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Depression by Sodium Ions of Calcium Uptake Mediated by Non-N-Methyl-d-Aspartate Receptors in Cultured Cerebellar Neurons and Correlation with Evoked $d-[^{3}$H]Aspartate Release
| Content Provider | Scilit |
|---|---|
| Author | Gallo, Vittorio Giovannini, Claudio Levi, Giulio |
| Copyright Year | 1992 |
| Description | Journal: Journal of Neurochemistry In a previous study we noted that the release of D-[3H]aspartate evoked by non-N-methyl-D-aspartate (non-NMDA) receptor agonists in cultured rat cerebellar granule cells was enhanced in the absence of extracellular Na+. To explain this apparent paradox, we tried in the present investigation to correlate the effect of Na+ removal on the kainate (KA)- and quisqualate (QA)-induced D-[3H]aspartate release with that on KA- and QA-induced 45Ca2+ accumulation. The releasing activity of KA, which was only partially Ca2+ dependent in the presence of Na+, became totally Ca2+ dependent in its absence. Moreover, the releasing activity of QA, which was Ca2+ independent in the presence of Na+, became 50% Ca2+ dependent in the absence of the monovalent cation. The releasing action of both agonists was in all cases antagonized by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and that induced by KA was also sensitive to kynurenic acid. When glutamate was tested as an agonist in the presence of Na+, it was found that its D-[3H]aspartate releasing action was Ca2+ independent and was largely due to heteroexchange. The evoked release was Ca2+ independent, scarcely sensitive to CNQX, and insensitive to NMDA antagonists. In Na(+)-free medium, the glutamate-evoked D-[3H]aspartate release was lower (due to the abolishment of heteroexchange), but was totally Ca2+ dependent and antagonized by CNQX and kynurenate. KA (30 microM-1 mM) stimulated the accumulation of 45Ca2+ in a dose-dependent and CNQX-sensitive way, the effect being progressively higher as the Na+ concentration in the medium was decreased. Li+ affected KA-induced 45Ca2+ accumulation in a way similar to Na+, although 45Ca2+ uptake was somewhat lower in Li(+)-containing medium. The voltage-activated calcium channel antagonists La3+ and (-)-202-791 caused only a limited inhibition of the KA-induced 45Ca2+ influx both in the presence and in the absence of Na+. Under all the conditions tested [presence and absence of Na+ and of (-)-202-791], the kainate-induced 45Ca2+ uptake was scarcely sensitive to the NMDA antagonist 2-amino-5-phosphonovalerate. QA and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid also stimulated 45Ca2+ influx in a CNQX-sensitive way, the effect being enhanced in Na(+)-free media. These agonists were, however, less effective than KA.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Related Links | http://onlinelibrary.wiley.com/doi/10.1111/j.1471-4159.1992.tb09737.x/pdf |
| Ending Page | 415 |
| Page Count | 10 |
| Starting Page | 406 |
| e-ISSN | 14714159 |
| DOI | 10.1111/j.1471-4159.1992.tb09737.x |
| Journal | Journal of Neurochemistry |
| Issue Number | 2 |
| Volume Number | 58 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 1992-02-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Journal of Neurochemistry D‐[3h]aspartate Release Non‐n‐methyl‐d‐aspartate Receptors |
| Content Type | Text |
| Resource Type | Article |
