Influence of lead nitrate on dimethylnitrosamine intoxication.

The effect of lead nitrate, an inhibitor of the hepatic drug-metabolizing enzyme system upon the acute, hepatotoxicity of dimethylnitrosamine (DMN) was studied. Lead pretreatment significantly prevented polysomal disaggregation induced by the nitrosamine. Cell necrosis, evaluated morphologically and by the release of serum glutamic-pyruvic transaminase (GPT), was also diminished. The metabolism of DMN in rats pretreated with lead nitrate was investigated by following its clearance from blood and by determining, in vitro the demethylation of the nitrosamine. Lead increased, although not significantly, the clearance of DMN from blood, but it lowered the activity of DMN-demethylase 24 h after its administration. Finally, lead lowered the lethal effects of DMN. The mechanism by which lead influenced DMN toxicity is discussed.