Abstract The relationship to gastric secretion of 2 types of gastric ulcer produced in pylorus-occluded rats was evaluated.

Exposure to stress for 2 hr produced a high incidence of lesions in the glandular part of the stomach.

Both the volume and total acid output of gastric secretion were significantly decreased.

Stress ulceration was prevented only by atropine, but not by antacids or adrenoreptor blocking agents.

Increase in gastric motility during stress appears to cause these ulcers.

The second type of gastric ulcer, produced during a 5 hr period following pyloric occlusion, was located only in the rumenal part of the stomach.

Both atropine and antacids prevented its development, indicating causation mainly by accumulation of gastric juice.

It is concluded that rats with experimentally induced rumenal ulcers may be a more logical model for assessing the activity of anti-ulcer agents in preventing peptic ulceration associated with accumulation of gastric acid.