Figure 1

Dose response curves of inhibition of adenylyl cyclase activity by representative ligands in HEK-κ cells. Varying concentration of 2 full agonists (lofentanil and fentanyl) and one partial agonist (nalbuphine) were used to determine the potency and intrinsic activity of each ligand in inhibiting the effect of 5 μM forskolin in producing cAMP, as described under methods. The 100% on the y-axis corresponds to the cAMP levels in the absence of any drug, i.e.: forskolin alone, for all figures. Data presented are the average from 2 or more experiments carried out in duplicate. Error bars represent standard error of the mean (SEM) of the normalized data. Data have been normalized and SEM calculated as described under methods. (A) Full agonist lofentanil, (B) Full agonist, fentanyl, (C) Partial agonist, nalbuphine.