Document Detail

Extracellular pH defense against lactic acid in normoxia and hypoxia before and after a Himalayan expedition.
MedLine Citation:
PMID:  11394258     Owner:  NLM     Status:  MEDLINE    
The extracellular pH defense against the lactic acidosis resulting from exercise can be estimated from the ratios -delta[La].delta pH-1 (where delta[La] is change in lactic acid concentration and delta pH is change in pH) and delta[HCO3-].delta pH-1 (where delta[HCO3-] is change in bicarbonate concentration) in blood plasma. The difference between -delta[La].delta pH-1 and delta[HCO3-].delta pH-1 yields the capacity of available non-bicarbonate buffers (mainly hemoglobin). In turn, delta[HCO3-].delta pH-1 can be separated into a pure bicarbonate buffering (as calculated at constant carbon dioxide tension) and a hyperventilation effect. These quantities were measured in 12 mountaineers during incremental exercise tests before, and 7-8 days (group 1) or 11-12 days (group 2) after their return from a Himalayan expedition (2800-7600 m altitude) under conditions of normoxia and acute hypoxia. In normoxia -delta[La].delta pH-1 amounted to [mean (SEM)] 92 (6) mmol.l-1 before altitude, of which 19 (4), 48 (1) and 25 (3) mmol.l-1 were due to hyperventilation, bicarbonate and non-bicarbonate buffering, respectively. After altitude -delta[La].delta pH-1 was increased to 128 (12) mmol.l-1 (P < 0.01) in group 1 and decreased to 72 (5) mmol.l-1 in group 2 (P < 0.05), resulting mainly from apparent large changes of non-bicarbonate buffer capacity, which amounted to 49 (14) mmol.l-1 in group 1 and to 10 (2) mmol.l-1 in group 2. In acute hypoxia the apparent increase in non-bicarbonate buffers of group 1 was even larger [140 (18) mmol.l-1]. Since the hemoglobin mass was only modestly elevated after descent, other factors must play a role. It is proposed here that the transport of La- and H+ across cell membranes is differently influenced by high-altitude acclimatization.
D Böning; N Maassen; A Thomas; J M Steinacker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of applied physiology     Volume:  84     ISSN:  1439-6319     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:    2001 Jan-Feb
Date Detail:
Created Date:  2001-06-07     Completed Date:  2001-10-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  78-86     Citation Subset:  IM    
Department of Sports Medicine, University Hospital Benjamin Franklin, Free University Berlin, Clayallee 229, 14195 Berlin, Germany.
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MeSH Terms
Acclimatization / physiology
Acid-Base Equilibrium / physiology*
Acidosis, Lactic / metabolism*
Anoxia / metabolism*
Extracellular Space / metabolism
Hydrogen-Ion Concentration
Lactic Acid / metabolism*
Oxygen / blood
Reg. No./Substance:
50-21-5/Lactic Acid; 7782-44-7/Oxygen

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