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.