Determinants of fasting plasma triglyceride levels: metabolism of hepatic and intestinal lipoproteins

. The contribution of the kinetics of exogen-eous and endogenous lipoproteins in determining the level of triglyceride in fasting plasma was assessed in a group of 19 normolipidaemic and hypertriglyceridae-mic subjects. From data derived during a 9-h infusion of [15N]-glycine, we have assessed very low density lipoprotein apolipoprotein B production, and from data analysed by kinetic modelling obtained following ingestion of retinol and triolein, we have assessed chylomicron and chylomicron remnant clearance in a group of 19 normolipidaemic and hypertriglyceridae-mic subjects. A strong positive correlation was observed between the fasting plasma triglyceride level and the reciprocal of the apolipoprotein B fractional synthetic rate (r= 0.83, P<0.01). A positive correlation was also found with the rate of clearance of chylomicron remnants (Sf 20–400; r= 0.87, P<0.01) and of chylomicrons (Sf400; r= 0.69, P < 0.01). No correlation was found between the fasting plasma triglyceride level and either of the plasma post-heparin lipolytic activities. Multivariate analysis revealed that 95% of the variance in triglyceride levels could be explained by the apolipoprotein B fractional synthetic rate and the chylomicron remnant clearance rate. The strong correlation between chylomicron remnant clearance, a measure of exogenous lipid metabolism, and fasting (hence, endogenous) plasma triglyceride levels suggests that remnants of chylomicrons and very low density lipoproteins share some common components of the removal process.