Bordey A, Sontheimer H
Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Glia. 2000 Mar;30(1):27-38. doi: 10.1002/(sici)1098-1136(200003)30:1<27::aid-glia4>3.0.co;2-#.
Patch-clamp recordings were obtained in brain slices from 283 rat astrocytes. The expression of voltage-activated whole-cell currents was compared in four different CNS regions (hippocampus, cerebral cortex, spinal cord, and cerebellum). Our data show that CNS astrocytes do not show significant regional differences in their ion channel complement. With the exception of cerebellar Bergmann glial cells, essentially all astrocytes express a combination of delayed rectifying outward K(+) currents, transient A-type K(+) currents, and small Na(+) currents. Developmentally, an increasing percentage of astrocytes and Bergmann glial cells express inwardly rectifying K(+) currents. We did not observe cells that were passive, i.e., lacking voltage-activated currents. A few cells that appeared "passive" in initial recordings showed voltage-activated K(+) currents after off-line leak subtraction. The heterogeneity observed in the ion channel complement was found to be identical when cell-to-cell variations observed within a given CNS region and between various CNS regions were compared, suggesting a common and fairly stereotypical complement of ion channels in CNS astrocytes. Ion channel expression in Bergmann glial cells differed from that of all other CNS regions studied. These cells typically showed very low input resistances attributable to a significant time- and voltage-independent resting K(+) conductance. However, as with electrophysiologically "passive"-appearing astrocytes, Bergmann glial cells showed expression of delayed rectifying K(+) currents after off-line leak subtraction. Inwardly rectifying K(+) currents were observed in Bergmann glial cells after postnatal day 17. Collectively, our data suggest that all astrocytes contain voltage-gated ion channels that display a common pattern of expression during development.
在取自283只大鼠星形胶质细胞的脑片中进行了膜片钳记录。比较了四个不同中枢神经系统区域（海马体、大脑皮层、脊髓和小脑）中电压激活全细胞电流的表达情况。我们的数据表明，中枢神经系统星形胶质细胞在其离子通道组成上没有显著的区域差异。除了小脑的伯格曼胶质细胞外，基本上所有星形胶质细胞都表达延迟整流外向钾离子电流、瞬时A型钾离子电流和小钠离子电流的组合。在发育过程中，表达内向整流钾离子电流的星形胶质细胞和伯格曼胶质细胞的比例不断增加。我们没有观察到无活性的细胞，即缺乏电压激活电流的细胞。在初始记录中表现为“无活性”的一些细胞在离线减去泄漏电流后显示出电压激活的钾离子电流。当比较给定中枢神经系统区域内和不同中枢神经系统区域之间观察到的细胞间差异时，发现离子通道组成中观察到的异质性是相同的，这表明中枢神经系统星形胶质细胞中离子通道的组成通常且相当刻板。伯格曼胶质细胞中的离子通道表达与所研究的所有其他中枢神经系统区域不同。这些细胞通常表现出非常低的输入电阻，这归因于显著的时间和电压无关的静息钾离子电导。然而，与电生理上“无活性”的星形胶质细胞一样，伯格曼胶质细胞在离线减去泄漏电流后显示出延迟整流钾离子电流的表达。出生后第17天之后在伯格曼胶质细胞中观察到内向整流钾离子电流。总体而言，我们的数据表明，所有星形胶质细胞都含有电压门控离子通道，这些通道在发育过程中呈现出共同的表达模式。
