Low intravenous infusion rates of [U-13C]palmitate were used to measure systemic palmitate flux at rest (0.5 nmol · kg-1 · min-1) and during exercise (2 nmol · kg-1 · min-) in healthy adults. The 13C enrichment of plasma palmitate was determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRM8). Palmitate flux was also measured using palmitate radiotracers, which were infused simultaneously to serve as a reference method. Flux values obtained using the two different methods were virtually identical. Overnight postabsorptive palmitate flux was measured on four occasions in three individuals; the flux values were highly reproducible with a coefficient of variation of 11% and 12% for intra-day measurement, and 13% and 8% for inter- day measurement, for [1-14C]palmitate and [U-13C~palmitate, respectively. During exercise, palmitate turnover measured with [U- 13C]palmitate and [3H] palmitate were well correlated (τ = 0.91). Compared to conventional stable isotope approaches, (e.g., [1-13C]palmitate analyzed by GC/MS), [U-13C]palmitate reduces the tracer dose by two orders of magnitude when the samples are analyzed with GC/G/IRMS. Uniformly labeled [13C]palmitate is suitable for the measurement of free fatty acid flux in humans.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Lipid Research|
|State||Published - Sep 1997|
- Gas chromatography/combustion/iso-tope ratio mass spectrometry
ASJC Scopus subject areas
- Cell Biology