Efficacy and potency of BUP and SAM alone and in combination in stimulating [35S]GTPγS binding mediated by the MOR, KOR, and DOR
Data are the mean values ± S.E.M. from three experiments performed in triplicate except where noted. The Emax value is the percentage of maximal stimulation and Imax is the percentage of maximal inhibition.
| Agonist Activity | Antagonist Activity | |||
|---|---|---|---|---|
| EC50 | Emax | IC50 | Imax | |
| nM | % | nM | % | |
| MOR | ||||
| BUP | 0.63 ± 0.40 | 57 ± 5.5 | 0.42 ± 0.014 | 49 ± 2.0 |
| SAM | NA | 3.8 ± 0.67 | 0.73 ± 0.052 | 92 ± 2.4 |
| 1:1 BUP/SAM* | 0.73 ± 0.72 | 32 ± 2.5 | ND | ND |
| 1:5 BUP/SAM | 2.1 ± 0.32 | 16 ± 0.78 | ND | ND |
| 1:50 BUP/SAM | NA | 7.2 ± 0.69 | ND | ND |
| KOR | ||||
| BUP | 0.46 ± 0.14 | 25 ± 1.3 | 0.71 ± 0.18 | 74 ± 0.98 |
| SAM | 1.4 ± 0.095 | 56 ± 0.59 | 15 ± 0.30 | 47 ± 3.3 |
| 1:1 BUP/SAM | 0.74 ± 0.16 | 29 ± 1.8 | ND | ND |
| 1:5 BUP/SAM | 1.2 ± 0.059 | 29 ± 0.19 | ND | ND |
| 1:50 BUP/SAM | 1.1 ± 0.23 | 40 ± 2.2 | ND | ND |
| DOR | ||||
| BUP | 1.3 ± 0.041 | 19 ± 1.2 | 4.2 ± 0.74 | 78 ± 3.6 |
| SAM | 1.9 ± 0.47 | 21 ± 1.6 | 14 ± 2.8 | 72 ± 1.4 |
NA, not applicable; ND, not determined.
↵* n = 2 independent experiments performed in triplicate with mean ± S.D. reported. Total molarity of BUP and SAM in combination was used to calculate the EC50 values.