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 GTP gamma S, 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.