IC50 values of different opioid agonists for inhibition of 0.5 nM [3H]diprenorphine binding in cell membranes expressing MOR or KOR singly, membranes coexpressing MOR-KOR, and mixed membranes expressing only MOR and KOR (MOR + KOR)
Data presented as mean ± S.E.M.; n = 3. Where only partial displacement occurs, the residual tracer binding was subtracted to calculate IC50 values for the displaceable portion of tracer binding.
| Compound | MOR-KOR | MOR + KOR | MOR | KOR |
|---|---|---|---|---|
| nM | ||||
| DAMGO | >3000 | 110 ± 36 | 123 ± 43 | >5000 |
| Endomorphine-1 | >1000 | 109 ± 28 | 116 ± 31 | >2000 |
| U69593 | 191 ± 82 | 137 ± 54 | >1000 | 116 ± 79 |
| U50488H | 70 ± 8 | 54 ± 8 | >1000 | 94 ± 8 |
| GR89696 | 0.6 ± 0.1 | 0.6 ± 0.1 | 29 ± 7 | 0.2 ± 0.1 |