calcimycin and gamma-glutamylaminomethylsulfonic-acid

Astrocyte-enriched cultures prepared from the neonatal rat cortex were prelabelled with either [3H]myoinositol or 45Ca2+ and then exposed to various excitatory amino acids. This resulted in an increase in both the breakdown of membrane inositol phospholipids and Ca2+ flux with the following rank order of efficacy: quisqualate greater than or equal to glutamate (Glu) greater than kainate much greater than N-methyl-D-aspartate. Experiments performed with the Ca2+ ionophore A23187 and in the absence of medium Ca2+ suggested that Glu-evoked 45Ca2+ efflux was primarily the result of an increased influx of extracellular Ca2+. However, Glu-stimulated inositol lipid metabolism was found to be only partially dependent on extracellular Ca2+. The quisqualate-preferring receptor antagonist gamma-glutamylaminomethylsulphonic acid was found to be effective in reversing both Glu-evoked inositol lipid breakdown and Ca2+ flux. The results presented are suggestive of some form of interaction between Glu receptors coupled to inositol lipid turnover and Ca2+ channel opening in astrocytes.

Topics: Amino Acids; Animals; Astrocytes; Calcimycin; Calcium; Cells, Cultured; Glutamates; Glutamine; Phosphatidylinositols; Rats; Receptors, Glutamate; Receptors, Neurotransmitter