| Normal aging impairs upregulation of the beta-adrenergic but not the alpha-adrenergic response: aging and adrenergic upregulation. | |
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MedLine Citation:
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PMID: 17086093 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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. |
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Authors:
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Kenneth M Madden; Wayne C Levy; John R Stratton |
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Publication Detail:
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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:
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Title: Journal of cardiovascular pharmacology Volume: 48 ISSN: 0160-2446 ISO Abbreviation: J. Cardiovasc. Pharmacol. Publication Date: 2006 Oct |
Date Detail:
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Created Date: 2006-11-06 Completed Date: 2006-12-04 Revised Date: 2007-12-03 |
Medline Journal Info:
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Nlm Unique ID: 7902492 Medline TA: J Cardiovasc Pharmacol Country: United States |
Other Details:
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Languages: eng Pagination: 153-9 Citation Subset: IM |
Affiliation:
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Division of Geriatric Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada. kmmadden@interchange.ubc.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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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:
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R01 AG15462/AG/NIA NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Receptors, Adrenergic, alpha; 0/Receptors, Adrenergic, beta; 4205-90-7/Clonidine; 59-42-7/Phenylephrine; 7683-59-2/Isoproterenol |
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