SMALL CONDUCTANCE CHLORIDE CHANNELS IN ACINAR-CELLS FROM THE RAT MANDIBULAR SALIVARY-GLAND ARE DIRECTLY CONTROLLED BY A G-PROTEIN

This paper reports a 5pS Cl— channel in endpiece cells from the rat mandibular gland. The anion selectivity of the channel was SCN— > (Br— = I—) > NO3— > Cl—, which was similar to whole-cell recordings of a macroscopic anion conductance in these cells. The channel was activated by intracellular Ca2+ at depolarising potentials, with no significant activation when the membrane patch was hyperpolarised. The channel was directly activated by an Al/F complex and GTPγS, in separate experiments, applied to the cytosolic face of inside-out excised patches. These G-protein activators stimulated the Cl channel when the Ca2+ concentration was below 1nM, and suggests that this channel may be coupled directly to a G-protein in the apical membrane. © 1993 Academic Press. All rights reserved.