Blockade of HERG K+ channel by isoquinoline alkaloid neferine in the stable transfected HEK293 cells.
We studied the effects of isoquinoline alkaloid neferine (Nef) extracted from the seed embryo of Nelumbo nucifera Gaertn on Human ether-à-go-go-related gene (HERG) channels stably expressed in human embryonic kidney (HEK293) cells using whole-cell patch clamp technique, western blot analysis and immunofluorescence experiment. Nef induced a concentration-dependent decrease in current amplitude according to the voltage steps and tail currents of HERG with an IC(50) of 7.419 microM (n(H) -0.5563). Nef shifted the activation curve in a significantly negative direction and accelerated recovery from inactivation and onset of inactivation, however, slowed deactivation. In addition, it had no significant influence on steady-state inactivation curve. Western blot and immunofluorescence results suggested Nef had no significant effect on the expression of HERG protein. In summary, Nef can block HERG K(+) channels that functions by changing the channel activation and inactivation kinetics. Nef has no effect on the generation and trafficking of HERG protein. A blocked-off HERG channel was one mechanism of the anti-arrhythmic effects by Nef.
Gu
Dong-fang
DF
Department of Pharmacology, Harbin Medical University, Harbin, People's Republic of China.
Li
Xue-lian
XL
Qi
Zhi-ping
ZP
Shi
Sha-shan
SS
Hu
Mei-qin
MQ
Liu
Dong-min
DM
She
Cheng-bai
CB
Lv
Yan-jie
YJ
Li
Bao-xin
BX
Yang
Bao-feng
BF
D044182:Benzylisoquinolines / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D020128:Inhibitory Concentration 50; D031653:Nelumbo / Q000737:chemistry*; D018408:Patch-Clamp Techniques; D012639:Seeds; D014162:Transfection
D044182:Benzylisoquinolines; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C057222:neferine