Sodium-Calcium Exchanger Modulates the L-Glutamate Cai2+ Signalling in Type-1 Cerebellar Astrocytes
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We have previously demonstrated that rat type-1 cerebellar astrocytes express a very active Na+/Ca2+ exchanger which accounts for most of the total plasma membrane Ca2+ fluxes and for the clearance of Ca i 2+ induced by physiological agonist. In this chapter, we have explored the mechanism by which the reverse Na+/Ca2+ exchange is involved in agonist-induced Ca2+ signalling in rat cerebellar astrocytes. Laser-scanning confocal microscopy experiments using immunofluorescence labelling of Na+/Ca2+ exchanger and RyRs demonstrated that they are highly co-localized. The most important finding presented in this chapter is that L-glutamate activates the reverse mode of the Na+/Ca2+ exchange by inducing a Na+ entry through the electrogenic Na+-glutamate co-transporter and not through the ionophoric L-glutamate receptors as confirmed by pharmacological experiments with specific blockers of ionophoric L-glutamate receptors, electrogenic glutamate transporters and the Na/Ca exchange.
KeywordsNa+/Ca2+ exchange CICR Glutamate Glutamate transporter
This work was supported by FONACIT-Venezuela (G-0010000637).
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