Document Detail

Cardiovascular responses to intrathecal dopamine receptor agonists in conscious DOCA-salt hypertensive rats.
MedLine Citation:
PMID:  10626749     Owner:  NLM     Status:  MEDLINE    
Previous studies have demonstrated that in conscious deoxycorticosterone acetate (DOCA)-salt hypertensive rats, the hypotensive action of intravenous (i.v.) bromocriptine, a selective dopamine D2 receptor agonist, was mediated partly by peripheral and partly by spinal dopamine D2 receptor stimulation, and that this effect was greater and longer-lasting than that in uninephrectomized control rats. To determine whether this amplification results partly from a putative spinal hypersensitivity phenomenon, cardiovascular responses to intrathecal (i.t.) administration of apomorphine and quinpirole were studied in conscious, 4-week DOCA-salt hypertensive rats and compared with those in uninephrectomized control rats. In both groups, upper thoracic (T2-T4) i.t. injections of apomorphine (9.1, 45.5 and 91.1 microg/rat) induced immediate and dose-dependent decreases in mean aortic pressure (MAP) and heart rate (HR), while i.t. quinpirole (38.4 microg/rat) induced only bradycardia. Neither magnitude nor duration of these responses was enhanced in DOCA-salt hypertensive rats when compared to control rats. In DOCA-salt hypertensive rats, apomorphine-induced hypotension and bradycardia remained unaffected by i.v. (500 microg/kg) pretreatment with domperidone, a selective dopamine D2 receptor antagonist that does not cross the blood-brain barrier. However, i.t. (40 microg/rat at T2-T4) pretreatment with domperidone significantly reduced apomorphine-induced hypotension, but fully suppressed bradycardia elicited by either apomorphine or quinpirole. These results demonstrated that in conscious DOCA-salt hypertensive rats, intrathecally-injected apomorphine or quinpirole decreased MAP and/or HR through a spinal D2 dopaminergic mechanism, as previously demonstrated in normotensive intact rats. Since both magnitude and duration of these responses were unchanged with respect to uninephrectomized control rats, enhancement of the hypotensive effect of intravenously-administered bromocriptine in DOCA-salt hypertensive rats does not appear to involve spinal dopamine D2 receptors.
S Lahlou
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Fundamental & clinical pharmacology     Volume:  13     ISSN:  0767-3981     ISO Abbreviation:  Fundam Clin Pharmacol     Publication Date:  1999  
Date Detail:
Created Date:  2000-01-28     Completed Date:  2000-01-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8710411     Medline TA:  Fundam Clin Pharmacol     Country:  FRANCE    
Other Details:
Languages:  eng     Pagination:  624-34     Citation Subset:  IM    
Departamento de Fisiologia e Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Cidade Universitária, Recife, Brazil.
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MeSH Terms
Analysis of Variance
Apomorphine / administration & dosage,  therapeutic use*
Blood Pressure / drug effects*
Dose-Response Relationship, Drug
Heart Rate / drug effects
Hypertension / chemically induced,  drug therapy*
Injections, Spinal
Quinpirole / administration & dosage,  therapeutic use*
Rats, Wistar
Receptors, Dopamine D2 / agonists*
Reg. No./Substance:
0/Receptors, Dopamine D2; 58-00-4/Apomorphine; 64-85-7/Desoxycorticosterone; 85760-74-3/Quinpirole

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

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