After receiving saline, 10 mg/kg chlorisondamine, 5 mg/kg intraperitoneal mecamylamine, or 1 mg/kg nicotine injection, male and female 129J mice were tested for isoflurane supramaximal stimulus (MAC). There was no significant difference in the MAC concentration of isoflurane with any antagonist. Nicotine treatment caused a small decrease in MAC. Isoflurane MAC was also tested in the nicotinic β2 knockout mice and generation-matched wild-type controls. Data are mean ± SE.