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Table 1 Activation Profiles of Opioid ligands in HEK-μ Cells

From: Activity of opioid ligands in cells expressing cloned mu opioid receptors

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

 
  1. 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).
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BMC Pharmacology

ISSN: 1471-2210