplitude (10 +/- 2.5%), which was associated with an increase in time to peak and in the time constant of decay. Consequently, peak force was increased by 35 +/- 4%, and both time to peak and the time constant of relaxation were prolonged. It is concluded that CPA effects, at a concentration of up to 2 microM, were associated with specific inhibition of sarcoplasmic reticulum Ca(2+)-adenosinetriphosphatase in intact skeletal muscle and that inhibition of the pump directly affected the handling of intracellular Ca2+ and force production.
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Affiliation(s)
- W Même
- Laboratoire de Physiologie Générale, Centre National de la Recherche Scientifique, ERS 6107, Faculté des Sciences et des Techniques, Nantes, France
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Herlofson BB, Brodin P, Røed A. The effects of sodium lauryl sulfate on the phrenic nerve diaphragm preparation from the rat. PHARMACOLOGY & TOXICOLOGY 1996; 79:217-24. [PMID: 8936553 DOI: 10.1111/j.1600-0773.1996.tb00263.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The time period to 50% inhibition of the twitches and compound action potential of the rat phrenic nerve-diaphragm preparation with sodium lauryl sulfate (2.5 x 10(-4)-5.0 x 10(-3)M) was recorded. The twitch contractions during indirect stimulation, the contraction during direct stimulation, and the compound action potential of the isolated phrenic nerve, were inhibited in that order. Depolarization due to high action potential activity induced by tetanic stimulation, veratridine, low Ca(2+)-or high K(+)-solutions, all enhanced the inhibitory effect of sodium lauryl sulfate (5.0 x 10(-4)M) during indirect stimulation. Hyperpolarization in K(+)-free solution and membrane stabilization by lidocaine antagonized the inhibitory effect of sodium lauryl sulfate. Accordingly, it probably induced inhibition by depolarization. The depolarization may decrease the influx of Ca2+ and the reuptake of choline+, as suggested by an observed synergism with tetraethylammonium CI and hemicholinium-3 Br, which antagonize the reuptake of choline+. On the opposite, 3,4-diaminopyridine, which increases the influx of Ca2+, antagonized the sodium lauryl sulfate-induced inhibition, and induced a biphasic contracture. The first phase was probably caused by a depolarization, and the second phase by release of Ca2+ from the sarcoplasmic reticulum. The potentiation of the second phase by dantrolene and in low Ca2+ solution, was attributed to sodium lauryl sulfate-induced desensitization.
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Affiliation(s)
- B B Herlofson
- Department of Oral Surgery, Dental Faculty, University of Oslo, Norway
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Kim AM, DiFranco M, Vergara JL. A gap isolation method to investigate electrical and mechanical properties of fully contracting skeletal muscle fibers. Biophys J 1996; 71:924-31. [PMID: 8842232 PMCID: PMC1233550 DOI: 10.1016/s0006-3495(96)79296-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We describe here a single-gap isolation method that allows the simultaneous measurement of electrical activity and tension output from fully contracting segments of frog skeletal muscle fibers. By using single pulses and pulse trains of varying frequency (5-100 Hz), records obtained for both electrical and mechanical fiber response demonstrate that the physiological properties of the fiber segments have been preserved. Action potentials could be recorded free of movement artifacts, even while segments were in fused tetani and developing maximum tensions of more than 600 kN/m2. Single current pulses evoked action potentials that averaged 144 +/- 16 mV (mean +/- SD, n = 8) in amplitude and twitches that averaged 285 +/- 66 kN/m2 and 55 +/- 5 ms (mean +/- SD, n = 20) in magnitude and time to peak, respectively. Trains of action potentials elicited patterns of tension development that exhibited summation, unfused tetani, and fused tetani in a frequency-dependent manner. The AC and DC electrical properties of the single grease gap were modeled with a simple Thévenin equivalent circuit, which satisfactorily predicted the experimental results. Our methodology is easily implemented and potentially applicable to any muscle preparation in which fiber segments with an intact end attached to a piece of tendon can be dissected.
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Affiliation(s)
- A M Kim
- Department of Physiology, School of Medicine, University of California at Los Angeles 90095, USA
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