Kinetics of 2-oxoglutarate uptake by synaptosomes from bovine and rat retina and cerebral cortex and regulation by glutamate and glutamine.

2-Oxoglutarate (2-OG) is a metabolic precursor of glutamate and may be utilized to replenish the neurotransmitter pool. 2-OG is rapidly transported into neurons by a high-affinity carrier that is particularly prevalent in glutamatergic terminals. Here we report the kinetics of [U-14C]2-OG uptake by crude synaptosomal preparations from bovine and rat retina and brain, and the modulatory effects of glutamate and glutamine. In all four tissues, 2-OG uptake was mediated by a high-affinity system (Kt approximately 1 microM) that was subject to negative feedback control by glutamate and biphasic modulation by glutamine (another precursor of neurotransmitter glutamate).