Adenosine deaminase activity in the human duodenal mucosa in relation to gastric acid secretion.

Adenosine deaminase (ADA) activity was estimated in mucosal specimens obtained endoscopically from the duodenal bulb. Three groups of subjects were studied: 1. 9 patients with achlorhydria, 2. 12 subjects with normal gastric acid secretion, 3. 5 patients with hypersecretion. Enzyme activity was measured by determination of ammonia liberated from the substrate according to the Chaney and Marbach method. In patients with hypersecretion the ADA activity was lower than in those with achlorhydria (p less than 0.001) and normal acid secretion (p less than 0.02). A significant negative correlation between ADA activity in the duodenal bulb mucosa and basal and maximal gastric acid outputs was found. The present study seems to indicate a possible relationship between gastric acid secretion and duodenal ADA activity.