A comparison of the binding and distribution of benzo[ a]pyrene in human and rat serum

Abstract

Uptake and distribution of benzo[ a]pyrene (B[ a]P) in human and rat serum were studied by incubation, gel filtration and ultracentrifugation. A maximum uptake of 230 and 120 μm B[ a]P/ml was found for human and rat serum, respectively. Of the B[ a]P uptake about 1% was irreversibly bound to serum constituents from both species. The uptake of B[ a]P by the lipoproteins was 90–95% and 80–85% for human and rat serum, respectively, the remainder being bound to albumin. In human serum B[ a]P was mainly associated with low density lipoproteins (44–47%) while in rat serum with high density lipoproteins (40–54%). However, the distribution of B[ a]P between the different lipoprotein fractions showed a high correlation with the concentration of cholesterol for both species. The present results demonstrate a serum uptake capacity of B[ a]P for both species which exceeds B[ a]P and lipoproteins may have implications for the availability of between B[ a]P and lipoproteins may have implications for the availability of B[ a]P for metabolizing organs, an area which should be further investigated. As far as the total serum uptake and distribution of B[ a]P are concerned, the rat seems to be an acceptable animal model for extrapolation of in vivo results to man.