Further evidence for a simple Cl- conductance pathway in nutrient membrane of frog stomach

A decrease in nutrient Cl- increases the negativity of the nutrient relative to the secretory side. It seemed possible that Cl- transport could result from a neutral Cl- mechanism in the nutrient membrane coupled to a simple Cl- conductance pathway in the secretory membrane. Experiments in HCO3(-)-free, K(+)-free and Na(+)-free solutions in both bathing media gave for a 10-fold change in nutrient Cl- a PD change of 9.5 mV. Similar experiments with 0.5 mM DIDS in the nutrient solution gave for a 10-fold change in nutrient Cl- a PD change of 7.9 mV. These experiments eliminated a neutral Cl(-)-HCO3- exchanger, a NaCl and a KCl symport. Thus the change in PD could best be explained by a simple Cl- conductance in the nutrient membrane.