AMPA/kainate receptor activation inhibits neuronal delayed rectifier K+ current via Na+ entry in rat cortical neurons |
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Authors: | H Houzen M Kanno S Kikuchi |
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Affiliation: | Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan. hohzen@med.hokudai.ac.jp |
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Abstract: | In the present study we evaluated the modulation of neuronal delayed rectifier K+ current (IK) by activation of ionotropic glutamate receptors. In whole-cell voltage-clamp experiments, an external application of 10-100 microM kainate suppressed the amplitude of IK following an inward shift of holding current. The effect of kainate on IK was eliminated by CN QX, an AMPA/kainate receptor antagonist, indicating that the receptor-mediated cation entry caused IK suppression. When external Na+ was completely replaced by equimolar choline+ or N-methyl-D-glucamine, kainate-induced IK suppression was abolished. Our results suggest that in cultured rat cortical neurons, AMPA/kainate receptor activation leads to an intracellular Na+ increase which blocks delayed rectifier K+ channels. This contributes to feed-forward excitation of neuronal cells in glutaminergic responses. |
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