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AMPA/kainate receptor activation blocks K + currents via internal Na + increase in mouse cultured stellate astrocytes
Author(s) -
Robert Antoine,
Magistretti Pierre J.
Publication year - 1997
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199705)20:1<38::aid-glia4>3.0.co;2-1
Subject(s) - kainate receptor , ampa receptor , biology , hepatic stellate cell , glutamate receptor , neuroscience , receptor , astrocyte , neuroglia , nmda receptor , endocrinology , central nervous system , biochemistry
Cultured mouse cortical astrocytes of the stellate type were studied by using the patch‐clamp technique in whole‐cell configuration. The astrocytes express at least two types of outwardly rectifying K + channels which mediate a transient and a sustained current. Activation of AMPA receptors by kainate leads to a substantial blockade of both types of K + currents. The blockade is absent when Na + is withdrawn from the external medium, suggesting that it is caused by constant Na + influx through AMPA receptors. The presence of high Na + solutions in the pipette induces a blockade of both K + currents which is very similar to the blockade induced by kainate, supporting thus the view that the mechanism of the blockade of K + channels by kainate involves Na + increases in the submembrane area. The blockade occurs between 20 and 40 mM [Na + ] i , which is within the physiological range of [Na + ] i in astrocytes. The data may suggest that the blockade of K + channels by high [Na + ] i conditions could provide a mechanism to prevent K + leakage from the astrocytes into the extracellular space during periods of intense neuronal activity. GLIA 20:38‐50, 1997. © 1997 Wiley‐Liss, Inc.