Beneficial effects of methionine and histidine in aspirin solutions on gastric mucosal damage in rats.

Amino acids methionine and histidine, which are soluble in propylene glycol, were investigated for their purported beneficial effects on aspirin-induced gastric mucosal damage in the rat. The pathognomonic changes observed microscopically in the fundic region of the stomach of animals administered daily doses (100 mg/kg), for up to 15 days, of aspirin solutions (0.36 M) in propylene glycol incorporated with the amino acids were compared with those of animals given equivalent quantities of aspirin in an aqueous suspension combined with an aluminum hydroxide antacid. A "delayed" onset of aspirin-induced cellular damage due to the presence of amino acids, analogous to that associated with the use of antacids, was found as determined partly by differences in the staining ability of injured cells with hematoxylin and eosin.