Document Detail

Effects of benzyltetrahydropalmatine on two components of the delayed rectifier K+ current in Guinea pig ventricular myocytes.
MedLine Citation:
PMID:  12652101     Owner:  NLM     Status:  MEDLINE    
The effects of benzyltetrahydropalmatine (BTHP), a new class III antiarrhythmic agent, on the action potential in guinea pig papillary muscle and the rapidly activating component (I(Kr)) and the slowly activating component (I(Ks)) of the delayed rectifier potassium current (I(K)) in isolated guinea pig ventricular myocytes were investigated. The action potentials of papillary muscles were studied using a standard microelectrode technique, while the K(+) currents were recorded using the whole-cell patch clamp technique. The results showed that BTHP prolonged the action potential duration (APD) without altering other variables of the action potential in guinea pig papillary muscles. The 2 components of I(K) were blocked by BTHP (1 approximately 100 micromol x L(-1)) in time-, concentration-, voltage-, and specifically frequency-dependent fashion. The IC(50) value for blockade of I(Kr) was 13.5 micromol x L(-1), while the IC(50) value for blockade of I(Ks) was 9.3 micromol x L(-1). BTHP 30.0 micromol x L(-1) reduced I(Kr) and I(Kr,tail) by 31 +/- 4.3% and 36 +/- 4.7% (n = 6, p < 0.01) and decreased I(Ks) and I(Ks,tail) by 40 +/- 6.3% and 39 +/- 4.6% (n = 7, p < 0.01) respectively. BTHP accelerated their deactivation course by reducing the time constants of deactivation of I(Kr) and I(Ks). The activation kinetics of I(Kr) or I(Ks) were not affected by BTHP. It is concluded that BTHP prolonged the action potential duration with respect to its non-selective action on I(Kr) and I(Ks) in single guinea pig ventricular cell in a frequency-dependent fashion.
Yang Li; Li ying Fu; Weixing Yao; Guojin Xia; Mingxing Jiang
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy     Volume:  16     ISSN:  0920-3206     ISO Abbreviation:  Cardiovasc Drugs Ther     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2003-03-24     Completed Date:  2003-06-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8712220     Medline TA:  Cardiovasc Drugs Ther     Country:  United States    
Other Details:
Languages:  eng     Pagination:  317-25     Citation Subset:  IM    
Department of Cardiology, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, People's Republic of China.
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MeSH Terms
Action Potentials / drug effects
Anti-Arrhythmia Agents / pharmacology*
Berberine Alkaloids / pharmacology*
Cells, Cultured
Delayed Rectifier Potassium Channels
Guinea Pigs
Heart Ventricles / cytology
Myocytes, Cardiac / drug effects*,  physiology
Papillary Muscles / cytology
Patch-Clamp Techniques
Potassium Channels / drug effects*,  physiology
Potassium Channels, Voltage-Gated*
Reg. No./Substance:
0/Anti-Arrhythmia Agents; 0/Berberine Alkaloids; 0/Delayed Rectifier Potassium Channels; 0/Potassium Channels; 0/Potassium Channels, Voltage-Gated; 114090-45-8/benzyltetrahydropalmatine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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