Albumin is the major plasma protein target of oxidant stress in uremia

Background. Patients with uremia are exposed to increased oxidative stress. Examination of the oxidation of individual plasma proteins may be useful i n establishing specific pathways of oxidative stress in vivo and in determi ning functional consequences of oxidant stress exposure. We therefore exami ned oxidative modification of plasma proteins by carbonyl formation using W estern blot immunoassay and enzyme-linked immunosorbent assay (ELISA) techn iques in patients with chronic renal failure (CRF) and on chronic hemodialy sis therapy (HD). Methods. Plasma was obtained from 25 HD 20 CRF, and 20 healthy volunteers, derivatized with 2.4 dinitrophenylhydrazine (DNP) and electrophoresed on du plicate 4 to 12% gradient sodium dodecyl sulfate-polyacrylamide gel electro phoresis (SDS-PAGE) gels, transferred to nitrocellulose, and stained for DN P for carbonyls and amido black for protein content. Data are recorded as D NP area/protein area and are reported in densitometry units, Total plasma c arbonyls were determined by ELISA. Results. Plasma albumin is substantially more oxidized in HD than in health y volunteers (1.22 +/- 0.14 densitometry units vs. 0.60 +/- 0.08, P = 0.002 ). There were no significant differences in oxidation of plasma transferrin , immunoglobulin. and fibrinogen in HD versus healthy volunteers. In CRF pa tients, plasma albumin is more oxidized compared with normal volunteers (1. 36 +/- 0.20 densitometry units vs. 0.94 + 0.08. P = 0.09). There were no di fferences in oxidation of plasma transferrin, fibrinogen, and immunoglobuli n in CRF patients versus healthy volunteers. An increased plasma protein ca rbonyl concentration in CRF patients compared with healthy volunteers was c onfirmed by ELISA (0.31 +/- 0.07 vs. 0.04 +/- 0.01 nmol/mg protein (P = 0.0 01). Conclusion. Albumin is the major plasma protein target of oxidant stress in CRF and HD patients.