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The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle
Treatment of rat ventricular cells with 10 mM EGTA makes the sarcolemma highly permeable to small ions and molecules without removing its restriction of the diffusion of larger molecules or inactivating all of its enzymatic functions. These hyperpermeable cardiac cells have been used to study the re...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1978
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228493/ https://www.ncbi.nlm.nih.gov/pubmed/215701 |
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collection | PubMed |
description | Treatment of rat ventricular cells with 10 mM EGTA makes the sarcolemma highly permeable to small ions and molecules without removing its restriction of the diffusion of larger molecules or inactivating all of its enzymatic functions. These hyperpermeable cardiac cells have been used to study the regulation of the range of concentration of Ca over which activation of the contractile proteins occurs (Ca sensitivity). The Ca sensitivity can varied from three- to sixfold without any significant alteration in the general shape of the relation between force and Ca concentrations. Although cyclic nucleotides in concentrations of 10(-9) to 10(-5) M do not influence Ca sensitivity, in the presence of a phosphodiesterase inhibitor, cGMP increases and cAMP decreases Ca sensitivity. Treatment of the hyperpermeable cells with a nonionic detergent raises Ca sensitivity as does removal of the phosphate donor by complete substitution of CTP for ATP. These data indicate that Ca sensitivity is probably modulated by a cAMP-dependent phosphorylation that decreases Ca sensitivity. The sarcolemma is required for this reaction to take place. The effect of this reaction is antagonized by a cGMP-dependent reaction occurring inside the cell. Studies involving the perfusion of the heart with and without epinephrine before the exposure to EGTA indicate that epinephrine can regulate this system of control of Ca sensitivity. The functional considerations of this regulatory system are discussed. |
format | Text |
id | pubmed-2228493 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1978 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22284932008-04-23 The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle J Gen Physiol Articles Treatment of rat ventricular cells with 10 mM EGTA makes the sarcolemma highly permeable to small ions and molecules without removing its restriction of the diffusion of larger molecules or inactivating all of its enzymatic functions. These hyperpermeable cardiac cells have been used to study the regulation of the range of concentration of Ca over which activation of the contractile proteins occurs (Ca sensitivity). The Ca sensitivity can varied from three- to sixfold without any significant alteration in the general shape of the relation between force and Ca concentrations. Although cyclic nucleotides in concentrations of 10(-9) to 10(-5) M do not influence Ca sensitivity, in the presence of a phosphodiesterase inhibitor, cGMP increases and cAMP decreases Ca sensitivity. Treatment of the hyperpermeable cells with a nonionic detergent raises Ca sensitivity as does removal of the phosphate donor by complete substitution of CTP for ATP. These data indicate that Ca sensitivity is probably modulated by a cAMP-dependent phosphorylation that decreases Ca sensitivity. The sarcolemma is required for this reaction to take place. The effect of this reaction is antagonized by a cGMP-dependent reaction occurring inside the cell. Studies involving the perfusion of the heart with and without epinephrine before the exposure to EGTA indicate that epinephrine can regulate this system of control of Ca sensitivity. The functional considerations of this regulatory system are discussed. The Rockefeller University Press 1978-12-01 /pmc/articles/PMC2228493/ /pubmed/215701 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 The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title | The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title_full | The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title_fullStr | The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title_full_unstemmed | The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title_short | The regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
title_sort | regulation of the calcium sensitivity of the contractile system in mammalian cardiac muscle |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228493/ https://www.ncbi.nlm.nih.gov/pubmed/215701 |