Reduction by cimetidine of acute gastric hemorrhage caused by reinfusion of blood after exposure to exogenous acid during gastric ischemia in rats.

The present study has been made in anesthetized rats to characterize conditions of exposure to acid and extent of ischemia which determine the development of gastric hemorrhage. Gastric hemorrhage occurred in rats subjected to shock during exposure of the gastric lumen to acid after the reinfusion of withdrawn blood. When the acid concentration was constant, bleeding was dependent on the degree of shock. When hemorrhage shock was constant, bleeding from the stomach appeared pH dependent, although this did not quite achieve statistical significance. Cimetidine 2 x 10(-6) mol kg-1 min-1 (30 mg kg-1 hr-1) and 1 x 10(-5) mol kg-1 min-1 (150 mg kg-1 hr-1) significantly reduced gastric hemorrhage whether given prophylactically before gastric injury or therapeutically after completion of gastric injury. Because protection can be demonstrated against an injury involving exogenous acid and after the injury has been established, it is probable that the effectiveness of cimetidine in these studies is independent of its antisecretory effects.