Table 1. Receptor affinity data for morphine.

Receptors	Hot Ligand	Source	Tissue	Ki(nM)	IC50(nM)	Reference
KOR	3H-U69,593	GUINEA PIG	ILEUM	217±49		PDSP; [17]
	3H-U69,593	Human	cloned	134±22		PDSP; [18]
	[Dmt]DALDA	Human	cloned	4.4±1.7		[19]
	DMAGO	Human	cloned	213±28		[19]
	[3H]U69593	rat	Brain	113±9		PDSP; [20]
				50		average human
MOR	3H-DAMGO	GUINEA PIG	ILEUM	1±0.04		PDSP; [17]
	3H-Diprenorphine	Human	cloned	2.06±0.48		PDSP; [18]
	3H-Dmt-DALDA	mouse	Brain	5.64±0.24		PDSP; [19]
	[Dmt]DALDA	human	cloned	0.172±0.026		[19]
	DMAGO	human	cloned	1.180±0.120		[19]
	[3H]DAMGO	rat	Brain	6.55±0.74		PDSP; [20]
			HEK-μ cells	2.2±0.5		[21]
	[3H]DAMGO	human	BE(2)-C memberanes	1.02±0.15		PDSP; [22]
		bovine	adrenals	1.86		[23]
				0.81		average human
DOR	3H-DSLET	MOUSE	vas deferens	32.6±3.7		PDSP; [17]
	3H-Naltrindole	Human	cloned	>10,000		PDSP; [18]
	[Dmt]DALDA	human	cloned	1670±40		[19]
	DMAGO	human	cloned	1430±20		[19]
	[3H][Ile5,6]deltorphin II	rat	Brain	217±19		PDSP; [20]
				278±49		[24]
	[3H]DPDPE	human	BE(2)-C memberanes	>100		PDSP; [22]
	[3H]enkephalin	rat	memberane		69.1±3.2	[25]
		bovine	adrenals	147.32		[23]
				1545		average human

Receptor affinity data for morphine collected from the literature. The columns identify the receptor, the radioligand used in determining affinity, the source species from which the receptor was used, the tissue from which the receptor was used, the K_i value in nanomoles or the IC50 (the molar concentration of an unlabeled agonist or antagonist that inhibits the binding of a radioligand by 50%, [26]) value in nanomoles, and the literature reference from which the data was obtained.