Document Detail

Dissociation between neural and vascular responses to sympathetic stimulation : contribution of local adrenergic receptor function.
MedLine Citation:
PMID:  10642278     Owner:  NLM     Status:  MEDLINE    
Sympathetic activation produced by various stimuli, eg, mental stress or handgrip, evokes regional vascular responses that are often nonhomogeneous. This phenomenon is believed to be the consequence of the recruitment of differential central neural pathways or of a sympathetically mediated vasodilation. The purpose of this study was to determine whether a similar heterogeneous response occurs with cold pressor stimulation and to test the hypothesis that local differences in adrenergic receptor function could be in part responsible for this diversity. In 8 healthy subjects, local norepinephrine spillover and blood flow were measured in arms and legs at baseline and during sympathetic stimulation induced by baroreflex mechanisms (nitroprusside infusion) or cold pressor stimulation. At baseline, legs had higher vascular resistance (27+/-5 versus 17+/-2 U, P=0.05) despite lower norepinephrine spillover (0.28+/-0.04 versus 0.4+/-0.05 mg. min(-1). dL(-1), P=0.03). Norepinephrine spillover increased similarly in both arms and legs during nitroprusside infusion and cold pressor stimulation. On the other hand, during cold stimulation, vascular resistance increased in arms but not in legs (20+/-9% versus -7+/-4%, P=0.03). Increasing doses of isoproterenol and phenylephrine were infused intra-arterially in arms and legs to estimate beta-mediated vasodilation and alpha-induced vasoconstriction, respectively. beta-Mediated vasodilation was significantly lower in legs compared with arms. Thus, we report a dissociation between norepinephrine spillover and vascular responses to cold stress in lower limbs characterized by a paradoxical decrease in local resistance despite increases in sympathetic activity. The differences observed in adrenergic receptor responses cannot explain this phenomenon.
G Jacob; F Costa; J Shannon; D Robertson; I Biaggioni
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Hypertension     Volume:  35     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:  2000 Jan 
Date Detail:
Created Date:  2000-02-09     Completed Date:  2000-02-09     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  76-81     Citation Subset:  IM; S    
Clinical Research Center, Department of Medicine, Pharmacology, and Neurology, Vanderbilt University Medical Center, Nashville, TN 37232-2195, USA.
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MeSH Terms
Adrenergic alpha-Agonists / administration & dosage
Adrenergic beta-Agonists / administration & dosage
Baroreflex / drug effects,  physiology
Cold Temperature
Isoproterenol / administration & dosage
Middle Aged
Nitroprusside / administration & dosage
Norepinephrine / blood
Phenylephrine / administration & dosage
Receptors, Adrenergic / drug effects,  physiology*
Sympathetic Nervous System / physiology*
Vascular Resistance / drug effects,  physiology
Vasodilation / physiology*
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Adrenergic beta-Agonists; 0/Receptors, Adrenergic; 15078-28-1/Nitroprusside; 51-41-2/Norepinephrine; 59-42-7/Phenylephrine; 7683-59-2/Isoproterenol
D Robertson / Vanderbilt U, Nashville, TN

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

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