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Effects of motilin on intracellular free calcium in cultured smooth muscle cells from the antrum of neonatal rats
Author(s) -
Fang P.,
Dong L.,
Luo J.Y.
Publication year - 2010
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/j.1748-1716.2010.02079.x
Subject(s) - motilin , antrum , intracellular , smooth muscle , calcium in biology , calcium , gastric antrum , medicine , endocrinology , biology , chemistry , microbiology and biotechnology , stomach
Aim: The aim of this study was to determine the effects of motilin on [Ca 2+ ] i regulation and its underlying molecular mechanism in cultured antral smooth muscle cells (ASMCs). Methods: Antral cells were isolated and cultured from neonatal rats, and then the [Ca 2+ ] i in these cells was evaluated by calcium fluorescent probe Fluo‐3/AM on a laser scanning confocal microscope. Results: We show that motilin dose‐dependently increased [Ca 2+ ] i concentration in cultured ASMCs. Pre‐incubation of cells with either the calcium antagonist verapamil (10 −5 mol L −1 ) or the calcium chelator Egtazic (EGTA, 0.1 mmol L −1 ) significantly suppressed motilin (10 −6 mol L −1 ) induced [Ca 2+ ] i increase as indicated by fluorescent intensity. Interestingly, after mixing with the non‐selective intracellular calcium release blocker TMB‐8 (10 −5 mol L −1 ), guanosine triphosphate regulatory protein antagonist NEM (10 −5 mol L −1 ), phospholipase C (PLC) inhibitor compound 48/80 (1.2 μg mL −1 ) and ryanodine at high concentration (10 −5 mol L −1 ), the motilin‐induced [Ca 2+ ] i increase was only partially blocked. The protein kinase C inhibitor d ‐sphingosine (10 −6 mol L −1 ), however, did not show any inhibitory effect on motilin‐induced [Ca 2+ ] i elevation. Conclusions: Our study suggests that motilin‐stimulated [Ca 2+ ] i elevation in ASMCs is probably due to sustained extracellular Ca 2+ influx and Ca 2+ release from Ca 2+ stores via inositol tris‐phosphate receptors and ryanodine receptors. Specifically, motilin‐induced [Ca 2+ ] i release is accompanied with guanosine triphosphate‐binding protein‐coupled receptor–PLC–inositol tris‐phosphate signalling cascades.