Rao V L, Murthy C R
Laboratory of Neurochemistry, Andre-Viallet Clinical Research Center, Hopital Saint-Luc, Montreal, Canada.
Biochem Mol Biol Int. 1993 Mar;29(4):711-7.
Kinetics of uptake and release, rates of oxidation of glutamate and aspartate, activities of the enzymes of glutamate metabolism were studied in the mitochondrial, synaptosomal and cytosolic preparations of rat cerebellum. Transport of these amino acids into mitochondria was by a single low affinity carrier, whereas in synaptosomes both high and low affinity uptake systems were observed. The depolarization induced release of these amino acids from nerve terminals was observed to be calcium dependent. Mitochondria oxidized both these two amino acids at a higher rate than synaptosomes and the oxidation in cytosol was very minimal. Transamination appears to be the major reaction for the metabolism of glutamate and aspartate. Activities of GDH, GLNSE and GABA-T were highest in mitochondria, whereas activities of GS and GAD were highest in cytosol and synaptosomes respectively.
在大鼠小脑的线粒体、突触体和胞质溶胶制剂中，研究了谷氨酸和天冬氨酸的摄取与释放动力学、氧化速率以及谷氨酸代谢酶的活性。这些氨基酸进入线粒体是通过单一的低亲和力载体，而在突触体中则观察到了高亲和力和低亲和力摄取系统。观察到这些氨基酸从神经末梢的去极化诱导释放是钙依赖性的。线粒体氧化这两种氨基酸的速率高于突触体，而胞质溶胶中的氧化非常少。转氨作用似乎是谷氨酸和天冬氨酸代谢的主要反应。谷氨酸脱氢酶、谷氨酰胺合成酶和γ-氨基丁酸转氨酶的活性在线粒体中最高，而谷氨酰胺合成酶和谷氨酸脱羧酶的活性分别在胞质溶胶和突触体中最高。
