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...

Full description

Bibliographic Details
Main Authors:	Szentesi, Péter, Collet, Claude, Sárközi, Sándor, Szegedi, Csaba, Jona, István, Jacquemond, Vincent, Kovács, László, Csernoch, László
Format:	Online
Language:	English
Published:	The Rockefeller University Press 2001
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233700/

id	pubmed-2233700
recordtype	oai_dc
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 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 ([Ca2+]i) by inhibiting the release of calcium from the SR. The suppression of [Ca2+]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 (ICa) were left, essentially, unaltered. However, the inactivation of ICa 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/).
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Szentesi, Péter Collet, Claude Sárközi, Sándor Szegedi, Csaba Jona, István Jacquemond, Vincent Kovács, László Csernoch, László
spellingShingle	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
author_facet	Szentesi, Péter Collet, Claude Sárközi, Sándor Szegedi, Csaba Jona, István Jacquemond, Vincent Kovács, László Csernoch, László
author_sort	Szentesi, Péter
title	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_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_sort	effects of dantrolene on steps of excitation-contraction coupling in mammalian skeletal muscle fibers
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 ([Ca2+]i) by inhibiting the release of calcium from the SR. The suppression of [Ca2+]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 (ICa) were left, essentially, unaltered. However, the inactivation of ICa 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.
publisher	The Rockefeller University Press
publishDate	2001
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233700/
_version_	1611438286911307776

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

Similar Items