Fig. 4.

Inhibition of acetylcholine-induced intracellular calcium response by mecamylamine, d-tubocurarine, bupropion or TMPH in HEK293 cell lines stably expressing human nicotinic acetylcholine receptor subtypes α3β4, α3β4α5D or α3β4α5N. Cells were stimulated with 1 mM acetylcholine in the presence of 10 mM Ca²⁺. Atropine (200 nM) was added to block muscarinic receptors. TMPH = 2,2,6,6-tetramethylpiperidin-4-yl heptanoate. n = 10–12. Results are given as means of normalized response ± SEM. Curves are normalized to the response at 0 μM of antagonist within each cell line.