Acetylcholine-induced change in intracellular Cl- activity of the mouse lacrimal acinar cells.

Using double-barreled Cl- -sensitive microelectrodes, intracellular Cl- activity (AiCl) in the mouse lacrimal acinar cells in vitro was determined in both resting and secretory phases. In the resting state AiCl was 31 mmol/l which was 1.4 times higher than that predicted for the passive distribution according to the membrane potential (Vm) of -41 mV. Addition of acetylcholine (ACh, 1 microM) hyperpolarized Vm to -63 mV and decreased AiCl to 20 mmol/l which was still twice the equilibrium activity. A-23178 produced similar changes in Vm and AiCl to those induced by ACh. It was concluded that Cl- was actively accumulated in the acinar cells and, in the secretory phase, Cl- efflux was enhanced by the increased driving force and Ca2+-mediated increase in the Cl- permeability across the cell membrane.