Fig. 5. Effect of ethanol on the internalization of δ opioid receptors. Cells were pretreated with buffer alone (A ) or ethanol (B ) for 30 min at 37°C. The kinetics of internalization of the epitope-tagged receptor on incubation with 100 nm DPDPE was conducted by flow cytometry as described in Materials and Methods. Results are the mean ± SD of triplicate determinations from three independent experiments; values that represent significant differences from control values (in the absence of ethanol) are indicated. **P < 0.01 (Dunnett test).