Document Detail

Oxygen uptake kinetics: Why are they so slow? And what do they tell us?
MedLine Citation:
PMID:  17242491     Owner:  NLM     Status:  MEDLINE    
VO(2) kinetics and O(2) deficit are important determinants of exercise tolerance. In "normal" conditions convective and diffusive O(2) delivery to skeletal muscle fibers do not represent important determinants of VO(2) kinetics, whose limiting factors seem mainly located within muscle fibers. Whereas a limiting role by PDH has not been confirmed, the role of inhibition of mitochondrial respiration by NO needs further investigations. Important determinants of skeletal muscle VO(2) kinetics likely reside in the interplay between bioenergetic mechanisms at exercise onset. By acting as high-capacitance energy buffers, PCr hydrolysis and anaerobic glycolysis would delay or attenuate the increase in [ADP] within muscle fibers following rapid increases in ATP demand, preventing a more rapid activation of oxidative phosphorylation. The different "localization" of the main limiting factors for VO(2) kinetics and VO(2)max offers the opportunity to perform a functional evaluation of oxidative metabolism at two different levels of the pathway for O(2), from ambient air to mitochondria. Whereas VO(2)max is mainly limited by the capacity of the cardiovascular system to deliver O(2) to exercising muscles, by analysis of VO(2) kinetics the functional evaluation is mainly related to skeletal muscle. In pathological conditions the situation may be less clear, and warrants further investigations.
B Grassi
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Journal of physiology and pharmacology : an official journal of the Polish Physiological Society     Volume:  57 Suppl 10     ISSN:  1899-1505     ISO Abbreviation:  J. Physiol. Pharmacol.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2007-01-23     Completed Date:  2007-12-21     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9114501     Medline TA:  J Physiol Pharmacol     Country:  Poland    
Other Details:
Languages:  eng     Pagination:  53-65     Citation Subset:  IM    
Department of Science and Biomedical Technologies, Università degli Studi di Milano, Milano, Italy.
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MeSH Terms
Energy Metabolism
Exercise / physiology*
Exercise Tolerance / physiology
Mitochondria, Muscle / metabolism
Muscle Fibers, Skeletal / metabolism
Muscle, Skeletal / metabolism*
Oxidative Phosphorylation
Oxygen Consumption / physiology*

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