[Effect of motilin on contractile activity of isolated smooth muscle of stomach].

The present study was conducted to investigate the contractile effect of motilin on isolated smooth muscle cells of rat stomach. The results were as follows: (1) Motilin elicited contraction of gastric smooth muscle cells in a dose-dependent manner from 10(-11) to 10(-10) mol. (2) At concentration of 10(-10) mol, the contractile response of antral smooth muscle cells exceeded that of the body and pyrous muscle cells. (3) Anti-motilin serum could completely eliminate the stimulatory effect of motilin, which was not affected by atropine, TTX, cimetidine or loxiglumide. (4) TMB-8, an inhibitor of intracellular Ca2+ release, could also suppress completely the motilin effect. The above results suggested that the motilin effect on isolated gastric smooth muscle cells is a direct one, being mediated by highly specific motilin receptors in connection with the event of intracellular release of Ca2+.