[Characteristics of the effect of 16,16-dimethyl prostaglandin E2 on the alkaline secretion of the proximal duodenal mucosa in rats--a comparison with the effect of secretin].

: Effect of intravenous infusion of 16,16-dimethyl prostaglandin E2 (16,16-dmPGE2) on the alkaline secretion of the proximal duodenal mucosa was investigated using a lumen perfusion system of the duodenal loop in rats. The following results were obtained: 1) 0.001 to 1 microgram/kg/hr of 16,16-dmPGE2 increased the alkaline secretion significantly and dose-dependently. 2) Indomethacin (5 mg/kg) inhibited the alkaline secretion and 16,16-dmPGE2 (0.1 microgram/kg/hr) completely repaired this inhibition. 3) In cysteamine-treated rats, 16,16-dmPGE2 (1 microgram/kg/hr) completely repaired the inhibition of the alkaline secretion induced by cysteamine. 4) Prostaglandin was a potent stimulator of alkaline secretion of the proximal duodenal mucosa not only in cysteamine-treated rats but also in normal rats. This is in contrast to our previous report which showed that secretin repaired the alkaline secretion in cysteamine-treated rats without affecting it in normal rats. We have concluded that prostaglandin and secretin may be involved differently in the mechanism of alkaline secretion of the proximal duodenal mucosa. Further investigation is required to elucidate the mechanism.