COMPARISON OF THE EFFECT OF CALCIUM WITHDRAWAL FROM THE MEDIUM AND OF BLOCKADE OF EXTRACELLULAR CALCIUM ENTRY BY ISRADIPINE ON THE CONTRACTILE RESPONSES OF THE ISOLATED RAT STOMACH

COMPARISON OF THE EFFECT OF CALCIUM WITHDRAWAL FROM THE MEDIUM AND OF BLOCKADE OF EXTRACELLULAR CALCIUM ENTRY BY ISRADIPINE ON THE CONTRACTILE RESPONSES OF THE ISOLATED RAT STOMACH

Author Smaili, Soraya Soubhi Autor UNIFESP Google Scholar
Jurkiewicz, Neide Hyppolito Autor UNIFESP Google Scholar
Garcia, A. G. Google Scholar
Jurkiewicz, Aron Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
UNIV AUTONOMA MADRID
Abstract The role of calcium in drug-induced contractions of rat gastric fundus strips was evaluated by determining the effect of two procedures on the dose-response curves of agonists: a) removal of calcium from the nutrient solution and b) blockade of calcium channels with the dihydropyridine isradipine. Gastric strips were obtained from adult Wistar rats and suspended in Tyrode solution at 37-degrees-C for contraction studies. Dose-response curves for carbachol (CCh), serotonin (5-HT), KCl and BaCl2 were constructed under the two conditions described above. A complete blockade of contractile effects was observed for 5-HT and KCl 60 min after calcium withdrawal or after using 3 nM (45 min) of the calcium antagonist. A lower dose of antagonist or a shorter incubation in calcium-free solution caused a partial decrease of dose-response curves, added to a 30-fold shift to the right after the calcium antagonist (1 nM), or a larger than 100-fold shift 3 min after calcium removal. In contrast, dose-response curves for CCh and BaCl2 were not significantly affected by either type of treatment. It is concluded that 5-HT and KCl utilize extracellular sources of calcium, whereas CCh or BaCl2 depends on a tightly-bound calcium pool in this preparation.
Keywords CALCIUM CHANNEL
RAT GASTRIC FUNDUS
ISRADIPINE
SEROTONIN
CARBACHOL
Language English
Date 1991-01-01
Published in Brazilian Journal Of Medical And Biological Research. Sao Paulo: Assoc Bras Divulg Cientifica, v. 24, n. 9, p. 953-956, 1991.
ISSN 0100-879X (Sherpa/Romeo, impact factor)
Publisher Assoc Bras Divulg Cientifica
Extent 953-956
Access rights Closed access
Type Article
Web of Science ID WOS:A1991GL87500014
URI http://repositorio.unifesp.br/11600/43010

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