Table 2

K_D and B_max values for net agonist-stimulated [³⁵S]GTPγS binding in mMOR-CHO cell and rat thalamic membranes

Agonist	mMOR-CHO		Rat thalamus
Agonist	K_D	B_max	K_D	B_max
	nM	pmol/mg	nM	pmol/mg
DAMGO†	1.20 ± 0.07^a	3.54 ± 0.31^abc	1.47 ± 0.08^ab	7.11 ± 0.43^ab
Methadone	1.21 ± 0.09^a	3.85 ± 0.39^ab	1.84 ± 0.22^ac	8.37 ± 0.65^a
Fentanyl†	1.32 ± 0.15^a	2.80 ± 0.30^cdef	1.96 ± 0.21^bc	5.94 ± 0.55^bc
Morphine†	1.32 ± 0.10^a	3.97 ± 0.35^a	2.17 ± 0.11^c	5.05 ± 0.33^c
Sufentanil	1.27 ± 0.17^a	2.66 ± 0.30^def	2.07 ± 0.18^c	5.60 ± 0.47^c
Alfentanil	1.49 ± 0.17^a	3.23 ± 0.43^abcd	ND‡	ND
Meperidine	1.92 ± 0.26^ab	2.93 ± 0.30^bcdef	ND	ND
Buprenorphine†	2.63 ± 0.19^b	3.14 ± 0.23^bcde	4.98 ± 0.54	2.93 ± 0.37
Nalorphine	4.10 ± 0.37^c	2.25 ± 0.29^ef	ND	ND
Nalbuphine	3.26 ± 0.31^bc	1.01 ± 0.11	ND	ND
Levallorphan†	5.40 ± 0.75	2.29 ± 0.24^f	ND	ND

Data were obtained from experiments depicted in figure 4. Values containing the same letter designations are not significantly different from each other, whereas those that do not contain any similar letter designations are significantly different (P < .05).

^† B_max and K_Dvalues are from Selley et al. (1997).
^‡ ND, not determined.