Anesthesiology. 2021 Jun 1;134(6):901-914. doi: 10.1097/ALN.0000000000003794.
Ndufs4 knockout (KO) mice are defective in mitochondrial complex I function and hypersensitive to inhibition of spinal cord-mediated response to noxious stimuli by volatile anesthetics. It was hypothesized that, compared to wild-type, synaptic or intrinsic neuronal function is hypersensitive to isoflurane in spinal cord slices from knockout mice.
Neurons from slices of the vestibular nucleus, central medial thalamus, and spinal cord from wild-type and the global Ndufs4 knockout were patch clamped. Unstimulated synaptic and intrinsic neuronal characteristics were measured in response to isoflurane. Norfluoxetine was used to block TREK channel conductance. Cholinergic cells were labeled with tdTomato.
All values are reported as means and 95% CIs. Spontaneous synaptic activities were not different between the mutant and control. Isoflurane (0.6%; 0.25 mM; Ndufs4[KO] EC95) increased the holding current in knockout (ΔHolding current, 126 pA [95% CI, 99 to 152 pA]; ΔHolding current P < 0.001; n = 21) but not wild-type (ΔHolding current, 2 7 pA [95% CI, 9 to 47 pA]; ΔHolding current, P = 0.030; n = 25) spinal cord slices. Knockout and wild-type ΔHolding currents were significantly different (P < 0.001). Changes comparable to those in the knockout were seen in the wild type only in 1.8% (0.74 mM) isoflurane (ΔHolding current, 72 pA [95% CI, 43 to 97 pA]; ΔHolding current, P < 0.001; n = 13), the control EC95. Blockade of action potentials indicated that the increased holding current in the knockout was not dependent on synaptic input (ΔHolding current, 154 pA [95% CI, 99 to 232 pA]; ΔHolding current, P = 0.506 compared to knockout without blockade; n = 6). Noncholinergic neurons mediated the increase in holding current sensitivity in Ndufs4 knockout. The increased currents were blocked by norfluoxetine.
Isoflurane increased an outwardly rectifying potassium current in ventral horn neurons of the Ndufs4(KO) mouse at a concentration much lower than in controls. Noncholinergic neurons in the spinal cord ventral horn mediated the effect. Presynaptic functions in Ndufs4(KO) slices were not hypersensitive to isoflurane. These data link anesthetic sensitivity, mitochondrial function, and postsynaptic channel activity.
Ndufs4 敲除（KO）小鼠在线粒体复合物 I 功能上存在缺陷，并且对挥发性麻醉剂抑制脊髓介导的伤害性刺激反应高度敏感。据推测，与野生型相比，突触或内在神经元功能对脊髓切片中的异氟醚更为敏感。
对来自野生型和全局 Ndufs4KO 的前庭神经核、中央中脑和脊髓切片中的神经元进行膜片钳记录。在异氟醚作用下，测量未受刺激的突触和内在神经元特征。使用 norfluoxetine 阻断 TREK 通道电导。用 tdTomato 标记胆碱能细胞。
所有值均以平均值和 95%置信区间（CI）表示。突变体和对照组之间的自发突触活动没有差异。异氟醚（0.6%；0.25 mM；Ndufs4[KO]EC95）增加了 KO 中的保持电流（ΔHolding current，126 pA[95%CI，99 至 152 pA]；ΔHolding current，P<0.001；n=21），但不增加野生型（ΔHolding current，27 pA[95%CI，9 至 47 pA]；ΔHolding current，P=0.030；n=25）脊髓切片中的电流。KO 和野生型的ΔHolding current 有显著差异（P<0.001）。只有在 1.8%（0.74 mM）异氟醚（ΔHolding current，72 pA[95%CI，43 至 97 pA]；ΔHolding current，P<0.001；n=13）中，野生型才会出现与 KO 中类似的变化，这是对照 EC95。阻断动作电位表明，KO 中保持电流的增加不依赖于突触输入（ΔHolding current，154 pA[95%CI，99 至 232 pA]；ΔHolding current，与未阻断时的 KO 相比，P=0.506；n=6）。非胆碱能神经元介导了 Ndufs4KO 中保持电流敏感性的增加。增加的电流被 norfluoxetine 阻断。
异氟醚在远低于对照组的浓度下增加了 Ndufs4（KO）小鼠腹角神经元的外向整流钾电流。脊髓腹角中的非胆碱能神经元介导了这种作用。Ndufs4（KO）切片中的突触前功能对异氟醚不敏感。这些数据将麻醉敏感性、线粒体功能和突触后通道活性联系起来。
