Abe K, Saito H
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, The University of Tokyo, Japan.
Biol Pharm Bull. 2000 Sep;23(9):1051-4. doi: 10.1248/bpb.23.1051.
When L-glutamate (150 microM) was added to rat cortical astrocyte cultures and incubated for 1-3 h, the extracellular L-glutamate concentration declined with time. The time-dependent decline of extracellular L-glutamate concentration was due to the uptake of L-glutamate by astrocytes. The clearance of extracellular L-glutamate by astrocytes was partly slowed down by replacing NaCl with choline chloride or LiCl in the extracellular medium or by adding KCI, and was completely blocked by replacing NaCl with KCI. Furthermore, the L-glutamate clearance was blocked by Na+-K+ pump inhibitors, ouabain and vanadate, but was not affected by Na+ channel modulators nor by K+ channel blockers. These results suggest that the clearance of extracellular L-glutamate by astrocytes is dependent on both Na+ and K+ gradients across the plasma membrane, and that the Na+-K+ pump plays a role in the regulation of L-glutamate clearance.
当向大鼠皮质星形胶质细胞培养物中加入L-谷氨酸（150微摩尔）并孵育1 - 3小时时，细胞外L-谷氨酸浓度随时间下降。细胞外L-谷氨酸浓度随时间的下降是由于星形胶质细胞对L-谷氨酸的摄取。通过用氯化胆碱或氯化锂替代细胞外培养基中的氯化钠或添加氯化钾，星形胶质细胞对细胞外L-谷氨酸的清除部分减慢，而用氯化钾替代氯化钠则完全阻断清除。此外，L-谷氨酸的清除被钠钾泵抑制剂哇巴因和钒酸盐阻断，但不受钠通道调节剂和钾通道阻滞剂的影响。这些结果表明，星形胶质细胞对细胞外L-谷氨酸的清除依赖于跨质膜的钠和钾梯度，并且钠钾泵在L-谷氨酸清除的调节中起作用。
