TABLE 3.

Radioligand displacement by cytisine, NS3861, and nicotine at α3β2, α3β4, α4β2, and α4β4 nAChRs

Radioligand binding was determined as the potency for displacement of [³H]epibatidine-binding in membrane preparations from HEK293 cell lines stably expressing human nAChRs. Saturation data were fitted using a hyperbolic function assuming a single binding site for [³H]epibatidine (K_d values). K_i values are reported as mean ± S.E.M. in nm, n = 3–4 determinations, each conducted in triplicate.

Compound	Ki
	α3β2	α3β4	α4β2	α4β4
Epibatidine Kd	0.025	0.082	0.012	0.022
Cytisine	8.7 ± 1.3	196 ± 19	0.43 ± 0.09	0.77 ± 0.09
NS3861	25 ± 4	0.62 ± 0.09	55 ± 11	7.8 ± 0.7
Nicotine	23 ± 2	250 ± 12	1.7 ± 0.2	13 ± 1