Table 2.

Bioactivities of the Partially Modified Bifunctional Peptides at the δ and μ Opioid Receptors

					[35S]GTP-γ-S binding
	hDORa [3H]DPDPEb		rMORa [3H]DAMGOc		hDORd			rMORd			IC50,e nM
	log IC50f,g	Ki,h nM	log IC50f,g	Ki,h nM	log EC50f	EC50, nM	Emax,i %	log EC50f	EC50, nM	Emax,i %	MVD(δ)	GPI(μ)
1	−7.03 ± 0.11	45	−7.19 ± 0.30	31	−7.13 ± 0.27	74	100	−6.69 ± 0.11	210	170	24 ± 5	460 ± 130
2	−8.49 ± 0.11	1.4	−8.92 ± 0.06	0.5	−8.02 ± 0.16	9.4	64	−8.02 ± 0.11	96	82	26 ± 5	81 ± 21
3	−8.04 ± 0.11	3.9	−6.88 ± 0.09	56	−7.91 ± 0.36	13	99	−6.76 ± 0.31	17	71	18 ± 4	530 ± 100
4	−8.29 ± 0.12	2.2	−8.10 ± 0.08	3.4	−7.83 ± 0.14	15	64	−8.11 ± 0.14	7.7	82	25 ± 7	76 ± 9
5	−8.86 ± 0.16	0.63	−6.92 ± 0.08	52	−8.23 ± 0.51	5.9	120	−6.20 ± 0.37	630	63	16 ± 2	240 ± 40
6	−8.59 ± 0.18	1.1	−7.54 ± 0.16	13	−7.7 ± 0.18	19	89	−7.13 ± 0.26	75	85	12 ± 2	93 ± 6
7	−7.79 ± 0.09	6.9	−7.10 ± 0.14	34	−8.08 ± 0.07	8.4	93	−8.90 ± 0.18	1.3	106	31 ± 5	210 ± 50
8	−8.78 ± 0.10	0.8	−8.16 ± 0.10	3.0	−7.68 ± 0.19	21	48	−8.73 ± 0.43	1.9	20	15 ± 3	97 ± 9
biphalin					−8.95 ± 0.17	1.1	84				2.7 ± 1.5	8.8 ± 0.3

^aCompetition analyses were carried out using membrane preparations from transfected HN9.10 cells that constitutively expressed the respective receptor types.

^bK_d = 0.50 ± 0.1 nM.

^cK_d = 0.85 ± 0.2 nM.

^dExpressed from CHO cells.

^eConcentration at 50% inhibition of muscle contraction at electrically stimulated isolated tissues.

^fLogarithmic values determined from the nonlinear regression analysis of data collected from at least two independent experiments.

^gCompetition against radiolabeled ligand.

^hAntilogarithmic value of the respective IC₅₀.

ⁱNet total bound/basal binding × 100 ± SEM.