Ascorbyl radical/ascorbate ratio in plasma from iron overloaded rats as oxidative stress indicator

Oxidative stress has been developed using dietary carbonyl-iron and iron-dextran parenteral administration as models of in vivo iron overload in rats. Carbonyl-iron led to a 2-fold increase in plasma iron content, a significant decrease (34%) in ascorbate plasma content and non-significant changes in plasma ascorbyl radical content. Iron-dextran produced a dramatic increase (6.7-fold) in plasma iron content, overwhelming the plasma total iron binding capacity. The ascorbyl radical content increased significantly in iron-dextran treatment (2.6-fold) and plasma ascorbate level was not affected. Ascorbyl radical/ascorbate ratio was significantly higher in both iron treated groups as compared with the control group (4 x 10(-4)+/-1 x 10(-4)). Data reported here indicate that the ascorbyl radical/ascorbate ratio is an appropriate in vivo indicator of oxidative stress under conditions of iron overload. The overall mechanism that describes the ascorbate status in plasma seems to be strongly dependent on the way the excess of iron is stored and thus, to the availability of the catalytically active iron for interacting with the plasma components. On this regard, evaluation of A*/AH(-) ratio did not help to discriminate between the possible involved mechanisms.