Na + Effects on Intracellular pH of Isolated,Perfused Rabbit Gastric Mucosal Surface Cells

Abstract

The effects of extracellular Na⁺ on intracellular pH were studied by perfusing BCECF loaded gastric mucosal surface cells adherent to glass coverslips held in a spectrophotofluorometer. Removal of Na⁺ from a NaCI Ringer perfusate (pH 7.4) resulted in progressive intracellular acidification, which was partially blocked by amiloride. An H⁺ conductance did not appear to be present. Acidification induced either by Na⁺ removal or by a NH₄ prepulse was reversed by extracellular Na⁺, but this effect was not completely prevented by amiloride. Amiloride significantly, but not completely, inhibited Na²² uptake by gastric mucosal surface cells. The data suggest that extracellular Na⁺ maintains intracellular pH of gastric mucosal surface cells through amiloride-sensitive and -insensitive pathways. In the absence of extracellular Na⁺, cellular acidification seemed to be partially due to Na⁺/H⁺ exchange.