Oxidation of intracellular and extracellular fatty acids in skeletal muscle

Zeng Kui Guo, Michael D. Jensen, Jinze Xu, Lianzhen Zhou, Xuan Mai T. Persson, Prabhakaran Balagopal, Kevin Yarasheski

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Fatty acids are a major fuel for many tissues, and abnormal utilization is implicated in diseases. However, tissue fatty acid oxidation has not been determined reliably in vivo. Furthermore, fatty acid oxidation has not been partitioned into intracellular and extracellular components. In this report, a one-pool model is described that enables direct quantitation of fluxes of intracellular and plasma fatty acids to mitochondria in skeletal muscle using dual stable isotopes and liquid chromatography/electrospray ionization ion-trap tandem mass spectrometry technology. It is validated by the determination of palmitate oxidation by skeletal muscle in lean and obese rats and the regulation by insulin. Resting postabsorptive intramyocellular and plasma palmitate oxidation by the gastrocnemius muscle was determined to be 3.47 ± 0.8 and 2.06 ± 0.5 nmol/g/min in lean and 6.96 ± 1.8 and 1.34 ± 0.2 nmol/g/min in obese rats, respectively. In obese rats, hyperinsulinemia (1 nmol/L) suppressed intramyocellular (by 59 ± 5% to 2.88 ± 0.3 nmol/g/ min; p <0.05) but not plasma (1.41 ± 0.14 nmol/g/min; p > 0.05) palmitate oxidation. The fractional turnover rate of palmitoylcarnitine (0.34 ± 0.1/min vs. 0.83 ± 0.2/min; p <0.05) was also suppressed by insulin in obese rats. In obese and lean rats, 83 and 51%, respectively (p = 0.08), of plasma fatty acids traverse the triacylglycerol pool before being oxidized. The results demonstrated that the methodology is feasible and sensitive to metabolic alterations and thus can be used to study fatty acid utilization at tissue level in vivo in a compartmentalized manner for the first time.

Original languageEnglish (US)
Pages (from-to)5-15
Number of pages11
JournalEuropean Journal of Lipid Science and Technology
Issue number1
StatePublished - 2008


  • Fatty acid
  • Intracellular
  • LC-MS
  • Oxidation
  • Rats
  • Skeletal muscle
  • Stable isotope

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • General Chemistry
  • Industrial and Manufacturing Engineering


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