Table 4

Scatchard analysis of net agonist-stimulated [³⁵S]GTPγS binding to rat thalamus, SK-N-SH, and mMOR-CHO membranes

Membrane	Agonist	K_D	B_max
		nm	pmol/mg
Rat thalamus	DAMGO	1.47 ± 0.08^4-a	7.11 ± 0.43^4-a
	Fentanyl	1.96 ± 0.21^4-a	5.94 ± 0.55^4-a
	Morphine	2.17 ± 0.11^4-a ^4-b	5.05 ± 0.33^4-a ^4-b
	Buprenorphine	4.98 ± 0.54^4-b	2.93 ± 0.37^4-b
SK-N-SH cells	DAMGO	7.22 ± 0.55^4-a	1.43 ± 0.14^4-a
	Fentanyl	5.71 ± 0.35^4-a	1.04 ± 0.10^4-a ^4-b
	Morphine	7.16 ± 0.32^4-a	1.17 ± 0.08^4-a
	Buprenorphine	10.3 ± 1.4^4-b	0.61 ± 0.09^4-b
mMOR-CHO cells	DAMGO	1.20 ± 0.07^4-a ^4-c	3.54 ± 0.31^4-c
	Fentanyl	1.32 ± 0.15^4-a ^4-c	2.80 ± 0.30
	Morphine	1.32 ± 0.10^4-a ^4-c	3.97 ± 0.35^4-c
	Buprenorphine	2.63 ± 0.19^4-b ^4-c	3.14 ± 0.23
	Levallorphan	5.40 ± 0.75^4-a ^4-c	2.29 ± 0.24^4-b

Membranes were incubated with 0.1 nm[³⁵S]GTPγS, 50 μm (rat thalamus), 30 μm (SK-N-SH), or 10 μm (mMOR-CHO) GDP and 0.01–50 nm GTPγS in the presence and absence of opioid agonists (concentrations shown in legend to Fig. 5). Data are mean ± standard error of K_D andB _max values from Scatchard analysis of net agonist-stimulated [³⁵S]GTPγS binding.

N.A., not applicable.
↵4-a p < 0.05, different from buprenorphine.
↵4-b p < 0.05, different from DAMGO.
↵4-c p < 0.05, different from levallorphan.