Figure 17.

Effects of microdialysis perfusion of the XII nucleus region with different K⁺ channel blockers in chronically instrumented, behaving rats. (A) Perfusion with a solution containing barium ions, which primarily block the inwardly rectifying (Kir) channels, resulted in GG muscle activity being elevated in all sleep-wake states and attaining the highest levels during wakefulness and REM sleep with muscle twitches (REM₍₊₎). (B) During perfusion with an antagonist of the tandem pore domain (TASK) channels, methanandamide, activation was limited to wakefulness. (C) Perfusion with 4-aminopyridine (4-AP, a blocker of voltage-dependent Kv4 channels) or TEA (a blocker of voltage-dependent Kv2 channels) increased GG activity across all sleep-wake states, with the strongest activation attained during REM sleep with twitches. Collectively, these experiments demonstrate that closure of certain K⁺ channels can elevate GG muscle activity during sleep to, or above, the levels seen during wakefulness. In all panels, integrated GG activity was measured during inspiration within different sleep-wake states using arbitrary units while the XII nucleus region was perfused with a vehicle [artificial cerebrospinal fluid (ACSF) with or without an emulsificant] or with one of the blockers. Symbols in the graphs indicate statistically significant elevation of activity with the blocker when compared to vehicle. (Panels A–C show Figs. 1E, 2B and 3C, respectively, from Ref. 171 and are republished with permission from the American Academy of Sleep Medicine obtained via the Copyright Clearance Center, Inc.)