The role of prostaglandins in the regulation of gastric mucosal blood flow.

It has been postulated that endogenous gastric prostaglandin activity contributes to the maintenance of non-stimulated gastric mucosal blood flow. Prostacyclin and PGE2 increase mucosal blood flow in the non-stimulated canine stomach. Inhibition of prostaglandin synthesis by aspirin or indomethacin causes a reduction of 30% to 50% in nonstimulated gastric mucosal blood flow in dog and rat. These observations are consistent with the hypothesis that endogenous prostaglandin activity within the gastric mucosa contributes to the maintenance of its blood flow. Also it has been postulated that endogenous prostaglandins may, in part, mediate the vasodilation associated with stimulated gastric acid secretion. Exogenous prostacyclin and PGE2 inhibit stimulated acid secretion while increasing mucosal blood flow. Indomethacin and aspirin-inhibited endogenous prostaglandin synthesis has been reported to increase stimulated acid secretion and reduce mucosal blood flow in anesthetized rat and dog. In gastric secretory fluid, prostaglandins have been detected during gastrin stimulated by some investigators and a dose response relationship between rate of secretion and fluid prostaglandin output has been observed. These observations may, in part, contribute to the regulation of mucosal blood flow during stimulated acid secretion. Further studies, directly measuring specific endogenous prostaglandin and their metabolic products within the gastric mucosa during stimulated and inhibited acid secretion will be necessary to prove or disprove this hypothesis.