Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel
Autor(a) principal: | |
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Data de Publicação: | 1999 |
Outros Autores: | , |
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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Repositório Institucional da UNIFESP |
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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 |
_version_ |
1814268313921912832 |