Effects of Xinjining extract on inward rectifier potassium current in ventricular myocytes of guinea pig.
OBJECTIVE
To study the effect of Xinjining extract (, XJN) on inward rectifier potassium current (I(K1)) in ventricular myocyte (VMC) of guinea pigs and its anti-arrhythmic mechanism on ion channel level.


METHODS
Single VMC was enzymatically isolated by zymolisis, and whole-cell patch clamp recording technique was used to record the I(k1) in VMC irrigated with XJN of different concentrations (1.25, 2.50, 5.00 g/L; six samples for each). The stable current and conductance of the inward component of I(K1) as well as the outward component of peak I(K1) and conductance of it accordingly was recorded when the test voltage was set on -110 mV.


RESULTS
The suppressive rate of XJN on the inward component of I(K1) was 9.54% + or - 5.81%, 34.82% + or - 15.03%, and 59.52% + or - 25.58% with a concentration of 1.25, 2.50, and 5.00 g/L, respectively, and that for the outward component of peak I(K1) was 23.94% + or - 7.45%, 52.98% + or - 19.62%, and 71.42% + or - 23.01%, respectively (all P<0.05). Moreover, different concentrations of XJN also showed effects for reducing I(K1) conductance.


CONCLUSIONS
XJN has inhibitory effect on I(K1) in guinea pig's VMC, and that of the same concentration shows stronger inhibition on outward component than on inward component, which may be one of the mechanisms of its anti-arrhythmic effect.
First Affiliated Hospital of Henan College of Traditional Chinese Medcine, Zhengzhou 450000, China. zhuyujl@163.com
Ming-jun
MJ
Zhu
Guo-juan
GJ
Wang
Yong-xia
YX
Wang
Jie-lin
JL
Pu
Hong-jun
HJ
Liu
Hai-bin
HB
Yu
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004594:Electrophysiology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D016276:Ventricular Function / Q000187:drug effects
D004365:Drugs, Chinese Herbal; D024661:Potassium Channels, Inwardly Rectifying; C548801:xinjining