Ion selective effects of salicylate on antral mucosa

The effects of luminal salicylate, 5mM, were measured on rates of ion transport by isolated antral mucosa. At neutral luminal pH, salicylate increases Na and decreases Cl permeability. Salicylate does not alter net Na transport but decreases net Cl secretion. At luminal pH 4, the effects of salicylate can be arbitrarily divided into two phases. The intitial phase is associated with an increase in Na and marked decrease in Cl permeability. Subsequently, a greater increase in Na permeability and a marked increase in Cl permeability occurs. Active Na transport persists in the presence of salicylate at pH 4. Indirect evidence also suggests that Cl secretion persists under these conditions, buy at a reduced rate. The rate of luminal acid acid loss also increases in the presence of salicylate. A 4-fold increase in salicylate concentration or decrease in luminal pH from 4 to 3 did not appear to intensify the effects observed for 5 mM salicylate at pH 4. The increase in cation and decrease in anion permeability observed at pH 7 and initially at pH 4 are compatible with an influence of a negative charge of the salicylate anion. The subsequent changes observed in the presence of acid also are compatible with the concept that as the mucosa becomes overwhelmed with acid, a nonspecific increase in permeability occurs. However, the effect of salicylate on active Cl transport is largely independent of acid diffusing into the mucosa.