Concentration and distribution of apolipoproteins A-I and E in normolipidemic, WHHL and diet-induced hyperlipidemic rabbit sera.
Two sandwich-type enzyme immunoassays have been developed to measure apolipoproteins A-I and E in rabbit serum. Specific goat antibodies were purified by affinity chromatography and used both for coating and for preparing antibody-peroxydase conjugates. The sensitivity of these assays is sufficient to allow studies of apo A-I and E distribution in lipoproteins fractionated by gel filtration from 50 microliters of serum. In WHHL rabbits, apo A-I is 5-fold lower (5.2 +/- 2.5 mg/dl) and apo E is 8-fold higher (9.9 +/- 3.5 mg/dl) than in normolipidemic rabbits (29 +/- 4.3 mg/dl and 1.3 +/- 0.5 mg/dl, respectively). In hyperlipidemic rabbits, fed 2 months on a 0.5% cholesterol diet, the apo A-I level was similar (32 +/- 12 mg/dl) to that of normolipidemic rabbits, but the apo E level is 12-fold higher (15.1 +/- 5.5 mg/dl). In addition, HDL particles were enriched with cholesterol and apo E. The bulk of apo E and cholesterol is located in large beta-VLDL in diet-induced hyperlipidemia, whereas they are mainly located in smaller size beta-VLDL in WHHL rabbits. In normolipidemic rabbits apo E occurs mainly in HDL, and cholesterol is distributed in the main three lipoprotein fractions VLDL, LDL and HDL. Interestingly, HDL of WHHL rabbit are deficient in apo A-I. These results are compatible with profound perturbations of lipoprotein composition and metabolism in atherogenic hyperlipidemia.
Mezdour
H
H
National Cardiovascular Center Research Institute, Department of Etiology and Pathophysiology, Osaka, Japan.
Nomura
S
S
Yamamura
T
T
Yamamoto
A
A
D000818:Animals; D000918:Antibody Specificity; D016632:Apolipoprotein A-I / Q000032:analysis*; D001057:Apolipoproteins E / Q000032:analysis*; D004032:Diet; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006949:Hyperlipidemias / Q000097:blood* / Q000209:etiology; D008074:Lipoproteins / Q000737:chemistry; D011817:Rabbits; D012680:Sensitivity and Specificity
D016632:Apolipoprotein A-I; D001057:Apolipoproteins E; D008074:Lipoproteins