PROTECTIVE EFFECTS OF ANTIOXIDANTS AGAINST UREMIA-INDUCED LIPID-PEROXIDATION AND GLUTATHIONE DEPLETION IN HUMANS

The effects of uraemias and antioxidant therapy for 40 days with vitam in A, vitamin C and vitamin E on blood and erythrocyte sulfhydryl (glu tathione, GSH) content and on erythrocyte glutathione-S transferase (G ST), glutathione reductase (GSR) and glutathione peroxidase activities were studied in six uraemic patients maintained on haemodialysis. In addition, the effect of antioxidant therapy on erythrocyte lipid perox idation was determined, and erythrocyte haemoglobin content was measur ed. Uraemic patients in dialysis exhibited significant decreases in bl ood and erythrocyte GSH content as well as significant decreases in th e activities of GST, GSR and GSH-peroxidase relative to control subjec ts. Furthermore, the uraemic patients had elevated erythrocyte malondi aldehyde levels. Blood and erythrocyte GSH content from uraemic patien ts was significantly elevated after 20 days of antioxidant treatment a nd remained elevated thereafter throughout the remaining 20 days of th e study (130% and 173%, respectively). Antioxidant therapy also produc ed significant increases in GSR and GSH-peroxidase activities after 20 days of treatment which remained relatively constant thereafter. No s ignificant change in GST activity was observed. Erythrocyte malondiald ehyde levels, as an index of oxidative tissue damage, exhibited a sign ificant decrease (70%) in the patients after 40 days of antioxidant th erapy. A gradual increase in erythrocyte haemoglobin content was obser ved following treatment of the uraemic subjects (45% at day 40). The r esults suggest that antioxidant therapy may protect against oxidative stress associated with uraemia.