Endogenous voltage-gated potassium channels in human embryonic kidney (HEK293) cells

✍ Scribed by Shan Ping Yu; Geoffrey A. Kerchner

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 92 KB
• Volume: 52
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/(sici)1097-4547(19980601)52:5<612::aid-jnr13>3.0.co;2-3

✦ Synopsis

Endogenous voltage-gated potassium currents were investigated in human embryonic kidney (HEK293) and Chinese hamster ovary (CHO) cells using wholecell 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 Ca 2؉ -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.