Fig. 3. Effect of ethanol on [³H]DPDPE saturation binding to δ opioid receptors expressed in N18TG2 cells. (A ) Cells were pretreated with buffer alone for 30 min at 37°C followed by incubation with [³H]DPDPE in the absence (control) or presence of ethanol at 4°C for 16 h. Scatchard analysis of the data is shown (upper right ). (B ) Cells were pretreated with ethanol for 30 min at 37°C followed by incubation with [³H]DPDPE in the presence of ethanol at 4°C for 16 h. Cells not exposed to ethanol throughout the assay were taken as control. Scatchard analysis of the data is shown (lower right ). Results are the mean ± SD of three independent experiments.