Correlation between plasma 5-aminolevulinic acid concentrations and indicators of oxidative stress in lead-exposed workers.
5-Aminolevulinic acid (ALA), a heme precursor accumulated in acute intermittent porphyria and lead poisoning, undergoes metal-catalyzed aerobic oxidation at physiological pH to yield reactive free radical species (O2., HO., and ALA.). We analyzed the relationships between plasma ALA concentrations, blood concentrations of lead, protoporphyrin IX (PP-IX), superoxide dismutase (SOD), and methemoglobin (metHb), and urine chemiluminescence (CL) in samples collected from lead-exposed workers. All variables measured were substantially (P < 0.01) higher (2-8-fold) in the lead-exposed workers (n = 60). Plasma ALA concentrations were, on average, 6-fold higher in lead-exposed workers. We observed positive linear relationships between ALA and lead (r = 0.992), ALA and PP-IX (r = 0.891), ALA and metHb (r = 0.984), lead and SOD (r = 0.948), ALA and urine CL (r = 0.987), and lead and PP-IX (r = 0.993). These data are consistent with our free radical hypothesis for lead poisoning, where ALA distribution to and accumulation in several organs may trigger oxidative stress responses.
Costa
C A
CA
Departamento de Toxicologia, Faculdade de Ciêancias Farmacêauticas da Universidade de São Paulo, Brazil.
Trivelato
G C
GC
Pinto
A M
AM
Bechara
E J
EJ
D000293:Adolescent; D000328:Adult; D000622:Aminolevulinic Acid / Q000097:blood*; D006801:Humans; D007854:Lead / Q000097:blood*; D008163:Luminescent Measurements; D008297:Male; D008708:Methemoglobinemia / Q000097:blood; D008875:Middle Aged; D016273:Occupational Exposure; D018384:Oxidative Stress; D011524:Protoporphyrins / Q000097:blood; D013482:Superoxide Dismutase / Q000097:blood
D011524:Protoporphyrins; D007854:Lead; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D013482:Superoxide Dismutase