Postnatal development of ionic currents in rat hippocampal astrocytes in situ
Postnatal development of ionic currents in rat hippocampal astrocytes in situ
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DOI：
10.1152/jn.1997.78.1.461
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发表时间：
1997-07-01
影响因子：
2.5
通讯作者：
Sontheimer, H
中科院分区：
文献类型：
--
作者：
Bordey, A;Sontheimer, H
用全细胞膜片钳记录技术研究了大鼠[生后5~P50天]海马片上神经胶质细胞离子通道表达和细胞形态的发育性变化。从CA1区放射层和腔隙分子层中的234个细胞中获得了记录，推测是胶质细胞。在66个充满荧光黄的记录细胞中，48个细胞的胶质纤维酸性蛋白染色阳性，这表明它们是星形胶质细胞。所有研究的神经胶质细胞都是星状的形态，发育变化主要包括细胞突起的长度和数量的增加，与细胞大小和膜电容的总体增加有关。可识别两种不同的外向钾电流：对四乙基铵(i-d)i-a敏感的瞬时外向钾电流(i-a)和对四乙基铵(i-d)i-a敏感的外向钾电流(i-a)，其稳态激活和失活中点分别为-16和-74 mV。衰减时间常数在-30 mV时为7ms，+80 mV时为19ms。I-d在-30 mV时激活。对铯敏感的第三个K+电流被超极化指令电压激活，并表现出强烈的内向整流。电压激活的瞬时钠电流对河豚毒素敏感(100 NM)，在-40 mV左右被激活，在-10 mV左右达到峰值，在+63 mV时逆转。MV.I-Na在-49 mV时半失活，在-19 mV时半激活。在出生后2周内，呈现内向整流钾电流(I-r)、I-a和I-Na的细胞百分比从P5时的40%显著增加到P20-P50时的90%。相比之下，几乎所有与年龄无关的细胞在P5和P20之间表达i-d比电导i-r(g(Ir))和i-a显著增加，伴随着输入电阻的降低。相反，外向整流钾电流的比电导(g(D))在P5和P20之间下降了三倍。比Na+电导一直是
Developmental changes in ion channel expression and cell morphology were studied in glial cells with the use of whole cell patch-clamp recordings in rat [postnatal day (P)5-P50] hippocampal slices. Recordings were obtained from 234 cells, presumed to be glia, in stratum radiatum and stratum lacunosum-moleculare of the CA1 region. Of 66 recorded cells filled with Lucifer yellow, 48 stained positive for glial fibrillary acidic protein, which identified them as astrocytes. All glial cells studied were of a stellate morphology, and developmental changes primarily comprised an increase in the length and number of cell processes associated with an overall increase in cell size and membrane capacitance. Two distinct outward potassium currents could be identified: a transient 4-aminopyridine-sensitive current (I-a) and a persistent outward current sensitive to tetraethylammonium (I-d) I-a activated at -40 mV, and steady state activation and inactivation midpoints were -16 and -74 mV, respectively. Decay time constants ranged from 7 ms at -30 mV to 19 ms at +80 mV. I-d activated at -30 mV. A third K+ current sensitive to cesium activated with hyperpolarizing command voltages and showed strong inward rectification. Transient, voltage-activated sodium currents (I-Na) were tetrodotoxin sensitive (100 nM) and activated at about -40 mV, peaked at about -10 mV, and reversed at +63 mV. mV. I-Na was half-inactivated at -49 mV and half-activated at -19 mV. During the first 2 wk of postnatal development, the percentage of cells showing inwardly rectifying K+ current (I-r), I-a and I-Na increased significantly from 40% (at P5) to 90% (at P20-P50). By contrast, almost all cells independent of age expressed I-d Specific conductances for I-r (g(ir)) and I-a increased significantly between P5 and P20, concomitant with a decrease in input resistance. By contrast, specific conductance of the outwardly rectifying K+ current (g(d)) decreased threefold between P5 and P20. Specific Na+ conductance was always