Document Detail


Role of adenosine in the sympathetic activation produced by isometric exercise in humans.
MedLine Citation:
PMID:  8163667     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Isometric exercise increases sympathetic nerve activity and blood pressure. This exercise pressor reflex is partly mediated by metabolic products activating muscle afferents (metaboreceptors). Whereas adenosine is a known inhibitory neuromodulator, there is increasing evidence that it activates afferent nerves. We, therefore, examined the hypothesis that adenosine stimulates muscle afferents and participates in the exercise pressor reflex in healthy volunteers. Intraarterial administration of adenosine into the forearm, during venous occlusion to prevent systemic effects, mimicked the response to exercise, increasing muscle sympathetic nerve activity (MSNA, lower limb microneurography) and mean arterial blood pressure (MABP) at all doses studied (2, 3, and 4 mg). Heart rate increased only with the highest dose. Intrabrachial adenosine (4 mg) increased MSNA by 96 +/- 25% (n = 6, P < 0.01) and MABP by 12 +/- 3 mmHg (P < 0.01). Adenosine produced forearm discomfort, but equivalent painful stimuli (forearm ischemia and cold exposure) increased MSNA significantly less than adenosine. Furthermore, adenosine receptor antagonism with intrabrachial theophylline (1 microgram/ml forearm per min) blocked the increase in MSNA (92 +/- 15% vs. 28 +/- 6%, n = 7, P < 0.01) and MABP (38 +/- 6 vs. 27 +/- 4 mmHg, P = 0.01) produced by isometric handgrip (30% of maximal voluntary contraction) in the infused arm, but not the contralateral arm. Theophylline did not prevent the increase in heart rate produced by handgrip, a response mediated more by central command than muscle afferent activation. We propose that endogenous adenosine contributes to the activation of muscle afferents involved in the exercise pressor reflex in humans.
Authors:
F Costa; I Biaggioni
Related Documents :
19371597 - Plasma nitrite response and arterial reactivity differentiate vascular health and perfo...
15890697 - Differential responses to co2 and sympathetic stimulation in the cerebral and femoral c...
434227 - Morphological and physiological correlation of bradykinin-induced macromolecular efflux.
8508527 - Regulation of capillary perfusion by small arterioles is spatially organized.
11950157 - The effects of altitude training are mediated primarily by acclimatization, rather than...
14575817 - Evaluation of nitric oxide release in the coronary effluent by a novel epr technique: a...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of clinical investigation     Volume:  93     ISSN:  0021-9738     ISO Abbreviation:  J. Clin. Invest.     Publication Date:  1994 Apr 
Date Detail:
Created Date:  1994-05-20     Completed Date:  1994-05-20     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7802877     Medline TA:  J Clin Invest     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1654-60     Citation Subset:  AIM; IM; S    
Affiliation:
Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232-2195.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Adenosine / pharmacology*
Adult
Blood Pressure / drug effects
Dose-Response Relationship, Drug
Exercise*
Female
Humans
Male
Muscles / drug effects,  innervation*
Reflex / drug effects
Sympathetic Nervous System / drug effects*,  physiology
Theophylline / pharmacology
Grant Support
ID/Acronym/Agency:
HL-14192/HL/NHLBI NIH HHS; RR-00095/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
58-55-9/Theophylline; 58-61-7/Adenosine
Comments/Corrections

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


Previous Document:  Oscillating activity of a Ca(2+)-sensitive K+ channel. A prerequisite for migration of transformed M...
Next Document:  Ventromedial hypothalamic lesions in rats suppress counterregulatory responses to hypoglycemia.