Document Detail

Reflex vasoconstrictor responses to cardiopulmonary baroreceptor unloading, head-up tilt, and cold pressor testing in elderly mild-to-moderate hypertensives: effect of clonidine.
MedLine Citation:
PMID:  2455165     Owner:  NLM     Status:  MEDLINE    
To determine whether clonidine treatment affects cardiopulmonary baroreflex induced sympathetic activation, we assessed the hemodynamic and hormonal responses to lower body negative pressure (LBNP) before and after 3 weeks of treatment with low-dose (0.2 mg daily) clonidine in eight older (mean age, 62 years) patients with established mild-to-moderate hypertension. Arterial pressure, heart rate (HR), forearm vascular resistance (FVR), plasma norepinephrine (NE), and renin activity (PRA) responses were assessed. Our results demonstrate that clonidine treatment had no effect on basal or stimulated PRA and plasma NE levels at baseline and during LBNP. Baseline FVR significantly decreased (48 +/- 3 to 35.5 +/- 6 U) and the FVR responses to LBNP were lower following clonidine therapy. Although baseline mean arterial pressure (MAP) and FVR as well as FVR responses to LBNP were lower after clonidine, the responses to tilt and cold pressor testing were unchanged. Thus clonidine appears to act via peripheral mechanisms, as well as by decreasing central sympathetic outflow to lower peripheral vascular resistance.
P K Mohanty; J R Sowers; C McNamara; M D Thames
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  10 Suppl 12     ISSN:  0160-2446     ISO Abbreviation:  J. Cardiovasc. Pharmacol.     Publication Date:  1987  
Date Detail:
Created Date:  1988-07-29     Completed Date:  1988-07-29     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  S135-7     Citation Subset:  IM; S    
Medical College of Virginia, V.A. Medical Center, Richmond 23249.
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MeSH Terms
Clonidine / therapeutic use*
Cold Temperature
Forearm / blood supply
Hypertension / drug therapy*,  physiopathology
Lower Body Negative Pressure
Middle Aged
Norepinephrine / blood
Pressoreceptors / metabolism
Time Factors
Grant Support
Reg. No./Substance:
4205-90-7/Clonidine; 51-41-2/Norepinephrine

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

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