A stable isotope method using a [(2)H(5)]glycerol bolus to measure very low density lipoprotein triglyceride kinetics in humans.

We have developed a method using a bolus of [(2)H(5)]glycerol to determine parameters of VLDL-triglyceride (VLDL-TG) turnover and have compared the data to that obtained using simultaneously a bolus of [2-(3)H]glycerol in six young normolipidemic men. No measurable enrichment was found after 12 h for [(2)H(5)]glycerol; therefore, we could only perform a monoexponential analysis of its data. No differences in fractional catabolic rate (FCR) were seen when comparing the multicompartmental modeling of [2-(3)H]glycerol data (modeled over 48 h) either to the monoexponential analyses of the [2-(3)H]glycerol or that of the [(2)H(5)]glycerol data. The two monoexponential approaches were highly correlated (r = 0.96 for FCR), however, FCR was 18% higher with the [(2)H(5)]glycerol than with the [2-(3)H]glycerol data (P < 0.003). In all six subjects, a 10-h infusion of [1-(13)C]acetate was started at the same time as the glycerol boluses were given. In two men we were able reliably to detect VLDL-TG-fatty acid enrichment. The measurement of FCR in these two subjects using the mass isotopomer distribution analysis (MIDA) approach was in good agreement (within 10%) with FCRs determined with the labeled glycerol methods. In conclusion, our results have shown that results obtained with the [(2)H(5)]glycerol bolus were highly correlated with those obtained with the [2-(3)H]glycerol, but the FCRs were slightly higher with the former. We have also demonstrated that FCRs determined from monoexponential modeling were in good agreement with those determined from the multicompartmental modeling of the TG-glycerol data.