Membrane currents and cytoplasmic sodium transients generated by glutamate transport in Bergmann glial cells

Item Type:	Article
Title:	Membrane currents and cytoplasmic sodium transients generated by glutamate transport in Bergmann glial cells
Creators Name:	Kirischuk, S. and Kettenmann, H. and Verkhratsky, A.
Abstract:	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 muM) 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 muM), 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 ( approximately 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.
Keywords:	Glia, Glutamate, [Ca2+]i, [Na+]I, Glutamate transporter, Sodium-calcium exchanger, Neuronal-glial interactions, Animals, Mice
Source:	Pfluegers Archiv European Journal of Physiology
ISSN:	0031-6768
Publisher:	Springer
Volume:	454
Number:	2
Page Range:	245-252
Date:	May 2007
Official Publication:	https://doi.org/10.1007/s00424-007-0207-5
PubMed:	View item in PubMed

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