Fig. 3. Effects of ketamine on the acetylcholine concentration–response curves of human neuronal nicotinic acetylcholine receptors. The concentration–response relations of the α³β⁴and α⁴β⁴channels for acetylcholine before and during perfusion of 10 μM ketamine were examined. The agonist concentration for half-maximal response (EC⁵⁰) values of the α³β⁴channel for acetylcholine before and during treatment with ketamine were 132 ± 26 and 138 ± 33 μM, and Hill coefficient values of those were 2.2 ± 0.3 and 2.6 ± 1.2, respectively (n = 6). The EC⁵⁰values of the α⁴β⁴channel for acetylcholine before and during treatment with ketamine were 42 ± 4 and 43 ± 4 μM, and Hill coefficient values of those were 2.3 ± 0.3 and 2.6 ± 0.7, respectively (n = 4).