Metabolism of apolipoprotein C-III in normolipemic human subjects.
Radioiodinated apolipoprotein C-III labeled either by the iodine monochloride procedure or by the Bolton-Hunter reagent were incubated in vitro with normal HDL. The labeled HDL-apo C-III, after ultracentrifugation and dialysis, was injected intravenously in 8 normolipidemic subjects. The label was followed in VLDL, IDL + LDL, HDL, d = 1.225 g/ml infranate as well as in total plasma and urine for the first time over a period of 2 weeks. Apolipoprotein C-III distributes readily between the different lipoprotein classes, only a small amount being present in the non-lipoprotein fraction. The percent distribution of apo C-III radioactivity and mass was found similar in VLDL, IDL and HDL using 3 different separation methods. Residence time in the whole system was 2.45 +/- 0.33 days. Fractional catabolic rates calculated from the urine/plasma radioactivity ratios or from the plasma curve were 0.731 +/- 0.096 and 0.767 +/- 0.125 pools/day. Synthetic rate was 2.28 +/- 0.32 mg/day/kg. The parameters seem not affected by the labeling procedure. The shapes of the plasma curve and of the urine/plasma ratio curve suggest a kinetic heterogeneity in the metabolism of apo C-III-containing particles.
Malmendier
C L
CL
Research Foundation on Atherosclerosis, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium.
Lontie
J F
JF
Grutman
G A
GA
Delcroix
C
C
D000328:Adult; D053305:Apolipoprotein C-III; D001056:Apolipoproteins C / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D007457:Iodine Radioisotopes / Q000008:administration & dosage; D007700:Kinetics; D008074:Lipoproteins / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000008:administration & dosage / Q000378:metabolism; D053419:Lipoproteins, IDL; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D008657:Metabolic Clearance Rate
D053305:Apolipoprotein C-III; D001056:Apolipoproteins C; D007457:Iodine Radioisotopes; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D053419:Lipoproteins, IDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL