Figure 4-6 Certain molluscan neurons having endogenous firing activity are extremely sensitive to volatile agents. The figure shows a continuous intracellular recording of membrane potential before, during (bar), and after exposure of a sensitive cell to normal saline solution containing halothane at a partial pressure of 0.0080 atm. (From Franks NP, Lieb WR: Volatile general anaesthetics activate a novel neuronal K⁺ current. Nature 333:662, 1988.)