6533b836fe1ef96bd12a09ec

RESEARCH PRODUCT

Sodium dynamics: another key to astroglial excitability?

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Astroglial excitability is largely mediated by fluctuations in intracellular ion concentrations. In addition to generally acknowledged Ca 2+ excitability of astroglia, recent studies have demonstrated that neuronal activity triggers transient increases in the cytosolic Na + concentration ([Na + ] i ) in perisynaptic astrocytes. These [Na + ] i transients are controlled by multiple Na + -permeable channels and Na + -dependent transporters; spatiotemporally organized [Na + ] i dynamics in turn regulate diverse astroglial homeostatic responses such as metabolic/signaling utilization of lactate and glutamate, transmembrane transport of neurotransmitters and K + buffering. In particular, near-membrane [Na + ] i transients determine the rate and the direction of the transmembrane transport of GABA and Ca 2+ . We discuss here the role of Na + in the regulation of various systems that mediate fast bidirectional communication between neurones and glia at the single synapse level.