EC50 values of different opioid agonists in stimulation of [35S]GTPγS binding in membranes from MOR and KOR singly expressing or MOR-KOR coexpressing cells as well as in mixtures of MOR and KOR membranes (MOR + KOR)
Data are mean ± S.E.M.; n = 3. Emax values did not differ significantly among different membrane preparations.
| Compound | MOR-KOR | MOR + KOR | MOR | KOR |
|---|---|---|---|---|
| nM | ||||
| DAMGO | 268 ± 65* | 68 ± 8 | 77 ± 8 | 2438 ± 65 |
| Endomorphin-1 | 377 ± 73* | 108 ± 8 | 134 ± 19 | 2872 ± 128 |
| U69593 | 0.5 ± 0.1 | 1.6 ± 1 | >1000 | 1.0 ± 1 |
| U58488H | 1.5 ± 1 | 2.8 ± 1 | >1000 | 1.9 ± 1 |
| GR89696 | 6 ± 1 fM | 4 ± 1 fM | >1 | 4 ± 1 fM |
| Morphine | 122 ± 7 | 232 ± 7 | 187 ± 43 | 160 ± 10 |
| Dynorphin A1-13 | 2.8 ± 1 | 11 ± 1 | 287 ± 63 | 1.8 ± 1.3 |
| Etorphine | 0.9 ± 0.1 | 1.2 ± 1.2 | 0.2 ± 0.3 | 0.9 ± 0.1 |
| Bremazocine | 0.2 ± 0.1 | 0.1 ± 0.2 | 0.1 ± 0.3 | 0.1 ± 0.1 |
↵* P < 0.05, analysis of variance with Dunnett's post test; compared with MOR and MOR + KOR.