Table 3. Stimulation of [³⁵S]GTPγS Binding^a.

	μ receptor		δ receptor		κ receptor
compd	EC50 (nM)	% stimb	EC50 (nM)	% stimc	EC50 (nM)	% stimd
17	0.69 ± 0.10	34.7 ± 6.6	0.69 ± 0.29	26.1 ± 3.0	1.28 ± 0.35	28.2 ± 1.0
18	1.06 ± 0.28	24.2 ± 3.0	4.24 ± 0.47	34.7 ± 0.6	11.0 ± 1.4	30.4 ± 3.3
morphine	15.6 ± 0.5	93 ± 2.8	316 ± 5	103 ± 7	484 ± 213	62 ± 7

^aMembranes from CHO cells stably transfected with human μ, δ, or κ opioid receptors were incubated with varying concentrations of the compounds.

^bCompared to DAMGO.

^cCompared to DPDPE.

^dCompared to U69,593. Data represent mean ± SEM.