Cimetidine and ranitidine protect against cold restraint-induced ulceration in rat by suppressing gastric acid secretion.

The effect of the H2-receptor antagonists cimetidine and ranitidine on pentagastrin-stimulated gastric acid secretion in anesthetized rats, and gastric mucosal lesion formation and gastric motility in unanesthetized cold-restrained rats was studied. Both cimetidine and ranitidine suppressed pentagastrin-stimulated gastric secretion in a dose-dependent fashion. Cold restraint-induced lesion formation was not prevented with doses of both agents that inhibited acid secretion by 75%. Doses which suppressed pentagastrin-stimulated acid secretion more than 90% significantly prevented the development of gastric mucosal lesions produced by cold restraint. Doses of both H2 blockers which demonstrated significant suppression of lesion formation had no effect on cold restraint-stimulated gastric contractility. We conclude that cimetidine and ranitidine suppress cold restraint-induced lesion formation by suppressing acid secretion and not by suppressing gastric contractility.