ATP-dependent regulation of SK4/IKl-like currents in rat submandibular acinar cells: possible role of cAMP-dependent protein kinase

摘要

SK4/IK1 encodes an intermediate conductance, Ca~(2+)-activated K~+ channel and fulfills a variety of physiological functions in excitable and nonexcitable cells. Although recent studies have provided evidence for the presence of SK4/IK1 channels in salivary acinar cells, the regulatory mechanisms and the physiological function of the channel remain unknown in these cells. Using molecular and electrophysiological techniques, we examined whether cytosolic ATP-dependent regulation of native SK4/ IKl-like channel activity would involve endogenous cAMP-depen-dent protein kinase (PKA) in rat submandibular acinar (RSA) cells. Electrophysiological properties of tetraethylammonium (TEA) (10 mM)-insensitive, Ca~(2+)-dependent K~+ currents in macropatches excised from RSA cells matched those of whole cell currents recorded from human embryonic kidney-293 cells heterologously expressing rat SK4/IK1 (rSK4/IKl) cloned from RSA cells.