Abstract
1. Glutamate uptake into isolated, whole-cell patch-clamped glial cells was studied by monitoring the increase of cell fluorescence generated as glutamate and NAD(P) were converted into alpha-ketoglutarate and NAD(P)H by glutamate dehydrogenase. The current generated by the glutamate uptake carrier was recorded simultaneously. 2. L-Glutamate evoked an increase of cell fluorescence and an inward uptake current. L- and D-aspartate generated an uptake current but no fluorescence response, consistent with the amino acid specificity of glutamate dehydrogenase. 3. In the absence of external sodium the glutamate-evoked fluorescence response and uptake current were abolished, showing that there is no sodium-independent glutamate uptake across the cell membrane. 4. Varying the glutamate concentration altered both the fluorescence response and the uptake current. The fluorescence response saturated at a lower glutamate concentration than the uptake current, and depended in a Michaelis-Menten fashion on the uptake current. 5. The fluorescence response and the uptake current were reduced by membrane depolarization, and also by removal of intracellular potassium. 6. The dependence of the fluorescence response on uptake current when membrane potential was altered or intracellular potassium was removed was the same as that seen when the external glutamate concentration was altered. 7. These fluorescence studies show that glutamate uptake is inhibited by depolarization and by removal of intracellular potassium, consistent with the conclusion of earlier work in which uptake was monitored solely as a membrane current. The data are consistent with high-affinity electrogenic sodium- and potassium-dependent glutamate uptake with fixed stoichiometry being the only significant influx route for glutamate. Other possible interpretations of the data are also discussed.
Full text
PDF
























Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Balcar V. J., Johnston G. A. High affinity uptake of transmitters: studies on the uptake of L-aspartate, GABA, L-glutamate and glycine in cat spinal cord. J Neurochem. 1973 Feb;20(2):529–539. doi: 10.1111/j.1471-4159.1973.tb12152.x. [DOI] [PubMed] [Google Scholar]
- Balcar V. J., Johnston G. A. The structural specificity of the high affinity uptake of L-glutamate and L-aspartate by rat brain slices. J Neurochem. 1972 Nov;19(11):2657–2666. doi: 10.1111/j.1471-4159.1972.tb01325.x. [DOI] [PubMed] [Google Scholar]
- Barbour B., Brew H., Attwell D. Electrogenic glutamate uptake in glial cells is activated by intracellular potassium. Nature. 1988 Sep 29;335(6189):433–435. doi: 10.1038/335433a0. [DOI] [PubMed] [Google Scholar]
- Barbour B., Brew H., Attwell D. Electrogenic uptake of glutamate and aspartate into glial cells isolated from the salamander (Ambystoma) retina. J Physiol. 1991 May;436:169–193. doi: 10.1113/jphysiol.1991.sp018545. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bouvier M., Szatkowski M., Amato A., Attwell D. The glial cell glutamate uptake carrier countertransports pH-changing anions. Nature. 1992 Dec 3;360(6403):471–474. doi: 10.1038/360471a0. [DOI] [PubMed] [Google Scholar]
- Brew H., Attwell D. Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells. 1987 Jun 25-Jul 1Nature. 327(6124):707–709. doi: 10.1038/327707a0. [DOI] [PubMed] [Google Scholar]
- Cornell-Bell A. H., Finkbeiner S. M., Cooper M. S., Smith S. J. Glutamate induces calcium waves in cultured astrocytes: long-range glial signaling. Science. 1990 Jan 26;247(4941):470–473. doi: 10.1126/science.1967852. [DOI] [PubMed] [Google Scholar]
- DERVARTANIAN D. V., VEEGER C. STUDIES ON SUCCINATE DEHYDROGENASE. I. SPECTRAL PROPERTIES OF THE PURIFIED ENZYME AND FORMATION OF ENZYME-COMPETITIVE INHIBITOR COMPLEXES. Biochim Biophys Acta. 1964 Nov 22;92:233–247. [PubMed] [Google Scholar]
- Engel P. C., Dalziel K. The equilibrium constants of the glutamate dehydrogenase systems. Biochem J. 1967 Nov;105(2):691–695. doi: 10.1042/bj1050691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Erecińska M., Silver I. A. Metabolism and role of glutamate in mammalian brain. Prog Neurobiol. 1990;35(4):245–296. doi: 10.1016/0301-0082(90)90013-7. [DOI] [PubMed] [Google Scholar]
- Fenwick E. M., Marty A., Neher E. A patch-clamp study of bovine chromaffin cells and of their sensitivity to acetylcholine. J Physiol. 1982 Oct;331:577–597. doi: 10.1113/jphysiol.1982.sp014393. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ferkany J., Coyle J. T. Heterogeneity of sodium-dependent excitatory amino acid uptake mechanisms in rat brain. J Neurosci Res. 1986;16(3):491–503. doi: 10.1002/jnr.490160305. [DOI] [PubMed] [Google Scholar]
