Document Detail


Do centrally-acting antihypertensive drugs act at non-adrenergic as well as alpha-2 adrenoceptor sites?
MedLine Citation:
PMID:  1327589     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Rabbits were treated with guanabenz, clonidine and rilmenidine for 6 days via osmotic minipumps. Blood pressure, heart rate and responses to intracisternal clonidine were measured after 1 and 6 days treatment. Radioligand binding to forebrain and hindbrain membranes after 6 days treatment was examined using [3H]yohimbine to measure the number of adrenergic binding sites and [3H]clonidine and [3H]idazoxan to assess nonadrenergic imidazoline sites. No change in nonadrenergic imidazoline binding was observed but adrenergic binding was decreased in forebrain and hindbrain by guanabenz and in hindbrain by clonidine treatment. Resting heart rate was decreased after 1 day's treatment with partial recovery by day 6. At this time heart rate significantly reduced in the clonidine and rilmenidine treated groups but not the guanabenz group. No significant change in baseline blood pressure was observed in normotensive rabbits. Both depressor and bradycardia responses to intracisternal clonidine were attenuated after 1 day's dosing but only depressor responses were influenced after 6 days. Blood pressure and heart rate thus appeared to be regulated independently. It is possible that imidazoline receptors predominate in the central control of blood pressure while central alpha-2 adrenoceptors play a greater part in heart rate regulation.
Authors:
C A Hamilton; M A Yakubu; C A Howie; J L Reid
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical and experimental hypertension. Part A, Theory and practice     Volume:  14     ISSN:  0730-0077     ISO Abbreviation:  Clin Exp Hypertens A     Publication Date:  1992  
Date Detail:
Created Date:  1992-11-04     Completed Date:  1992-11-04     Revised Date:  2008-02-12    
Medline Journal Info:
Nlm Unique ID:  8207790     Medline TA:  Clin Exp Hypertens A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  815-35     Citation Subset:  IM    
Affiliation:
University Department of Medicine and Therapeutics Western Infirmary, Glasgow.
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MeSH Terms
Descriptor/Qualifier:
Animals
Antihypertensive Agents / pharmacology*
Binding Sites
Blood Pressure / drug effects
Brain / metabolism,  physiology*
Cisterna Magna
Clonidine / pharmacology
Guanabenz / pharmacology
Heart Rate / drug effects
Infusion Pumps
Injections
Male
Osmosis
Oxazoles / pharmacology
Rabbits
Radioligand Assay
Receptors, Adrenergic, alpha / metabolism*
Receptors, Cell Surface / metabolism*
Chemical
Reg. No./Substance:
0/Antihypertensive Agents; 0/Oxazoles; 0/Receptors, Adrenergic, alpha; 0/Receptors, Cell Surface; 4205-90-7/Clonidine; 5051-62-7/Guanabenz; 54187-04-1/rilmenidine

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


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