Table 1.
Inhibitory concentrations 50% (IC50) ± SE of receptorphin competition on different opioid sites, assayed by displacement binding of a variety of opioid ligands.
| Opioid Source | DPDPE or DSLET | DAGO | EKC | Diprenorphin | EKC +DADLE | Diprenorphin +DADLE |
| MCF7 | 3.25 ± 0.42 × 10-9 | 1.43 ± 0.20 × 10-10 | 6.65 ± 1.01 × 10-11 | 5.78 ± 0.64 × 10-13 | 1.59 ± 0.14 × 10-10 | >10-12 |
| T47D | ND | ND | 5.14 ± 0.74 × 10-10 | >10-12 | 5.41 ± 0.57 × 10-11 | >10-12 |
| DU145 | ND | 6.52 ± 0.58 × 10-11 | 2.34 ± 0.55 × 10-11 | ND | 2.87 ± 0.22 × 10-11 | ND |
| PC3 | ND | 4.30 ± 0.97 × 10-11 | >10-6 | ND | >10-6 | ND |
| Rat | 8.25 ± 0.81 × 10-8 | 1.81 ± 0.23 × 10-7 | *1.85 ± 0.11 × 10-10 | **5.77 ± 0.87 × 10-10 | - | 1.85 ± 0.43 × 10-10 |
| Brain | 2.65 ± 0.13 × 10-9 |
*[3H]U60-593 was used as a selective kappa1 opioid ligand **Displacement curves were best fitted with a two-site model. See text for details. IC50s (in Moles/L) were calculated by sigmoidal fitting of displacement experiments. ND = not detected. Mean ± SE of three different experiments performed in duplicate.