Changes in the plasma free fatty acid composition during VLDL lipolysis induced by heparin: their effect on platelet phosphatidylcholine biosynthesis.

The contribution of the acyl specificity of post heparin lipolytic enzymes to changes in the plasma free fatty acid (FFA) pattern during very low density lipoproteins (VLDL) lipolysis, was studied. The effect of these changes in the 3H-choline incorporation into platelet phosphatidylcholine (PC) during incubation, was also investigated. "In vitro" experiments with post heparin plasma and isolated VLDL showed an increase of 61.1 in the percentage of linoleic acid (C 18:2) concomitant with a decrease of 57.1% in the relative concentration of stearic acid (C 18:0) during VLDL triacylglycerol lipolysis. Similarly, a decrease of 39.2% in the plasma concentration of C 18:0 and an increase of 29.4% in the C 18:2 and 9.6% in the oleic acid (C 18:1) concentration were observed after intravenous injection of low doses of heparin. The plasma FFA compositional changes that occur during "in vitro" VLDL lipolysis accelerate not only the incorporation of labeled choline but also the incorporation of C 18:2 into platelet PC. It is suggested that the above observed changes on platelet response are due to the increase in the C 18:2 concentration during incubation.