期刊
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
卷 454, 期 2, 页码 245-252出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00424-007-0207-5
关键词
glia; glutamate; [Ca2+](i); [Na+](i); glutamate transporter; sodium-calcium exchanger; neuronal-glial interactions
类别
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.
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