TY - JOUR
T1 - Metabolic fate of VLDL apolipoproteins B and E in hepatectomized rats
AU - Davis, Roger A.
AU - Hartman, Arthur D.
AU - Dory, Ladislav
AU - Van Lenten, Brian J.
AU - Roheim, Paul S.
N1 - Funding Information:
We wish to thank Ms. Monica McNeal, Mr. Enrique Irizarry and Ms. Margaret Balzer for their excellent technical assistance.T his work was supported by researchg rants HL23895, HL2.5596a nd AM19995 and training grant HL07095 from the National Institutes of Health and by a grant from the Louisiana Heart Association.
PY - 1981/7/24
Y1 - 1981/7/24
N2 - The metabolic fate of VLDL apolipoproteins B and E was examined in functionally hepatectomized rats. 1 h after hepatectomy, there was almost complete absence of ultracentrifugally isolated VLDL lipid and protein, including apolipoproteins B and E. Analysis of apolipoprotein concentrations by electroimmunoassay showed hepatectomy did not affect the total serum concentrations of apolipoproteins B and E; thus, hepatectomy caused a redistribution of these apolipoproteins from VLDL to higher density lipoproteins. In the LDL (d = 1.03-1.063 g/ml) fraction, hepatectomy increased the concentrations of free cholesterol (40%), esterified cholesterol (57%) and protein (18-67%), due to an increase in apolipoproteins B (22-48%) and E (250-300%). After hepatectomy, the HDL fraction accumulated the greatest total amount of apolipoprotein E. Since the majority of apolipoprotein E was isolated in the d > 1.21 g/ml fraction after sequential ultracentrifugation, the redistribution of apolipoproteins B and E was further defined by fractionation of serum on 5 M agarose columns. Electroimmunoassay of the column fractions showed that the apolipoprotein B peak eluted before the apolipoprotein E peak. Although a considerable portion of apolipoprotein E eluted with A-I, the peak of apolipoprotein E eluted before the A-I peak in both groups. These data suggest that a portion of apolipoprotein E is associated with particles which are smaller than LDL but are larger than A-I-rich HDL. Hepatectomy caused an accumulation of apolipoprotein B in LDL, and apolipoprotein E and cholesterol in particles which were smaller than LDL and may represent HDL1. It is likely that under normal physiological conditions the liver plays a role in the removal of these apolipoprotein E-rich particles which are derived, at least in part, from the metabolism of VLDL.
AB - The metabolic fate of VLDL apolipoproteins B and E was examined in functionally hepatectomized rats. 1 h after hepatectomy, there was almost complete absence of ultracentrifugally isolated VLDL lipid and protein, including apolipoproteins B and E. Analysis of apolipoprotein concentrations by electroimmunoassay showed hepatectomy did not affect the total serum concentrations of apolipoproteins B and E; thus, hepatectomy caused a redistribution of these apolipoproteins from VLDL to higher density lipoproteins. In the LDL (d = 1.03-1.063 g/ml) fraction, hepatectomy increased the concentrations of free cholesterol (40%), esterified cholesterol (57%) and protein (18-67%), due to an increase in apolipoproteins B (22-48%) and E (250-300%). After hepatectomy, the HDL fraction accumulated the greatest total amount of apolipoprotein E. Since the majority of apolipoprotein E was isolated in the d > 1.21 g/ml fraction after sequential ultracentrifugation, the redistribution of apolipoproteins B and E was further defined by fractionation of serum on 5 M agarose columns. Electroimmunoassay of the column fractions showed that the apolipoprotein B peak eluted before the apolipoprotein E peak. Although a considerable portion of apolipoprotein E eluted with A-I, the peak of apolipoprotein E eluted before the A-I peak in both groups. These data suggest that a portion of apolipoprotein E is associated with particles which are smaller than LDL but are larger than A-I-rich HDL. Hepatectomy caused an accumulation of apolipoprotein B in LDL, and apolipoprotein E and cholesterol in particles which were smaller than LDL and may represent HDL1. It is likely that under normal physiological conditions the liver plays a role in the removal of these apolipoprotein E-rich particles which are derived, at least in part, from the metabolism of VLDL.
KW - Apolipoprotein E
KW - Hepatectomy
KW - VLDL metabolism
UR - http://www.scopus.com/inward/record.url?scp=0019887430&partnerID=8YFLogxK
U2 - 10.1016/0005-2760(81)90243-5
DO - 10.1016/0005-2760(81)90243-5
M3 - Article
C2 - 7284413
AN - SCOPUS:0019887430
SN - 0005-2760
VL - 665
SP - 154
EP - 164
JO - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
JF - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
IS - 1
ER -