title: Determination of leucine flux in vivo by gas chromatography-mass spectrometry utilizing stable isotopes for trace and internal standard.
abstract: A simple and reliable method is described for the determination of leucine flux in vivo using two stable isotopes of leucine and gas chromatography-mass spectrometry (GC-MS). [6,6,6-2H3]Leucine is administered as a primed-dose constant infusion in vivo and DL-[2H7]-leucine is added to plasma as an internal standard. Plasma leucine concentration and moles per cent enrichment of [2H3]leucine can be determined simultaneously by GC-MS and selected ion monitoring. Leucine flux calculated from the [6,6,6-2H3]leucine data was nearly identical to that obtained with L-[U-14C]leucine in dogs. This method is readily applicable to the study of leucine metabolism in humans of all ages and laboratory animals.
mesh_terms: D000818:Animals; D003903:Deuterium; D004285:Dogs; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007263:Infusions, Parenteral; D007930:Leucine / Q000008:administration & dosage / Q000097:blood*
chemical_list: D003903:Deuterium; D007930:Leucine