Table 1.

EC₅₀ values for agonist-induced stimulation of intracellular calcium response and IC₅₀ values for antagonist-induced inhibition of acetylcholine-induced intracellular calcium response in HEK293 cells stably expressing human α3β4, α3β4α5D or α3β4α5N nicotinic acetylcholine receptor subtypes. Stimulation was performed in the presence of 10 mM Ca²⁺.

Compound	n		α3β4	α3β4α5D	α3β4α5N
Agonists
Nicotine	8	EC50 (μM)	198 ± 26	149 ±11	531 ± 251#
		Rmax %	88 ±5	36 ± 5**	29 ± 3***
Acetylcholine	6	EC50 (μM)	112 ± 28	89 ± 31	53 ± 21
		Rmax %	100 ± 10	73 ± 23	24 ± 6*
Varenicline	12	EC50 (μM)	24 ± 12	10 ± 2	36 ±26
		Rmax %	110 ± 9	69 ±4*	32 ± 5***
Antagonists
Mecamylamine	12	IC50 (μM)	1.18 ± 0.17	0.62 ± 0.09	0.44 ± 0.09**
D-Tubocurarine	12	IC50 (μM)	1.01 ± 0.24	0.94 ± 0.21	0.64 ± 0.15
Bupropion	12	IC50 (μM)	0.67 ± 0.07	0.52 ± 0.07	0.38 ± 0.09*
TMPH	12	IC50 (μM)	0.83 ± 0.10	0.36 ± 0.02***	0.45 ± 0.04*
Desensitization
Nicotine	10	IC50 (μM)	0.7 ± 0.2	1.9 ± 0.7	0.8 ± 0.3

Results of the statistical tests: Kruskal–Wallis tests for EC₅₀, IC₅₀ and R _max values: nicotine EC₅₀ H = 8.405; p < 0.05, R_max H = 15.77; p < 0.001; acetylcholine EC₅₀ H = 2.558, p > 0.05, R_max H = 7.797, p < 0.05; varenicline EC₅₀ H = 0.4230; p > 0.05, R_max H = 23.42; p < 0.001; mecamylamine IC₅₀ H = 12.53; p < 0.01; d-tubocurarine IC₅₀ H = 1.891; p > 0.05; bupropion IC₅₀ H = 6.444; p < 0.05; TMPH IC₅₀ H = 14.77; p < 0.001; nicotine desensitization IC₅₀ H = 4.025; p > 0.05.

^*p < 0.05,

^**p < 0.01,

^***p < 0.001 α3β4 vs. α3β4α5D or α3β4α5N;

^#p < 0.05 α3β4α5D vs. α3β4α5N. Data are given as means ± SEM.