APOLIPOPROTEIN OXIDATION IN THE ABSENCE OF LIPID-PEROXIDATION ENHANCES LDL UPTAKE BY MACROPHAGES

A characteristic of the antioxidant, probucol, is its inability to inh ibit apolipoprotein B fragmentation in low density lipoprotein (LDL), despite a pronounced ability to inhibit lipid oxidation on relatively lengthy exposure to Cu(II). Here we show that a short exposure of LDL to hydrogen peroxide and Cu(II) leads to I-125-labelled apolipoprotein B fragmentation, the production of malondialdehyde and hydroperoxides and leads to increased uptake by macrophages on subsequent culture. H owever, pre-loading LDL with probucol protects LDL from lipid oxidatio n but not protein fragmentation or macrophage uptake. The use of probu col to conduct studies on apolipoprotein B oxidation without extensive lipid oxidation may prove useful when studying LDL apolipoprotein dam age on exposure to an aqueous free radical insult.