The function of carbonic anhydrase in the stomach

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Abstract
The presence of carbonic anhydrase in frog and toad gastric mucosa is confirmed. Complete inhibition of HC1 secretion was produced, after a lag period, in isolated frog and toad gastric mucosa by the following concns. of carbonic anhydrase inhibitors: 1.7 x 10-2 [image] p-toluenesulfonamide, 10-2 [image] sulfonamidobenzoate, 10-2 [image] thiophene-2-sulfonamide, and 10-3 [image] prontosil soluble, but not by lower concns. or by 7 x 10-3 [image] sulfanilamide. The unstimulated respiration of frog and toad liver slices, sartorius muscle, back skin, pancreas or gastric mucosa was unaltered by these concns. of the inhibitors. The respiration of acid-secreting frog and toad gastric mucosa was inhibited by these compounds; also, after a lag period, by the amt. expected if the acid-secreting cells were damaged following the accumulation of alkali within them. A similar inhibition of respiration occurred in toad kidney slices. No trace of carbonic anhydrase activity, even in concentrated extracts of frog and toad gastric mucosa, could be found after these expts.; the extracted enzyme was inhibited more than 99%. The results are in accordance with the view that carbonic anhydrase plays a role in maintaining the acid-base balance in oxyntic cells during HCl secretion, but that the amt. of carbonic anhydrase required is only a very small proportion of the total potential activity.