TY - JOUR
T1 - TREK-1 and TREK-2 knockout mice are not resistant to halothane or isoflurane
AU - Spencer, Kira A.
AU - Woods, Christian B.
AU - Worstman, Hailey M.
AU - Johnson, Simon
AU - Ramirez, Jan-Marino
AU - Morgan, Philip G.
AU - Sedensky, Margaret M.
N1 - Funding information: MMS, JMR, SJ, KAS, and CW were supported in part by NIH grant R01GM105696 and by continued support from the Northwest Mitochondrial Research Guild. KAS was supported in part by T32 GM086270. PGM, CW were supported in part by NIH grant R35GM139566.
PY - 2023/4/7
Y1 - 2023/4/7
N2 - Background. A variety of molecular targets for volatile anesthetics have been suggested including the anesthetic-sensitive K+ leak channel, TREK-1. Knockout of TREK-1 is reported to render mice resistant to volatile anesthetics, making TREK-1 channels compelling targets for anesthetic action. Spinal cord slices from mice, either wildtype or an anesthetic-hypersensitive mutant, Ndufs4, display an isoflurane-induced outward K+ leak that correlates with their minimum alveolar concentrations (MAC) and is blocked by norfluoxetine. We hypothesized that TREK-1 channels conveyed this current and contribute to the anesthetic hypersensitivity of Ndufs4. Our results led to evaluation of a second TREK channel, TREK-2, in control of anesthetic sensitivity. Methods. We measured anesthetic sensitivities of mice carrying knockout alleles of Trek-1 and Trek-2, the double knockout Trek-1;Trek-2, and Ndufs4;Trek-1. Neurons from spinal cord slices from each mutant were patch clamped to characterize isoflurane-sensitive currents. Norfluoxetine was used to identify TREK-dependent currents. Results. We compared mean values for MAC (+/- SD) between wildtype and two Trek-1 knockout alleles in mice (p-values, Trek-1 compared to wildtype). Wildtype: (MAC(Hal), 1.30%(0.10); MAC(Iso), 1.40%(0.11): Trek-1tm1Lex (MAC(Hal), 1.27%(0.11); p=0.387; MAC(Iso), 1.38%(0.09); p=0.268): Trek-1tm1Lzd (MAC(Hal); 1.27%(0.11); p=0.482: MAC(Iso); 1.41%(0.12); p=0.188). Neither allele was resistant for loss of righting reflex. The EC50s of Ndufs4;Trek-1tm1Lex did not differ from Ndufs4. Ndufs4: (EC50(Hal), 0.65%(0.05); EC50 (Iso), 0.63%(0.05): Ndufs4;Trek-1tm1Lex (EC50(Hal), 0.58%(0.07); p=0.004; EC50(Iso); 0.61%(.06); p=0.442). Loss of TREK-2 did not alter anesthetic sensitivity in a wildtype or Trek-1 genetic background. Loss of TREK-1 or TREK-2, or both, did not alter the isoflurane-induced currents in wildtype cells but did cause them to be norfluoxetine-insensitive. Conclusions. Loss of TREK channels did not alter anesthetic sensitivity in mice, nor did it eliminate isoflurane-induced transmembrane currents. However, the isoflurane-induced currents are norfluoxetine-resistant in Trek mutants indicating that other channels may function in this role when TREK channels are deleted.
AB - Background. A variety of molecular targets for volatile anesthetics have been suggested including the anesthetic-sensitive K+ leak channel, TREK-1. Knockout of TREK-1 is reported to render mice resistant to volatile anesthetics, making TREK-1 channels compelling targets for anesthetic action. Spinal cord slices from mice, either wildtype or an anesthetic-hypersensitive mutant, Ndufs4, display an isoflurane-induced outward K+ leak that correlates with their minimum alveolar concentrations (MAC) and is blocked by norfluoxetine. We hypothesized that TREK-1 channels conveyed this current and contribute to the anesthetic hypersensitivity of Ndufs4. Our results led to evaluation of a second TREK channel, TREK-2, in control of anesthetic sensitivity. Methods. We measured anesthetic sensitivities of mice carrying knockout alleles of Trek-1 and Trek-2, the double knockout Trek-1;Trek-2, and Ndufs4;Trek-1. Neurons from spinal cord slices from each mutant were patch clamped to characterize isoflurane-sensitive currents. Norfluoxetine was used to identify TREK-dependent currents. Results. We compared mean values for MAC (+/- SD) between wildtype and two Trek-1 knockout alleles in mice (p-values, Trek-1 compared to wildtype). Wildtype: (MAC(Hal), 1.30%(0.10); MAC(Iso), 1.40%(0.11): Trek-1tm1Lex (MAC(Hal), 1.27%(0.11); p=0.387; MAC(Iso), 1.38%(0.09); p=0.268): Trek-1tm1Lzd (MAC(Hal); 1.27%(0.11); p=0.482: MAC(Iso); 1.41%(0.12); p=0.188). Neither allele was resistant for loss of righting reflex. The EC50s of Ndufs4;Trek-1tm1Lex did not differ from Ndufs4. Ndufs4: (EC50(Hal), 0.65%(0.05); EC50 (Iso), 0.63%(0.05): Ndufs4;Trek-1tm1Lex (EC50(Hal), 0.58%(0.07); p=0.004; EC50(Iso); 0.61%(.06); p=0.442). Loss of TREK-2 did not alter anesthetic sensitivity in a wildtype or Trek-1 genetic background. Loss of TREK-1 or TREK-2, or both, did not alter the isoflurane-induced currents in wildtype cells but did cause them to be norfluoxetine-insensitive. Conclusions. Loss of TREK channels did not alter anesthetic sensitivity in mice, nor did it eliminate isoflurane-induced transmembrane currents. However, the isoflurane-induced currents are norfluoxetine-resistant in Trek mutants indicating that other channels may function in this role when TREK channels are deleted.
U2 - 10.1097/aln.0000000000004577
DO - 10.1097/aln.0000000000004577
M3 - Article
JO - Anesthesiology
JF - Anesthesiology
SN - 0003-3022
ER -