Incorporation of deuterium-labeled trans- and cis-13-octadecenoic acids in human plasma lipids.

The absorption and distribution of deuterated trans- and cis-l S-octadecenoic acid (1 3t-18: 1 and 13c-18: 1) in plasma lipids were compared to deuterated cis-9-octadecenoic acid (9c- 18: 1) in two young adult male subjects. A mixture of triglyc- erides was fed in a multiple-labeled experiment where each triglyceride contained a fatty acid labeled with a different number of deuterium atoms. Analysis of human plasma lipids by mass spectroscopy allowed the distribution of the two 13- octadecenoic acid isomers to be directly compared to cis-9- octadecenoic acid. Plasma lipids selectively excluded both the 13t- 18: 1 and 13c-18: 1 isomers relative to 9c-18: 1 in all neutral and phospholipid fractions. Discrimination against incorpo- ration of the 13t-18: 1 isomer into plasma cholesteryl ester and 2-acyl phosphatidylcholine was nearly absolute. The 1 -acyl phosphatidylcholine fraction exhibited a large positive selec- tivity for the 13t-18: 1 isomer. Differences in the relative dis- tribution of the trans and cis 13- 18: 1 isomers vs. 9c-18: 1 in the various lipoprotein lipid classes were found. Analysis of the chylomicron triglyceride component of the plasma lipids in- dicated all three fatty acids were equally well absorbed.- Emken, E. A., R. 0. Adlof, W. K. Rohwedder, and R. M. Gulley. Incorporation of deuterium-labeled trans- and cis-13- octadecenoic acids in human plasma lipids./. Lipid Res. 1983. 24: 34-46.