Ionic currents in neuroblastoma clone E-7 cells.

Ionic currents were studied in exponentially growing neuroblastoma cells (clone E-7) derived from mouse neuroblastoma C-1300 with the patch-clamp technique in the whole cell mode (Pflügers Arch., 391 (1981) 85-100). In differentiated cells, with one or several processes, an early inactivating inward current approximately equal to 50 microA/cm2 was observed in response to depolarizing steps from the holding potential -60 to -70 mV, which was insensitive to 2 microM tetrodotoxin but readily blocked by Co2+ (6 mM). This inward current was followed by a delayed outward current which was eliminated by 12 mM tetraethylammonium. In the undifferentiated cells, only delayed outward current was observed. It is suggested that, in differentiated cells both Ca2+ and delayed rectifier K+ channels exist, while only the latter are present in undifferentiated cells.