Document Detail


Persistence of the lactate paradox over 8 weeks at 3,800 m.
MedLine Citation:
PMID:  14672546     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The arterial blood lactate [La] response to exercise increases in acute hypoxia, but returns to near the normoxic (sea level, SL) response after 2 to 5 weeks of altitude acclimatization. Recently, it has been suggested that this gradual return to the SL response in [La], known as the lactate paradox (LP), unexpectedly disappears after 8 to 9 weeks at altitude. We tested this idea by recording the [La] response to exercise every 2 weeks over 8 weeks at altitude. Five normal, fit SL-residents were studied at SL and 3,800 m (Pbar = 485 torr) in both normoxia (PIO2 = 150 torr) and hypoxia (PIO2 = 91 torr approximately air at 3,800 m). Arterial [La] and blood gas values were determined at rest and during cycle exercise at the same absolute workloads (0, 25, 50, 75, 90, and 100% of initial SL-VO2Max) and exercise duration (4, 4, 4, 2, 1.5, and 0.75 min, respectively) at each time point. [La] curves were elevated in acute hypoxia at SL (p < 0.01) and at 3,800 m fell progressively toward the SL-normoxic curve (p < 0.01). On the same days, [La] responses in acute normoxia showed essentially no changes over time and were similar to initial SL normoxic responses. We also measured arterial catecholamine levels at each load and found a close relationship to [La] over time, supporting a role for adrenergic influence on [La]. In summary, extending the time at this altitude to 8 weeks produced no evidence for reversal of the LP, consistent with prior data obtained over shorter periods of altitude residence.
Authors:
Marieke Pronk; Ivo Tiemessen; Maarten D W Hupperets; Brian P Kennedy; Frank L Powell; Susan R Hopkins; Peter D Wagner
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  High altitude medicine & biology     Volume:  4     ISSN:  1527-0297     ISO Abbreviation:  High Alt. Med. Biol.     Publication Date:  2003  
Date Detail:
Created Date:  2003-12-15     Completed Date:  2004-02-24     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100901183     Medline TA:  High Alt Med Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  431-43     Citation Subset:  IM; S    
Affiliation:
Division of Physiology, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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MeSH Terms
Descriptor/Qualifier:
Acclimatization*
Adult
Altitude*
Analysis of Variance
Anoxia / physiopathology*
California
Epinephrine / blood
Exercise*
Exercise Test
Female
Hemodynamics / physiology
Humans
Lactic Acid / blood*
Male
Mountaineering
Norepinephrine / blood
Reference Values
Time Factors
Grant Support
ID/Acronym/Agency:
HL17731/HL/NHLBI NIH HHS; M01 RR00827/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
50-21-5/Lactic Acid; 51-41-2/Norepinephrine; 51-43-4/Epinephrine
Comments/Corrections
Comment In:
High Alt Med Biol. 2004 Summer;5(2):195-6; author reply 197-8   [PMID:  15265341 ]

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


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