出版社：American Society for Biochemistry and Molecular Biology
摘要：This study reports methods for the quantitative determinationof stable isotope-labeled essential fatty acids (EFAs) as wellas an experiment in which deuterium-labeled linoleic acid (18:2n-6)and -linolenic acid (18:3n-3) were compared with those labeledwith carbon-13 in rat plasma in vivo. Standard curves were constructedto compensate for concentration and plasma matrix effects. Itwas observed that endogenous pools of fatty acids had a greatersuppressing effect on the measurements of 13C-U-labeled EFAsrelative to those labeled with 2H5. Using these methods, thein vivo metabolism of orally administered deuterated-linolenate,13C-U-labeled linolenate, deuterated-linoleate, and 13C-U-labeledlinoleate was compared in adult rats (n = 11). There were nosignificant differences in the concentrations of the 2H versus13C isotopomers of 18:2n-6, 18:3n-3, arachidonic acid (20:4n-6),and docosahexaenoic acid (22:6n-3) in rat plasma samples at24 h after dosing.
Thus, there appears to be little isotope effect for 2H5- versus13C-U-labeled EFAs when the data are calculated using the conventionalstandard curves and corrected for endogenous fatty acid poolsize and matrix effects.Abbreviations: 18:2n-6, linoleic acid; 18:3n-3, -linolenic acid; 20:4n-6, arachidonic acid; 20:3n-6, dihomo--linolenic acid; 22:6n-3, docosahexaenoic acid; 20:5n-3, eicosapentaenoic acid; EFA, essential fatty acid; FID, flame ionization detector; ISTD, internal standard; NCI, negative chemical ionization; PFB, pentafluorobenzyl
Supplementary key words deuterated linolenate • deuterated linoleate • carbon-13-labeled linolenate • carbon-13-labeled linoleate • standard curves • concentration effect curves • gas chromatography-mass spectrometry negative chemical ionization analysis
-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.
Abbreviations: 18:2n-6, linoleic acid; 18:3n-3, 
-linolenic acid; 22:6n-3, docosahexaenoic acid; 20:5n-3, eicosapentaenoic acid; EFA, essential fatty acid; FID, flame ionization detector; ISTD, internal standard; NCI, negative chemical ionization; PFB, pentafluorobenzyl
Supplementary key words deuterated linolenate • deuterated linoleate • carbon-13-labeled linolenate • carbon-13-labeled linoleate • standard curves • concentration effect curves • gas chromatography-mass spectrometry negative chemical ionization analysis
