Membrane currents and cytoplasmic sodium transients generated by glutamate transport in Bergmann glial cells
Membrane currents and cytoplasmic sodium transients generated by glutamate transport in Bergmann glial cells
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DOI：
10.1007/s00424-007-0207-5
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发表时间：
2007-05-01
影响因子：
4.5
通讯作者：
Verkhratsky, Alexei
中科院分区：
文献类型：
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作者：
Kirischuk, Sergei;Kettenmann, Helmut;Verkhratsky, Alexei
应用膜片钳技术结合SBFI钠离子荧光显微镜技术，研究了谷氨酸和红藻氨酸（KA）对小鼠小脑脑片Bergmann胶质细胞的影响。L-谷氨酸（1 mM）和KA（100 μ M）诱导内向电流在Bergmann神经胶质细胞电压钳位在-70 mV。这些电流伴随着细胞内Na+浓度（[Na+]（i））从平均静息水平5.2 +/- 0.5 mM分别增加至26 +/- 5 mM和33 +/- 7 mM。KA诱发信号（1）在6-氰基-7-硝基喹喔啉-2，3-二酮存在下被完全阻断（CNQX，10 μ M），α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）/KA离子型谷氨酸受体的拮抗剂;（2）在0 mV时逆转;（3）在无Na+、含N-甲基-D-葡糖胺（NMDG（+））的溶液中消失，但在无Na+、含Li+的溶液中几乎保持不变。相反，L-谷氨酸诱导的信号（1）对CNQX的敏感性略低（类似于10%抑制），（2）在+20 mV的保持电位下不逆转，（3）被NMDG（+）和Li+取代的Na+显著抑制，（4）被D，L-苏型-β-苄氧基天冬氨酸抑制。此外，D-谷氨酸，L-和D-天冬氨酸也能够诱导Na+依赖性内向电流。平行纤维的刺激触发了对CNQX和MK-801不敏感的内向电流和[ Na+]（i）瞬变;因此，我们认为突触释放的谷氨酸激活Bergmann神经胶质细胞中的谷氨酸/Na+转运蛋白，这导致细胞内Na+浓度大幅增加。
Effects of glutamate and kainate (KA) on Bergmann glial cells were investigated in mouse cerebellar slices using the whole-cell configuration of the patch-clamp technique combined with SBFI-based Na+ microfluorimetry. L-Glutamate ( 1 mM) and KA ( 100 mu M) induced inward currents in Bergmann glial cells voltage-clamped at -70 mV. These currents were accompanied by an increase in intracellular Na+ concentration ([Na+](i)) from the average resting level of 5.2 +/- 0.5 mM to 26 +/- 5 mM and 33 +/- 7 mM, respectively. KA-evoked signals ( 1) were completely blocked in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione( CNQX, 10 mu M), an antagonist of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid(AMPA)/KA ionotropic glutamate receptors; ( 2) reversed at 0 mV, and ( 3) disappeared in Na+-free, N-methyl-D-glucamine (NMDG(+))-containing solution, but remained almost unchanged in Na+-free, Li+-containing solution. Conversely, L-glutamate-induced signals ( 1) were marginally CNQX sensitive (similar to 10% inhibition), ( 2) did not reverse at a holding potential of + 20 mV, ( 3) were markedly suppressed by Na+ substitution with both NMDG(+) and Li+, and ( 4) were inhibited by D, L-threo-beta-benzyloxyaspartate. Further, D-glutamate, L-,and D-aspartate were also able to induce Na+-dependent inward current. Stimulation of parallel fibres triggered inward currents and [ Na+](i) transients that were insensitive to CNQX and MK-801; hence, we suggested that synaptically released glutamate activates glutamate/Na+ transporter in Bergmann glial cells, which produces a substantial increase in intracellular Na+ concentration.