TABLE 2.
Intrinsic activities and potencies of opioids for receptor-G protein coupling
Data are derived from concentration response curve measured in membranes and are calculated and presented as in Table 1. enk, enkephalins; DAGO, [d-Ala2,N-Me-Phe4, glycinol5]-enkephalins.
| Ligands | DOPR/Gβ1 |
MOPR/Gβ1 |
||||
|---|---|---|---|---|---|---|
| Emax (±S.E.) | Log EC50 (±S.E.) | n | Emax (±S.E.) | Log EC50 (±S.E.) | n | |
| Bremazocine | 0.51 (0.07) | −7.9 (0.08) | 3 | 0.22 (0.01) | −9.4 (0.15) | 5 |
| Buprenorphine | 0.14 (0.10) | −8.8 (0.21) | 3 | 0.65 (0.06) | −8.8 (0.14) | 4 |
| DAGO | 0.72a (0.04) | −5.3a (0.13) | 3 | 0.91 (0.07) | −7.5 (0.07) | 5 |
| [d-Ala2]-deltorphin | 1.03 (0.03) | −7.7 (0.07) | 3 | 1.02a (0.02) | −5.3a (0.14) | 4 |
| Dermorphin | 0.98a (0.06) | −5.5a (0.34) | 3 | 0.97 (0.06) | −8.2 (0.15) | 3 |
| Diprenorphine | 0.60 (0.07) | −8.6 (0.08) | 4 | 0.18 (0.04) | −8.7 (0.26) | 6 |
| [d-Pen2,d-Pen5]-enk | 1.01 (0.02) | −7.5 (0.14) | 3 | 0.98a (0.02) | −5.7a (0.05) | 3 |
| Ethylketocyclazocine | 0.75 (0.10) | −7.5 (0.05) | 3 | 0.65 (0.01) | −8.5 (0.12) | 3 |
| Endomorphine 2 | NM | >−3 | 2 | 1.05 (0.04) | −7.3 (0.11) | 5 |
| Etorphine | 0.94 (0.07) | −7.7 (0.10) | 3 | 0.97 (0.01) | −9.4 (0.10) | 4 |
| Fentanyl | 0.99 (0.06) | −5.5 (0.12) | 3 | 0.98 (0.03) | −8.0 (0.06) | 3 |
| Lofentanyl | 0.99 (0.03) | −8.3 (0.03) | 4 | 1.11 (0.02) | −9.5 (0.13) | 4 |
| Meperidine | 1 | −3.5 (0.1)(b) | 2 | 0.86 (0.03) | −5.6 (0.17) | 3 |
| Met-enkephalins | 1.03 (0.12) | −7.4 (0.10) | 3 | 1.04 (0.08) | −7.4 (0.12) | 3 |
| Morphiceptin | 0.95a (0.05) | −3.0a (0.36) | 2 | 0.93 (0.042) | −5.9 (0.02) | 3 |
| Morphine | 0.75 (0.05) | −5.7 (0.17) | 3 | 0.73 (0.10) | −7.8 (0.23) | 3 |
| Oxymorphone | 0.87 (0.03) | −5.7 (0.05) | 3 | 0.94 (0.02) | −8.1 (0.11) | 4 |
| SNC-121 | 1.10 (0.05) | −6.9 (0.14) | 3 | NM | >−3 | 2 |
| UFP-512 | 0.60 (0.05) | −8.9 (0.13) | 4 | 0.59 (0.05) | −7.4 (0.05) | 5 |
| [d-Ala2,d-leu5]-enk | 1 | −7.5 (0.04) | 19 | 1 | −7.3 (0.06) | 24 |
a Values were extrapolated from data fitting but were not well defined experimentally because the curve did not reach a full upper asymptote.