The nonlinear dependence between administered pro-oxidant doses and intensity of free-radical processes observed in rats

The influence of iron, copper and nitrate ions on free-radical processes in rats and the dependence between dose and effect of pro-oxidants were studied. Rats were divided into 14 groups and administered differing concentrations and combinations of chemicals with drinking water. Concentrations of iron, copper and nitrate in the water were 1, 0.5 and 0.33 of maximum permissible concentrations (MPCs) for every chemical. The action of the investigated pollutants on the intensity of free-radical processes was estimated by the determination of conjugated dienes in liver homogenate and the intensity of Fe2+-induced chemiluminescence of the blood serum. It is estimated that chemicals entering the organism in doses that do not exceed their MPC lead to an increase in free-radical oxidation in comparison to the controls. A maximal effect of iron on the concentration of conjugated dienes was observed in a dose equal to 0.33 MPC, while copper and nitrate possess maximal activity in concentrations of 0.5 MPCs. Fast flash amplitude of chemiluminescence in serum was not dose-dependent in rats obtaining iron and copper, while nitrate had a reverse dose-dependent effect. Total luminosity was maximal in doses of chemicals equal to 0.33 MPCs. The combined action of pollutants was more evident in comparison to isolated chemicals in doses equal to 1 MPC.