Document Detail


Effect of beta-adrenergic receptor blockade on blood flow to collateral-dependent myocardium during exercise.
MedLine Citation:
PMID:  7867199     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: beta-Adrenergic receptors have been identified in isolated coronary collateral blood vessels, but their functional significance in the intact heart has not been demonstrated. METHODS AND RESULTS: We measured myocardial blood flow with radioactive microspheres in normal and collateral-dependent myocardium in eight dogs trained to run on a treadmill before and after beta-adrenergic blockade with propranolol, 200 micrograms/kg, a dose that effectively inhibited the increase in coronary blood flow produced by selective beta 1- and beta 2-adrenergic agonists. Collateral vessel growth was stimulated with 2-minute intermittent occlusions of the left anterior descending artery followed by permanent occlusion. During control exercise, blood flow in the collateral zone was 38 +/- 5% less than in the normal zone. At identical levels of exercise, with heart rate maintained constant by atrial pacing, propranolol decreased mean blood flow in the collateralized myocardium from 1.93 +/- 0.17 to 1.50 +/- 0.14 mL.min-1.g-1 (P < .01), while increasing the subendocardial to subepicardial blood flow ratio from 0.78 +/- 0.11 to 0.91 +/- 0.10 (P < .05). The decrease in collateral zone blood flow in response to propranolol resulted from an increase in both transcollateral resistance from 25.9 +/- 2.3 to 35.2 +/- 4.3 mm Hg.mL-1.min.g (P < .05) and small-vessel resistance in the collateral-dependent myocardium from 30.9 +/- 4.7 to 44.0 +/- 8.8 mm Hg.mL-1.min.g (P < .07). Blood flow to the normal zone was also significantly reduced from 3.14 +/- 0.21 to 2.23 +/- 0.12 mL.min-1.g-1 (P < .01) after propranolol. CONCLUSIONS: beta-Adrenergic blockade decreased blood flow to collateral-dependent myocardium during exercise. These results indicate that beta-adrenergic receptor activation contributes to vasodilation of coronary collateral vessels during exercise.
Authors:
J H Traverse; J D Altman; J Kinn; D J Duncker; R J Bache
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  91     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1995 Mar 
Date Detail:
Created Date:  1995-03-24     Completed Date:  1995-03-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1560-7     Citation Subset:  AIM; IM    
Affiliation:
Department of Medicine, University of Minnesota Medical School, Minneapolis 55455.
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MeSH Terms
Descriptor/Qualifier:
Animals
Collateral Circulation / physiology*
Coronary Circulation / physiology*
Coronary Vessels / physiology*
Dogs
Heart Rate / physiology
Microspheres
Physical Conditioning, Animal / physiology*
Propranolol / pharmacology*
Receptors, Adrenergic, beta / drug effects,  physiology*
Vascular Resistance / physiology
Vasoconstriction / physiology
Grant Support
ID/Acronym/Agency:
HL-20598/HL/NHLBI NIH HHS; HL-32427/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, beta; 525-66-6/Propranolol

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


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