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

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 SO₄^2? 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.