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

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dc.contributor.author Silva, Bagnolia Araujo da [UNIFESP]
dc.contributor.author Nouailhetas, Viviane Louise Andree [UNIFESP]
dc.contributor.author Aboulafia, Jeannine [UNIFESP]
dc.date.accessioned 2018-06-15T13:20:12Z
dc.date.available 2018-06-15T13:20:12Z
dc.date.issued 1999-10-01
dc.identifier http://ajpcell.physiology.org/content/277/4/C739
dc.identifier.citation American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 277, n. 4, p. C739-C745, 1999.
dc.identifier.issn 0363-6143
dc.identifier.uri http://repositorio.unifesp.br/11600/42345
dc.description.abstract 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. en
dc.format.extent C739-C745
dc.language.iso eng
dc.publisher Amer Physiological Soc
dc.relation.ispartof American Journal Of Physiology-cell Physiology
dc.rights Acesso aberto
dc.subject isometric contraction en
dc.subject patch-clamp technique en
dc.subject acetylcholine en
dc.subject maxi-K+ channel en
dc.subject iberiotoxin en
dc.title Desensitization to ANG II in guinea pig ileum depends on membrane repolarization: role of maxi-K+ channel en
dc.type Artigo
dc.contributor.institution Universidade Federal de São Paulo (UNIFESP)
dc.description.affiliation Univ Fed Sao Paulo, Dept Biophys, Escola Paulista Med, BR-04023062 Sao Paulo, Brazil
dc.description.affiliationUnifesp Univ Fed Sao Paulo, Dept Biophys, Escola Paulista Med, BR-04023062 Sao Paulo, Brazil
dc.description.source Web of Science
dc.identifier.wos WOS:000083919100017



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