Comparison of the effect of post-heparin and pre-heparin lipoprotein lipase and hepatic triglyceride lipase on remnant lipoprotein metabolism

Background: A comparison of post-heparin and pre-heparin plasma lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) on the metabolism of remnant lipoproteins (RLPs) has not been reported yet. Methods: Healthy volunteers were injected with heparin for LPL and HTGL determination in the fasting (8:00) and postprandial (20:00) plasma on the same day. Plasma total cholesterol (TC), triglycerides (TG), LDL-C, HDL-C, small dense LDL (sdLDL)-C, remnant lipoprotein (RLP)-C, RLP-TG, the RLP-TG/RLP-C ratio, adiponectin and apoCIII were measured. Results: LPL activity and concentration in the post-heparin plasma exhibited a significant inverse correlation with TG, RLP-C, RLP-TG, and RLP particle size estimated as RLP-TG/RLP-C ratio and sdLDL-C, and positively correlated with HDL-C. HTGL was only inversely correlated with HDL-C. LPL concentration in the pre-heparin plasma was also inversely correlated with the RLP-TG/RLP-C ratio and other lipoprotein parameters. Adiponectin was inversely correlated with RLP-TG/RLP-C ratio and apoC III was positively correlated with RLP-TG/RLP-C ratio, but not correlated with LPL activity. Conclusion: LPL activity and concentration were inversely and significantly correlated with the particle size of RLP in both the post-heparin and pre-heparin plasma. Those results suggest that LPL concentration in pre-heparin plasma can take the place of LPL activity in the post-heparin plasma.