Cr(VI) induces lipid peroxidation, protein oxidation and alters the activities of antioxidant enzymes in human erythrocytes. 
The effect of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, on human erythrocytes was studied under in vitro conditions.  Incubation of erythrocytes with different concentrations of K(2)Cr(2)O(7) resulted in marked hemolysis in a concentration-dependent manner.  K(2)Cr(2)O(7) treatment also caused significant increase in protein oxidation, lipid peroxidation and decrease in total sulfhydryl content, indicating that it causes oxidative stress in human erythrocytes.  However, there was no concomitant nitrosative stress as the nitric oxide levels in hemolysates from K(2)Cr(2)O(7)-treated erythrocytes were lower than in control.  Exposure of erythrocytes to K(2)Cr(2)O(7) decreased the activities of catalase, glutathione peroxidase, thioredoxin reductase, glucose-6-phosphate dehydrogenase, and glutathione reductase, whereas the activities of Cu-Zn superoxide dismutase and glutathione S-transferase were increased.  These results show that K(2)Cr(2)O(7) induces oxidative stress and alters the antioxidant defense mechanism of human erythrocytes.