Plasma HDL levels are regulated by the catabolic rate of large particles of lipoprotein containing apo-A-I.
Lp-A-I was isolated by immunoaffinity chromatography and then separated into two fractions of large and small Lp-A-I particles by conventional ultracentrifugation with a cut-off density of 1.125 g/ml. The large and small particle-rich fractions were then radiolabeled with [125I]-Na and [131I]-Na, respectively. Both of the labeled lipoproteins were injected (20 microCi, i.v.) simultaneously into normolipidemic rabbits. The FCR of the large Lp-A-I particles was much less than that of the small Lp-A-I particles (0.801 +/- 0.026/day vs. 2.227 +/- 0.067/day, P < 0.0001). These data indicate that the two particles have distinctly different metabolic pathways and that the lower FCR of larger Lp-A-I particles can effectively raise plasma HDL levels.
Saku
K
K
Department of Internal Medicine, Fukuoka University School of Medicine, Japan.
Liu
R
R
Ohta
T
T
Jimi
S
S
Matsuda
I
I
Arakawa
K
K
D000818:Animals; D016632:Apolipoprotein A-I / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D007457:Iodine Radioisotopes; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood* / Q000302:isolation & purification; D008297:Male; D008657:Metabolic Clearance Rate; D011817:Rabbits; D013997:Time Factors
D016632:Apolipoprotein A-I; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL