Competition of a fluorescent 5-HT3 receptor competitive antagonist. (A) Competition of 10 nM G-FL with the agonist 5-HT (pIC50 = 6.10 ± 0.03, nH = 2.1, IC50 = 0.79 µM, n = 4) and the competitive antagonist granisetron (pIC50 = 8.42 ± 0.03, nH = 1.1, IC50 = 3.8 nM, n = 6). (B) The test compounds citral (n = 3), eucalyptol (n = 3), and linalool (n = 3) show no competition with G-FL.