Human apolipoprotein (Apo) B-48 and ApoB-100 kinetics with stable isotopes.
The kinetics of apolipoprotein (apo) B-100 and apoB-48 within triglyceride-rich lipoproteins (TRLs) and of apoB-100 within IDL and LDL were examined with a primed-constant infusion of (5,5,5-(2)H(3)) leucine in the fed state (hourly feeding) in 19 subjects after consumption of an average American diet (36% fat). Lipoproteins were isolated by ultracentrifugation and apolipoproteins by SDS gels, and isotope enrichment was assessed by gas chromatography/mass spectrometry. Kinetic parameters were calculated by multicompartmental modeling of the data with SAAM II. The pool sizes (PS) of TRL apoB-48, VLDL apoB-100, and LDL apoB-100 were 17+/-10, 273+/-167, and 3325+/-1146 mg, respectively. There was a trend toward a faster fractional catabolic rate (FCR) for VLDL apoB-100 than for TRL apoB-48 (6.73+/-3.48 versus 5.02+/-2.07 pools/d, respectively, P=0.06). The mean FCRs for IDL and LDL apoB-100 were 10.07+/-7.28 and 0.27+/-0.08 pools/d, respectively. The mean production rate (PR) of TRL apoB-48 was 6.5% of VLDL apoB-100 (1. 3+/-0.90 versus 20.06+/-6.53 mg. kg(-1). d(-1), P<0.0001). TRL apoB-48 PS was correlated with apoB-48 PR (r=0.780, P<0.0001) but not FCR (r=-0.1810, P=0.458). VLDL apoB-100 PS was correlated with both PR (r=0.713, P=0.0006) and FCR (r=-0.692, P=0.001) of VLDL apoB-100 and by apoB-48 PR (r=0.728, P=0.0004). LDL apoB-100 PS was correlated with FCR (r=-0.549, P=0.015). These data indicate that (1) the FCRs of TRL apoB-48 and VLDL apoB-100 are similar in the fed state, (2) TRL apoB-48 PS is correlated with TRL apoB-48 PR, (3) VLDL apoB-100 PS is correlated with both PR and FCR of VLDL apoB-100 and PR of TRL apoB-48, and (4) LDL apoB-100 PS is correlated with LDL FCR.
Welty
F K
FK
Lipid Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA. fwelty@caregroup.harvard.edu
Lichtenstein
A H
AH
Barrett
P H
PH
Dolnikowski
G G
GG
Schaefer
E J
EJ
D000368:Aged; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B / Q000493:pharmacokinetics*; D002784:Cholesterol / Q000378:metabolism; D008078:Cholesterol, LDL / Q000378:metabolism; D015243:Cholesterol, VLDL / Q000378:metabolism; D003903:Deuterium; D005260:Female; D006801:Humans; D007700:Kinetics; D007930:Leucine / Q000493:pharmacokinetics*; D008074:Lipoproteins / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008875:Middle Aged
D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001055:Apolipoproteins B; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D008074:Lipoproteins; C030104:lipoprotein cholesterol; D002784:Cholesterol; D003903:Deuterium; D007930:Leucine