Duodenal ulcer: a model of impaired mucosal defence.

There is a new model of chronic duodenal ulcer in which the ulcer is generated by irradiating the lower mediastinum of mice with a single dose of 18 Gy 250 kV x rays. Single ulcers develop in the proximal duodenum of about half the animals. Previous studies have shown a remarkable morphological and behavioural similarity to duodenal ulcer in man. Ulceration occurs because of an imbalance between aggressive and defensive forces within the duodenum and an attempt has been made to elucidate the pathomechanism of this ulcer by determining acid and pepsin secretion. The basal and pentagastrin stimulated secretion of acid, pepsin, and histamine were measured and no changes in acid or pepsin secretion were shown to occur (risk of type II error < 1%). It is therefore concluded that this chronic ulcer is a model of impaired duodenal defence.