Induction of a chloride conductance in gastric vesicles by limited trypsin or chymotrypsin digestion or ageing

Abstract Transport activity of the hog gastric (H + + K + )-ATPase system was measured either as the formation of a proton gradient using the dye probe acridine orange or as the formation of a proton diffusion potential using the cyanine dye 3,3′-diethyloxdicarbocyanine iodide in the presence of the protonophore tetrachlorosalicylanilide. The development of these gradients has been compared in K + media in the presence of either Cl − or SO 4 2− as the anionic species. This comparison of proton diffusion potential formation to proton gradient formation has been used to demonstrate that a Cl − conductance in this vesicular system results from limited enzymic digestion with either trypsin or α-chymotrypsin and from the ageing process itself. The possible significance of this finding is discussed.