Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel

Detalhes bibliográficos
Autor(a) principal: Silva, Bagnolia Araujo da [UNIFESP]
Data de Publicação: 1999
Outros Autores: Nouailhetas, Viviane Louise Andree [UNIFESP], Aboulafia, Jeannine [UNIFESP]
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Institucional da UNIFESP
Texto Completo: http://ajpcell.physiology.org/content/277/4/C739
http://repositorio.unifesp.br/handle/11600/42345
Resumo: Desensitization of ANG II tonic contractile response of the guinea pig ileum is related to membrane repolarization determined by Ca2+-activated K+ (maxi-K+) channel opening. ANG II-stimulated depolarized myocytes presented sustained activation of maxi-K+ channels, characterized by reduction from 415 to 12 ms of the closed time constant. ANG II desensitization was prevented by 100 nM iberiotoxin, being reversible within 30 min. Depolarization by KCl, higher than 4 mM, impaired desensitization, suggesting that the membrane potential must attain a threshold to counteract the repolarization induced by maxi-K+ channel opening. Once this value is attained, there is no time dependency because the desensitization process was shut off by addition of KCl along the time course of the tonic response. In contrast, the sustained ACh tonic component was not altered by these maneuvers. We conclude that desensitization of the ANG II tonic component is foremost due to the opening of maxi-K+ channels, leading to membrane repolarization, thus dosing the voltage-dependent Ca2+ channels responsible for the Ca2+ influx that sustains the tonic component in this muscle.
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spelling Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channelisometric contractionpatch-clamp techniqueacetylcholinemaxi-K+ channeliberiotoxinDesensitization of ANG II tonic contractile response of the guinea pig ileum is related to membrane repolarization determined by Ca2+-activated K+ (maxi-K+) channel opening. ANG II-stimulated depolarized myocytes presented sustained activation of maxi-K+ channels, characterized by reduction from 415 to 12 ms of the closed time constant. ANG II desensitization was prevented by 100 nM iberiotoxin, being reversible within 30 min. Depolarization by KCl, higher than 4 mM, impaired desensitization, suggesting that the membrane potential must attain a threshold to counteract the repolarization induced by maxi-K+ channel opening. Once this value is attained, there is no time dependency because the desensitization process was shut off by addition of KCl along the time course of the tonic response. In contrast, the sustained ACh tonic component was not altered by these maneuvers. We conclude that desensitization of the ANG II tonic component is foremost due to the opening of maxi-K+ channels, leading to membrane repolarization, thus dosing the voltage-dependent Ca2+ channels responsible for the Ca2+ influx that sustains the tonic component in this muscle.Univ Fed Sao Paulo, Dept Biophys, Escola Paulista Med, BR-04023062 Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Biophys, Escola Paulista Med, BR-04023062 Sao Paulo, BrazilWeb of ScienceAmer Physiological SocUniversidade Federal de São Paulo (UNIFESP)Silva, Bagnolia Araujo da [UNIFESP]Nouailhetas, Viviane Louise Andree [UNIFESP]Aboulafia, Jeannine [UNIFESP]2018-06-15T13:20:12Z2018-06-15T13:20:12Z1999-10-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionC739-C745http://ajpcell.physiology.org/content/277/4/C739American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 277, n. 4, p. C739-C745, 1999.0363-6143http://repositorio.unifesp.br/handle/11600/42345WOS:000083919100017engAmerican Journal Of Physiology-cell Physiologyinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UNIFESPinstname:Universidade Federal de São Paulo (UNIFESP)instacron:UNIFESP2024-05-02T13:44:16Zoai:repositorio.unifesp.br/:11600/42345Repositório InstitucionalPUBhttp://www.repositorio.unifesp.br/oai/requestbiblioteca.csp@unifesp.bropendoar:34652024-05-02T13:44:16Repositório Institucional da UNIFESP - Universidade Federal de São Paulo (UNIFESP)false
dc.title.none.fl_str_mv Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
title Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
spellingShingle Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
Silva, Bagnolia Araujo da [UNIFESP]
isometric contraction
patch-clamp technique
acetylcholine
maxi-K+ channel
iberiotoxin
title_short Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
title_full Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
title_fullStr Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
title_full_unstemmed Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
title_sort Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
author Silva, Bagnolia Araujo da [UNIFESP]
author_facet Silva, Bagnolia Araujo da [UNIFESP]
Nouailhetas, Viviane Louise Andree [UNIFESP]
Aboulafia, Jeannine [UNIFESP]
author_role author
author2 Nouailhetas, Viviane Louise Andree [UNIFESP]
Aboulafia, Jeannine [UNIFESP]
author2_role author
author
dc.contributor.none.fl_str_mv Universidade Federal de São Paulo (UNIFESP)
dc.contributor.author.fl_str_mv Silva, Bagnolia Araujo da [UNIFESP]
Nouailhetas, Viviane Louise Andree [UNIFESP]
Aboulafia, Jeannine [UNIFESP]
dc.subject.por.fl_str_mv isometric contraction
patch-clamp technique
acetylcholine
maxi-K+ channel
iberiotoxin
topic isometric contraction
patch-clamp technique
acetylcholine
maxi-K+ channel
iberiotoxin
description Desensitization of ANG II tonic contractile response of the guinea pig ileum is related to membrane repolarization determined by Ca2+-activated K+ (maxi-K+) channel opening. ANG II-stimulated depolarized myocytes presented sustained activation of maxi-K+ channels, characterized by reduction from 415 to 12 ms of the closed time constant. ANG II desensitization was prevented by 100 nM iberiotoxin, being reversible within 30 min. Depolarization by KCl, higher than 4 mM, impaired desensitization, suggesting that the membrane potential must attain a threshold to counteract the repolarization induced by maxi-K+ channel opening. Once this value is attained, there is no time dependency because the desensitization process was shut off by addition of KCl along the time course of the tonic response. In contrast, the sustained ACh tonic component was not altered by these maneuvers. We conclude that desensitization of the ANG II tonic component is foremost due to the opening of maxi-K+ channels, leading to membrane repolarization, thus dosing the voltage-dependent Ca2+ channels responsible for the Ca2+ influx that sustains the tonic component in this muscle.
publishDate 1999
dc.date.none.fl_str_mv 1999-10-01
2018-06-15T13:20:12Z
2018-06-15T13:20:12Z
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://ajpcell.physiology.org/content/277/4/C739
American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 277, n. 4, p. C739-C745, 1999.
0363-6143
http://repositorio.unifesp.br/handle/11600/42345
WOS:000083919100017
url http://ajpcell.physiology.org/content/277/4/C739
http://repositorio.unifesp.br/handle/11600/42345
identifier_str_mv American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 277, n. 4, p. C739-C745, 1999.
0363-6143
WOS:000083919100017
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv American Journal Of Physiology-cell Physiology
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv C739-C745
dc.publisher.none.fl_str_mv Amer Physiological Soc
publisher.none.fl_str_mv Amer Physiological Soc
dc.source.none.fl_str_mv reponame:Repositório Institucional da UNIFESP
instname:Universidade Federal de São Paulo (UNIFESP)
instacron:UNIFESP
instname_str Universidade Federal de São Paulo (UNIFESP)
instacron_str UNIFESP
institution UNIFESP
reponame_str Repositório Institucional da UNIFESP
collection Repositório Institucional da UNIFESP
repository.name.fl_str_mv Repositório Institucional da UNIFESP - Universidade Federal de São Paulo (UNIFESP)
repository.mail.fl_str_mv biblioteca.csp@unifesp.br
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