Human erythrocyte delta-aminolevulinate dehydratase activity and oxidative stress in hemodialysis patients.
BACKGROUND
Oxidative stress is a complicating factor in chronic renal failure, especially in hemodialysis (HD) patients. Also, aluminum intoxication may occur during hemodialysis treatment. Aluminum has been shown to inhibit the sulfhydryl-containing enzyme delta-aminolevulinate dehydratase (ALA-D). Thus, the involvement of -SH oxidation in ALA-D inhibition and its relationship with serum Al levels and lipid peroxidation in HD patients were evaluated.


METHODS
Blood ALA-D activity, plasma thiobarbituric acid reactive substances (TBARS), and serum aluminum levels were measured in HD patients (n=37) and healthy controls (n=20).


RESULTS
TBARS and Al levels were higher in HD patients than in controls (p<0.01), while ALA-D activity was lower (p<0.05). The sulfhydryl-reducing agent dithiothreitol (DTT) reactivated ALA-D of HD patients, but activity was still lower than that of controls. ALA-D activity was negatively correlated with TBARS (r=-0.63, p<0.01) and aluminum levels (r=-0.31, p<0.05).


CONCLUSIONS
Reduced ALA-D activity in HD patients was found to be related to the oxidation of -SH groups essential for enzyme activity. Our results suggest that increased oxidative stress may have contributed to enzyme inhibition in HD patients.
Valentini
Juliana
J
Department of Clinical and Toxicological Analysis, Federal University of Santa Maria, Santa Maria, RS, Brazil.
Schmitt
Gabriela C
GC
Grotto
Denise
D
Santa Maria
Lucas D
LD
Boeira
Silvana P
SP
Piva
Silvia J
SJ
Brucker
Natalia
N
Bohrer
Denise
D
Pomblum
Valdeci J
VJ
Emanuelli
Tatiana
T
Garcia
Solange C
SC
D000368:Aged; D000535:Aluminum / Q000097:blood; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors / Q000097:blood*; D006435:Renal Dialysis; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D017392:Thiobarbituric Acid Reactive Substances; D000535:Aluminum; D000623:Porphobilinogen Synthase; D004229:Dithiothreitol