Kinetics of preβ1 HDL and αHDL in type II diabetic patients

Background The aim of this study was to analyze the recycling of high density lipoprotein (HDL) in six type II diabetic patients compared with six control subjects by endogenous labelling of apolipoprotein A-I (Apo A-I) with stable isotope Apo A. Materials and methods The -I-HDL kinetics were performed by infusion of (5.5.5-H-2(3))-leucine for 14 h. The pre beta(1) and alpha HDL were separated by gel filtration fast protein liquid chromatrography system (FPLC). Kinetics of isotopic enrichment of Apo A-I were analyzed with a multi-compartmental model software (SAAM II, SAAM Institute, Seattle, WA). Results Plasma Apo A-I concentration was decreased in patients with type II diabetes as a result of a decrease in Apo A-I-alpha HDL (P < 0.05). Diabetic patients were also characterized by an increased relative contribution of Apo A-I in pre beta(1) HDL (18.3 +/- 2.8% vs 11.9 +/- 3.7%, P < 0.01). The synthetic rate of pre beta(1) HDL was slightly increased in diabetic patients compared with control (NS) and an increase of recycling rate of alpha to pre beta(1) HDL was observed (11.67 +/- 3.14 d(-1) vs 7.09 +/- 4.51 d(-1), P < 0.05). The clearance rate of Apo A-I was higher in diabetic patients (P < 0.05 for Apo A-I-pre beta(1) HDL and P < 0.005 for Apo A-I-alpha HDL). Conclusion This study suggests that the usual increase in pre beta(1) HDL in type II diabetic patients is mainly related to an increased conversion rate of alpha to pre beta(1) HDL.