Properties of the gastric proton pump in unstimulated permeable gastric glands.

It was found that digitonin-permeabilized resting gastric glands retained considerable acid-secretory ability. Oligomycin abolished this, and ATP was able to bypass this inhibition and restore acid secretion. Moreover, the effect of anoxia was also bypassed by ATP in these preparations. As in intact glands, acid secretion was K+ dependent, and the concentration for half-maximal effect was 18.5 +/- 1.76 mM in Na+-free solutions, a value similar to that found for resting intact glands. The slight inhibition of ATP-dependent secretion by either valinomycin or 2,4-dinitrophenol, but total inhibition by a combination of the ionophores, is interpreted to mean that, in resting gastric glands, the in situ proton pump is electroneutral and the KCl pathway supplying K+ to the luminal face of the pump is probably electroneutral.