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Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle
Malignant hyperthermia (MH) is a fatal hypermetabolic state that may occur during general anesthesia in susceptible individuals. It is often caused by mutations in the ryanodine receptor RyR1 that favor drug-induced release of Ca(2+) from the sarcoplasmic reticulum. Here, knowing that membrane depol...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5749113/ https://www.ncbi.nlm.nih.gov/pubmed/29247050 http://dx.doi.org/10.1085/jgp.201711864 |
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author | Zullo, Alberto Textor, Martin Elischer, Philipp Mall, Stefan Alt, Andreas Klingler, Werner Melzer, Werner |
author_facet | Zullo, Alberto Textor, Martin Elischer, Philipp Mall, Stefan Alt, Andreas Klingler, Werner Melzer, Werner |
author_sort | Zullo, Alberto |
collection | PubMed |
description | Malignant hyperthermia (MH) is a fatal hypermetabolic state that may occur during general anesthesia in susceptible individuals. It is often caused by mutations in the ryanodine receptor RyR1 that favor drug-induced release of Ca(2+) from the sarcoplasmic reticulum. Here, knowing that membrane depolarization triggers Ca(2+) release in normal muscle function, we study the cross-influence of membrane potential and anesthetic drugs on Ca(2+) release. We used short single muscle fibers of knock-in mice heterozygous for the RyR1 mutation Y524S combined with microfluorimetry to measure intracellular Ca(2+) signals. Halothane, a volatile anesthetic used in contracture testing for MH susceptibility, was equilibrated with the solution superfusing the cells by means of a vaporizer system. In the range 0.2 to 3%, the drug causes significantly larger elevations of free myoplasmic [Ca(2+)] in mutant (YS) compared with wild-type (WT) fibers. Action potential–induced Ca(2+) signals exhibit a slowing of their time course of relaxation that can be attributed to a component of delayed Ca(2+) release turnoff. In further experiments, we applied halothane to single fibers that were voltage-clamped using two intracellular microelectrodes and studied the effect of small (10-mV) deviations from the holding potential (−80 mV). Untreated WT fibers show essentially no changes in [Ca(2+)], whereas the Ca(2+) level of YS fibers increases and decreases on depolarization and hyperpolarization, respectively. The drug causes a significant enhancement of this response. Depolarizing pulses reveal a substantial negative shift in the voltage dependence of activation of Ca(2+) release. This behavior likely results from the allosteric coupling between RyR1 and its transverse tubular voltage sensor. We conclude that the binding of halothane to RyR1 alters the voltage dependence of Ca(2+) release in MH-susceptible muscle fibers such that the resting membrane potential becomes a decisive factor for the efficiency of the drug to trigger Ca(2+) release. |
format | Online Article Text |
id | pubmed-5749113 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-57491132018-07-02 Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle Zullo, Alberto Textor, Martin Elischer, Philipp Mall, Stefan Alt, Andreas Klingler, Werner Melzer, Werner J Gen Physiol Research Articles Malignant hyperthermia (MH) is a fatal hypermetabolic state that may occur during general anesthesia in susceptible individuals. It is often caused by mutations in the ryanodine receptor RyR1 that favor drug-induced release of Ca(2+) from the sarcoplasmic reticulum. Here, knowing that membrane depolarization triggers Ca(2+) release in normal muscle function, we study the cross-influence of membrane potential and anesthetic drugs on Ca(2+) release. We used short single muscle fibers of knock-in mice heterozygous for the RyR1 mutation Y524S combined with microfluorimetry to measure intracellular Ca(2+) signals. Halothane, a volatile anesthetic used in contracture testing for MH susceptibility, was equilibrated with the solution superfusing the cells by means of a vaporizer system. In the range 0.2 to 3%, the drug causes significantly larger elevations of free myoplasmic [Ca(2+)] in mutant (YS) compared with wild-type (WT) fibers. Action potential–induced Ca(2+) signals exhibit a slowing of their time course of relaxation that can be attributed to a component of delayed Ca(2+) release turnoff. In further experiments, we applied halothane to single fibers that were voltage-clamped using two intracellular microelectrodes and studied the effect of small (10-mV) deviations from the holding potential (−80 mV). Untreated WT fibers show essentially no changes in [Ca(2+)], whereas the Ca(2+) level of YS fibers increases and decreases on depolarization and hyperpolarization, respectively. The drug causes a significant enhancement of this response. Depolarizing pulses reveal a substantial negative shift in the voltage dependence of activation of Ca(2+) release. This behavior likely results from the allosteric coupling between RyR1 and its transverse tubular voltage sensor. We conclude that the binding of halothane to RyR1 alters the voltage dependence of Ca(2+) release in MH-susceptible muscle fibers such that the resting membrane potential becomes a decisive factor for the efficiency of the drug to trigger Ca(2+) release. The Rockefeller University Press 2018-01-02 /pmc/articles/PMC5749113/ /pubmed/29247050 http://dx.doi.org/10.1085/jgp.201711864 Text en © 2018 Zullo et al. http://www.rupress.org/terms/https://creativecommons.org/licenses/by-nc-sa/4.0/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 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Research Articles Zullo, Alberto Textor, Martin Elischer, Philipp Mall, Stefan Alt, Andreas Klingler, Werner Melzer, Werner Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title | Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title_full | Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title_fullStr | Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title_full_unstemmed | Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title_short | Voltage modulates halothane-triggered Ca(2+) release in malignant hyperthermia-susceptible muscle |
title_sort | voltage modulates halothane-triggered ca(2+) release in malignant hyperthermia-susceptible muscle |
topic | Research Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5749113/ https://www.ncbi.nlm.nih.gov/pubmed/29247050 http://dx.doi.org/10.1085/jgp.201711864 |
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