TABLE 3.
HEK-α1A-Adr, HEK- α1B-Adr, and HEK- α1D-Adr: effects of fentanyl, carfentanil, morphine, naloxone, and Adr1 agonists and antagonists on [3H]prazosin binding and IP-1 formation
For each receptor, standard agonists and antagonists were tested: Adr1 agonists NE, epinephrine (EPI), and phenylephrine and Adr1 antagonists prazosin and tamulosin.
| Drug | [3H]Prazosin Binding | Drug-Stimulated IP-1 Accumulation | Inhibition of NE-Stimulated IP-1 Accumulation | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Ki (nM) ± S.E.M. (n) | EC50 (nM) ± S.E.M. (n) | IC50 (nM) ± S.E.M. (n) | |||||||
| Hill Slope ±S.E.M. | % Max NE ± S.E.M.a | % Max Inhibition ± S.E.M.b | |||||||
| α1A-Adr | α1B-Adr | α1D-Adr | α1A-Adr | α1B-Adr | Adr1D | α1A-Adr | α1B-Adr | α1D-Adr | |
| Fentanyl | 1407 ± 81 (5) | 1100 ± 250 (3) | 4110 ± 450 (4) | >100 µM (2) | >100 µM (2) | >20 µM (6) | 3660 ± 790 (3) | 3690 ± 300 (3) | 11,900 ± 1600 (3) |
| −1.32 ± 0.05 | −1.51 ± 0.08 | −1.41 ± 0.21 | 0% | <1% | 3.5 ± 2.5% | 100% | 100% | 73 ± 13% | |
| Carfentanil | 418 ± 24 | 828 ± 57 | 2490 ± 530 | >10 µM (5) | >10 µM (2) | >10 µM (2) | 2040 ± 380 (6) | 1030 ± 150 (6) | >10 µM (3) |
| −1.35 ± 0.04 | −1.93 ± 0.31 | −1.54 ± 0.11 | 0% | 0% | 0% | 100% | 99.9 ± 0.1% | 5.7 ± 2.6% | |
| Morphine | >100 µM (2) | >100 µM (2) | >100 µM (2) | >100 µM (2) | >100 µM (2) | >100 µM (4) | >100 µM (2) | >100 µM (2) | >100 µM (2) |
| ND | ND | ND | 0% | <3% | 0% | 16.3% ± 3.7% | <7% | <5% | |
| Naloxone | >100 µM (2) | >100 µM (2) | >100 µM (2) | ||||||
| ND | ND | ND | |||||||
| Norepinephrine | 1580 ± 220 (5) | 1920 ± 490 (3) | 131 ± 40 (5) | 55 ± 12 (3) | 39.7 ± 5.8 (3) | 37.0 ± 5.8 (3) | |||
| −1.01 ± 0.04 | −1.45 ± 0.20 | −0.94 ± 0.15 | 102.8% ± 3.3% | 104.1% ± 3.6% | 95.89% ± 0.63% | ||||
| Epinephrine | 730 ± 140 (3) | 790 ± 150 (3) | 185 ± 22 (3) | 22.7 ± 5.0 (4) | 10.0 ± 2.3 (3) | 32.1 ± 9.8 (3) | |||
| −1.05 ± 0.07 | −1.23 ± 0.05 | −1.06 ± 0.03 | 106.1% ± 1.4% | 100.6% ± 4.7% | 103.0% ± 4.6% | ||||
| Phenylephrine | 4880 ± 410 (5) | 4900 ± 1100 (3) | 1850 ± 230 (3) | 318 ± 13 (3) | 330 ± 110 (4) | 620 ± 140 (4) | |||
| −1.26 ± 0.09 | −1.92 ± 0.39 | −1.11 ± 0.05 | 106.3% ± 1.6% | 95.3% ± 5.9% | 70.1% ± 1.2% | ||||
| Prazosin | 0.134 ± 0.057 (3) | 0.027 ± 0.008 (3) | 0.115 ± 0.037 (4) | 4.02 ± 0.54 (3) | 8.7 ± 2.7 (5) | 0.48 ± 0.12 (3) | |||
| −0.72 ± 0.09 | −0.56 ± 0.04 | −0.51 ± 0.09 | 100% | 100% | 99.06% ± 0.77% | ||||
| Tamsulosin | 0.038 ± 0.013 (3) | 0.769 ± 0.043 (3) | 0.084 ± 0.023 (3) | 1.95 ± 0.85 (4) | 5.04 ± 0.44 (4) | 0.339 ± 0.061 (4) | |||
| −0.96 ± 0.05 | −1.05 ± 0.05 | −0.56 ± 0.07 | 100% | 100% | 100% | ||||
n, number of independent experiments, each conducted with duplicate determinations; ND, not determined.
a
Maximal agonist effects were normalized to the maximal stimulation by 10 µM norepinephrine.
b
Maximal antagonist effects were normalized to the maximal inhibition by 100 nM tamsulosin.