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KMID : 0578320080250010124
Molecules and Cells
2008 Volume.25 No. 1 p.124 ~ p.130
Expression of Kir2.1 Channels in Astrocytes Under Pathophysiological Conditions
Kang Shin-Jung

Park Kyoung-Jun
Lee Ji-Hyung
Yoo Soon-Ji
Shin Ki-Soon
Abstract
Astrocyte ion channels participate in ionic homeostasis in the brain. Inward rectifying potassium channels (Kir channels) in astrocytes have been particularly implicated in K+ homeostasis because of their high open probability at resting potential and their increased conductance at high concentrations of extracellular K+. We examined the expression of the Kir2.1 subunit, one of the Kir channel subunits, in the mouse brain by immunohistochemistry. Kir2.1 channels were widely distributed throughout the brain, with high expression in the olfactory bulb and the cerebellum. Interestingly, they were abundantly expressed in astrocytes of the olfactory bulb, while astrocytes in other brain regions including the hippocampus did not show any detectable expression. However, Kir2.1 channel-expressing cells were dramatically increased in the hippocampus by kainic acid-induced seizure and the cells were glial fibrillary acidic protein (GFAP)-positive, which confirms that astrocytes in the hippocampus express Kir2.1 channels under pathological conditions. Our results imply that Kir2.1 channels in astrocyte may be involved in buffering K+ against accumulated extracellular K+ caused by neuronal hyperexcitability under phathophysiological conditions.
KEYWORD
Astrocytes, Hippocampus, K+ Homeostasis, Kainic Acid-induced Seizures, Kir2.1, Olfactory Bulb
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