Inhalational anesthetics activate two-pore-domain background K+ channels

Volatile anesthetics produce safe, reversible unconsciousness, amnesia and analgesia via hyperpolarization of mammalian neurons. In molluscan pacemake r neurons, they activate an inhibitory synaptic K+ current (I-KAn), propose d to be important in general anesthesia. Here we show that TASK and TREK-1, two recently cloned mammalian two-P-domain K+ channels similar to I-KAn in biophysical properties, are activated by volatile general anesthetics. Chl oroform, diethyl ether, halothane and isoflurane activated TREK-1, whereas only halothane and isoflurane activated TASK. Carboxy (C)-terminal regions were critical for anesthetic activation in both channels. Thus both TREK-1 and TASK are possibly important target sites for these agents.