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

Adenosine deaminase (ADA) activity was estimated in human gastric mucosal specimens taken endoscopically. Three groups of patients were studied: 6 subjects with achlorhydria, 11 patients with normal gastric acid secretion and 6 patients with hypersecretion. The activity of ADA in mucosal homogenates was measured by determination of the ammonia liberated from the substrate. It was found that in the subjects with normal or increased gastric acid secretion, ADA activities were higher in specimens taken from the gastric fundus than in slices coming from the antral region. In the fundic mucosa the highest ADA activity was noted in patients with hypersecretion. Moreover, in this gastric region a positive correlation between ADA activity and basal or maximal acid output values was found. It is concluded that ADA might be involved in the regulatory system of gastric acid secretion.