Document Detail

Fate of fatty acids at rest and during exercise: regulatory mechanisms.
MedLine Citation:
PMID:  12864743     Owner:  NLM     Status:  MEDLINE    
Fatty acids are a major fuel source for humans both at rest and during exercise. Plasma free fatty acids (FFA), although present only in micromolar concentrations, are the major circulating lipid fuel. FFA availability can increase two- to four-fold with moderate intensity exercise. Other potential sources of fatty acids include circulating very low-density lipoprotein (VLDL) triglycerides (TGs) ( approximately 1/5 the fuel availability of FFA) and intramyocellular TGs ( approximately 2 mmol kg-1 muscle). At rest approximately 40% of systemic FFA uptake occurs in the splanchnic bed and uptake in legs is approximately 15-20%. During leg exercise the uptake of FFA in leg tissue increases to 30-60% of systemic uptake and splanchnic uptake decreases to 15%. The fate of VLDL TG fatty acids has not been adequately studied. Intramyocellular TG hydrolysis increases during exercise, but the factors that regulate this response are not clear. The fact that contraction of isolated muscles can stimulate the hydrolysis and oxidation of intramyocellular TGs (in the absence of hormonal or neural input) suggests an intracellular regulation of this process. Additional regulation from changes in catecholamines and insulin may also occur. During moderate intensity exercise circulating FFA and intramyocellular TG provide roughly equal portions of fatty acids for oxidation. In addition to endurance training, dietary factors have been shown to modulate the fatty acid oxidation response to exercise. Much remains to be learned about fatty acid trafficking during exercise. What role do VLDL TG play? How is the oxidation of intramyocellular TGs regulated? Techniques to address these questions in humans are only now becoming available.
M D Jensen
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  178     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-07-16     Completed Date:  2003-08-26     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  England    
Other Details:
Languages:  eng     Pagination:  385-90     Citation Subset:  IM    
Endocrine Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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MeSH Terms
Calorimetry / methods
Exercise / physiology*
Fatty Acids, Nonesterified / metabolism*
Isotopes / diagnostic use
Lipolysis / physiology
Lipoproteins, VLDL / metabolism
Muscle Contraction / physiology
Muscle, Skeletal / metabolism
Physical Endurance
Rest / physiology*
Triglycerides / metabolism
Reg. No./Substance:
0/Fatty Acids, Nonesterified; 0/Isotopes; 0/Lipoproteins, VLDL; 0/Triglycerides

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