Calcium and secretagogues-induced conductances in rat exocrine pancreas.

The electrical properties of single acinar cells isolated from rat pancreas were studied with the whole-cell tight-seal recording method. Under resting conditions, the relative permeabilities of Cl and K were PCl/PK approximately equal to 3. At 1 microM internal calcium, a Ca and voltage-dependent Cl conductance was activated. At 10 microM internal calcium, the major conductance was selective for cations. It was not voltage-dependent. Acetylcholine and cholecystokinin induced an increase of internal Ca which in turn activated either only a Cl conductance or both Cl and cationic conductances. The secretagogue-induced conductance was increased to a variable extent by depolarisation. The absence of K channels activated by internal calcium indicates that, in pancreatic acinar cells, the mechanism of fluid secretion differs from that observed in other exocrine glands.