Uptake, release and metabolism of glutamate and aspartate by rat cerebellar subcellular preparations.

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.