| Abstrakt: |
We have studied the induction of cytochrome P-450b,e-ype antigen and mRNA by phenpbarbital, 4,4'-dichlorobiphenyl and 2,4,5,2',4'.5'-hexacholorobiphenyl in male Wistar rat liver. Chronic treatment of rats with 4,4'-dichlorobiphenyl leads to a relatively slow. 20-fold increase in the cytochrome P-450b,e-type antigen level and to an equivalent increase in the concentration of the corresponding mrNA. Treatment of rats with phenobarbital or 2,45,2',4',5'-hexachlorobiphenyl results in a faster and more pronounced increase of cytochrome P-450b,e-type antigen and mRNA levels. Analysis of clones from cDNA banks showed that two types of sequences are induced by phenobarbital corresponding to cytochrome P-450 b and cytochrome P-450 respectively. 2,4,5,2',4',5'-Hexachlorobiphenyl appears to induce primarily a cytochrome P-450 b-type sequence. The implications off these results for the study of the mechanism of induction are discussed. [ABSTRACT FROM AUTHOR] |
