Document Detail


Normal aging impairs upregulation of the beta-adrenergic but not the alpha-adrenergic response: aging and adrenergic upregulation.
MedLine Citation:
PMID:  17086093     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVES: To determine if centrally reducing sympathetic tone with clonidine will reverse the downregulation in the alpha-adrenergic (alphaAR) and beta-adrenergic (betaAR) responses seen with normal aging. METHODS: Twelve rigorously screened young adult (mean age, 26 years) and 15 older adult (mean age, 69 years) subjects were studied before and after using the clonidine patch (TTS-2) for 2 weeks. betaAR (isoproterenol at 35 ng/kg/min) and alphaAR (phenylephrine at 1.0 microg/kg/min) were assessed using radionuclide measures of end diastolic, end systolic, and stroke volume indices, cardiac index, and ejection fraction. RESULTS: Clonidine reduced resting plasma norepinephrine and this reduction was greater in older subjects (-47 +/- 3 versus -26 +/- 6%, P = 0.001). After 2 weeks of clonidine patch, upregulation of the betaAR was significantly higher in young subjects for heart rate (+10.7 +/- 1.5 versus +4.6 +/- 1.5 bpm; P = 0.01). There was no significant age-associated difference in the upregulation of the alphaAR with clonidine for systolic, diastolic, and mean blood pressure or systemic vascular resistance. CONCLUSIONS: With aging, there is an impaired resensitization of the chronotropic betaAR response with central sympathetic downregulation that is not seen with the alphaAR.
Authors:
Kenneth M Madden; Wayne C Levy; John R Stratton
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  48     ISSN:  0160-2446     ISO Abbreviation:  J. Cardiovasc. Pharmacol.     Publication Date:  2006 Oct 
Date Detail:
Created Date:  2006-11-06     Completed Date:  2006-12-04     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  153-9     Citation Subset:  IM    
Affiliation:
Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. kmmadden@interchange.ubc.ca
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Aged, 80 and over
Aging / physiology*
Blood Pressure / drug effects
Clonidine / pharmacology
Female
Humans
Isoproterenol / pharmacology
Male
Middle Aged
Phenylephrine / pharmacology
Receptors, Adrenergic, alpha / physiology*
Receptors, Adrenergic, beta / physiology*
Sex Characteristics
Up-Regulation
Grant Support
ID/Acronym/Agency:
R01 AG15462/AG/NIA NIH HHS
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, alpha; 0/Receptors, Adrenergic, beta; 4205-90-7/Clonidine; 59-42-7/Phenylephrine; 7683-59-2/Isoproterenol

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


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