ROLE OF GASTRIC-MUCOSAL PROSTAGLANDIN-E(2) IN THE INHIBITORY-ACTION OF SECRETIN AND SOMATOSTATIN ON GASTRIC-ACID SECRETION IN THE RAT

We investigated the effect of indomethacin on secretin- and somatostatin-induced inhibition of gastric acid secretion stimulated by intravenous infusion of pentagastrin (0.3 mug/kg.h) in anesthetized rats. Intravenous administration of a prostaglandin synthesis inhibitor, indomethacin (2 mg/kg + 1 mg/kg.h), completely abolished the inhibition of gastric acid secretion induced by intravenous infusion of secretin (0.05 CU/kg.h). The inhibitory effect of intravenous infusion of somatostatin (Sandostatin; 0.2 mug/kg.h) on the gastric acid was not significantly changed by indomethacin. Secretin significantly increased the gastric mucosal content of prostaglandin E2, and the increase was completely blocked by indomethacin. Somatostatin, however, had no significant effect on gastric mucosal prostaglandin E2. The results suggest that endogenous prostaglandin is involved in the mechanism of inhibition of gastric acid secretion by secretin, but not by somatostatin.