Hyperoxia-induced changes in antioxidant capacity and the effect of dietary antioxidants

We investigated, by measuring oxygen radical absorbance capacity (ORAC), wh ether hyperoxia causes alterations in antioxidant status and whether these alterations could be modulated by dietary antioxidants. Rats were fed for 8 wk a Control diet or a control diet supplemented with vitamin E (500 IU/kg ) or with aqueous extracts (ORAC: 1.36 mmol Trolox equivalents/kg) from blu eberries dr spinach and then were exposed to air or >99% O-2 for 48 h. Alth ough the constituents of the extracts were ndt extensively characterized, H PLC indicated that blueberry extract was particularly rich in anthocyanins, and the spinach extract did not contain any anthocyanins. The ORAC was det ermined in samples without proteins [serum treated with perchloric acid (PC A); ORAC(PCA)] and with proteins (ORAC(tot)). Hyperoxia induced a decrease in serum protein concentration, an increase in serum ORAC(PCA), decreases i n lung ORAC(PCA) and ORAC(tot), and an equilibration of proteins and ORAC(P CA) between serum and pleural effusion. These alterations suggested a redis tribution of antioxidants between tissues and an increase in capillary perm eability during hyperoxia. Only the blueberry extract was effective in alle viating the hyperoxia-induced redistribution of antioxidants between tissue s.