Document Detail


Beta-adrenergic modulation of direct defibrillation energy in anesthetized dog heart.
MedLine Citation:
PMID:  2986468     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Catecholamines facilitate ventricular defibrillation in animals. We examined the effects of beta-adrenergic stimulation and blockade on ventricular defibrillation threshold in anesthetized dogs. Calibrated shocks were delivered between epicardial and superior vena caval electrodes, and defibrillation threshold was measured before and after administration of isoproterenol and propranolol. Eight dogs (group 1) received isoproterenol before propranolol. Nine dogs (group 2) received propranolol before isoproterenol. In group 1, the minimum energy required to defibrillate before isoproterenol was 10.6 +/- 1.7 (SE) J and decreased to 5.9 +/- 1.3 with isoproterenol (P less than 0.001). In group 2, the minimum energy required to defibrillate was 8.3 +/- 2.4 J before propranolol and increased to 10.7 +/- 2.2 after propranolol (P less than 0.001). In group 1, propranolol after isoproterenol increased defibrillation threshold (P less than 0.07), whereas in group 2 isoproterenol after propranolol produced no significant change in defibrillation threshold. Thus beta-stimulation decreased defibrillation threshold significantly in the anesthetized dog heart, an effect that was blocked by propranolol. Conversely, propranolol increased defibrillation threshold, an effect that occurred despite prior beta-stimulation, probably because of the short half-life of isoproterenol.
Authors:
R Ruffy; K Schechtman; E Monje
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  248     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1985 May 
Date Detail:
Created Date:  1985-06-14     Completed Date:  1985-06-14     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H674-7     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Dogs
Electric Stimulation
Half-Life
Heart / physiology*
Isoproterenol / pharmacology
Propranolol / pharmacology
Receptors, Adrenergic, beta / physiology*
Ventricular Fibrillation / physiopathology*
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, beta; 525-66-6/Propranolol; 7683-59-2/Isoproterenol

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


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