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Antioxidant Enzymes Show Adaptation to Oxidative Stress in Athletes and Increased Stress in Hemodialysis Patients

The aim of the study is to compare oxidative stress in hemodialysis patients in controls and in rowers. The patients are a model of decreased antioxidant capacity, and the athletes (rowers) are a model of the highest antioxidant capacity due to their chronic adaptation to demanding training. Thirty‐five subjects participated in the study, 9 patients with end‐stage renal disease treated by hemodialysis, 12 healthy young subjects from the normal population, and 14 rowers. The antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as non‐transferrin‐bound iron as a promoter of free radical damage, were determined. Blood analysis was taken in dialysis patients in the morning, before the dialysis procedure. There was significantly higher activity of catalase in dialysis patients (catalase 4.26 ± 0.35 mkat/g Hb) compared to the controls (catalase 2.73 ± 0.38 mkat/g Hb) and rowers (catalase 1.71 ± 0.30 mkat/g Hb). Superoxide dismutase activity was significantly lower (10.42 ± 1.46 µkat/g Hb) than in the controls (11.94 ± 1.18 µkat/g Hb) and rowers (14.09 ± 0.92 µkat/g Hb). There was no significant differences between glutathione peroxidase activities in the three groups. Superoxide dismutase and Se were higher in rowers than in dialysis patients (P < 0.05). The concentrations of both non‐transferrin‐bound iron and ferritin were significantly higher in dialysis patients. Hemodialysis patients might have increased oxidative stress, which is characterized by significantly higher erythrocyte enzyme activity of catalase and lower activity of superoxide dismutase. Top rowers had increased superoxide dismutase and glutathione peroxidase, perhaps because of adaptation during training, which was not the case in dialysis patients and controls.