TABLE 1

Binding parameters of δ- or μ-OR in the presence or absence of the δ-i3L minigene

The specific binding of varying concentrations of [³H]diprenorphine (0.1–16 nM) [³H]DADLE (0.2–6 nM), and [³H]DAMGO (0.1–6 nM) was measured in membranes of HEK293 cells expressing the δ- or the μ-ORs after transient transfection with either empty vector (pcDNA3) or the minigene δ-i3L expression construct. Nonspecific binding was assessed in the presence of 10 μM naloxone.

Receptor Type	Expressed Plasmid	[³H]DADLE Binding			[³H]DAMGO Binding			[³H]Diprenorphine Binding
Receptor Type	Expressed Plasmid			K_d	B_max	K_d	B_max	K_d	B_max
		nM	pmol/mg	nM	pmol/mg	nM	pmol/mg
δ-OR	pcDNA3	2.1 ± 0.9	0.4 ± 0.18			0.83 ± 0.3	2.02 ± 0.2
δ-OR	δ-i3L	2.0 ± 0.4	0.25 ± 0.02			0.92 ± 0.2	2.15 ± 0.6
μ-OR	pcDNA3			1.6 ± 0.3	0.9 ± 0.2	2.3 ± 0.3	5.48 ± 1.4
μ-OR	δ i3L			1.4 ± 0.2	0.6 ± 0.15	3.27 ± 0.8	5.82 ± 1.3