INDICATIONS FOR THE PRESENCE OF CIRCULATING PEROXIDIZED LOW-DENSITY LIPOPROTEINS IN WHHL RABBITS TREATED WITH ANTIOXIDANTS

Low density apolipoprotein (apo) B-100 in homozygous WHHL rabbits appe ars heterogeneous on SDS-PAGE. At least four high molecular weight apo lipoproteins were identified in contrast to the uniform apo B-100 band in the very low density lipoprotein (VLDL) fraction of WHHL-homozygot es and the apo B containing lipoproteins present in WHHL heterozygotes or New Zealand White rabbits. We studied whether these abberations in homozygote WHHL-LDL were due to physical changes induced by lipid per oxidation. Therefore we treated WHHL rabbits for 28 days with a standa rd dose of 1% probucol or with a dose of 0.1% vitamin E and studied th e parameters indicating lipid peroxidation in circulating LDL and in v itro in relation to its antioxidant content. The LDL of probucol-fed r abbits appeared completely resistant against oxidation in vitro with C u2+ ions. LDL fluorescence and serum malondialdehyde concentrations. i ndicators of lipid peroxidized LDL, were lower than in the control WHH L rabbits. LDL of vitamin E-fed WHHL rabbits showed a twofold increase d lag phase in comparison with LDL of control-fed animals; the maximal rate of oxidation was 2- to 3-fold lower while LDL fluorescence was b etween the values obtained in the two other groups. Malondialdehyde co ncentration in the vitamin E-treated group was also decreased when com pared with controls. Despite these indications of increased lipid pero xidized circulating LDL in WHHL controls which could be reversed, at l east partially, by the antioxidant treatments applied, these treatment s were without effect on the physical structure of LDL as examined wit h agarose gel electrophoresis. Neither antioxidant treatment changed t he typical apo B-100 pattern in WHHL-LDL.