Kinetic characteristics of the glutamate uptake into normal astrocytes in cultures
Kinetic characteristics of the glutamate uptake into normal astrocytes in cultures
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DOI：
10.1007/bf00964356
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发表时间：
1978-02
影响因子：
4.4
通讯作者：
L. Hertz;A. Schousboe;N. Boechler;S. Mukerji;S. Fedoroff
中科院分区：
文献类型：
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作者：
L. Hertz;A. Schousboe;N. Boechler;S. Mukerji;S. Fedoroff
在正常，即，从新生DBA小鼠脑半球分离的皮质富集的浅表部分获得的培养物中的非转化星形胶质细胞。吸收动力学表明，一个次要的，不饱和的成分，以及强烈的吸收后，米氏动力学。Km（50 μM）与脑切片和其他神经胶质制备物中的相应值相当。然而，Vmax（58.8 nmol min− 1 mg − 1 protein）远高于在神经胶质细胞系或外周卫星细胞中观察到的值，也远高于通常报道的脑切片。谷氨酸的释放远远小于吸收，只有很少的外部谷氨酸浓度的增加的影响，这表明净积累的谷氨酸，而不是homoexchange。这种谷氨酸在正常星形胶质细胞中的强烈积累可能在脑代谢中起主要作用，并可能有助于保持细胞外谷氨酸浓度低于兴奋水平。
Kinetics for uptake and release of glutamate were measured in normal, i.e., nontransformed, astrocytes in cultures obtained from the dissociated, cortexenriched superficial parts of the brain hemispheres of newborn DBA mice. The uptake kinetics indicated a minor, unsaturable component together with an intense uptake following Michaelis-Menten kinetics. TheKm(50 μM) was reasonably comparable to the corresponding values in brain slices and in other glial preparations. TheVmax(58.8 nmol min−1mg−1protein) was, however, much higher than that observed in glial cell lines or peripheral satellite cells, and also considerably higher than that generally reported for brain slices. The release of glutamate was much smaller than the uptake, and only little affected by an increase of the external glutamate concentration, suggesting a net accumulation of glutamate rather than a homoexchange. Such an intense accumulation of glutamate into normal astrocytes may play a major role in brain metabolism and may help keep the extracellular glutamate cohcentration below excitatory levels.