Laboratory of Neurobiology, Kazan Federal University, Kazan 420008, Russia.
Department of Physiology, Kazan State Medical University, Kazan 420012, Russia.
Int J Mol Sci. 2023 Jun 28;24(13):10769. doi: 10.3390/ijms241310769.
Brain ischemia induces slow voltage shifts in the cerebral cortex, including waves of spreading depolarization (SD) and negative ultraslow potentials (NUPs), which are considered as brain injury markers. However, different electrode materials and locations yield variable SD and NUP features. Here, we compared terminal cortical events during isoflurane or sevoflurane euthanasia using intracortical linear iridium electrode arrays and Ag/AgCl-based electrodes in the rat somatosensory cortex. Inhalation of anesthetics caused respiratory arrest, associated with hyperpolarization and followed by SD and NUP on both Ir and Ag electrodes. Ag-NUPs were bell shaped and waned within half an hour after death. Ir-NUPs were biphasic, with the early fast phase corresponding to Ag-NUP, and the late absent on Ag electrodes, phase of a progressive depolarizing voltage shift reaching -100 mV by two hours after death. In addition, late Ir-NUPs were more ample in the deep layers than at the cortical surface. Thus, intracortical Ag and Ir electrodes reliably assess early manifestations of terminal brain injury including hyperpolarization, SD and the early phase of NUP, while the late, giant amplitude phase of NUP, which is present only on Ir electrodes, is probably related to the sensitivity of Ir electrodes to a yet unidentified factor related to brain death.
脑缺血会在大脑皮层引起缓慢的电压变化，包括扩布性去极化（SD）波和负超慢电位（NUPs），这些被认为是脑损伤的标志物。然而，不同的电极材料和位置会产生不同的 SD 和 NUP 特征。在这里，我们比较了使用皮层内线性铱电极阵列和基于 Ag/AgCl 的电极在大鼠体感皮层中异氟烷或七氟烷安乐死期间的终末皮层事件。麻醉剂的吸入会导致呼吸停止，伴随着超极化，随后在 Ir 和 Ag 电极上出现 SD 和 NUP。Ag-NUP 呈钟形，在死亡后半小时内逐渐减弱。Ir-NUP 呈双相性，早期快速相对应于 Ag-NUP，而晚期在 Ag 电极上消失，在死亡后两小时内，逐渐去极化电压变化的晚期相达到-100 mV。此外，晚期 Ir-NUP 在深层比在皮层表面更为丰富。因此，皮层内 Ag 和 Ir 电极可靠地评估终末脑损伤的早期表现，包括去极化和 NUP 的早期相，而晚期、幅度较大的 NUP 相只存在于 Ir 电极上，可能与 Ir 电极对与脑死亡相关的未知因素的敏感性有关。