- Garthwaite J. Cellular uptake disguises action of L-glutamate on N-methyl-D-aspartate receptors. With an appendix: diffusion of transported amino acids into brain slices. Br J Pharmacol. 1985 May;85(1):297–307. doi: 10.1111/j.1476-5381.1985.tb08860.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hertz L. Functional interactions between neurons and astrocytes I. Turnover and metabolism of putative amino acid transmitters. Prog Neurobiol. 1979;13(3):277–323. doi: 10.1016/0301-0082(79)90018-2. [DOI] [PubMed] [Google Scholar]
- Hertz L., Schousboe A., Boechler N., Mukerji S., Fedoroff S. Kinetic characteristics of the glutamate uptake into normal astrocytes in cultures. Neurochem Res. 1978 Feb;3(1):1–14. doi: 10.1007/BF00964356. [DOI] [PubMed] [Google Scholar]
- Horton R. W., Meldrum B. S., Bachelard H. S. Enzymic and cerebral metabolic effects of 2-deoxy-D-glucose. J Neurochem. 1973 Sep;21(3):507–520. doi: 10.1111/j.1471-4159.1973.tb05996.x. [DOI] [PubMed] [Google Scholar]
- Kanner B. I., Sharon I. Active transport of L-glutamate by membrane vesicles isolated from rat brain. Biochemistry. 1978 Sep 19;17(19):3949–3953. doi: 10.1021/bi00612a011. [DOI] [PubMed] [Google Scholar]
- Kimelberg H. K., Pang S., Treble D. H. Excitatory amino acid-stimulated uptake of 22Na+ in primary astrocyte cultures. J Neurosci. 1989 Apr;9(4):1141–1149. doi: 10.1523/JNEUROSCI.09-04-01141.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LaNoue K. F., Schoolwerth A. C. Metabolite transport in mitochondria. Annu Rev Biochem. 1979;48:871–922. doi: 10.1146/annurev.bi.48.070179.004255. [DOI] [PubMed] [Google Scholar]
- Logan W. J., Snyder S. H. High affinity uptake systems for glycine, glutamic and aspaspartic acids in synaptosomes of rat central nervous tissues. Brain Res. 1972 Jul 20;42(2):413–431. doi: 10.1016/0006-8993(72)90540-9. [DOI] [PubMed] [Google Scholar]
- Madl J. E., Clements J. R., Beitz A. J., Wenthold R. J., Larson A. A. Immunocytochemical localization of glutamate dehydrogenase in mitochondria of the cerebellum: an ultrastructural study using a monoclonal antibody. Brain Res. 1988 Jun 14;452(1-2):396–402. doi: 10.1016/0006-8993(88)90047-9. [DOI] [PubMed] [Google Scholar]
- Minn A., Gayet J. Kinetic study of glutamate transport in rat brain mitochondria. J Neurochem. 1977 Nov;29(5):873–881. doi: 10.1111/j.1471-4159.1977.tb10731.x. [DOI] [PubMed] [Google Scholar]
- Newman E. A. Voltage-dependent calcium and potassium channels in retinal glial cells. 1985 Oct 31-Nov 6Nature. 317(6040):809–811. doi: 10.1038/317809a0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nicholls D. G., Sihra T. S., Sanchez-Prieto J. Calcium-dependent and -independent release of glutamate from synaptosomes monitored by continuous fluorometry. J Neurochem. 1987 Jul;49(1):50–57. doi: 10.1111/j.1471-4159.1987.tb03393.x. [DOI] [PubMed] [Google Scholar]
- Nicholls D. G., Sihra T. S. Synaptosomes possess an exocytotic pool of glutamate. Nature. 1986 Jun 19;321(6072):772–773. doi: 10.1038/321772a0. [DOI] [PubMed] [Google Scholar]
- Nicholls D., Attwell D. The release and uptake of excitatory amino acids. Trends Pharmacol Sci. 1990 Nov;11(11):462–468. doi: 10.1016/0165-6147(90)90129-v. [DOI] [PubMed] [Google Scholar]
- Pin J. P., Bockaert J., Recasesn M. The Ca2+/C1- dependent L-[3H]glutamate binding: a new receptor or a particular transport process? FEBS Lett. 1984 Sep 17;175(1):31–36. doi: 10.1016/0014-5793(84)80563-3. [DOI] [PubMed] [Google Scholar]
- WICK A. N., DRURY D. R., NAKADA H. I., WOLFE J. B. Localization of the primary metabolic block produced by 2-deoxyglucose. J Biol Chem. 1957 Feb;224(2):963–969. [PubMed] [Google Scholar]
- Waniewski R. A., Martin D. L. Characterization of L-glutamic acid transport by glioma cells in culture: evidence for sodium-independent, chloride-dependent high affinity influx. J Neurosci. 1984 Sep;4(9):2237–2246. doi: 10.1523/JNEUROSCI.04-09-02237.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wheeler D. D., Hollingsworth R. G. A model of high affinity glutamic acid transport by cortical synaptosomes from the Long-Evans rat. J Neurochem. 1978 Jun;30(6):1311–1319. doi: 10.1111/j.1471-4159.1978.tb10461.x. [DOI] [PubMed] [Google Scholar]
- White R. D., Neal M. J. The uptake of L-glutamate by the retina. Brain Res. 1976 Jul 23;111(1):79–93. doi: 10.1016/0006-8993(76)91050-7. [DOI] [PubMed] [Google Scholar]
- Wyllie D. J., Mathie A., Symonds C. J., Cull-Candy S. G. Activation of glutamate receptors and glutamate uptake in identified macroglial cells in rat cerebellar cultures. J Physiol. 1991 Jan;432:235–258. doi: 10.1113/jphysiol.1991.sp018383. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zaczek R., Balm M., Arlis S., Drucker H., Coyle J. T. Quisqualate-sensitive, chloride-dependent transport of glutamate into rat brain synaptosomes. J Neurosci Res. 1987;18(3):425–431. doi: 10.1002/jnr.490180307. [DOI] [PubMed] [Google Scholar]