Role of capacitative calcium entry on glutamate‐induced calcium influx in type‐I rat cortical astrocytes
Résumé
Capacitative calcium entry (CCE) has been described in a variety of cell types. To date, little is known about its role in the CNS, and in particular in the cross‐talk between glia and neurons. We have first analyzed the properties of CCE of astrocytes in culture, in comparison with that of the rat basophilic leukemia cell line (RBL‐2H3), a model where calcium release‐activated Ca 2+ (CRAC) channels have been unambiguously correlated with CCE. We here show that (i) in astrocytes CCE activated by store depletion and Ca 2+ influx induced by glutamate share the same pharmacological profile of CCE in RBL‐2H3 cells and (ii) glutamate‐induced Ca 2+ influx in astrocytes plays a primary role in glutamate‐dependent intracellular Ca 2+ concentration ([Ca 2+ ] i ) oscillations, being these latter reduced in frequency and amplitude by micromolar concentrations of La 3+ . Finally, we compared the expression of various mammalian transient receptor potential genes ( TRP ) in astrocytes and RBL‐2H3 cells. Despite the similar pharmacological properties of CCE in these cells, the pattern of TRP expression is very different. The involvement of CCE and TRP s in glutamate dependent activation of astrocytes is discussed.