title: Simultaneous quantitative determination of deuterium- and carbon-13-labeled essential fatty acids in rat plasma.
abstract: This study reports methods for the quantitative determination of stable isotope-labeled essential fatty acids (EFAs) as well as an experiment in which deuterium-labeled linoleic acid (18:2n-6) and alpha-linolenic acid (18:3n-3) were compared with those labeled with carbon-13 in rat plasma in vivo. Standard curves were constructed to compensate for concentration and plasma matrix effects. It was observed that endogenous pools of fatty acids had a greater suppressing effect on the measurements of 13C-U-labeled EFAs relative to those labeled with 2H5. Using these methods, the in vivo metabolism of orally administered deuterated-linolenate, 13C-U-labeled linolenate, deuterated-linoleate, and 13C-U-labeled linoleate was compared in adult rats (n = 11). There were no significant differences in the concentrations of the 2H versus 13C isotopomers of 18:2n-6, 18:3n-3, arachidonic acid (20:4n-6), and docosahexaenoic acid (22:6n-3) in rat plasma samples at 24 h after dosing. Thus, there appears to be little isotope effect for 2H5- versus 13C-U-labeled EFAs when the data are calculated using the conventional standard curves and corrected for endogenous fatty acid pool size and matrix effects.
authors.affiliation: Section of Nutritional Neuroscience, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-9410, USA.
authors.forename: Yu Hong
authors.initials: YH
authors.lastname: Lin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Pawlosky
authors.forename: Norman
authors.initials: N
authors.lastname: Salem
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000097:blood; D002247:Carbon Isotopes; D002849:Chromatography, Gas / Q000379:methods; D003903:Deuterium; D004281:Docosahexaenoic Acids / Q000097:blood; D005228:Fatty Acids, Essential / Q000097:blood* / Q000493:pharmacokinetics; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D007553:Isotope Labeling; D019787:Linoleic Acid / Q000097:blood; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017962:alpha-Linolenic Acid / Q000097:blood
chemical_list: D002247:Carbon Isotopes; D005228:Fatty Acids, Essential; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D019787:Linoleic Acid; D003903:Deuterium