| Autor: |
Barry, J., Vincendon, G., Gombos, G. |
| Zdroj: |
Neurochemical Research; Oct1983, Vol. 8 Issue 10, p1321-1335, 15p |
| Abstrakt: |
Using very low concentrations (1 μmol range) of l-2-3-[H]glutamate, (H-Glu) or l-2-3-[H]glutamine (H-Gln), we have previously shown by autoradiography that these amino acids were preferentially taken up in the molecular layer of the cerebellar cortex. Furthermore, the accumulation ofH-Glu was essentially glial in these conditions. We report here experiments in which uptake and metabolism of either (H-Glu) or (H-Gln) were studied in adult rat cerebellar slices. Both amino acids were rapidly converted into other metabolic compounds: after seven minutes of incubation in the presence of exogenousH-Glu, 70% of the tissue accumulated radioactivity was found to be in compounds other than glutamate. The main metabolites were Gln (42%), α-ketoglutarate (25%) and GABA (1,4%). In the presence of exogenousH-Gln the rate of metabolism was slightly slower (50% after seven minutes of incubation) and the metabolites were also Glu (29%), α-ketoglutarate (15%) and GABA (5%). Using depolarizing conditions (56 mM KCl) with either exogenousH-Glu orH-Gln, the radioactivity was preferentially accumulated in glutamate compared to control. From these results we conclude: i) there are two cellular compartments for the neurotransmission-glutamate-glutamine cycle; one is glial, the other neuronal; ii) these two cellular compartments contain both Gln and Glu; iii) transmitter glutamate is always in equilibrium with the so-called 'metabolic' pool of glutamate; iv) the regulation of the glutamate-glutamine cycle occurs at least at two different levels: the uptake of glutamate and the enzymatic activity of the neuronal glutaminase. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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