TABLE 6.
Effects of fentanyl and morphine on recombinant human dopamine D1 and D4.4 receptor function
Assays were run in duplicate with six to seven concentrations of the test compound. The standard agonist dopamine was tested in the agonist experiments, and the antagonists SCH23390 (D1) or haloperidol (D4.4) were tested in the antagonist experiment.
| Drug (Agonists) | C6-D1 EC50 (nM) ± S.E.M. (n) % Max Dopamine ±S.E.M. | C6-D1 IC50 (nM) ± S.E.M. (n) % Max Inhibition of 100 nM Dihydrexidine ± S.E.M. | HEK-D4.4-AC1 EC50 (nM) ± S.E.M. (n) % Max Quinpirole ± S.E.M. | HEK-D4.4-AC1 IC50 (nM) ± S.E.M. (n) % Max Reversal of 100 nM Quinpirole ±S.E.M. |
|---|---|---|---|---|
| Fentanyl | >100 µM (2) | 27,000 ± 5500 (5) | >50 µM (6) (three of six curves could be fit) | 12,700 ± 2500 (4) |
| 0% | 65.5% ± 4.0% | 36% ± 11% | 63% ± 20% | |
| Morphine | >100 µM (2) | >100 µM (2) | >40 µM (5) (three of five curves could be fit) | >100 µM (3) |
| 13% ± 13% | 4.5% ± 4.5% | 20% ± 11% | Minimal effect | |
| Dopamine | 19.5 ± 1.7 | 4.4 ± 1.5 (4) | ||
| 91.6% ± 5.9% | 95.1% ± 1.8% | |||
| Quinpirole | 0.60 ± 0.25 (6) | |||
| 95.4 ± 3.9% | ||||
| SCH23390 | 3.90 ± 0.52 (4) | |||
| 98.36% ± 0.26% | ||||
| Haloperidol | 152 ± 55 (4) | |||
| 117% ± 26% |
n, number of independent experiments, each conducted with duplicate determinations.