The effects of metiamide on the "activity-stress" ulcer in rats.

Forty rats were housed in standard activity wheel cages and fed for only 1 hr per day. The animals were equally divided into 4 groups that received either saline, 12.5 mg/kg, 25.0 mg/kg or 50.0 mg/kg of metiamide, an H2 receptor antagonist, 3 times a day. All animals died within 11 days and all demonstrated significant gastric lesions in the glandular fundus of the stomach. The 50.0 mg/kg dosage group, however, demonstrated significantly fewer ulcers than the saline animals and the lesions that did occur were significantly smaller than those noted in the control animals. Several hypotheses were offered to explain these results which took into account metiamide's effects on gastric secretion and motor activity. It was suggested that secretion of acid may be an important contributing factor in the formation of gastric ulcers in animals subjected to the "activity-stress" procedure.

Effects of manipulating cholinergic tone upon the activity-stress ulcer.

Eighty rats were housed in standard activity wheel cages and fed for only 1 hr per day. The animals were divided into 10-animal drug groups that received either 0.25, 050, 1.0 mg/kg of scopolamine methylbromide, or 0.06, 0.125, 0.250 mg/kg of carbachol, 3 times a day. Two separate 10-animal saline control groups accompaned each drug series. All animals died within 6 days and most demonstrated significant gastric lesions in the glandular fundus of the stomach. All dosages of scopolamine methylbromide significantly reduced the number and severity of gastric lesions and in some cases abolished all signs of stomach pathology. None of the dosages of carbachol significantly affected either the number of degree of gastric ulceration noted in the body of the stomach. These results were interpreted to suggest that the secretion of gastric acid may be an important contributing factor in the formation of gastric ulcers in animals subjected to the activity-stress procedure.