title: Effects of benzyltetrahydropalmatine on the rapidly activating component of delayed rectifier potassium current in guinea pig ventricular myocytes.
abstract: 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.
authors.affiliation: Department of Cardiology, Tongji Hospital, Wuhan 430030, China. liyang40@hotmail.com
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Li-ying
authors.initials: LY
authors.lastname: Fu
authors.forename: Wei-xing
authors.initials: WX
authors.lastname: Yao
authors.forename: Guo-jin
authors.initials: GJ
authors.lastname: Xia
authors.forename: Ming-xing
authors.initials: MX
authors.lastname: Jiang
mesh_terms: 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
chemical_list: D000889:Anti-Arrhythmia Agents; D001600:Berberine Alkaloids; D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C060778:benzyltetrahydropalmatine