Depletion of hepatic non-protein sulfhydryl content during exposure of rats and mice to butadiene.

B6C3F1 mice, Sprague-Dawley and Wistar rats were exposed to 1,3-butadiene in a closed exposure system. Exposure concentrations were kept above 2000 ppm to ensure saturation of butadiene metabolism in both species (Vmax conditions). Hepatic non-protein sulfhydryl (NPSH) content was determined in butadiene-exposed animals (and air-exposed controls) after exposures for 0, 7 and 15 h. Depletion of hepatic NPSH content was different for the species and strains investigated. In mice, hepatic NPSH content declined to about 20% after 7 h and was further depleted to about 4% at 15 h when signs of acute toxicity were observed. After a 7 h exposure of rats to butadiene, hepatic NPSH content was depleted to about 65% (Wistar) or 80% (Sprague-Dawley) of the corresponding controls but remained practically stable after a 15 h exposure to butadiene. The time-courses of depletion by butadiene of hepatic NPSH support previous findings on differences in butadiene metabolism between rats and mice and offer an additional explanation for the considerable species differences observed in the toxicity and carcinogenicity of this compound.