Document Detail

Propranolol unmasks class III like electrophysiological properties of norepinephrine.
MedLine Citation:
PMID:  8133907     Owner:  NLM     Status:  MEDLINE    
Isolated perfused spontaneously beating rabbit hearts were treated with increasing concentrations of norepinephrine (0.01, 0.1, 0.5 mumol/l) either alone or in presence of propranolol (0.1 mumol/l). For analysis of the epicardial activation and repolarization process and epicardial mapping (256 unipolar leads) was performed. For each electrode the activation and repolarization time was determined. From these data the "breakthrough-points" (BTP) of epicardial activation were determined. At each electrode an activation vector (VEC) was calculated giving direction and velocity of the local excitation wave. The beat similarity of various heart beats (under NE) compared to control was evaluated by determination of the percentage of identical BTP and of similar VEC (deviation < or = 5 degrees). Moreover at each electrode the local activation recovery interval (ARI) and its standard deviation (of 256 leads, dispersion, DISP) were determined. Norepinephrine alone (0.01, 0.1, 0.5 mumol/l) led to an increase in left ventricular pressure, heart rate and DISP with concomitant frequency dependent reduction in ARI, and to changes in the epicardial activation pattern (reduction in BTP, VEC). We found that in the presence of propranolol (0.1 mumol/l) norepinephrine prolonged ARI and reduced ARI-dispersion. This effect was not due to changes in heart rate. The disturbing effects on the activation pattern were diminished. These effects could be prevented by pretreatment with 1 mumol/l prazosin. From these results we conclude, that norepinephrine prolongs the relative action potential duration via stimulation of alpha 1-adrenoceptor and enhances cellular coupling.(ABSTRACT TRUNCATED AT 250 WORDS)
S Dhein; R Gerwin; U Ziskoven; M Schott; A F Rump; Y Zhao; A Salameh; W Klaus
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Naunyn-Schmiedeberg's archives of pharmacology     Volume:  348     ISSN:  0028-1298     ISO Abbreviation:  Naunyn Schmiedebergs Arch. Pharmacol.     Publication Date:  1993 Dec 
Date Detail:
Created Date:  1994-04-20     Completed Date:  1994-04-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0326264     Medline TA:  Naunyn Schmiedebergs Arch Pharmacol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  643-9     Citation Subset:  IM    
Institut für Pharmakologie, Universität Köln, Germany.
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MeSH Terms
Action Potentials / drug effects
Anti-Arrhythmia Agents / pharmacology*
Electric Stimulation
Heart Rate / drug effects
Norepinephrine / pharmacology*
Prazosin / pharmacology
Propranolol / pharmacology*
Receptors, Adrenergic, alpha-1 / antagonists & inhibitors
Ventricular Pressure / drug effects
Reg. No./Substance:
0/Anti-Arrhythmia Agents; 0/Receptors, Adrenergic, alpha-1; 19216-56-9/Prazosin; 51-41-2/Norepinephrine; 525-66-6/Propranolol

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