OBJECTIVE: To assess the effect of a hemodialysis (HD) session on systemic oxidative stress of chronic renal patients. METHODS AND RESULTS: The study comprised 17 patients (10 women and 7 men with mean age of 39.9 ± 13.5 years) undergoing hemodialytic treatment at the Unit of Nephrology of Hospital de Clínicas de Porto Alegre, and a control group formed by 18 healthy individuals (4 women and 14 men with mean age of 34.8 ± 10.1 years). Renal patients had blood samples withdrawn before and after HD session. Means were analyzed by Student t test (p < 0.05). In red blood cells, the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) was assessed. In plasma, the non-enzymatic antioxidant system was assessed by measuring the total reactive antioxidant potential (TRAP). No significant differences were observed between the values of SOD and CAT before and after HD. Comparison with the control group showed a significant reduction in the activity of those enzymes. After HD session, a significant reduction in TRAP was observed. Oxidative damage to membrane lipids was assessed through chemiluminescence (CL), and the damage to proteins through carbonyl assay. No significant difference was observed in the values of CL and carbonyls after HD. However, when compared with the control group, a significant difference was observed, indicating a greater damage to membrane lipids and proteins in renal patients. CONCLUSIONS: Chronic renal patients on HD treatment show a reduction in the activity of antioxidant enzymes SOD and CAT, in addition to an increase in oxidative damage, when compared with healthy individuals. One HD session does not change those levels.
oxidative stress; hemodialysis; chronic kidney disease
