Changes in plasma lipoproteins during lipolysis in vivo in the hypertriglyceridemic state

We investigated the effects of the severity of the hypertriglyceridemic state on lipolysis of very-low-density lipoproteins (VLDLs) in vivo. In six patients with mild (Mild, fasting triglyceride 2.54 ± 0.27 mmol/L) and six with moderate hypertriglyceridemia (Mod, fasting triglyceride 4.63 ± 0.47 mmol/L), heparin infusion decreased plasma triglycerides in direct correlation with the baseline triglyceride (r = 0.92 in Mild, r = 0.96 in Mod) concentration. Fasting VLDL-triglyceride correlated inversely with postheparin lipoprotein lipase (LPL) (r = -0.85). A decrease in VLDL- triglyceride correlated with baseline VLDL-triglyceride (r = 0.93), but not with postheparin LPL. In the Mild group, low-density-lipoprotein (LDL) cholesterol steadily increased (baseline, 2.90 ± 0.18 mmol/L; 30 min, 3.03 ± 0.23 mmol/L; 2 h, 3.15 ± 0.18 mmol/L) in correlation with the decrease in VLDL-triglyceride (r = 0.89). In the Mod group, LDL cholesterol initially decreased (baseline, 2.51 ± 0.34 mmol/L; 30 min, 2.30 ± 0.23 mmol/L) and then increased (2 h, 2.82 ± 0.28 mmol/L). These results demonstrate a delay in conversion of VLDLs into LDLs in pronounced hypertriglyceridemia, which may contribute to the etiology of low plasma LDL cholesterol.