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Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers

The effects of the muscle relaxant dantrolene on steps of excitation-contraction coupling were studied on fast twitch muscles of rodents. To identify the site of action of the drug, single fibers for voltage-clamp measurements, heavy SR vesicles for calcium efflux studies and solubilized SR calcium...

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Autores principales: Szentesi, Péter, Collet, Claude, Sárközi, Sándor, Szegedi, Csaba, Jona, István, Jacquemond, Vincent, Kovács, László, Csernoch, László
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2001
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233700/
https://www.ncbi.nlm.nih.gov/pubmed/11585849
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author Szentesi, Péter
Collet, Claude
Sárközi, Sándor
Szegedi, Csaba
Jona, István
Jacquemond, Vincent
Kovács, László
Csernoch, László
author_facet Szentesi, Péter
Collet, Claude
Sárközi, Sándor
Szegedi, Csaba
Jona, István
Jacquemond, Vincent
Kovács, László
Csernoch, László
author_sort Szentesi, Péter
collection PubMed
description The effects of the muscle relaxant dantrolene on steps of excitation-contraction coupling were studied on fast twitch muscles of rodents. To identify the site of action of the drug, single fibers for voltage-clamp measurements, heavy SR vesicles for calcium efflux studies and solubilized SR calcium release channels/RYRs for lipid bilayer studies were isolated. Using the double Vaseline-gap or the silicone-clamp technique, dantrolene was found to suppress the depolarization-induced elevation in intracellular calcium concentration ([Ca(2)+](i)) by inhibiting the release of calcium from the SR. The suppression of [Ca(2)+](i) was dose-dependent, with no effect at or below 1 μM and a 53 ± 8% (mean ± SEM, n = 9, cut fibers) attenuation at 0 mV with 25 μM of extracellularly applied dantrolene. The drug was not found to be more effective if injected than if applied extracellularly. Calculating the SR calcium release revealed an equal suppression of the steady (53 ± 8%) and of the early peak component (46 ± 6%). The drug did not interfere with the activation of the voltage sensor in as much as the voltage dependence of both intramembrane charge movements and the L-type calcium currents (I(Ca)) were left, essentially, unaltered. However, the inactivation of I(Ca) was slowed fourfold, and the conductance was reduced from 200 ± 16 to 143 ± 8 SF(−1) (n = 10). Dantrolene was found to inhibit thymol-stimulated calcium efflux from heavy SR vesicles by 44 ± 10% (n = 3) at 12 μM. On the other hand, dantrolene failed to affect the isolated RYR incorporated into lipid bilayers. The channel displayed a constant open probability for as long as 30–50 min after the application of the drug. These data locate the binding site for dantrolene to be on the SR membrane, but be distinct from the purified RYR itself.
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spelling pubmed-22337002008-04-22 Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers Szentesi, Péter Collet, Claude Sárközi, Sándor Szegedi, Csaba Jona, István Jacquemond, Vincent Kovács, László Csernoch, László J Gen Physiol Original Article The effects of the muscle relaxant dantrolene on steps of excitation-contraction coupling were studied on fast twitch muscles of rodents. To identify the site of action of the drug, single fibers for voltage-clamp measurements, heavy SR vesicles for calcium efflux studies and solubilized SR calcium release channels/RYRs for lipid bilayer studies were isolated. Using the double Vaseline-gap or the silicone-clamp technique, dantrolene was found to suppress the depolarization-induced elevation in intracellular calcium concentration ([Ca(2)+](i)) by inhibiting the release of calcium from the SR. The suppression of [Ca(2)+](i) was dose-dependent, with no effect at or below 1 μM and a 53 ± 8% (mean ± SEM, n = 9, cut fibers) attenuation at 0 mV with 25 μM of extracellularly applied dantrolene. The drug was not found to be more effective if injected than if applied extracellularly. Calculating the SR calcium release revealed an equal suppression of the steady (53 ± 8%) and of the early peak component (46 ± 6%). The drug did not interfere with the activation of the voltage sensor in as much as the voltage dependence of both intramembrane charge movements and the L-type calcium currents (I(Ca)) were left, essentially, unaltered. However, the inactivation of I(Ca) was slowed fourfold, and the conductance was reduced from 200 ± 16 to 143 ± 8 SF(−1) (n = 10). Dantrolene was found to inhibit thymol-stimulated calcium efflux from heavy SR vesicles by 44 ± 10% (n = 3) at 12 μM. On the other hand, dantrolene failed to affect the isolated RYR incorporated into lipid bilayers. The channel displayed a constant open probability for as long as 30–50 min after the application of the drug. These data locate the binding site for dantrolene to be on the SR membrane, but be distinct from the purified RYR itself. The Rockefeller University Press 2001-10-01 /pmc/articles/PMC2233700/ /pubmed/11585849 Text en © 2001 The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Original Article
Szentesi, Péter
Collet, Claude
Sárközi, Sándor
Szegedi, Csaba
Jona, István
Jacquemond, Vincent
Kovács, László
Csernoch, László
Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title_full Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title_fullStr Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title_full_unstemmed Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title_short Effects of Dantrolene on Steps of Excitation-Contraction Coupling in Mammalian Skeletal Muscle Fibers
title_sort effects of dantrolene on steps of excitation-contraction coupling in mammalian skeletal muscle fibers
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233700/
https://www.ncbi.nlm.nih.gov/pubmed/11585849
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