The TASK Family: Two-Pore Domain Background K+ Channels

Locus coeruleus neurons express TASK channel transcripts and a pH- and anesthetic-sensitive open-rectifier K⁺ channel. A. Darkfield photomicrograph of emulsion-dipped sections hybridized with a [³³P]-labeled cRNA probe specific to TASK1 (left) and TASK-3 (right) show high density of silver grains overlaying neurons in the nucleus locus coeruleus (LC) (see arrows). B. Halothane (0.3 mM) caused a membrane hyperpolarization that was completely reversed by bath acidification C. (Left) Voltage clamp recording of net membrane current in a locus coeruleus cell held at 60 mV. An acidified bath solution (pH 6.5) induced an inward shift in current and completely blocked a halothane-evoked outward current shift. (Right) Averaged data (± SEM, n=4) showing the IV relationship of the joint pH- and halothane-sensitive current in locus coeruleus neurons; this current was well fitted by using the GHK constant field equation (adapted from 44).