Figure 1

Dose response curves of inhibition of adenylyl cyclase activity by representative ligands in HEK-μ cells. Varying concentration of opioid ligands were used to determine the potency and efficacy of each ligand in inhibiting the effect of 5 μM forskolin in producing cAMP, as described under methods. Maximal cAMP levels were in the range of 400–1000 pmole/well. The 100% on the x-axis corresponds to the cAMP levels in the absence of any drug, i.e.: forskolin alone for all figures including Fig. 1D. Data presented are the average data from 2 or more experiments carried out in duplicate. Data have been normalized as described under methods. Error bars represent standard error of the mean of the normalized data. (A) Xorphanol, (B) Fentanyl, (C) Nalbuphine and (D) Naltrexone.