Glutamate receptors activate Ca super(2+) mobilization and Ca super(2+) influx into astrocytes

The authors measured changes in the molar concentration of cytosolic Ca super(2+) ((Ca super(2+)) sub(i)) in individual astrocytes in culture produced by the glutamate analog quisqualate (QA) and related substances by using fura-2 digital fluorescence microscopy. In cells cultured from the cortex, hippocampus, and cerebellum, the QA analog alpha -amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) produced a slow increase in (Ca super(2+)) sub(i). In cerebellar astrocytes, similar effects were produced by QA. However, in cortical and hippocampal astrocytes, the response to QA was much more complex. Thus, QA appears to trigger a complex response in some astrocytes consisting of Ca super(2+) mobilization from intracellular stores and also Ca super(2+) influx resulting from the activation of AMPA-sensitive and -insensitive pathways.