Endogenous voltage-gated potassium channels in human embryonic kidney (HEK293) cells.
Endogenous voltage-gated potassium currents were investigated in human embryonic kidney (HEK293) and Chinese hamster ovary (CHO) cells using whole-cell voltage clamp recording. Depolarizing voltage steps from -70 mV triggered an outwardly rectified current in nontransfected HEK293 cells. This current had an amplitude of 296 pA at +40 mV and a current density of 19.2 pA/pF. The outward current was eliminated by replacing internal K+ with Cs+ and suppressed by the K+ channel blockers tetraethylammonium and 4-aminopyridine. Raising external K+ attenuated the outward current and shifted the reversal potential towards positive potentials as predicted by the Nernst equation. The current had a fast activation phase but inactivated slowly. These features implicate delayed rectifier (I(K))-like channels as mediators of the observed current, which was comparable in size to I(K) currents in many other cells. A small native inward rectifier current but no transient outward current I(A), the M current I(M), or Ca2+-dependent K+ currents were detected in HEK293 cells. In contrast to these findings in HEK293 cells, little or no I(K)-like current was detected in CHO cells. The difference in endogenous voltage-activated currents in HEK293 and CHO cells suggest that CHO cell lines are a preferred system for exogenous K+ channel expression.
Yu
S P
SP
Department of Neurology, Center for the Study of Nervous System Injury, Washington University School of Medicine, St. Louis, Missouri 63110, USA. yus@neuro.wustl.edu
Kerchner
G A
GA
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D051668:Delayed Rectifier Potassium Channels; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D019789:Tetraethylammonium / Q000494:pharmacology
D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D019789:Tetraethylammonium; D015761:4-Aminopyridine