Effect of ZnSO4 upon gastric acid secretion and carbonic anhydrase

Starting from the multiple role zinc holds in the enzymatic processes of the body and from some positive data concerning treatment with zinc sulphate in gastric ulcer, we have studied the effect of ZnSO4 on gastric acid secretion in duodenal ulcer patients, as well as that on purified and gastric mucosa carbonic anhydrase. Gastric secretory testing showed that zinc sulphate administered in doses of 60 ml/day (1% solution) for 10 days reduced basal acid secretion in duodenal ulcer patients by 57.7%. In vitro, concentrations of ZnSO4 ranging between 10(-6) and 10(-2)M, inhibit purified carbonic anhydrase activity in a dose-dependent manner, reaching maximum effect at 10(-2)M, when carbonic anhydrase activity dropped from 2060 +/- 65 IU to 660 +/- 85 IU. A similar dose-dependent inhibition was found with gastric mucosa carbonic anhydrase activity, where ZnSO4 at 10(-2)M reduces enzyme activity from its basal value of 1.58 +/- 0.36 EU/mg to 0.88 +/- 0.21 EU/mg. Besides this effect, zinc sulphate antagonized in vitro the activation of both purified and gastric mucosa carbonic anhydrase by histamine. In conclusion, the mechanism of antisecretory effect of ZnSO4 might well be the inhibition of the carbonic anhydrase in the gastric mucosa.