[2 types of calcium-dependent outward potassium currents in the somatic membrane of Helix pomatia neurons].

Peculiarities of delayed potassium outward current were studied in voltage clamp experiments on nonidentified intracellularly perfused neurons of the snail Helix pomatia. Together with voltage operated potassium currents which depend on the intracellular Ca2+ ions (IK(Cain], another peculiar calcium-dependent potassium current was shown to exist. This current increases with an increase of the external Ca2+ concentration (IK(Caout] and is insensitive to intracellular administration of EGTA and fluoride. It is blocked by extracellular application of cobalt ions (1.5 mmol/l). As distinct from (IK(Cain), IK(Caout] rapidly reaches a maximum and then inactivates to a steady-state level.