Document Detail


Systemically administered alpha2-agonist-induced peripheral vasoconstriction in humans.
MedLine Citation:
PMID:  12826844     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: alpha(2)-Adrenoceptors mediate both sympatholytic and vasoconstrictive hemodynamic effects. The goal of this study was to profile the peripheral vasoconstrictive effects of a selective alpha(2)-adrenoceptor agonist in isolation from the sympatholytic effects it also induces. METHODS: The authors administered increasing plasma target concentrations of dexmedetomidine (0.075, 0.15, 0.3, and 0.6 ng/mL) or saline placebo to healthy young volunteers in whom the sympatholytic effects of the drug were attenuated in one of two ways: general anesthesia (propofol-alfentanil-nitrous oxide) or axillary brachial plexus block. Measurements were made of finger blood volume (an indicator of vasoconstriction) by photoplethysmographic determination of light transmitted through a finger (LTF) and hemodynamic variables. Measurements made before and during the four steps of infusion were compared by repeated-measures ANOVA. RESULTS: In anesthetized volunteers, all concentrations of dexmedetomidine increased LTF (vasoconstriction) and systolic blood pressure (P < 0.001 for both), whereas placebo did not. In awake volunteers, all concentrations decreased systolic blood pressure (P < 0.001). Concentrations of 0.15, 0.3, and 0.6 ng/mL decreased LTF (vasodilation) in the neurally intact hand; in contrast, the same concentrations increased LTF (vasoconstriction) in the sympathectomized hand (P < 0.001 for both). CONCLUSIONS: The results of this study are the first to characterize the lower end of the dose-response curve for vasoconstriction induced by dexmedetomidine. By denervating the vascular bed of interest or by decreasing sympathetic nervous system activity, the authors were able to observe vasoconstriction induced by a systemically administered alpha(2)-agonist with minimal interference from the sympatholytic effects of the drug.
Authors:
Pekka Talke; Errol Lobo; Ronald Brown
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article    
Journal Detail:
Title:  Anesthesiology     Volume:  99     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  2003 Jul 
Date Detail:
Created Date:  2003-06-26     Completed Date:  2003-07-24     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  65-70     Citation Subset:  AIM; IM    
Affiliation:
Department of Anesthesia and Perioperative Medicine, University of California, San Francisco, 94143, USA. talkep@anesthesia.ucsf.edu
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MeSH Terms
Descriptor/Qualifier:
Adrenergic alpha-Agonists / pharmacokinetics,  pharmacology*
Adult
Anesthesia, General
Blood Pressure / drug effects
Body Temperature / drug effects
Brachial Plexus
Dexmedetomidine / pharmacokinetics,  pharmacology
Female
Fingers / blood supply
Hemodynamics / drug effects
Hemoglobinometry
Humans
Male
Nerve Block
Plethysmography
Receptors, Adrenergic, alpha-2 / agonists*
Regional Blood Flow / drug effects
Sympathectomy, Chemical
Vasoconstriction / drug effects*
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Receptors, Adrenergic, alpha-2; 113775-47-6/Dexmedetomidine

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


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