Cytochrome P450-specific monooxygenase activities after various treatments (mean ± S.D.)
Control (untreated cells), RIF (rifampicin-treated cells), TCDD (dioxin-treated cells), and S 16020 (S 16020-treated cells) results are compared. The enzyme activities (see Materials and Methods) reflecting more specifically P450 proteins (isoform) were normalized with respect to the maximum attained in each culture in response to prototypical inducers RIF and TCDD, taken as 100.
Activity | Isoform | Control | 25 μM RIF | 1 nM TCDD | 2 μM S 16020 |
|---|---|---|---|---|---|
| Ethoxyresorufin O-deethylasea | CYP1A1/2 | 1.3 ± 0.7 | 1.2 ± 0.5 | 100 | 72 ± 48 |
| Acetanilide 4-hydroxylase | CYP1A2 | 1.9 ± 2.5 | 3.3 ± 3.0 | 100 | 110 ± 13 |
| S-Mephenytoin N-demethylase | CYP2B6 | 18 ± 7 | 100 | 29 ± 13 | 33 ± 19 |
| Tolbutamide 4-hydroxylase | CYP2C9 | 18 ± 6 | 100 | 30 ± 7 | 29 ± 2 |
| S-Mephenytoin 4-hydroxylase | CYP2C19 | 7 ± 6 | 100 | 11 ± 9 | 9 ± 6 |
| Chlorzoxazone 6-hydroxylase | CYP2E1 | 16 ± 5 | 26 ± 10 | 100 | 127 ± 3 |
| CYP1A1 | |||||
| Cyclosporin A oxidasea | CYP3A4 | 17 ± 15 | 100 | 16 ± 13 | 17 ± 18 |
↵ a Mean of three preparations of primary hepatocytes from three different donors.