Table 1

Activation Profiles of Opioid ligands in HEK-μ Cells

Agonist
IC50 ± SEM (nM)
Max Inhibition (%)

β-Endorphin
526 ± 105
71 ± 5
Butorphanol
3 ± 2
58 ± 5
Cyclazocine
21 ± 8
37 ± 2**##
DAMGO
35 ± 9
58 ± 5
Dezocine
1.3 ± 0.6
43 ± 2**##
Etorphine
0.6 ± 0.3
60 ± 6
Fentanyl
8.4 ± 1.6
69 ± 4⊕
Hydromorphone
0.8 ± 0.1
67 ± 4⊕
Lofentanil
3.8 ± 2.0
56 ± 6
Metazocine
2.0 ± 0.1
41 ± 4**##
Morphine
17 ± 8
48 ± 4*##
Nalbuphine
11 ± 2
49 ± 4*##
Nalorphine
2.7 ± 1.4
50 ± 2#
Xorphanol
3.4 ± 1.7
29 ± 2** ⊕⊕##
Naltrexone
Antagonist

SKF 10047
Antagonist

WIN 44,441
Antagonist


Inhibitory effect of opioid ligands on Forskolin-stimulated adenylyl cyclase activity was measured as described under "Materials and Methods". Data for IC50's represent the mean ± SEM obtained from two or more experiments carried out in duplicate. Maximum inhibition data represent the mean ± SEM obtained from the best fit curve for data from three to four experiments carried out in duplicate. (** = P < 0.001, * = P < 0.05; compared to fentanyl), (⊕⊕ = P < 0.001, P, ⊕ = P < 0.05 compared to morphine), (## = P < 0.001, # = P < 0.05; compared to β-endorphin).

Gharagozlou et al. BMC Pharmacology 2003 3:1   doi:10.1186/1471-2210-3-1