出版社：American Society for Biochemistry and Molecular Biology
摘要：Apolipoprotein B (apoB) metabolism was investigated in 20 men with plasma triglyceride 0.66–2.40 mmol/l and plasma cholesterol 3.95–6.95 mmol/l. Kinetics of VLDL1 (Sf 60–400), VLDL2 (Sf 20–60), IDL (Sf 12–20), and LDL (Sf 0–12) apoB were analyzed using a trideuterated leucine tracer and a multicompartmental model which allowed input into each fraction. VLDL1 apoB production varied widely (from 5.4 to 26.6 mg/kg/d) as did VLDL2 apoB production (from 0.18 to 8.4 mg/kg/d) but the two were not correlated. IDL plus LDL apoB direct production accounted for up to half of total apoB production and was inversely related to plasma triglyceride ( r = −0.54, P = 0.009). Percent of direct apoB production into the IDL/LDL density range ( r = 0.50, P 1 and VLDL2 apoB fractional transfer rates (FTR), i.e., lipolysis. IDL apoB concentration was regulated mainly by the IDL to LDL FTR ( r = −0.71, P 2 apoB production ( r = 0.48, P = 0.018) and the LDL FCR ( r = −0.77, P 1, IDL, or LDL apoB production. Subjects with predominantly small, dense LDL (pattern B) had lower VLDL1 and VLDL2 apoB FTRs, higher VLDL2 apoB production, and a lower LDL apoB FCR than those with large LDL (pattern A). Thus, the metabolic conditions that favored appearance of small, dense LDL were diminished lipolysis of VLDL, resulting in a raised plasma triglyceride above the putative threshold of 1.5 mmol/l, and a prolonged residence time for LDL. This latter condition presumably permitted sufficient time for the processes of lipid exchange and lipolysis to generate small LDL particles. —Packard, C. J., T. Demant, J. P. Stewart, D. Bedford, M. J. Caslake, G. Schwertfeger, A. Bedynek, J. Shepherd, and D. Seidel. Apolipoprotein B metabolism and the distribution of VLDL and LDL subfractions. J. Lipid Res. 2000. 41: 305–317.
关键词：stable isotopes ; multicompartmental modelling ; synthesis ; catabolism ; mass spectrometry ; small dense LDL
