ANTIOXIDANT AND PROOXIDANT ROLES OF COPPER IN TWEEN 20-INDUCED HEMOLYSIS OF HAMSTER AND PIG ERYTHROCYTES CONTAINING MARGINAL VITAMIN-E

The concentration-dependent effects of copper acting either as an anti oxidant or as a prooxidant were examined in vitro using Tween 20-induc ed hemolysis. When cupric ion concentration was more than 10 mu M, fre e copper(II) acted as a prooxidant; both extensive hemolysis and produ ction of unknown thiobarbituric acid-reactive substance occurred in ha mster and pig erythrocytes irrespective of vitamin E status. However, when cupric ion concentration was 2-4 mu M in the incubation medium, c opper showed a dear antioxidant activity, reducing both hemolysis and malondialdehyde production induced either by diluted peroxide-containi ng Tween 20 with ascorbic acid and sodium azide in vitamin E-deficient hamster erythrocytes, or by peroxide-containing Tween 20 in pig eryth rocytes containing marginal amounts of vitamin E. Copper(II) is taken up by the erythrocytes, where copper(I)-complexes may contribute to th e protection of cells with membrane vitamin E against oxidative radica l attack.