Glutathione, glutathione-related enzymes, and total antioxidant capacity in patients on maintenance dialysis

ABSTRACT

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. We compared glutathione levels, glutathione peroxidase and glutathione reductase activities, and total antioxidant capacity between patients on hemodialysis and peritoneal dialysis and healthy individuals. Thirty patients receiving regular hemodialysis and 12 on continuous ambulatory peritoneal dialysis were recruited as well as 25 healthy volunteers. Diabetes mellitus, recent febrile or infectious episodes, and hospitalization during the past month were the exclusion criteria. Erythrocyte glutathione level, plasma activities of glutathione peroxidase and glutathione reductase, total antioxidant capacity were determined and compared between the three studied groups. Glutathione levels and glutathione peroxidase activity were markedly lower in the patient groups than in the controls. Conversely, higher activity of glutathione reductase and total antioxidant capacity were noted in the patients than in the controls. There were no significant differences between antioxidant markers of the patients on hemodialysis and peritoneal dialysis. Strong positive correlation were observed between total antioxidant capacity and uric acid in the patients [r = 0.59, P = .045 and r = 0.63, P = .03, respectively]. Although total antioxidant capacity of plasma is increased in patient on dialysis, depletion of glutathione as a key antioxidant component and disturbances in its related enzymes show oxidative stress. This condition may increase the risk of developing cardiovascular disease in patients with end-stage renal disease