Relative affinities and potencies of various μ- and δ-opioid receptor agonists for DOR-1 and MOR-1 stably expressed in CHO cells
| Ligands | DOR-1 | MOR-1 | ||||
|---|---|---|---|---|---|---|
| Ki | IC50 | IC50 | Ki | IC50 | IC50 | |
| nM | nM | Ki | nM | nM | Ki | |
| Etorphine | 6.0 ± 1.3 | 0.68 ± 0.05 | 0.11 | 0.31 ± 0.04 | 1.1 ± 0.2 | 3.5 |
| DPDPE | 2.9 ± 0.41 | 0.26 ± 0.09 | 0.09 | 160 ± 63 | 2600 ± 140 | 16 |
| Deltorphin II | 5.5 ± 1.9 | 0.39 ± 0.05 | 0.07 | >10,000 | >10,000 | |
| NTB | 0.81 ± 0.14 | 0.54 ± 0.12 | 0.66 | 12 ± 1.3 | 21 ± 4.3 | 1.7 |
| TIPPψ | 1.9 ± 0.37 | 0.85 ± 0.08 | 0.45 | >10,000 | >10,000 | |
| Oxymorphone | 250 ± 93 | 5.6 ± 0.8 | 0.02 | 0.82 ± 0.24 | 19 ± 9.2 | 23 |
| DAMGO | 2900 ± 550 | 700 ± 70 | 0.24 | 1.6 ± 0.35 | 4.5 ± 0.6 | 2.8 |
| PL017 | >10,000 | >10,000 | 6.2 ± 1.4 | 12 ± 4.8 | 1.9 | |
| Naloxone | 130 ± 28 | 59 ± 15 | 0.45 | 3.5 ± 0.44 | 3.6 ± 0.5 | 1.0 |
| CTOP | >10,000 | >10,000 | 0.96 ± 0.31 | 44 ± 26 | 46 | |
Relative affinities of various opioid agonists in CHO cells stably expressing DOR-1 or MOR-1 were determined by competition binding studies using [3H]diprenorphine as radioactive ligand. IC50 values of ligands were obtained from computer analysis of competition curves using Sigma Plot (Jandel, San Rafael, CA).K i values were then calculated using the Cheng-Prusoff equation. Relative potencies were determined by ability of various concentrations of agonists to inhibit 10 μM forskolin-stimulated [3H]cAMP production in CHO cells stably expressing DOR-1 or MOR-1. IC50 values ± S.E. were obtained from computer analysis of dose-response curves using Sigma Plot.