Lipid peroxidation, antioxidant enzymes and glutathione levels in human erythrocytes exposed to colloidal iron hydroxide in vitro

The free form of the iron ion is one of the strongest oxidizing agents in t he cellular environment. The effect of iron at different concentrations (0, 1, 5, 10, 50, and 100 mu M Fe3+) on the normal human red blood cell (RBC) antioxidant system was evaluated in vitro by measuring total (GSH) and oxid ized (GSSG) glutathione levels, and superoxide dismutase (SOD), catalase, g lutathione peroxidase (GSH-Px) and reductase (GSH-Rd) activities. Membrane lipid peroxidation was assessed by measuring thiobarbituric acid reactive s ubstance (TBARS). The RBC were incubated with colloidal iron hydroxide and phosphate-buffered saline, pH 7.45, at 37 degrees C, for 60 min. For each a ssay, the results for the control group were: a) GSH = 3.52 +/- 0.27 mu M/g Hb; b) GSSG = 0.17 +/- 0.03 mu M/g Hb; c) GSH-Px = 19.60 +/- 1.96 IU/g Hb; d) GSH-Rd = 3.13 +/- 0.17 IU/g Hb; e) catalase = 394.9 +/- 22.8 IU/g Hb; f ) SOD = 5981 +/- 375 IU/g Hb. The addition of 1 to 100 mu M Fe3+ had no eff ect on the parameters analyzed. No change in TEARS levels was detected at a ny of the iron concentrations studied. Oxidative stress, measured by GSH ki netics over time, occurs when the RBC are incubated with colloidal iron hyd roxide at concentrations higher than 10 mu M of Fe3+. Overall, these result s show that the intact human RBC is prone to oxidative stress when exposed to Fe3+ and that the RBC has a potent antioxidant system that can minimize the potential damage caused by acute exposure to a colloidal iron hydroxide in vitro.