Role of prostaglandins in alkaline secretion from the gastroduodenal mucosa exposed to acid and taurocholate.

Gastroduodenal mucosa produces alkaline secretion (AS) that is several times greater in the duodenum, particularly in its proximal part, than in the fundic or antral portions of the stomach. Exogenous prostaglandins (PGs) of E and F but not of I series are capable of augmenting AS. Similar stimulatory effects on AS were observed after topical administration of arachidonic acid and HCl solution. Endogenous PGs appear to mediate this AS as their release from the mucosa is increased upon exposure to arachidonic acid and the pretreatment with indomethacin reduced the alkaline response to arachidonic acid and HCl. Taurocholate-induced alkaline response is probably due to increased mucosal permeation for HCO3 as it was accompanied by a decrease in PD value and indomethacin failed to affect this response.