Table 1.

Comparison among the number and affinity of μ, δ, and κ opioid receptors in wild-type (+/+) and transgenic mice lacking PLC β3 (−/−)

PLC β3	Kd, nM		Bmax, fmol/mg of protein
	+/+	−/−	+/+	−/−
[3H]DAMGO (μ)	0.49 ± 0.06	0.51 ± 0.01	120 ± 11	110 ± 8.5
[3H]Naltrindole (δ)	0.55 ± 0.02	0.54 ± 0.07	86 ± 0.07	76 ± 1.8
[3H]U69,593 (κ)	0.36 ± 0.04	0.59 ± 0.19	13 ± 0.83	18 ± 3.3

Murine brain membranes were prepared and used in opioid-binding assays. [³]DAMGO, [³H]naltrindole, and [³H]U69,593 saturation binding at concentrations ranging from 0.025 to 3.2 nM was measured in 50 mM Tris⋅HCl, pH 7.5, at 25° as described in Materials and Methods. Data are expressed as mean ± SEM for at least three experiments performed in triplicate.