PROTEIN OXIDATION IN HEMODIALYSIS AND KIDNEY-TRANSPLANTATION

Oxidative damage of plasma proteins determined with the markers carbon yl group (CG) content and thiobarbituric acid-reactive substances (TBA RS) was studied in 13 hemodialyzed and eight kidney-transplanted patie nts. The level of CGs was 38% higher in hemodialysis (HD) patients (1. 49 +/- 0.05 nmol/mg protein) than in the healthy subjects (1.08 +/- 0. 03 nmol/mg protein); the TEARS level was also higher in HD patients th an in the control group (2.64 +/- 0.15 v 1.81 +/- 0.09 nmol/mL, P <.00 1). These date confirm that in end-stage renal failure,an increased ox idative stress is present and is able to induce protein damage. After transplantation, the Co content in protein was reduced (1.34 +/- 0.08 nmol/mg protein), but it was not significantly different from the leve l in the HD group. The failure to return to the normal range suggests that an impaired redox status is maintained, resulting in a sustained elevation of CG. Conversely, the level of TEARS in transplanted patien ts (1.99 +/- 0.22 nmol/mL) was not significantly different from that i n the control group (1.81 a 0.09), suggesting that lipoperoxidation ma y be inhibited. These results may be explained by the different turnov er rates of the molecules and by the distinct origin of the two marker s, resulting from the damage of proteins or lipids. Thus, lipoperoxida tion would produce rapidly removable molecules, whereas protein oxidat ion damage would tend to accumulate. However, the significant correlat ion found between CGs and TEARS indicates that a common cause (oxidati ve stress) binds the two markers of damage. Copyright (C) 1996 by W.B. Saunders Company