Fig. 4. Inhibition of the nicotine-induced current by halogenated compounds in rat medial habenula neurons. Neurons were held at −60 mV, and 30 μm nicotine was applied for 2.5 s before (left column ) and after (right column ) coapplication with the halogenated agents, as indicated by a continuous line. Neurons were preincubated with the agents for 1 min before coapplication (middle column ), as indicated by a broken line. Isoflurane (top ) and F6 (middle ) reversibly inhibited the nicotine-induced current at an MAC of 0.6 and a predicted MAC of 0.55, while depression by a 0.9 predicted MAC of F8 was minimal (bottom ).