Changes in plasma lipoprotein distribution and formation of two unusual particles after heparin-induced lipolysis in hypertriglyceridemic subjects.

Lipoprotein morphology and distribution were studied in three moderately to severely hypertriglyceridemic patients after heparin-induced lipolysis. Lipoproteins with a flotation rate of Sf degrees 12-20 in rho 1.063-g/ml NaCl solution increased substantially in mass 2.5-10 min after heparin administration. This fraction contained 40- to 120-nm flattened particles and increased concentrations of phospholipid and free cholesterol. At 2.5 and 10 min after heparin, the high density lipoproteins (HDL) of rho, 1.126-1.21 g/ml contained small (5.8-nm diameter) spherical particles. Both types of particles disappeared 30-60 min after heparin. Results indicated that with lipolysis HDL3 may be transformed into HDL2a by incorporation of chylomicron and very low density lipoprotein constituents. It is suggested that the 40- to 120-nm particles represent surface fragments of chylomicrons and very low density lipoproteins generated during lipolysis, whereas the 5.8-nm particles are produced either by fragmentation of the large surface constituents or by loss of lipid from existing HDL3.