Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Neurochem Res. 2012 Nov;37(11):2310-6. doi: 10.1007/s11064-012-0759-4. Epub 2012 Apr 6.
Astrocytes utilize two major pathways to achieve long distance intercellular communication. One pathway involves direct gap junction mediated signal transmission and the other consists of release of ATP through pannexin channels and excitation of purinergic receptors on nearby cells. Elevated extracellular potassium to levels occurring around hyperactive neurons affects both gap junction and pannexin1 channels. The action on Cx43 gap junctions is to increase intercellular coupling for a period that long outlasts the stimulus. This long term increase in coupling, termed "LINC", is mediated through calcium and calmodulin dependent activation of calmodulin dependent kinase (CaMK). Pannexin1 can be activated by elevations in extracellular potassium through a mechanism that is quite different. In this case, potassium shifts activation potentials to more physiological range, thereby allowing channel opening at resting or slightly depolarized potentials. Enhanced activity of both these channel types by elevations in extracellular potassium of the magnitude occurring during periods of high neuronal activity likely has profound effects on intercellular signaling among astrocytes in the nervous system.
星形胶质细胞利用两种主要途径实现长距离细胞间通讯。一种途径涉及直接缝隙连接介导的信号传递，另一种途径则包括通过连接蛋白通道释放 ATP 以及兴奋附近细胞上的嘌呤能受体。升高至过度活跃神经元周围发生的水平的细胞外钾影响缝隙连接和连接蛋白 1 通道。对 Cx43 缝隙连接的作用是在很长一段时间内增加细胞间偶联，远远超过刺激时间。这种称为“LINC”的长期耦合增加是通过钙和钙调蛋白依赖性钙调蛋白依赖性激酶（CaMK）的激活介导的。通过一种完全不同的机制，细胞外钾的升高可以激活连接蛋白 1。在这种情况下，钾会将激活电位转移到更接近生理范围，从而使通道在静息或轻微去极化电位下打开。在神经元活动高的时期，细胞外钾升高增强这两种通道类型的活性，这可能对神经系统中星形胶质细胞之间的细胞间信号传递产生深远影响。
