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Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique

Relations between the membrane potential and the tension associated with changes in membrane potential were analyzed in barnacle giant muscle fibers by using voltage clamp techniques. With a step change in membrane potential the tension reaches its final level with a time course which is expressed b...

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Detalles Bibliográficos
Autores principales: Hagiwara, S., Takahashi, K., Junge, D.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1968
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2201122/
https://www.ncbi.nlm.nih.gov/pubmed/5641633
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author Hagiwara, S.
Takahashi, K.
Junge, D.
author_facet Hagiwara, S.
Takahashi, K.
Junge, D.
author_sort Hagiwara, S.
collection PubMed
description Relations between the membrane potential and the tension associated with changes in membrane potential were analyzed in barnacle giant muscle fibers by using voltage clamp techniques. With a step change in membrane potential the tension reaches its final level with a time course which is expressed by the difference of two exponential functions. The time constants τ(1) (0.2–0.4 sec at 23°C) and τ(2) (0.07–0.12 sec at 23°C) are independent of the new membrane potential at least for a relatively small membrane potential change while the final level of tension is a function of the potential. Decreasing the temperature increases both τ(1) and τ(2) (Q (10) = -2 to -3) and the increase of the tonicity of the external medium increases τ(1) but not τ(2). The final level of tension is related by an S-shaped curve to the membrane potential. The slope of the final tension-membrane potential curve increases with increasing external Ca concentration and is reduced when a small amount of transition metal ions is added to the medium. This suggests that the influx of Ca ions through the membrane is an important factor in the development of tension.
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spelling pubmed-22011222008-04-23 Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique Hagiwara, S. Takahashi, K. Junge, D. J Gen Physiol Article Relations between the membrane potential and the tension associated with changes in membrane potential were analyzed in barnacle giant muscle fibers by using voltage clamp techniques. With a step change in membrane potential the tension reaches its final level with a time course which is expressed by the difference of two exponential functions. The time constants τ(1) (0.2–0.4 sec at 23°C) and τ(2) (0.07–0.12 sec at 23°C) are independent of the new membrane potential at least for a relatively small membrane potential change while the final level of tension is a function of the potential. Decreasing the temperature increases both τ(1) and τ(2) (Q (10) = -2 to -3) and the increase of the tonicity of the external medium increases τ(1) but not τ(2). The final level of tension is related by an S-shaped curve to the membrane potential. The slope of the final tension-membrane potential curve increases with increasing external Ca concentration and is reduced when a small amount of transition metal ions is added to the medium. This suggests that the influx of Ca ions through the membrane is an important factor in the development of tension. The Rockefeller University Press 1968-02-01 /pmc/articles/PMC2201122/ /pubmed/5641633 Text en Copyright © 1968 by 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 Article
Hagiwara, S.
Takahashi, K.
Junge, D.
Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title_full Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title_fullStr Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title_full_unstemmed Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title_short Excitation-Contraction Coupling in a Barnacle Muscle Fiber As Examined with Voltage Clamp Technique
title_sort excitation-contraction coupling in a barnacle muscle fiber as examined with voltage clamp technique
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2201122/
https://www.ncbi.nlm.nih.gov/pubmed/5641633
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