Kinetics of Exogenous Di-Linoleyl Phosphatidylcholine and Incorporation in Plasma and RBC Lipids in Man

The plasma kinetics and the incorporation in plasma and red blood cell lipids of di-linoleyl phosphatidyl choline (DLPC), labeled with 3H in the choline moiety and with 14C linoleic acid ony in position 2, were studied in normal volunteers. The peaks of activity were at around 24 h for 3H and at around 8-16 h for 14C. The 3H/14C ratio progressively increased in total plasma lipids. The 3H label was mainly incorporated in HDL, but radioactivity was retained longer and with the same 3H/14C ratio as in the administered compound in LDL. Incorporation of both labels in red blood cell lipids was slower than in plasma lipids, but they were retained much longer. Unlabeled DLPC (4g/day, four weeks) was also administered to moderately hyper-cholesterolemic women. At the end of treatment, significant elevation of plasma PC (concentration and percentage of phospholipids) and of linoleic acid in PC and cholesterol esters were observed. These findings indicate that exogenous DLPC is retained in plasma (unmodified in the LDL fraction) and in circulating cells, and significantly raises plasma PC and linoleic acid in selected lipid pools.