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Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig

Isometric tension and isotonic shortening were measured at constant levels of calcium activation of varying magnitude in mechanically disrupted EGTA-treated ventricular bundles from guinea pigs. The results were as follows: (a) The effect of creatine phosphate (CP) on peak tension and rate of shorte...

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Autores principales: Maughan, DW, Low, ES, Alpert, NR
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1978
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215736/
https://www.ncbi.nlm.nih.gov/pubmed/149182
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author Maughan, DW
Low, ES
Alpert, NR
author_facet Maughan, DW
Low, ES
Alpert, NR
author_sort Maughan, DW
collection PubMed
description Isometric tension and isotonic shortening were measured at constant levels of calcium activation of varying magnitude in mechanically disrupted EGTA-treated ventricular bundles from guinea pigs. The results were as follows: (a) The effect of creatine phosphate (CP) on peak tension and rate of shortening saturated at a CP concentration more than 10 mM; below that level tension was increased and shortening velocity decreased. We interpreted this to mean that CP above 10 mM was sufficient to buffer MgATP(2-) intracellularly. (b) The activated bundles exhibited an exponential stress-strain relationship and the series elastic properties did not vary appreciably with degree of activation or creatine phosphate level. (c) At a muscle length 20 percent beyond just taut, peak tension increased with Ca(2+) concentration over the range slightly below 10(-6) to slightly above 10(-4)M. (d) By releasing the muscle length-active tension curves were constructed. Force declined to 20 percent peak tension with a decrease in muscle length (after the recoil) of only 11 percent at 10(-4)M Ca(2+) and 6 percent at 4x10(-6)M Ca(2+). (e) The rate of shortening after a release was greater at lower loads. At identical loads (relative to maximum force at a given Ca(2+) level), velocity at a given time after the release was less at lower Ca(2+) concentrations; at 10 M(-5), velocity was 72 percent of that at 10(-4)M, and at 4x10(-6)M, active shortening was usually delayed and was 40 percent of the velocity at 10(-4) M. Thus, under the conditions of these experiments, both velocity and peak tension depend on the level of Ca(2+) activation over a similar range of Ca(2+) concentration.
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spelling pubmed-22157362008-04-23 Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig Maughan, DW Low, ES Alpert, NR J Gen Physiol Articles Isometric tension and isotonic shortening were measured at constant levels of calcium activation of varying magnitude in mechanically disrupted EGTA-treated ventricular bundles from guinea pigs. The results were as follows: (a) The effect of creatine phosphate (CP) on peak tension and rate of shortening saturated at a CP concentration more than 10 mM; below that level tension was increased and shortening velocity decreased. We interpreted this to mean that CP above 10 mM was sufficient to buffer MgATP(2-) intracellularly. (b) The activated bundles exhibited an exponential stress-strain relationship and the series elastic properties did not vary appreciably with degree of activation or creatine phosphate level. (c) At a muscle length 20 percent beyond just taut, peak tension increased with Ca(2+) concentration over the range slightly below 10(-6) to slightly above 10(-4)M. (d) By releasing the muscle length-active tension curves were constructed. Force declined to 20 percent peak tension with a decrease in muscle length (after the recoil) of only 11 percent at 10(-4)M Ca(2+) and 6 percent at 4x10(-6)M Ca(2+). (e) The rate of shortening after a release was greater at lower loads. At identical loads (relative to maximum force at a given Ca(2+) level), velocity at a given time after the release was less at lower Ca(2+) concentrations; at 10 M(-5), velocity was 72 percent of that at 10(-4)M, and at 4x10(-6)M, active shortening was usually delayed and was 40 percent of the velocity at 10(-4) M. Thus, under the conditions of these experiments, both velocity and peak tension depend on the level of Ca(2+) activation over a similar range of Ca(2+) concentration. The Rockefeller University Press 1978-04-01 /pmc/articles/PMC2215736/ /pubmed/149182 Text en 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 Articles
Maughan, DW
Low, ES
Alpert, NR
Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title_full Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title_fullStr Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title_full_unstemmed Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title_short Isometric force development, isotonic shortening, and elasticity measurements from Ca(2+)-activated ventricular muscle of the guinea pig
title_sort isometric force development, isotonic shortening, and elasticity measurements from ca(2+)-activated ventricular muscle of the guinea pig
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215736/
https://www.ncbi.nlm.nih.gov/pubmed/149182
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