Fig. 1. Effects of anesthetics on 5-hydroxytryptamine (5-HT)–induced currents in the 5-HT³receptor. One percent halothane (A ) and 1% isoflurane (B ) potentiated the 5-HT³receptor, but 1% sevoflurane (C ), 70% N²O (D ), and 70% Xe (E ) reversibly inhibited 1 μm (EC¹⁵: agonist concentration giving 15% of maximal response) 5-HT–induced currents. The horizontal bars indicate the duration of application of the drugs. Anesthetic solutions were preperfused for 30 s before application of an anesthetic-containing 5-HT solution.