RT Journal Article SR Electronic T1 Cardiac metabolic effects of KNa1.2 channel deletion, and evidence for its mitochondrial localization JF bioRxiv FD Cold Spring Harbor Laboratory SP 223321 DO 10.1101/223321 A1 Charles O. Smith A1 Yves T. Wang A1 Sergiy M Nadtochiy A1 James H. Miller A1 Elizabeth A. Jonas A1 Robert T. Dirksen A1 Keith Nehrke A1 Paul S. Brookes YR 2018 UL http://biorxiv.org/content/early/2018/01/23/223321.abstract AB Controversy surrounds the molecular identity of mitochondrial K+ channels that are important for protection against cardiac ischemia-reperfusion injury. While KNa1.2 (Kcnt2 gene) is necessary for cardioprotection by volatile anesthetics, electrophysiologic evidence for a channel of this type in mitochondria is lacking. The endogenous physiologic role of a potential mito-KNa1.2 channel is also unclear. Herein, single channel patch-clamp of 27 independent cardiac mitochondrial inner membrane (mitoplast) preparations from wild type (WT) mice yielded 6 channels matching the known ion-sensitivity, ion-selectivity, pharmacology and conductance properties of KNa1.2 (slope conductance 138±1 pS). However, similar experiments on 40 preparations from Kcnt2-/- mice yielded zero such channels. The KNa opener bithionol uncoupled respiration in WT but not Kcnt2-/- cardiomyocytes. Furthermore, when oxidizing only fat as substrate, Kcnt2-/- cardiomyocytes and hearts were less responsive to increases in energetic demand. Kcnt2-/- mice also had elevated body fat, but no baseline differences in the cardiac metabolome. These data support the existence of a cardiac mitochondrial KNa1.2 channel, and a role for cardiac KNa1.2 in regulating metabolism under conditions of high energetic demand.Non-standard abbreviationsIR injuryIschemia-Reperfusion injuryIPCIschemic PreconditioningAPCAnesthetic PreconditioningKNaSodium activated potassium channelKNa1.1(channel encoded by Kcnt1 (formerly Slo2.2)), aka Slack, KCa4.1, SLO2.2KNa1.2(channel encoded by Kcnt2 (formerly Slo2.1)), aka Slick, KCa4.2, SLO2.1BTBithionol, aka Bis(2-hydroxy-3,5-dichlorophenyl)SulfideOCROxygen consumption rateROSReactive oxygen species