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The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes
In freshly dispersed guinea pig taenia coli myocytes the activity of the large conductance Ca(2+)-activated K+ channel (maxi-K+ channel) predominates. The open probability (Po) of this channel is increased by micromolar concentrations of the beta-adrenergic agonist isoproterenol (ISO). Low concentra...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1993
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229144/ https://www.ncbi.nlm.nih.gov/pubmed/8228911 |
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collection | PubMed |
description | In freshly dispersed guinea pig taenia coli myocytes the activity of the large conductance Ca(2+)-activated K+ channel (maxi-K+ channel) predominates. The open probability (Po) of this channel is increased by micromolar concentrations of the beta-adrenergic agonist isoproterenol (ISO). Low concentrations of cholera toxin (CTX, 1 pM) and guanosine 5'- O-2-thiodiphosphate (GDP beta S, 0.5 mM) suppress the ISO-induced increase of Po. Higher concentrations of CTX (e.g., 0.5 nM) as well as forskolin and dibutyryl cAMP increase the Po. 1,9-Dideoxyforskolin, the forskolin analogue, which lacks the adenylate cyclase-stimulating effect, does not. A specific protein kinase A inhibitor (Wiptide), applied intracellularly via diffusion from the patch electrode, suppresses the ISO-induced increase of whole-cell outward K+ current during step depolarization. In contrast, intracellularly applied protein kinase C (19-36), a specific protein kinase C inhibitor, has no effect on the whole-cell current. TMB-8, an inhibitor of intracellular calcium mobilization, does not affect either the whole-cell outward K+ current during step depolarization or the Po. These observations show that ISO increases the Po of the maxi-K+ channels in the guinea pig taenia coli myocytes through the G protein-adenylate cyclase-protein kinase A system. |
format | Text |
id | pubmed-2229144 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1993 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22291442008-04-23 The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes J Gen Physiol Articles In freshly dispersed guinea pig taenia coli myocytes the activity of the large conductance Ca(2+)-activated K+ channel (maxi-K+ channel) predominates. The open probability (Po) of this channel is increased by micromolar concentrations of the beta-adrenergic agonist isoproterenol (ISO). Low concentrations of cholera toxin (CTX, 1 pM) and guanosine 5'- O-2-thiodiphosphate (GDP beta S, 0.5 mM) suppress the ISO-induced increase of Po. Higher concentrations of CTX (e.g., 0.5 nM) as well as forskolin and dibutyryl cAMP increase the Po. 1,9-Dideoxyforskolin, the forskolin analogue, which lacks the adenylate cyclase-stimulating effect, does not. A specific protein kinase A inhibitor (Wiptide), applied intracellularly via diffusion from the patch electrode, suppresses the ISO-induced increase of whole-cell outward K+ current during step depolarization. In contrast, intracellularly applied protein kinase C (19-36), a specific protein kinase C inhibitor, has no effect on the whole-cell current. TMB-8, an inhibitor of intracellular calcium mobilization, does not affect either the whole-cell outward K+ current during step depolarization or the Po. These observations show that ISO increases the Po of the maxi-K+ channels in the guinea pig taenia coli myocytes through the G protein-adenylate cyclase-protein kinase A system. The Rockefeller University Press 1993-08-01 /pmc/articles/PMC2229144/ /pubmed/8228911 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 transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title | The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title_full | The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title_fullStr | The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title_full_unstemmed | The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title_short | The transduction system in the isoproterenol activation of the Ca(2+)- activated K+ channel in guinea pig taenia coli myocytes |
title_sort | transduction system in the isoproterenol activation of the ca(2+)- activated k+ channel in guinea pig taenia coli myocytes |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229144/ https://www.ncbi.nlm.nih.gov/pubmed/8228911 |