THE GLIAL-CELL GLUTAMATE UPTAKE CARRIER COUNTERTRANSPORTS PH-CHANGING ANIONS
THE GLIAL-CELL GLUTAMATE UPTAKE CARRIER COUNTERTRANSPORTS PH-CHANGING ANIONS
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DOI：
10.1038/360471a0
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发表时间：
1992-12-03
期刊：
影响因子：
64.8
通讯作者：
ATTWELL, D
中科院分区：
文献类型：
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作者：
BOUVIER, M;SZATKOWSKI, M;ATTWELL, D
神经胶质细胞的摄取有助于终止谷氨酸的神经递质作用并保持其细胞外浓度Glu低于神经毒性水平。摄取载体的累积能力源于其对无机离子的运输，例如钠（进入细胞）和钾（离开细胞）1-3。关于载体是否也运输质子（或改变 pH 值的阴离子）4,5 存在争议。在这里，我们发现载体在神经胶质细胞外部产生碱化，在神经胶质细胞内部产生酸化，并将阴离子转运出细胞，这表明存在一个载体循环，其中两个Na+伴随每个谷氨酸阴离子进入细胞，同时一个K+和一个OH-（或HCO3-）被转运出细胞。该化学计量预测正常情况下最小Glu为0.6μM（强直性激活突触前自身受体和突触后NMDA受体），在脑缺氧期间为370μM（高到足以杀死神经元）。摄取载体上 OH-/HCO3- 的运输会产生显着的 pH 变化，并可能提供神经元-胶质细胞相互作用的机制。
UPTAKE into glial cells helps to terminate glutamate's neurotransmitter action and to keep its extracellular concentration, [Glu]o, below neurotoxic levels. The accumulative power of the uptake carrier stems from its transport of inorganic ions such as sodium (into the cell) and potassium (out of the cell)1-3. There is controversy over whether the carrier also transports a proton (or pH-changing anion)4,5. Here we show that the carrier generates an alkalinization outside and an acidification inside glial cells, and transports anions out of the cells, suggesting that there is a carrier cycle in which two Na+ accompany each glutamate anion into the cell, while one K+ and one OH- (or HCO3-) are transported out. This stoichiometry predicts a minimum [Glu]o of 0.6 muM normally (tonically activating presynaptic autoreceptors and postsynaptic NMDA receptors), and 370 muM during brain anoxia (high enough to kill neurons). Transport of OH-/HCO3- on the uptake carrier generates significant pH changes, and may provide a mechanism for neuron-glial interaction.