EVIDENCE FOR OXIDATIVE STRESS DURING IN-VITRO DIALYSIS

The evidence for oxidative stress during haemodialysis is controversia l. We therefore examined markers of oxidative stress and lipid peroxid ation using an in vitro dialysis circuit. A unit of fresh blood (500 m l) therapeutically removed from each of 7 haemochromatosis patients wa s oxygenated and circulated for 4 h at 37 degrees C through a cupropha ne dialyser (Clirans C08) against saline dialysate (1,000 ml recircula ting; +FIL group). In a second series of experiments (n = 7), the dial yser was omitted from the circuit (-FIL group). Concentrations of anti -oxidants and malondialdehyde (MDA) were measured at 7 time points dur ing the study. Blood thiol concentrations decreased by 25.6% in the +F IL group (p < 0.05) but were unchanged in the -FIL group (p > 0.05; gr oup comparison, p = 0.006). There were no significant differences betw een the groups, for the lipid-soluble anti-oxidants alpha-tocopherol, retinol and beta-carotene. Plasma MDA concentrations increased in both circuits (p < 0.001, respectively, no difference between groups). How ever, the susceptibility of red blood cells to lipid peroxidation (as determined by MDA production following a challenge with hydrogen perox ide) was unchanged by 120 min of dialysis. These in vitro experiments provide supporting evidence that haemodialysis is accompanied by measu rable oxidative stress and plasma lipid peroxidation.