Document Detail

Analysis of adrenoceptor blockade and hypotension elicited by urapidil and prazosin in conscious rat.
MedLine Citation:
PMID:  2871176     Owner:  NLM     Status:  MEDLINE    
The adrenoceptor blocking properties and hypotensive effects of the alpha-1 blocking agents urapidil and prazosin were compared in conscious instrumented rats. Both urapidil and prazosin in i.v. doses of 3 and 6 mg/kg and 0.125 and 0.25 mg/kg, respectively, blocked the pressor response to the alpha-1 adrenoceptor agonist phenylephrine. The hypotensive effects of urapidil and prazosin in these doses were equivalent. Mechanisms of the blood pressure compensation to urapidil-induced hypotension were examined with the arginine vasopressin (AVP) antagonist, d(CH2)5Tyr(Me)AVP, and the angiotensin converting enzyme inhibitor, MK-422. Urapidil alone (6 mg/kg i.v.) and after the AVP antagonist caused a similar degree of hypotension (22 and 15% decrease, respectively, in mean blood pressure). When the alpha-1 antagonist was administered after converting enzyme inhibition, it caused a significantly greater decrease in blood pressure (37%) than in the previous two groups, but not different from that obtained after combined AVP antagonism and converting enzyme inhibition (30% decrease). These results indicate that the renin-angiotensin system compensates for the hypotensive effect due to alpha-1 adrenoceptor blockade, whereas AVP, even assuming that the circulating level was increased by urapidil, was without effect on blood pressure.
J Goering; B G Zimmerman
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  237     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1986 May 
Date Detail:
Created Date:  1986-06-23     Completed Date:  1986-06-23     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  553-7     Citation Subset:  IM    
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MeSH Terms
Adrenergic alpha-Antagonists / pharmacology*
Analysis of Variance
Antihypertensive Agents / pharmacology*
Arginine Vasopressin / physiology
Blood Pressure / drug effects*
Enalapril / analogs & derivatives,  pharmacology
Phenylephrine / pharmacology
Piperazines / pharmacology*
Prazosin / pharmacology*
Rats, Inbred Strains
Renin-Angiotensin System
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Antihypertensive Agents; 0/Piperazines; 113-79-1/Arginine Vasopressin; 19216-56-9/Prazosin; 34661-75-1/urapidil; 59-42-7/Phenylephrine; 75847-73-3/Enalapril; 84680-54-6/Enalaprilat

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