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 in establishing specific pathways of oxidative stress in vivo and in determining functional consequences of oxidant stress exposure. We therefore examined oxidative modification of plasma proteins by carbonyl formation using Western blot immunoassay and enzyme-linked immunosorbent assay (ELISA) techniques in patients with chronic renal failure (CRF) and on chronic hemodialysis therapy (HD).


METHODS
Plasma was obtained from 25 HD, 20 CRF, and 20 healthy volunteers, derivatized with 2,4 dinitrophenylhydrazine (DNP) and electrophoresed on duplicate 4 to 12% gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, transferred to nitrocellulose, and stained for DNP for carbonyls and amido black for protein content. Data are recorded as DNP area/protein area and are reported in densitometry units. Total plasma carbonyls were determined by ELISA.


RESULTS
Plasma albumin is substantially more oxidized in HD than in healthy 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 patients, 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 differences in oxidation of plasma transferrin, fibrinogen, and immunoglobulin in CRF patients versus healthy volunteers. An increased plasma protein carbonyl concentration in CRF patients compared with healthy volunteers was confirmed by ELISA (0.31 +/- 0.07 vs. 0.04 +/- 0.01 nmol/mg protein (P = 0.001).


CONCLUSIONS
Albumin is the major plasma protein target of oxidant stress in CRF and HD patients.
Himmelfarb
J
J
Division of Nephrology and Renal Transplantation, Maine Medical Center, Portland, Maine 04102, USA. Himmej@mmc.org
McMonagle
E
E
D000368:Aged; D001798:Blood Proteins / Q000032:analysis; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D012016:Reference Values; D006435:Renal Dialysis; D012709:Serum Albumin / Q000378:metabolism*; D014511:Uremia / Q000097:blood*
D001798:Blood Proteins; D012709:Serum Albumin