A K+ current in Xenopus muscle cells which shows inactivation.

The purpose of this study was to describe an inactivating potassium current that is present in Xenopus muscle cells in culture. Whole cell currents were recorded from muscle cells grown in culture for 16-30 h. The majority of muscle cells had an outward current which inactivated during a 100 ms maintained depolarization. The outward current was reduced by tetraethylammonium or the aminopyridines, but not completely eliminated by either agent. Depolarizing prepulses reduced both the peak current and the late component of the current. The results suggest that by one day in culture these skeletal muscle cells develop an inactivating outward potassium current.