INCORPORATION OF DEUTERIUM LABELED CIS-9-OCTABECENOIC AND TRANS-9-OCTADECENOIC ACID IN HUMANS - PLASMA, ERYTHROCYTE, AND PLATELET NEUTRAL LIPIDS

Mixtures of specifically deuterated triolein and trielaidin were fed to three subjects, and the incorporation of these labeled fats into human plasma, erythrocyte, and platelet neutral lipids was followed by gas chromatography-mass spectrometry analysis. Plasma triglycerides selectively incorporated 10% more oleic acid than elaidic acid. Plasma cholesterol ester samples contained three times more oleic acid than elaidic acid. Plasma free fatty acid fractions also contained about 25% more elaidic acid than oleic acid. Low levels of deuterated fatty acids were found in the platelet neutral lipids. These samples followed the same general selectivities observed in the plasma samples. Results from analysis of erythrocyte neutral lipids were inconsistent. Erythrocytes from one subject contained high levels of deuterated fat in the triglyceride fraction, whereas erythrocytes from a second subject contained very low levels of deuterated fat. Uptake of elaidic acid by blood lipids confirms selectivities and distribution patterns previously reported in animal and in vitro studies. Effect of the number and position of the deuterium atoms on fatty acid metabolism is evaluated by feeding three differently labeled deuterated elaidic acids and two differently labeled deuterated oleic acids as paired mixtures. A 28% deuterium isotope effect due to deuterium on the fatty acid double bond was observed in the cholesteryl ester samples when oleic-9,10-d2 acid was fed against oleic-8,8,13,13,14,14-d6 acid. No evidence for a similar isotope effect was found for deuterated fatty acid incorporation into triglycerides and free fatty acid fractions. © 1979.