Impact of global cerebral ischemia on K+ channel expression and membrane properties of glial cells in the rat hippocampus
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- 作者：Helena Pivonkova ; Jana Benesova ; Olena Butenko ; Alex ; r Chvatal ; Miroslava Anderova
- 关键词：CNS injury ; Patch-cl K+ channels ; Proliferation ; Kir4.1 ; Astrocytes ; NG2 glia
- 刊名：Neurochemistry International
- 出版年：2010
- 出版时间：December 2010
- 年：2010
- 卷：57
- 期：7
- 页码：783-794
- 全文大小：1015 K
文摘
Astrocytes and NG2 glia respond to CNS injury by the formation of a glial scar. Since the changes in K+ currents in astrocytes and NG2 glia that accompany glial scar formation might influence tissue outcome by altering K+ ion homeostasis, we aimed to characterize the changes in K+ currents in hippocampal astrocytes and NG2 glia during an extended time window of reperfusion after ischemic injury. Global cerebral ischemia was induced in adult rats by bilateral, 15-min common carotid artery occlusion combined with low-pressure oxygen ventilation. Using the patch-clamp technique, we investigated the membrane properties of hippocampal astrocytes and NG2 glia in situ 2 hours, 6 hours, 1 day, 3 days, 7 days or 5 weeks after ischemia. Astrocytes in the CA1 region of the hippocampus progressively depolarized starting 3 days after ischemia, which coincided with decreased Kir4.1 protein expression in the gliotic tissue. Other K+ channels described previously in astrocytes, such as Kir2.1, Kir5.1 and TREK1, did not show any changes in their protein content in the hippocampus after ischemia; however, their expression switched from neurons to reactive astrocytes, as visualized by immunohistochemistry. NG2 glia displayed increased input resistance, decreased membrane capacitance, increased delayed outwardly rectifying and A-type K+ currents and decreased inward K+ currents 3 days after ischemia, accompanied by their proliferation. Our results show that the membrane properties of astrocytes after ischemia undergo complex alterations, which might profoundly influence the maintenance of K+ homeostasis in the damaged tissue, while NG2 glia display membrane currents typical of proliferating cells.