In vivo release from cerebral cortex of [14C]glutamate synthesized from [U-14C]glutamine.
Awake, unrestrained, and behaviourally normal animals with superfusion cannulae implanted over the sensorimotor cortex were used in a study of the capacity of infused [U-14C]glutamine for labelling glutamate and other amino acids released by depolarising stimuli. A spontaneous background release of [14C]glutamate was detected. This was increased by tityustoxin (1 microM). The specific radioactivity of glutamate increased eightfold during the evoked-release period. [14C]Aspartate was also detected and showed increased release, but not increased specific labelling, in response to depolarisation. Evoked gamma-aminobutyric acid (GABA) release occurred but only small amounts of [14C]GABA were detected. Glutamine showed increased rates of uptake to the sensorimotor cortex during stimulation periods, suggesting an accelerated breakdown via glutaminase.
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D005971:Glutamates / Q000096:biosynthesis*; D018698:Glutamic Acid; D005973:Glutamine / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012604:Scorpion Venoms / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D005971:Glutamates; D012604:Scorpion Venoms; D005973:Glutamine; D001224:Aspartic Acid; C003609:tityustoxin; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid