Ionic fluxes of Rana pipiens stomach bathed by sulfate solutions

Abstract

Efforts to understand the interdependence of the active transport of hydrogen and chloride ion by bathing gastric mucosae with sulfate-substituted salines have not led to agreement. For Rana pipiens, an independent hydrogen ion pump has been proposed, and an anion transporting system has been implicated in H⁺ transport by Rana catesbiana. This discrepancy prompted further study of the former gastric mucosa. The results show that the R. pipiens stomach does not actively transport SO₄^– and is able to secrete H⁺ without concomitant transport of anion. This is in agreement with the initial observation of Heinz and Durbin. Reversal of the spontaneous transepithelial potential upon exposure of the stomach to sulfate salines, however, is highly variable and in these experiments is attributed to a net transfer of Na⁺ from serosa to mucosa as well as to secretion of H⁺, not to the transport of the latter ion alone. For the gastric mucosa whose serosal aspect is bathed by sulfate saline, substitution of the mucosal fluid by an isoosmotic sucrose solution resulted in a reversible cessation of hydrogen ion secretion.