Protective effect of cimetidine on tannic acid-induced gastric damage in rats.

The effect of cimetidine on the acidified tannic acid-induced back diffusion of gastric acid and mucosal damage was investigated in the vagotomized rat. After intragastric irrigation for 1 to 3 h, tannic acid (20-500 mg kg-1) produced a dose-related increase in gastric volume and the loss of luminal H+. The change of mucosal permeability to the electrolyte, either the loss of H+ or the gain of Na+, K+, and Ca2+, induced by tannic acid was significantly diminished by the combination with intragastric cimetidine. However, intravenous injection of cimetidine did not protect this damage and back diffusion of acid neutralized intragastric cimetidine did not reduce the back diffusion of acid and Na+, K+, and Ca2+ output provoked by acid solution. Thus, the neutralizing action of cimetidine seems responsible.