Fig. 8.

Effects of varying extracellular calcium (Panel A) and absence of sodium (Panel B) on ACh-induced intracellular calcium response in HEK293 cell lines stably expressing human α3β4, α3β4α5D or α3β4α5N. The cells were stimulated with 1 mM acetylcholine in the presence of varying Ca²⁺ and Na⁺ concentrations. Atropine (200 nM) was included in the assay mix to block muscarinic receptors. Panel A: Ca²⁺ concentration effect: F_{7, 227} = 116.2, p < 0.001; subtype effect: F_{2, 227} = 11.08, p < 0.001; concentration × subtype interaction: F_{14, 227} = 2.095, p < 0.05; Bonferroni post hoc comparisons: α3β4 vs. α3β4α5N p < 0.001, α3β4α5D vs. α3β4α5N p < 0.05. Panel B: subtype effect: F_{2, 41} = 35.73, p < 0.001. ** = p < 0.01, *** = p < 0.001, α3β4 vs. α3β4α5N, ^# = p < 0.05, ^### = p < 0.001 α3β4α5D vs. α3β4α5N. n = 12–14. Results are given as means of normalized response ± SEM. Data is normalized to the average maximal response of α3β4 subtype to 1 mM ACh in the presence of 10 mM Ca²⁺.