Intracellular calcium mobilization by muscarinic receptors is regulated by micromolar concentrations of external Ca2+

Intracellular calcium mobilization by muscarinic receptors is regulated by micromolar concentrations of external Ca2+

Autor Smaili, Soraya Soubhi Autor UNIFESP Google Scholar
Carvalho, Solange Maria Torchia Autor UNIFESP Google Scholar
Cavalcanti, Paulo MS Autor UNIFESP Google Scholar
Jurkiewicz, Neide H. Autor UNIFESP Google Scholar
Garcia, Antonio G. Google Scholar
Jurkiewicz, Aron Autor UNIFESP Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Univ Autonoma Madrid
Resumo Carbachol-induced contractions of rat stomach fundus strips, obtained in a nutrient solution containing 1.8 mM Ca2+, were resistant to Ca2+ withdrawal, even after 1 h of bathing the tissues in a nominal 0 Ca2+ solution. This was not observed when K+ was used to evoke contractions, which were rapidly inhibited after Ca2+ removal (t(1/)2=2 min). the effect of carbachol in 0 Ca2+ solution was reduced by using drugs that reduce intracellular pools of Ca2+, such as caffeine (1-3 mM), ryanodine (30 muM) or thapsigargin (1 muM), corroborating the involvement of intracellular Ca2+ stores. On the other hand, when the 0 Ca2+ solution contained EGTA, a complete decline of carbachol effects was observed within about 8 min, indicating the involvement of extracellular Ca2+. Atomic absorption spectrometry showed that our 0 Ca2+ solution still contained 45 muM Ca2+, which was drastically reduced to 5.9 nM in the presence of EGTA. Taken together, our results indicate that the effects of carbachol are due to the mobilization of caffeine-, ryanodine- and thapsigargin-sensitive intracellular Ca2+ stores, and that these stores are not inactivated or depleted if micromolar concentrations (45 muM), but not nanomolar concentrations (5.9 nM) of Ca2+ are maintained in the extracellular milieu.
Palavra-chave caffeine
stomach fundus
Idioma Inglês
Data de publicação 2001-06-01
Publicado em Pflugers Archiv-european Journal of Physiology. New York: Springer-verlag, v. 442, n. 3, p. 376-382, 2001.
ISSN 0031-6768 (Sherpa/Romeo, fator de impacto)
Publicador Springer
Extensão 376-382
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000169629100008
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