SOMATOSTATIN INHIBITS PEPSINOGEN SECRETION WITHOUT INFLUENCING CYTOSOLIC-FREE CA2-OCTAPEPTIDE IN RAT CHIEF CELLS( INCREASE INDUCED BY CARBACHOL AND CHOLECYSTOKININ)

Gastric chief cells were isolated from the rat stomach in an attempt t o identify those involved in the mechanism of action of somatostatin o n pepsinogen secretion. The effects of several kinds of secretagogues on cytosolic free Ca2+ concentration ([Ca2+]i) were examined in the ra t chief cells. Carbachol and cholecystokinin octapeptide (CCK-8) marke dly induced [Ca2+]i increase, while histamine, gastrin I and secretin did not. Carbachol and CCK-8 also stimulated pepsinogen secretion. A s imilar dose-response relationship was seen in carbachol- and CCK-8-ind uced [Ca2+]i increase and pepsinogen secretion. Somatostatin did not i nhibit carbachol- or CCK-8-induced [Ca2+]i increase, but did inhibit c arbachol- and CCK-8-induced pepsinogen secretion by 30 and 50%, respec tively.