White H S, Chow S Y, Yen-Chow Y C, Woodbury D M
Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84108.
Can J Physiol Pharmacol. 1992;70 Suppl:S263-8. doi: 10.1139/y92-271.
Potassium is tightly regulated within the extracellular compartment of the brain. Nonetheless, it can increase 3- to 4-fold during periods of intense seizure activity and 10- to 20-fold under certain pathological conditions such as spreading depression. Within the central nervous system, neurons and astrocytes are both affected by shifts in the extracellular concentration of potassium. Elevated potassium can lead to a redistribution of other ions (e.g., calcium, sodium, chloride, hydrogen, etc.) within the cellular compartment of the brain. Small shifts in the extracellular potassium concentration can markedly affect acid-based homeostasis, energy metabolism, and volume regulation of these two brain cells. Since normal neuronal function is tightly coupled to the ability of the surrounding glial cells to regulate ionic shifts within the brain and since both cell types can be affected by shifts in the extracellular potassium, it is important to characterize their individual response to an elevation of this ion. This review describes the results of side-by-side studies conducted on cortical neurons and astrocytes, which assessed the effect of elevated potassium on their resting membrane potential, intracellular volume, and their intracellular concentration of potassium, sodium, and chloride. The results obtained from these studies suggest that there exists a marked cellular heterogeneity between neurons and astrocytes in their response to an elevation in the extracellular potassium concentration.
钾在脑的细胞外间隙中受到严格调控。尽管如此，在剧烈的癫痫活动期间，它可增加3至4倍，而在某些病理状况下，如扩散性抑制时，可增加10至20倍。在中枢神经系统中，神经元和星形胶质细胞都会受到细胞外钾浓度变化的影响。钾浓度升高可导致脑内细胞内其他离子（如钙、钠、氯、氢等）的重新分布。细胞外钾浓度的微小变化可显著影响这两种脑细胞的酸碱平衡、能量代谢和体积调节。由于正常的神经元功能与周围神经胶质细胞调节脑内离子变化的能力紧密相关，且这两种细胞类型都会受到细胞外钾变化的影响，因此表征它们对该离子升高的个体反应非常重要。本综述描述了对皮质神经元和星形胶质细胞进行的并行研究结果，这些研究评估了钾浓度升高对它们静息膜电位、细胞内体积以及细胞内钾、钠和氯浓度的影响。从这些研究中获得的结果表明，神经元和星形胶质细胞在对细胞外钾浓度升高的反应方面存在明显的细胞异质性。
