ELECTROMOTIVE CHLORIDE TRANSPORT AND GASTRIC ACID SECRETION IN THE FROG

The total active transport of chloride ions across the gastric mucosa can be considered as the sum of two fractions; an acidic one which is equivalent to the acid secreted, and an electromotive one which accounts for the electric energy generated by the gastric mucosa. In the present studies, the relationship between this electromotive chloride transport and acid secretion has been investigated, using specific inhibitors. The rate of electromotive chloride transport was found to be essentially unaffected by changes in the rate of acid secretion, and also by inhibition of acid secretion by thiocyanate. On the other hand, diamox, in combination with histamine, was shown to depress or abolish the gastric electromotive force and to inhibit partially the total chloride transport, while acid was secreted at an almost normal rate. This kind of inhibition is undefined as to its mechanism but seems to be more specific for the gastric chloride transport than any other inhibitor known. It is concluded that acid secretion and electromotive chloride transport involve two different mechanisms, and are not absolutely essential for each other. The present results do not support the view that carbonic anhydrase is essential for acid secretion. They rather suggest an important function of this enzyme in the mechanism of active chloride transport.