Alkylation of nuclear proteins and DNA after exposure of rats and mice to [1,4-14C]1,3-butadiene.

B6C3F1 mice and Wistar rats were exposed to [1,4-14C]1,3-butadiene in a closed exposure system. Based on body weight, mice metabolized the test compound at about twice the rate, compared to rats. Nucleoproteins and DNA were isolated from the livers of the animals and covalent binding of [14C]-butadiene-derived radioactivity was determined. In both species comparable amounts of radioactivity were covalently bound to liver DNA. Covalent binding to mouse-liver nucleoproteins was twice as high as in rats and thus it paralleled the higher metabolic rate for butadiene in this species.