Khanna R, Roy L, Zhu X, Schlichter L C
Division of Cellular and Molecular Biology, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.
Am J Physiol Cell Physiol. 2001 Apr;280(4):C796-806. doi: 10.1152/ajpcell.2001.280.4.C796.
Microglial activation following central nervous system damage or disease often culminates in a respiratory burst that is necessary for antimicrobial function, but, paradoxically, can damage bystander cells. We show that several K+ channels are expressed and play a role in the respiratory burst of cultured rat microglia. Three pharmacologically separable K+ currents had properties of Kv1.3 and the Ca2+/calmodulin-gated channels, SK2, SK3, and SK4. mRNA was detected for Kv1.3, Kv1.5, SK2, and/or SK3, and SK4. Protein was detected for Kv1.3, Kv1.5, and SK3 (selective SK2 and SK4 antibodies not available). No Kv1.5-like current was detected, and confocal immunofluorescence showed the protein to be subcellular, in contrast to the robust membrane localization of Kv1.3. To determine whether any of these channels play a role in microglial activation, a respiratory burst was stimulated with phorbol 12-myristate 13-acetate and measured using a single cell, fluorescence-based dihydrorhodamine 123 assay. The respiratory burst was markedly inhibited by blockers of SK2 (apamin) and SK4 channels (clotrimazole and charybdotoxin), and to a lesser extent, by the potent Kv1.3 blocker agitoxin-2.
中枢神经系统损伤或疾病后，小胶质细胞的激活通常会导致呼吸爆发，这对抗菌功能是必需的，但矛盾的是，它会损害周围细胞。我们发现几种钾离子通道在培养的大鼠小胶质细胞的呼吸爆发中表达并发挥作用。三种药理学上可分离的钾电流具有Kv1.3以及钙调蛋白门控通道SK2、SK3和SK4的特性。检测到Kv1.3、Kv1.5、SK2和/或SK3以及SK4的信使核糖核酸。检测到Kv1.3、Kv1.5和SK3的蛋白质（没有选择性的SK2和SK4抗体）。未检测到类似Kv1.5的电流，共聚焦免疫荧光显示该蛋白质位于亚细胞中，这与Kv1.3在细胞膜上的强烈定位形成对比。为了确定这些通道是否在小胶质细胞激活中发挥作用，用佛波醇12-肉豆蔻酸酯13-乙酸酯刺激呼吸爆发，并使用单细胞荧光二氢罗丹明123测定法进行测量。SK2通道阻滞剂（蜂毒明肽）和SK4通道阻滞剂（克霉唑和蝎毒素）可显著抑制呼吸爆发，强效Kv1.3阻滞剂阿基毒素-2的抑制作用较小。
