Document Detail

Effects of BW A256C, a novel class 1 antiarrhythmic agent, on maximum rate of depolarisation of cardiac action potentials in vitro: frequency, use, and voltage dependence.
MedLine Citation:
PMID:  2434786     Owner:  NLM     Status:  MEDLINE    
The frequency, use, and voltage-dependence of the effects of a novel antiarrhythmic agent, BW A256C, on the maximum rate of depolarization (Vmax) of action potentials in guinea-pig right ventricle were studied using standard microelectrode recording techniques in vitro. BW A256C (10(-6) M) reduced Vmax in a frequency-dependent way in the range 0.33-3.3 Hz; the maximum reduction was at the highest frequency. BW A256C did not cause resting block of Vmax. The onset of use-dependent Vmax reduction at 3.3 Hz followed a monoexponential function with a very slow rate constant, 0.019 +/- 0.003 AP-1. The recovery from use-dependent reduction, studied by applying single extra stimuli at various times after trains of stimuli at 3.3 Hz, was also very slow; half-life (t 1/2) for recovery was 119.0 +/- 19.2 s, and the time constant tre was 171.7 +/- 27.7 s. For comparison, the values for Flecainide (10(-5) M), obtained under identical conditions, were: rateon, 0.106 +/- 0.010 AP-1; t 1/2, 7.68 +/- 0.20 s; tre 11.07 +/- 0.29 s (means +/- SEM). In the presence of BW A256C (10(-6) M), the normalised diastolic membrane potential-Vmax curve was significantly shifted in the hyperpolarizing direction. The mean shift was 5.5 +/- 1.1 mV, measured at the 50% reduction of Vmax level. BW A256C is therefore classified as a novel "slow" class 1C antiarrhythmic agent.
S Donoghue; P N Payne; G Allan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  9     ISSN:  0160-2446     ISO Abbreviation:  J. Cardiovasc. Pharmacol.     Publication Date:  1987 Jan 
Date Detail:
Created Date:  1987-04-20     Completed Date:  1987-04-20     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  12-8     Citation Subset:  IM    
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MeSH Terms
Action Potentials / drug effects
Flecainide / pharmacology
Guinea Pigs
Heart / drug effects*
Membrane Potentials / drug effects
Triazines / pharmacology*
Reg. No./Substance:
0/Triazines; 54143-55-4/Flecainide; 98410-36-7/BWA 256C

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

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