Table 2

Activation of the human PXR by metyrapone, rifampicin, and dexamethasone

TreatmentFold (ER6)3-tk-CAT versus Control
Rifampicin (20 μM)3.0  ± 0.552-a
Rifampicin (20 μM), no PXR plasmid1.1  ± 0.60
Metyrapone (10 μM)1.5  ± 1.41
Metyrapone (100 μM)3.3  ± 0.292-a
Metyrapone (500 μM)9.7  ± 3.052-a
Dexamethasone (100 μM)5.1  ± 1.832-a

CV-1 cells transiently cotransfected with an expression vector pSG5-hPXRΔATG and a CAT reporter construct (ER6)3-tk-CAT were treated with inducers from stocks prepared in dimethyl sulfoxide at a concentration 1000-fold of that required in the medium. Controls were treated with 0.1% (v/v) dimethyl sulfoxide. After 24 h, cells were harvested, extracts were prepared by freeze-thaw, and normalized CAT activities were determined. No PXR plasmid: transfection control, cells transfected with reporter plasmid but not with the PXR expression plasmid.

  • 2-a Significantly different-fold induction versus control using Student's t test (two-tailed), P > 95%.