Document Detail

Effects of respiratory alkalosis on human skeletal muscle metabolism at the onset of submaximal exercise.
MedLine Citation:
PMID:  12356901     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to examine the effects of respiratory alkalosis on human skeletal muscle metabolism at rest and during submaximal exercise. Subjects exercised on two occasions for 15 min at 55 % of their maximal oxygen uptake while either hyperventilating (R-Alk) or breathing normally (Con). Muscle biopsies were taken at rest and after 1 and 15 min of exercise. At rest, no effects on muscle metabolism were observed in response to R-Alk. In the first minute of exercise, there was a delayed activation of pyruvate dehydrogenase (PDH) in R-Alk compared with Con, resulting in a reduced rate of pyruvate oxidation. Also, glycogenolysis was higher in R-Alk compared with Con, which was attributed to a higher availability of the monoprotonated form of inorganic phosphate (P(i)), resulting in an elevated rate of pyruvate production. The mismatch between pyruvate production and its oxidation resulted in net lactate accumulation. These effects were not seen after 15 min of exercise, with no further differences in muscle metabolism between conditions. The results from the present study suggest that respiratory alkalosis may play an important role in lactate accumulation during the transition from rest to exercise in acute hypoxic conditions, but that other factors mediate lactate accumulation during steady-state exercise.
P J LeBlanc; M L Parolin; N L Jones; G J F Heigenhauser
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  544     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2002 Oct 
Date Detail:
Created Date:  2002-10-01     Completed Date:  2003-03-14     Revised Date:  2013-06-09    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  303-13     Citation Subset:  IM    
Department of Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5.
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MeSH Terms
Adenosine Triphosphate / metabolism
Alkalosis, Respiratory / metabolism*
Blood / metabolism
Exercise / physiology*
Glycogen / biosynthesis
Heart / physiology
Lactic Acid / metabolism
Muscle, Skeletal / metabolism*
Pyruvates / metabolism
Respiratory Physiological Phenomena
Time Factors
Reg. No./Substance:
0/Pyruvates; 50-21-5/Lactic Acid; 56-65-5/Adenosine Triphosphate; 9005-79-2/Glycogen

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

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