Role of Na+/Ca++ exchange in the relaxant effect of sodium taurocholate on the guinea-pig ileum smooth muscle

Role of Na+/Ca++ exchange in the relaxant effect of sodium taurocholate on the guinea-pig ileum smooth muscle

Author Romero, Fernando Autor UNIFESP Google Scholar
Frediani-Neto, Eugenio Autor UNIFESP Google Scholar
Paiva, Therezinha Bandiera Autor UNIFESP Google Scholar
Paiva, Antonio Cechelli de Mattos Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract Sodium taurocholate (NaTC), at concentrations below the critical micellar concentration, caused a transient relaxation of isolated guinea-pig ileum smooth muscle strips. The relaxation was not inhibited by previous incubation with either 10 muM ouabain, 0.4 mM d-tubocurarine or 0.5 muM apamin, ruling out the participation of hyperpolarization of the plasma membrane induce by either stimulation of Na+/K+ ATPase or by opening of Ca++-dependent K+ channels. In guinea-pig ileum smooth muscle cultured cells, addition of NaTC (1 mM) stimulated Na+ uptake and Ca++ efflux. The relaxation induced by NaTC was inhibited by 3', 4'-dichlorobenzamil, a blocker of the Na+/Ca++ exchanger. Preincubation with NaTC, or its addition during the early stage of the tonic response, of the ileum to acetylcholine, enhanced that response, whereas a relaxation was observed when NaTC was added at the late stage of the acetylcholine response. In cultured cells, NaTC potentiated the stimulation of Ca2+ influx by acetylcholine. Our results suggest that NaTC acts on the smooth muscle cell membrane causing a stimulation of the Na+/Ca++ exchange mechanism.
Keywords BILE SALTS
GUINEA-PIG ILEUM
SMOOTH MUSCLE
SODIUM CALCIUM EXCHANGE
SODIUM TAUROCHOLATE
Language English
Date 1993-09-01
Published in Naunyn-schmiedebergs Archives Of Pharmacology. New York: Springer Verlag, v. 348, n. 3, p. 325-331, 1993.
ISSN 0028-1298 (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 325-331
Origin http://dx.doi.org/10.1007/BF00169163
Access rights Closed access
Type Article
Web of Science ID WOS:A1993LW88700017
URI http://repositorio.unifesp.br/11600/44977

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