RESUMO
Oxidative stress due to overproduction of reactive oxygen species and impairment in antioxidant defense mechanisms have been suggested as possible factors contributing to the pathogenesis of atherosclerosis in patients with end- stage renal disease. The aim of this study was to evaluate antioxidant markers of oxidative stress including glutathione and glutathione related enzymes [i.e. glutathione peroxidase [GPx] and glutathione reductase [GR]] as well as total antioxidant capacity in peritoneal dialysis [PD] patients. Twelve PD patients and 17 healthy controls [age range: 25-60 and 22-53 years respectively] were selected. Erythrocyte glutathione levels and plasma activities of GPx, GR and total antioxidant capacity were determined spectrophtometrically. Glutathione levels and GPx activity were significantly lower in the patients group than in controls [1.17 +/- 0.28 vs. 1.42 +/- 0.25 micro mol/ml and 57.1 +/- 21.8 vs. 142.5 +/- 31.7 U/L; p<0.05, respectively]. Higher levels of GR activity and total antioxidant capacity were noted in patient group [57.5 +/- 16.4 U/L and 0.60 +/- 0.09 micro mol/ml; respectively] in comparison to control group [32 +/- 9.4 U/L and 0.47 +/- 0.11 micro mol/ml; p<0.05, respectively]. Decreased glutathione levels and alteration in the activities of its related enzymes imply increased oxidative stress and disturbances of antioxidant defense systems in peritoneal dialysis patients. This condition may contribute to the development of accelerated cardiovascular disease and its morbidity and mortality in these patients