Role of endogenous prostaglandins in secretin- and plaunotol-induced inhibition of gastric acid secretion in the rat.

We investigated the role of endogenous prostaglandins in the inhibitory effect of exogenous secretin and the antiulcer agent plaunotol on gastric acid secretion in the rat. Intravenous infusion of secretin (0.05 CU/kg/h) and intraduodenal administration of the secretin-releasing agent, plaunotol (320 mg/h), resulted in significant inhibition of gastric acid secretion stimulated by intravenous infusion of pentagastrin (0.3 micrograms/kg/h), and this was accompanied by an increase in the prostaglandin E2 content of the gastric mucosa. Intraduodenal administration of plaunotol (320 mg/h) produced plasma secretin levels comparable to the levels achieved by intravenous infusion of secretin (0.05 CU/kg/h). Intravenous administration of prostaglandin synthesis inhibitor, indomethacin (2 mg/kg + 1 mg/kg/h), completely abolished both the inhibitory action of secretin and plaunotol on gastric acid secretion, and the increase in gastric mucosa prostaglandin E2 induced by secretin and plaunotol. The results indicate that endogenous prostaglandins play a significant role in the inhibitory action of exogenous and plaunotol-released endogenous secretin in the rat.