Nicotinamide adenine dinucleotide synthetase activity in erythrocytes as a tool for the biological monitoring of lead exposure.
OBJECTIVE
The objective of this study was to evaluate the usefulness of nicotinamide adenine dinucleotide synthetase (NADS) activity for the biological monitoring of lead exposure.


METHODS
The subjects were 76 male lead workers and 13 normal volunteers (7 males and 6 females). NADS activity and blood lead concentration (Pb-B) was determined in each subject. Delta-aminolevulinic acid dehydratase (ALAD) activity was determined in 58 lead workers out of 76 subjects.


RESULTS
NADS activity in the lead workers ranged from 0.08 to 1.1 mumol/h per g of hemoglobin (gHb) and decreased linearly (r = -0.867) as Pb-B increased up to 81.6 micrograms/dl. The pattern of depressed activity of NADS was different from that of ALAD activity, which decreased rapidly and reached a plateau at the Pb-B level between 40 and 60 micrograms/dl. The Pb-B levels inducing 50% inhibition of the enzyme activities were calculated to be 43 micrograms/dl and 20 micrograms/dl for NADS and ALAD, respectively. At the Pb-B level of 40 micrograms/dl, NADS activity showed high validity (1.77) with predictivity of 0.92 at the cut-off level of 0.4 mumol/h per gHb, which were higher than those of ALAD activity.


CONCLUSIONS
These results show an apparent dose-effect relationship of NADS activity versus Pb-B. NADS activity can be used for the biological monitoring of lead exposure.
Morita
Y
Y
Department of Experimental Toxicology, National Institute of Industrial Health, Kawasaki, Japan.
Sakai
T
T
Araki
S
S
Araki
T
T
Masuyama
Y
Y
D000328:Adult; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D007855:Lead Poisoning / Q000097:blood*; D008297:Male; D008875:Middle Aged; D000623:Porphobilinogen Synthase / Q000097:blood; D012680:Sensitivity and Specificity
D000623:Porphobilinogen Synthase; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C063522:NAD+ synthase (glutamine-hydrolysing)