Document Detail

Comparative effects of propranolol and practolol in the early stages of experimental canine myocardial infarction.
MedLine Citation:
PMID:  938798     Owner:  NLM     Status:  MEDLINE    
1 The effects of propranolol and practolol, at equivalent myocardial beta-adrenoceptor blocking doses, (as assessed by the degree of shift of isoprenaline dose-response curves) were investigated in anaesthetized greyhounds before and after acute coronary artery ligation. 2 When administered intravenously to the intact close-chest dog, propranolol (0.1 mg/kg) and practolol (0.5 mg/kg) caused similar decreases in heart rate, left ventricular dP/dt max, myocardial blood flow and cardiac output. Only propranolol increased peripheral vascular resistance. 3 When administered 2-3h after acute coronary artery ligation, propranolol (0.1 mg/kg) significantly decreased blood flow in both normally perfused and ischaemic regions of the heart. There was also electrocardiographic evidence of further deterioration after propranolol; two out of seven animals died following this treatment. 4 Practolol (0.5 mg/kg) when administered after coronary artery ligation also decreased normal myocardial blood flow but flow in the ischaemic area remained unchanged. Evidence was obtained from electrocardiographic, myocardial temperature, myocardial O2 consumption and lactate measurements that the administration of practolol, in contrast to propranolol, benefited the ischaemic myocardium. 5 Analysis of the results suggests that this beneficial action of practolol may be related to at least two mechanisms. Firstly the ability of practolol to increase the period during diastole when perfusion of the subendocardium is possible, without decreasing the transventricular pressure during this period. Secondly that practolol does not unmask alpha-adrenoceptor vasoconstriction in the ischaemic region.
R J Marshall; J R Parratt
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  British journal of pharmacology     Volume:  57     ISSN:  0007-1188     ISO Abbreviation:  Br. J. Pharmacol.     Publication Date:  1976 Jun 
Date Detail:
Created Date:  1976-09-25     Completed Date:  1976-09-25     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7502536     Medline TA:  Br J Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  295-303     Citation Subset:  IM    
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MeSH Terms
Body Temperature / drug effects
Coronary Circulation / drug effects
Coronary Vessels / physiology
Dipyridamole / pharmacology
Hemodynamics / drug effects
Ischemia / physiopathology
Myocardial Infarction / drug therapy,  physiopathology*
Oxygen Consumption / drug effects
Practolol / pharmacology*,  therapeutic use
Propranolol / adverse effects,  pharmacology*
Time Factors
Reg. No./Substance:
525-66-6/Propranolol; 58-32-2/Dipyridamole; 6673-35-4/Practolol

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

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