Table 6.

Inhibition of Agonist-Stimulated [³⁵S]GTPγS Binding in Cloned Human μ, δ, and κ Opioid Receptors, Importance of the Isopropyl and 7-Hydroxy-d-Tic Groups

compd	Ke (nM)a			μ/κ	δ/κ
	μ, DAMGO	δ, DPDPE	κ, U69,593
34	>3000	>3000	113 ± 21	>27	>27
35	586 ± 130	>3000	5.58 ± 1.6	105	>538
36	>3000	>3000	387 ± 89	>8	>8
37	431 ± 110	>3000	20.5 ± 4.6	21	>146
38	153 ± 37	>3000	11.1 ± 2.9	14	>270
39	569 ± 110	>3000	17.2 ± 5.8	33	>174

^aData are mean ± SEM of at least three independent experiments conducted in duplicate. None of the compounds had agonist activity at 10 μM.