Hormonal activation of single K+ channels via internal messenger in isolated pancreatic acinar cells.

The mechanism underlying hormonal activation of potassium channels was investigated in pig pancreatic acinar cells by patch-clamp single-channel and whole-cell current recordings. It was shown directly that a peptide hormone belonging to the cholecystokinin-gastrin family, CCK5, can activate single voltage-sensitive potassium channels which can be blocked by tetraethylammonium. The single-channel currents were recorded from electrically isolated cell-attached membrane patches to which the hormone had no access and the activation must therefore involve an intracellular messenger. The hormonal response requires external Ca2+ in the isolated membrane-patch area indicating that calcium gating is not directly linked to hormone-receptor interaction.