Tanaka E, Niiyama S, Sato S, Yamada A, Higashi H
Departments of Physiology, Cognitive and Molecular Research Institute of Brain Disease, Kurume University School of Medicine, Kurume 830-0011 Japan.
J Neurophysiol. 2003 Nov;90(5):3213-23. doi: 10.1152/jn.00542.2003. Epub 2003 Aug 13.
Intracellular recordings were made from hippocampal CA1 neurons in rat slice preparations. Superfusion with oxygen- and glucose-deprived medium (in vitro ischemia) produced a rapid depolarization approximately 5 min after the onset of the superfusion. Even when oxygen and glucose were reintroduced immediately after rapid depolarization, the membrane depolarized further (persistent depolarization) and reached 0 mV (irreversible depolarization) after 5 min from the reintroduction. The pretreatment of the slice preparation with a phospholipase A2 (PLA2) inhibitor, para-bromophenacyl bromide, or a cytochrome p-450 inhibitor, 17-octadecynoic acid, significantly restored the membrane to the preexposure potential level after the reintroduction of oxygen and glucose. The administration of 14,15-epoxyeicosatrienoic acid or 20-hydroxyeicosatetraenoic acid did not change the latency of the rapid depolarization and did not allow the membrane potential to recover after the ischemic exposure. In contrast, after pretreatment with cyclooxygenase or lipoxygenase inhibitors, such as indomethacin, resveratrol, Dup-697, nordihydroguaiaretic acid, and 3,4-dihydrophenyl ethanol, a minority of neurons tested showed postischemic recovery from the persistent depolarization. Improved recovery was also seen after treatment with the free radical scavengers, edaravone and alpha-tocopherol. These results suggest that the activation of the arachidonic acid cascade via PLA2 and the free radicals produced by arachidonic acid metabolism contribute to the irreversible depolarization produced by in vitro ischemia.
在大鼠脑片制备中，从海马CA1神经元进行细胞内记录。用缺氧缺糖培养基（体外缺血）灌注，在灌注开始后约5分钟产生快速去极化。即使在快速去极化后立即重新引入氧气和葡萄糖，膜仍进一步去极化（持续性去极化），并在重新引入后5分钟达到0 mV（不可逆去极化）。用磷脂酶A2（PLA2）抑制剂对溴苯甲酰溴或细胞色素p-450抑制剂17-十八炔酸预处理脑片制备，在重新引入氧气和葡萄糖后，膜电位显著恢复到暴露前水平。给予14,15-环氧二十碳三烯酸或20-羟基二十碳四烯酸不会改变快速去极化的潜伏期，并且在缺血暴露后膜电位无法恢复。相反，在用环氧化酶或脂氧化酶抑制剂（如吲哚美辛、白藜芦醇、Dup-697、去甲二氢愈创木酸和3,4-二氢苯乙醇）预处理后，少数测试神经元显示出从持续性去极化中缺血后恢复。在用自由基清除剂依达拉奉和α-生育酚治疗后也观察到恢复改善。这些结果表明，通过PLA2激活花生四烯酸级联反应以及花生四烯酸代谢产生的自由基，有助于体外缺血产生的不可逆去极化。
