Document Detail

Functional significance of alpha-adrenergic receptors in mature coronary collateral circulation of dogs.
MedLine Citation:
PMID:  2888319     Owner:  NLM     Status:  MEDLINE    
There is little information on the functional significance of alpha-adrenergic receptors in the dog's coronary collateral circulation. Accordingly, we investigated the effects of infusion of either norepinephrine (NE) or B-HT 920 (BHT), an alpha 2-adrenergic agonist, on vascular resistance of coronary collaterals in chloralose-anesthetized dogs 2-3 mo after placement of an Ameroid constrictor around the left circumflex coronary (LCX) artery. To accomplish this, the vagotomized left ventricle was autoperfused through the left main coronary ostium using a servo-controlled constant-pressure pump. Pressures of the left anterior descending (LAD) and peripheral LCX arteries were measured, and regional blood flow in LAD and LCX regions were determined with radioactive microspheres before and during NE infusion in the unblocked condition, following beta-adrenergic and beta + alpha 1-adrenergic blockade with the use of propranolol and prazosin, respectively. The same parameters were also measured before and during BHT infusion following beta-adrenergic and beta + alpha 2-adrenergic blockade with the use of propranolol and idazoxan, respectively. In the unblocked condition, NE reduced LAD, LCX, and collateral resistance by 43, 50, and 31%, respectively. After beta-adrenergic blockade, NE increased LAD resistance (29%) but did not alter LCX or collateral resistance. The increase in LAD resistance was abolished following alpha 1-adrenergic blockade. BHT increased vascular resistance in LAD, LCX, and collateral circulations by 35, 29, and 45%, respectively. Selective alpha 2-adrenergic blockade significantly attenuated the vasoconstrictor response to BHT.(ABSTRACT TRUNCATED AT 250 WORDS)
Y Maruoka; M D McKirnan; R L Engler; J C Longhurst
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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:  The American journal of physiology     Volume:  253     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1987 Sep 
Date Detail:
Created Date:  1987-10-22     Completed Date:  1987-10-22     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H582-90     Citation Subset:  IM    
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MeSH Terms
Adrenergic alpha-Antagonists / pharmacology
Adrenergic beta-Antagonists / pharmacology
Azepines / pharmacology
Collateral Circulation / drug effects*
Coronary Circulation
Coronary Vessels / physiology*
Epinephrine / pharmacology
Hemodynamics / drug effects
Receptors, Adrenergic, alpha / physiology*
Regional Blood Flow
Vascular Resistance / drug effects
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Adrenergic beta-Antagonists; 0/Azepines; 0/Receptors, Adrenergic, alpha; 36085-73-1/talipexole; 51-43-4/Epinephrine

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