Endothelin 1 action on isolated rat stomach and the role of calcium ions in ET 1 induced depolarization of smooth muscle cells BC3H1.

Endothelins; (ET1, ET2 and ET3) are a family of peptides which acts on different smooth muscle preparations inducing a slow long lasting contraction. We investigated the effects of ET 1 modulatory action on adrenergic, cholinergic and serotoninergic transmission on an isolated mouse's stomach with gastric nerves. The endothelin 1 stimulation of the mouse stomach tone was abolished by the specific serotonin antagonist methizergid. This study suggests that endothelin 1 plays a role in the regulation of nonvascular smooth muscle tone. The endothelin effect was dependent on free intracellular Ca++ which can be recruited from an extracellular solution as well as from intracellular stores. Complete reduction of Ca++ from the extracellular solution with a simultaneous depletion of calcium stores abolished endothelin 1 depolarization of BC3H1 cells.