ALTERATIONS IN THE MICROENVIRONMENT DURING SPREADING DEPRESSION ASSOCIATED WITH EPILEPTIFORM ACTIVITY IN THE IMMATURE NEOCORTEX
ALTERATIONS IN THE MICROENVIRONMENT DURING SPREADING DEPRESSION ASSOCIATED WITH EPILEPTIFORM ACTIVITY IN THE IMMATURE NEOCORTEX
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DOI：
10.1016/0165-3806(89)90288-5
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发表时间：
1989-04-01
期刊：
影响因子：
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通讯作者：
HEINEMANN, U
中科院分区：
文献类型：
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作者：
HABLITZ, JJ;HEINEMANN, U
使用离子敏感微电极在体外维持的成熟（>40天龄）或未成熟（16-30天龄）大鼠新皮质切片中测量细胞外离子浓度的局部变化。重复刺激导致细胞外钾 ([K+]o) 增加至 8.85 .+- 水平。成年动物切片中 2.1 mM，12.77 .+-。未成熟动物切片中的浓度为 1.8 mM。在接触印防己毒素期间，最高水平为 11.3 .+-。 2.6 和 14.8.+-。成熟组和未成熟组分别为2.5 mM。在未成熟动物的切片中，印防己毒素（50μM）诱导自发的重复尖峰爆发，随后产生缓慢的负场电位，与扩散抑制（SD）相关。 [K+]o 水平增加至 10.2 .+-。重复尖峰放电期间为 3.9 mM，达到 30.3 .+-。 SD 期间为 18.5 mM。在 SD 过程中检查了细胞外间隙 (ES) 大小的变化。发现ES可逆地降低了39.+-。 4.5%。重复尖峰簇与[Ca2+]o 0.1-0.2 mM 降低相关，而1.12 .+- 相关。 SD 期间观察到 0.06 mM 降低。 [Na+]o 和 [Cl-]o 减少 56 .+-。 10 mM 和 41.+-。在 SD 期间分别观察到 9 mM，表明在 SD 期间发生了水的净跨膜运动。这些结果表明，未成熟神经系统中与癫痫样活动相关的[K+]o 变化在数量上与成熟大脑中观察到的不同。 [K+]o 的大幅增加可能导致发育中的神经系统中癫痫样放电的延长。
Local changes in extracellular ion concentrations were measured with ion-sensitive microelectrodes in slices of mature (>40 days of age) or immature (16-30 days of age) rat neocortex maintained in vitro. Repetitive stimulation resulted in increases in extracellular potassium ([K+]o) to levels of 8.85 .+-. 2.1 mM in slices form adult animals and 12.77 .+-. 1.8 mM in slices from immature animals. During exposure to picrotoxin, maximum levels were 11.3 .+-. 2.6 and 14.8 .+-. 2.5 mM in the mature and immature groups, respectively. Picrotoxin (50 .mu.M) induced spontaneous bursts of repetitive spiking, following by a slow, negative field potential, associated with spreading depression (SD), in slices from immature animals. [K+]o levels increased to 10.2 .+-. 3.9 mM during repetitive spike discharges and reached 30.3 .+-. 18.5 mM during SDs. Variations in the size of the extracellular space (ES) were examined during SD. The ES was found to reversibly decrease by 39 .+-. 4.5%. Clusters of repetitive spikes were associated with 0.1-0.2 mM decreases in [Ca2+]o, whereas 1.12 .+-. 0.06 mM decreases were observed during SDs. Decreases in [Na+]o and [Cl-]o of 56 .+-. 10 mM and 41 .+-. 9 mM, respectively, were observed during SDs suggesting that a net transmembrane movement of water occurred during SDs. These results indicate that changes in [K+]o associated with epileptiform activity in the immature nervous system are quantitatively different from those observed in the mature brain. These large increases in [K+]o may contribute to the prolonged nature of epileptiform discharges in the developing nervous system.