Duodenal ulcerogens cysteamine and propionitrile decrease duodenal neutralization of acid in the rat.

Neutralization of acid was evaluated in rat proximal duodenal segments isolated from biliary and pancreatic secretions. Duodenal ulcerogenic doses of cysteamine produced a significant decrease in acid disposal 0.5-2 hr after treatment. Oral or subcutaneous administration of the duodenal ulcerogen was effective. The potent ulcerogen cysteamine produced a more pronounced decrease than propionitrile (a weak duodenal ulcerogen). The failure of ethanolamine, a nonulcerogenic structural analog of cysteamine to significantly alter acid disposal suggests that the effect is not due to the toxic properties of the duodenal ulcerogen. The results reinforce the concept that the duodenum is able to dispose of significant quantities of acid. The decrease in acid-handling may contribute to duodenal susceptibility to acid after treatment with ulcerogens and possibly reflects pathophysiologic changes early in duodenal ulceration.