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Sci Signal. 2012 Apr 3;5(218):ra26. doi: 10.1126/scisignal.2002334.

Astrocytes modulate neural network activity by Ca²+-dependent uptake of extracellular K+.

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  • 1Division of Glia Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical School, Rochester, NY 14640, USA.


Astrocytes are electrically nonexcitable cells that display increases in cytosolic calcium ion (Ca²+) in response to various neurotransmitters and neuromodulators. However, the physiological role of astrocytic Ca²+ signaling remains controversial. We show here that astrocytic Ca²+ signaling ex vivo and in vivo stimulated the Na+,K+-ATPase (Na+- and K+-dependent adenosine triphosphatase), leading to a transient decrease in the extracellular potassium ion (K+) concentration. This in turn led to neuronal hyperpolarization and suppressed baseline excitatory synaptic activity, detected as a reduced frequency of excitatory postsynaptic currents. Synaptic failures decreased in parallel, leading to an increase in synaptic fidelity. The net result was that astrocytes, through active uptake of K+, improved the signal-to-noise ratio of synaptic transmission. Active control of the extracellular K+ concentration thus provides astrocytes with a simple yet powerful mechanism to rapidly modulate network activity.

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