Mechanism of prevention of aspirin-induced gastric lesions by bile duct legation in the rat

Abstract

Gastric reflux of bile has been reported to be essential for the production of acute gastric mucosal lesions by intragastric aspirin in the rat. The purpose of the present study was to determine whether bile duct legation of pylorus ligation in the rat inhibits asprin-induced gastric lesions, and, if so, what the protective mechanisms are. Operations were performed under ether anesthesia. Asprin, 200 mg per kg, was instilled into the stomach 1/2 hr postsurgery (bile duct ligation or pylorus ligation). Four hours later the rats were killed, the stomachs were examined, and mucosal lesions were scored. Bile duct ligation, but not pylorus ligation, significantly protected against aspirin-induced gastric-lesions. Bile duct ligation, in pylorus-ligated rats, inhibited gastric acid output by 78%. Instilling HCl + aspirin in bile duct-ligated rats restored lesion formation. Shunting bile to the colon (to prevent bile reflux) did not prevent aspirin lesions. Salicylate determination, to ascertain whether bile duct ligation altered asprin absorption, revealed no significant differences between bile duct ligation and aspirin, shunt + aspirin, and sham shunt + aspirin in plasma and gastric tissue salicylate concentrations.

Conclusions: (1) Bile duct legation protects against aspirin-induced gastric mucosal lesions by inhibiting gastric HCl secretion. As a corollary, a certain amount of acid in the stomach is necessary for aspirin-induced gastric lesions to form. (2) Bile reflux is not necessary for aspirn-induced gastric lesions in the rat.