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.
Department of Pharmacology, Harbin Medical University, Harbin, People's Republic of China.
Dong-fang
DF
Gu
Xue-lian
XL
Li
Zhi-ping
ZP
Qi
Sha-shan
SS
Shi
Mei-qin
MQ
Hu
Dong-min
DM
Liu
Cheng-bai
CB
She
Yan-jie
YJ
Lv
Bao-xin
BX
Li
Bao-feng
BF
Yang
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