FIG. 7.

TCDF has a higher apparent binding affinity for guinea pig hepatic cytosolic AhR when incubated prior to [³H]TCDD addition. Simultaneous addition: Guinea pig hepatic cytosol (2 mg/ml) was incubated with 2nM [³H]TCDD in the absence or presence of TCDF at the indicated concentration for 3 h at 20°C. Preincubation: Guinea pig hepatic cytosol (2 mg/ml) was incubated in the absence or presence of the indicated concentration of TCDF for 1 h at 20°C followed by the addition of 2nM [³H]TCDD and further incubation for 2 h. Specific binding of [³H]TCDD was determined by the HAP assay at the indicated times. Data are presented as the mean ± SD of at least triplicate incubations.