Changes in the apparent chloride permeability of Necturus enterocytes during the sodium-coupled transport of alanine.

The membrane potential and intracellular Cl- activity of Necturus enterocytes were measured with double-barrelled ion-selective microelectrodes and apparent permeability coefficients (PCl) for the apical membrane calculated from Cl(-)-replacement experiments. In the presence of L-alanine in the mucosal solution an increase in PCl took place. It is proposed that this might reflect the activation of a Cl- conductance during active substrate transport.