Effects of benzyltetrahydropalmatine on the rapidly activating component of delayed rectifier potassium current in guinea pig ventricular myocytes.
OBJECTIVE
To investigate the effect of benzyltetrahydropalmatine (BTHP) on the rapidly activating component of delayed rectifier K+ current (Ikr) in single guinea pig ventricular myocytes.


METHODS
Whole-cell patch clamp technique was used to record Ikr.


RESULTS
Ikr was blocked by 1-100 mumol.L-1 BTHP in concentration-, voltage-, and specifically frequency-dependent fashion, with IC50 of 13.5 mumol.L-1 (95% confidence range: 11.2-15.8 mumol.L-1). 30 mumol.L-1 BTHP reduced Ikr and Ikr.tail by (31 +/- 4)% and (36 +/- 5)% (n = 6, P < 0.01), respectively. The time constant for deactivation (tau') of the tail current was decreased by 30 mumol.L-1 BTHP from (238 +/- 16) ms to (196 +/- 14) ms, while drug had no any effect on the time constant for activation (tau) of Ikr,tail.


CONCLUSIONS
BTHP inhibited Ikr in a frequency-dependent fashion.
Li
Yang
Y
Department of Cardiology, Tongji Hospital, Wuhan 430030, China. liyang40@hotmail.com
Fu
Li-ying
LY
Yao
Wei-xing
WX
Xia
Guo-jin
GJ
Jiang
Ming-xing
MX
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D001600:Berberine Alkaloids / Q000494:pharmacology*; D002469:Cell Separation; D051668:Delayed Rectifier Potassium Channels; D005260:Female; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated
D000889:Anti-Arrhythmia Agents; D001600:Berberine Alkaloids; D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C060778:benzyltetrahydropalmatine