Oral vitamin C supplementation in hemodialysis patients and its effect on the plasma level of oxidized ascorbic acid and Cu/Zn superoxide dismutase, an oxidative stress marker.
OBJECTIVE
Oxidative stress is known to be enhanced in hemodialysis patients, and one of its useful markers is plasma copper/zinc superoxide dismutase (Cu/Zn-SOD). The increase in plasma Cu/Zn-SOD can be inhibited by orally administered lipid-soluble vitamin E. We examined the antioxidative effects of water-soluble vitamin C administered orally on Cu/Zn-SOD levels in hemodialysis patients.


METHODS
Vitamin C was orally administered to 16 maintenance hemodialysis patients before each dialysis session. Doses were increased from 200 to 1,000 mg over 3 months. The levels of plasma vitamin C and Cu/Zn-SOD and its mRNA expression in leukocytes were determined 1, 2, and 3 months after the start of vitamin C administration. Furthermore, the levels of oxidized and reduced forms of plasma vitamin C were determined before the start of vitamin C administration and before and after dialysis at 1,000-mg vitamin C doses.


RESULTS
Following oral administration, the plasma levels of vitamin C and its oxidized form were increased. However, significant changes in plasma Cu/Zn-SOD or its mRNA expression in leukocytes were not observed.


CONCLUSIONS
In maintenance hemodialysis patients, vitamin C administration resulted in a significant increase in the postdialysis level of the oxidized form of vitamin C, which suggested an increase in antioxidant effect. However, water-soluble vitamin C did not significantly suppress Cu/Zn-SOD expression enhancement.
Washio
Kazunori
K
Department of Pharmacology, School of Medicine, Showa University, Tokyo, Japan. washio@med.showa-u.ac.jp
Inagaki
Masahiro
M
Tsuji
Mayumi
M
Morio
Yuri
Y
Akiyama
Shinichiro
S
Gotoh
Hiromichi
H
Gotoh
Tomomi
T
Gotoh
Yoshikazu
Y
Oguchi
Katsuji
K
D000284:Administration, Oral; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D006435:Renal Dialysis; D013482:Superoxide Dismutase / Q000097:blood*
D015415:Biomarkers; D013482:Superoxide Dismutase; D001205:Ascorbic Acid