Preferential glutamine uptake in rat brain synaptic mitochondria.
Glutamine uptake has been studied in purified rat brain mitochondria of synaptic or non-synaptic origin. It was taken up by an active saturable transport mechanism, with an affinity two-times higher in synaptic than in non-synaptic mitochondria (Km = 0.45 and 0.94 mM, respectively). Vmax of uptake was 7-times higher in synaptic mitochondria (Vmax = 9.2 and 1.3 nmol/min per mg protein, respectively). Glutamine transport was found to be inhibited by L-glutamate (IC50 = 0.64 mM) as well as thiol reagents (mersalyl, N-ethylmaleimide). It is suggested that differential uptake of glutamine in mitochondria of synaptic or non-synaptic origin may be a major mechanism in the regulation of the synthesis of the neurotransmitter glutamate.
D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D005973:Glutamine / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013569:Synapses / Q000378:metabolism*; D014316:Tritium
D005971:Glutamates; D013439:Sulfhydryl Reagents; D005973:Glutamine; D014316:Tritium; D018698:Glutamic Acid