Distribution of carbonic anhydrase I in gastric and duodenal tissue sections.

Forty-four sections of normal and abnormal gastric and duodenal tissue were examined by an immunoperoxidase technique for the demonstration of carbonic anhydrase I. The presence of the enzyme in normal gastric parietal and surface epithelial cells was confirmed. The enzyme was also demonstrated in normal and metaplastic intestinal absorptive cells, and in gastric adenocarcinoma of the usual and superficial types. The enzyme was normally absent in antral and Brunner's glands, normal and metaplastic goblet cells, and signet ring tumor cells. Gastritis and duodenitis were associated with a decrease in the staining intensity of the enzyme in surface epithelial cells, suggesting a possible decreased enzyme activity, which may enhance the risk for peptic ulceration in susceptible persons.