High density lipoprotein subfractions in relation to lipoprotein lipase activity of tissues in man--evidence for reciprocal regulation of HDL2 and HDL3 levels by lipoprotein lipase.

High density lipoprotein subfractions HDL2 and HDL3 were separated from plasma of 22 normolipidemic healthy human subjects and analyzed for cholesterol, triglyceride, phospholipid and protein. In the same subjects the heparin-releasable lipoprotein lipase activity was assayed from biopsies of adipose tissue and skeletal muscle. A significant inverse correlation was found between the plasma concentrations of HDL2 and HDL3 (4= -0.55, p less than 0.01). The HDL2 cholesterol and HDL2 phospholipid levels were negatively correlated with HDL3 protein levels. The total HDL2 and HDL2 cholesterol, phospholipid and protein concentrations were all positively correlated with lipoprotein lipase activity of both adipose tissue and skeletal muscle. In contrast, the corresponding HDL3 values did not show any correlation with adipose tissue lipoprotein lipase but the HDL3 cholesterol, triglyceride and protein levels were inversely correlated with skeletal muscle lipoprotein lipase activity. The results suggest that plasma HDL2 and HDL3 concentrations are reciprocally regulated by the activity of lipoprotein lipase. THe data are compatible with a concept proposing conversion of HDL3 to HDL2 through assimilation of cholesterol, phospholipids and apoproteins from triglyceride-rich lipoproteins during their degradation by lipoprotein lipase. Particularly the concentration of the HDL2 is closely related to the rat of intravascular lipolysis.