Table 2.

Opioid receptor affinities and efficacies of arodyn (1) and its N-terminal substituted analogs

X-NMePhe-Phe-R-Arg-Leu-Arg-Arg-D-Ala-Arg-Pro-Lys-NH₂^a

Peptide	X	R	Ki ± SEM (nM)		Ki ratio (μ/κ)	AC % control @ 10 μMb
			κ	μ
1, arodyn c	Acd	Phe	10.0 ± 3.0	1750 ± 130	175	88 ± 8
2 e	Ac	Phe	4.56 ± 0.45	5056 ± 790	1100	86 ± 1
5	CH3OCO	Phe	4.93 ± 0.15	1750 ± 100	355	74 ± 13
6	C6H5OCH2CO	Phe	7.34 ± 1.37	1450 ± 190	198	98 ± 21
7	Gly	Phe	28.9 ± 7.5	3070 ± 130	106	75 ± 8
8	Ac-Gly	Phe	8.04 ± 3.14	>10,000	>1240	82 ± 17
3	Ac	Trp	13.0 ± 2.6	2990 ± 700	230	105 ± 16
4	Acd	Trp	16.1 ± 2.1	1180 ± 290	73	108 ± 5
9	CH3OCO	Trp	9.52 ± 1.73	1280 ± 280	134	98 ± 13
10	C6H5OCH2CO	Trp	13.3 ± 3.6	1250 ± 140	94	> 90
11	Gly	Trp	15.4 ± 4.2	502 ± 145	33	90 ± 8
12	Ac-Gly	Trp	21.9 ± 4.8	3760 ± 910	172	83 ± 7

^aThe values are the mean ± SEM from at least three independent experiments.

^bRelative to the full agonist Dyn A (1-13)NH₂ (0% control, 100% inhibition).

^cFrom reference ²⁸.

^dPhe instead of NMePhe in position 1.

^eFrom reference ³⁰.