Table 2.

Ki values for opioid ligand inhibition of [³H]diprenorphine binding to WT and NY1DD REC membranes

Ligand	Mean ± SEM
	WT		NY1DD
	Ki, nM	Displacement, %*	Ki, nM	Displacement, %*
Morphine	111 ± 11.36	71.69 ± 2.54	42.33 ± 10.17	82.84 ± 3.87
DAMGO	86.37 ± 10.84	82.05 ± 2.61	62.83 ± 12.56	81.98 ± 3.33
Etorphine	8.78 ± 0.46	83.25 ± 3.29	1.74 ± 0.54	90.39 ± 3.37
DPDPE	2214 ± 205.5	12.21 ± 4.98	2808 ± 431.9	8.36 ± 3.18
U50488H	535.55 ± 6.56	6.35 ± 0.62	320.3 ± 70.76	10.48 ± 4.19

From 3 experiments performed in triplicate.

^*Percentage of displacement of [³H]diprenorphine. Nonspecific binding was determined in the presence of 10 μM of naloxone.