Document Detail


Effects of high-altitude chronic hypoxia on platelet alpha 2-receptors in man.
MedLine Citation:
PMID:  9134380     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
During chronic high-altitude (HA) exposure, basal and exercise-induced noradrenaline (NA) increases do not parallel blood pressure (BP) changes observed; unlike beta-adrenergic receptors, to our knowledge no data are available on alpha-receptors. We studied platelet alpha 2- and leucocyte beta-receptors and basal catecholamine levels in 11 trained climbers before and after they had spent a 15-day period at a height of over 4400 m. In six of the climbers we also evaluated catecholamines after maximal bicycle ergometer exercise. After chronic high-altitude exposure, a significant decrease was found in platelet alpha 2-receptor density and affinity [Bmax from 92.6 +/- 6.7 to 54.6 +/- 4.2 fmol mg-1 protein (P < 0.001) and KD from 1.271 +/- 0.034 to 1.724 +/- 0.077 nmol L-1 (P < 0.05)], although no changes to beta-receptors were observed. No changes were found in basal pre- and post-expedition NA and adrenaline (A), and there was only a slight decrease in post-expedition NA after maximal exercise. Our results suggest that prolonged exposure to hypoxia induces a down-regulation of alpha 2-receptors, which may be a contributory factor in the regulation of the physiological vascular response to acclimatization.
Authors:
M Zaccaria; P A Borea; G Opocher; A Ponchia; K Varani; D Fraccarollo; C Scandellari
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of clinical investigation     Volume:  27     ISSN:  0014-2972     ISO Abbreviation:  Eur. J. Clin. Invest.     Publication Date:  1997 Apr 
Date Detail:
Created Date:  1997-06-26     Completed Date:  1997-06-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0245331     Medline TA:  Eur J Clin Invest     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  316-21     Citation Subset:  IM; S    
Affiliation:
Division of Internal Medicine (Sports Medicine Unit), University of Padua, Italy.
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MeSH Terms
Descriptor/Qualifier:
Adult
Altitude*
Anoxia / blood*
Chronic Disease
Exercise
Female
Humans
Male
Norepinephrine / blood
Receptors, Adrenergic, alpha-2 / blood*
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, alpha-2; 51-41-2/Norepinephrine

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


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