Document Detail

Clonidine and carotid baroreflex in essential hypertension.
MedLine Citation:
PMID:  541039     Owner:  NLM     Status:  MEDLINE    
Clonidine is believed to reduce blood pressure by a neural action and animal experiments suggest that this consists in potentiation of baroreflexes. In 16 patients with essential hypertension we studied the effects of alterations in carotid sinus baroreceptor activity (neck chamber technique) on arterial blood pressure (catheter measurements) and heart rate, before and after intravenous administration of 150 microgram and 300 microgram of clonidine. The magnitude of the reflex responses was assessed by the slope of the linear regressions relating applied increase and decrease in tissue pressure at the carotid sinus (and therefore applied decrease and increase in carotid sinus transmural pressure) and resulting changes in mean arterial pressure and R-R interval. Clonidine caused a marked reduction in mean arterial pressure (-26 +/- 3 mm Hg) and a slight but significant reduction in heart rate (-5 +/- 1 b/min). There was no evidence for a potentiation of the baroreceptor influence on blood pressure, although a slight potentiation of the baroreceptor influence on heart rate was observed in few instances. We conclude that in man clonidine can exert a pronounced hypotensive effect without potentiating baroreceptor influence on blood pressure. Therefore this mechanism does not play a prominent role in the clinical antihypertensive action of the drug.
G Mancia; A Ferrari; L Gregorini; A Zanchetti
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Hypertension     Volume:  1     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:    1979 Jul-Aug
Date Detail:
Created Date:  1980-06-16     Completed Date:  1980-06-16     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  362-70     Citation Subset:  IM    
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MeSH Terms
Blood Pressure / drug effects
Carotid Sinus / drug effects
Clonidine / pharmacology*
Cold Temperature
Drug Evaluation
Heart Rate / drug effects
Hypertension / drug therapy*,  physiopathology
Isometric Contraction
Middle Aged
Pressoreceptors / drug effects*
Reg. No./Substance:

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

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