THE RESISTANCE OF LOW-DENSITY-LIPOPROTEIN TO OXIDATION PROMOTED BY COPPER AND ITS USE AS AN INDEX OF ANTIOXIDANT THERAPY

The measurement ex vivo of the resistance of low density lipoprotein ( LDL) to oxidation promoted by copper is now being used in surveys of h uman populations at risk of developing atherosclerosis. However, it is not known whether a relationship between LDL oxidisability measured i n this way and the development of atherosclerotic lesions exists. Usin g Watanabe rabbits as a model of the disease, we have found that dieta ry supplementation with the antioxidants, probucol and a-tocopherol, i ncreased the resistance of LDL isolated from small volumes of plasma t o oxidation. The antioxidant effects of probucol incorporated into LDL through dietary supplementation were greater than when incorporated e x vivo. When dietary supplementation was extended to a period of three months; the well established anti-atherosclerotic effects of probucol were confirmed and a highly significant relationship between the prob ucol content of the LDL particle and the extent of the atherosclerotic lesion in the aorta emerged. These results suggest that the assessmen t of the resistance of LDL isolated from plasma to oxidation promoted by copper may reflect the response of the arterial atherosclerotic pro cess to antioxidant therapy.