[Bepridil inhibition on the delayed rectifier K+ currents in thyroxine induced hypertrophied guinea pig ventricular myocytes].
OBJECTIVE
To study the effects of bepridil on the rapidly activating component (IKr), the slowly activating component (IKs) of the delayed rectifier potassium current and the inward rectifier potassium current (IK1) in hypertrophied guinea pig ventricular myocytes.


METHODS
The whole cell patch clamp techniques were used.


RESULTS
In hypertrophied guinea pig ventricular myocytes, bepridil 30 mumol.L-1 markedly inhibited IKr and IKs (by 20.9% and 27.2% at 0 mV and  mV, respectively). The effect of bepridil on IKs was larger than on IKr. Bepridil 30 mumol.L-1 also significantly inhibited the inward component of IK1 (by 15.1% at +100 mV), but the reverse potential of IK1 was unaffected. Bepridil (1-100 mumol.L-1) was shown to inhibit IKr and IKs in a concentration-dependent manner. Their IC50 were 46.7 mumol.L-1 and 23.8 mumol.L-1, respectively.


CONCLUSIONS
Bepridil inhibit IKr, IKs and IK1 in hypertrophied guinea pig ventricular myocytes, which may be important in understanding the antiarrhythmic effects of this drug.
Zhang
G Q
GQ
National Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871, China.
Hao
X M
XM
Ma
Y P
YP
Zhou
P A
PA
Wu
C H
CH
Dai
D Z
DZ
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D015764:Bepridil / Q000494:pharmacology*; D002312:Cardiomyopathy, Hypertrophic / Q000139:chemically induced / Q000473:pathology*; D002469:Cell Separation; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D006168:Guinea Pigs; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D013974:Thyroxine
D000889:Anti-Arrhythmia Agents; D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C059983:potassium channel protein I(sk); D015764:Bepridil; D013974:Thyroxine