Document Detail

Comparative effects of alpha-1 and alpha-2 adrenoceptors in modulation of coronary flow during exercise.
MedLine Citation:
PMID:  2900330     Owner:  NLM     Status:  MEDLINE    
During submaximal exercise, an alpha adrenergic vasoconstriction that opposes metabolic dilation exists in the coronary circulation. Fifteen dogs were given i.c. injections of prazosin (0.5 mg) or yohimbine (0.7 mg) to determine the participation of alpha 1 and alpha 2 adrenoceptors in the vasoconstriction during exercise. All dogs were chronically instrumented to measure left circumflex blood flow, heart rate, regional left ventricular function and global left ventricular function. The experimental protocol consisted of a graded exercise regimen during which, at the highest level of exercise an alpha antagonist was given i.c. Exercise significantly increased heart rate, left ventricular pressure, dP/dt, systolic shortening and rate of shortening, and coronary blood flow. After the prazosin injection there was an increase in circumflex blood flow (25 +/- 3%) as well as regional (38 +/- 6%) and global (20 +/- 3%) contractile function. However, there was no change in circumflex blood flow or myocardial function after yohimbine. These data indicate that during exercise the sympathetic constrictor tone in the coronary circulation is mediated primarily by alpha 1 adrenoceptors, with little or no involvement from alpha 2 adrenoceptors.
J R Strader; P A Gwirtz; C E Jones
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  246     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1988 Aug 
Date Detail:
Created Date:  1988-09-19     Completed Date:  1988-09-19     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  772-8     Citation Subset:  IM    
Department of Physiology, Texas College of Osteopathic Medicine, Fort Worth.
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MeSH Terms
Adrenergic alpha-Antagonists / pharmacology*
Coronary Circulation / drug effects*
Hemodynamics / drug effects*
Injections, Intra-Arterial
Myocardial Contraction / drug effects
Physical Exertion*
Prazosin / pharmacology
Receptors, Adrenergic, alpha / classification,  drug effects*
Yohimbine / pharmacology
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Receptors, Adrenergic, alpha; 146-48-5/Yohimbine; 19216-56-9/Prazosin

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

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