Distribution of carbonic anhydrase within the gastric mucosa.

Bullfrog fundic mucosa was separated into fractions containing predominantly surface epithelial cells, mucous neck cells, and and oxyntic cells, respectively, and the carbonic anhydrase concentration of each fraction and of antral mucosa was measured. There were no significant differences between the enzyme concentrations of these fractions. The mean level was 12.4 units of activity per milligram of protein. The cellular localization of carbonic anhydrase in the gastric fundic and antral mucosa of the bullfrog, rat, rabbit, and dog was studied using a specific histochemical technique. The enzyme was shown to be present in both parietal and nonparietal epithelium of all species and to characterize a specific cell type in the dog antrum. The widespread distribution of high levels of carbonic anhydrase activity in both acid secreting and nonsecreting cells of the gastric mucosa suggests a possible role for the enzyme beyond one solely relating to acid secretion.