Efflux of 45calcium from cultured primary astrocytes: Effects of glutamate receptor agonists and antagonists
| Autor: | I. Holopainen, K.E.O. Åkerman |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Agonist
medicine.medical_specialty Kainic acid N-Methylaspartate medicine.drug_class Kainate receptor AMPA receptor Cellular and Molecular Neuroscience chemistry.chemical_compound Glutamates Internal medicine medicine Animals Quisqualic acid Cells Cultured Pharmacology Kainic Acid Calcium Radioisotopes Glutamate receptor Quisqualic Acid Valine Rats Receptors Neurotransmitter medicine.anatomical_structure Endocrinology Animals Newborn Receptors Glutamate chemistry Astrocytes NMDA receptor Calcium Excitatory Amino Acid Antagonists Astrocyte |
| Zdroj: | Neuropharmacology. 29:713-717 |
| ISSN: | 0028-3908 |
| DOI: | 10.1016/0028-3908(90)90123-9 |
| Popis: | The effects of high-K, glutamate and glutamate receptor agonists on the efflux of Ca2+ were studied in cultured primary astrocytes, prepared from the brains of newborn rats. An increase in efflux of 45Ca2+ of produced by a large extracellular concentration of K+ was effectively inhibited by verapamil, a blocker of voltage-gated Ca2+ channels, suggesting that these cells have functional voltage-sensitive Ca2+ channels. Glutamate and its agonists kainate, quisqualate and N-methyl-D-aspartate (NMDA) stimulated the efflux of preloaded 45Ca2+, in a dose-dependent manner. The most effective agonist was quisqualate followed by glutamate, whereas kainate and NMDA were less potent. In the Mg-free medium, the response to NMDA was significantly increased. The quisqualate receptor agonist (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) also stimulated the efflux, about equally effectively as quisqualate. The glutamate-, quisqualate- and kainate-induced efflux of 45Ca2+ was significantly inhibited by L-glutamatediethylester (GDEE) and that of NMDA by DL-2-amino-5-phosphonopentanoic acid (AP5). The kainate-induced efflux was totally inhibited by verapamil, but that of glutamate only partially. No effect of verapamil was observed on the quisqualate-induced efflux of 45Ca2+. The results imply that, in cultured astrocytes, Ca2+ fluxes induced by glutamate agonists, occur partially through voltage-dependent Ca2+ channels. The extensive release of 45Ca2+ caused by quisqualate was mainly due to a release from internal stores. |
| Databáze: | OpenAIRE |
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