Associations of lead exposure and dose measures with erythrocyte protein kinase C activity in 212 current Korean lead workers

Lead can replace calcium in enzyme assays that measure protein kinase C act ivity and lead activates protein kinase C in human erythrocytes after expos ure to lead in vitro. To examine the relevance of these observations to lea d exposure in humans, we studied the associations of lead found in blood or tibia with activation of protein kinase C in erythrocytes isolated from wo rkers in the lead industry. We examined erythrocytes among 212 lead workers , with a mean (+/- SD) age of 39.1 (10.0) years and exposure duration of 8. 1 (6.5) years and measured protein kinase C activation by an in vitro back- phosphorylation assay. After adjustment for potential confounding factors ( age and sex), tibia lead and exposure duration were significantly associate d with erythrocyte protein kinase C activation (both p values < 0.05). No a ssociations were observed between protein kinase C activation and blood-lea d or zinc-protoporphyrin levels. These findings suggest that human exposure to lead results in activation of erythrocyte protein kinase C, which may b e directly relevant to the neurotoxicity of lead.