TABLE 1.
Intrinsic activities (Emax) and potencies (log EC50, m) of opioids for receptor-arrestin interactions
Concentration-response curves were analyzed as described under “Experimental Procedures.” Emax values were expressed and averaged as fraction of the Emax of DADLE, which was present in every experiment. Data are the means (±S.E.) of the indicated number of experiments (n). NM, not measurable; enk, enkephalins; DAGO, [d-Ala2,N-Me-Phe4, glycinol5]-enkephalins.
| Ligands | DOPR/βarr2 |
MOPR/βarr2 |
||||
|---|---|---|---|---|---|---|
| Emax (±S.E.) | Log EC50 (±S.E.) | n | Emax (±S.E.) | Log EC50 (±S.E.) | n | |
| Bremazocine | 0.01 (0.02) | NM | 3 | <0.01 | NM | 2 |
| Buprenorphine | 0.013 (0.06) | NM | 3 | 0.023 (0.01) | −7.2 (0.14) | 3 |
| DAGO | 0.8 (0.1)a | −3.2 (0.3)a | 3 | 0.89 (0.06) | −6.7 (0.08) | 13 |
| [d-Ala2]-deltorphin | 1.07 (0.02) | −7.5 (0.32) | 3 | 0.95 (0.05)a | −4.1 (0.2)a | 3 |
| Dermorphin | 0.97 (0.02) | −4.2 (0.10) | 3 | 0.93 (0.02) | −7.5 (0.06) | 6 |
| Diprenorphine | 0.14 (0.09) | −7.9 (0.19) | 5 | 0.012 (0.002) | NM | 3 |
| [d-Pen2,d-Pen5]-enk | 0.97 (0.04) | −7.6 (0.27) | 3 | 0.71a | −3.1 (0.6)a | 3 |
| Ethylketocyclazocine | 0.12 (0.03) | −6.0 (0.17) | 3 | 0.05 (0.02) | −7.8 (0.14) | 3 |
| Endomorphine 2 | NM | >−3 | 2 | 0.94 (0.04) | −7.3 (0.33) | 8 |
| Etorphine | 0.74 (0.07) | −6.8 (0.25) | 4 | 0.95 (0.02) | −8.5 (0.11) | 5 |
| Fentanyl | 0.01 (0.06) | NM | 3 | 0.77 (0.10) | −6.6 (0.18) | 3 |
| Lofentanyl | 0.78 (0.02) | −7.0 (0.13) | 3 | 1.06 (0.04) | −8.4 (0.08) | 7 |
| Meperidine | 0.013 | NM | 2 | 0.41 (0.2)a | −3.2 (0.31)a | 3 |
| Met-enkephalins | 1.05 | −7.1 | 1 | 1.08 | −6.4 | 1 |
| Morphiceptin | <0.01 | NM | 2 | 0.68 (0.07) | −5.0 (0.21) | 5 |
| Morphine | 0.08 (0.04) | NM | 3 | 0.24 (0.02) | −6.4 (0.08) | 6 |
| Oxymorphone | 0.09 (0.03) | −5.3 (0.46) | 3 | 0.20 (0.02) | −6.8 (0.09) | 8 |
| SNC-121 | 0.96 (0.09) | −5.3 (0.29) | 6 | NM | >−3 | 2 |
| UFP-512 | 0.27 (0.02) | −9.0 (0.15) | 3 | <0.01 | NM | 2 |
| [d-Ala2,d-Leu5]-enk | 1 | −7.6 (0.1) | 17 | 1 | −6.5 (0.08) | 21 |
a Values were extrapolated from data fitting but were not well defined experimentally because the curve did not reach a full upper asymptote.