Document Detail

Effect of ramipril on alpha-adrenoceptor-mediated oscillatory contractions in tail artery of hypertensive rats.
MedLine Citation:
PMID:  8281989     Owner:  NLM     Status:  MEDLINE    
Recent studies indicate that norepinephrine-induced contractile oscillations in the tail artery from stroke-prone spontaneously hypertensive rats (SHRSP) may be a vascular phenomenon independent of blood pressure level. The objectives of this study were: (1) to characterize pharmacologically the alpha-adrenoceptor mediating norepinephrine-induced oscillations in tail artery; and (2) to investigate the relationship between blood pressure level, altered by treatments with hydralazine/hydrochlorothiazide or the angiotensin converting enzyme inhibitor ramipril, and the observation of norepinephrine-induced oscillations in tail artery. The alpha 2-adrenoceptor agonists clonidine and guanabenz potently stimulated oscillatory contractions in the tail artery while the alpha 1-adrenoceptor agonists phenylephrine and methoxamine were considerably less potent. Yohimbine, an alpha 2-adrenoceptor antagonist, but not the alpha 1-adrenoceptor antagonist prazosin demonstrated high affinity for the receptor mediating norepinephrine-induced oscillatory contractions. These results support the hypothesis that norepinephrine-induced oscillatory contractions in the tail artery from SHRSP occur primarily through stimulation of alpha 2-adrenoceptors. Ramipril lowered blood pressure in SHRSP after 4 weeks of treatment during 6-10 weeks of life but did not alter the ability of the alpha 2-adrenoceptor agonist clonidine (10(-5) M) to induce contractile oscillations in tail arteries from SHRSP, indicating these oscillations are not a secondary effect of high blood pressure. These studies suggest that norepinephrine-induced oscillations in tail artery from SHRSP may be a vascular trait separate and distinct from blood pressure level and angiotensin II expression early in life.
S W Watts; O Traub; F S Lamb; J H Myers; R C Webb
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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:  European journal of pharmacology     Volume:  242     ISSN:  0014-2999     ISO Abbreviation:  Eur. J. Pharmacol.     Publication Date:  1993 Oct 
Date Detail:
Created Date:  1994-02-14     Completed Date:  1994-02-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  1254354     Medline TA:  Eur J Pharmacol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  245-53     Citation Subset:  IM    
Department of Physiology, University of Michigan, Ann Arbor 48109.
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MeSH Terms
Arteries / drug effects
Blood Pressure / drug effects
Cerebrovascular Disorders / genetics
Disease Susceptibility
Hypertension / genetics,  physiopathology*
Muscle, Smooth, Vascular / drug effects
Norepinephrine / antagonists & inhibitors,  pharmacology
Ramipril / pharmacology*
Rats, Inbred SHR
Rats, Inbred WKY
Receptors, Adrenergic, alpha / drug effects*
Tail / blood supply
Vasoconstriction / drug effects*
Grant Support
Reg. No./Substance:
0/Receptors, Adrenergic, alpha; 51-41-2/Norepinephrine; 87333-19-5/Ramipril

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