Newman E A
Can J Physiol Pharmacol. 1987 May;65(5):1028-32. doi: 10.1139/y87-162.
The membrane properties of Müller cells, the principal glial cells of the vertebrate retina, have been characterized in a series of physiological experiments on freshly dissociated cells. In species lacking a retinal circulation (tiger salamander, rabbit, guinea pig), the end-foot of the Müller cell has a much higher K+ conductance than do other cell regions. In species with retinal circulation (mouse, cat, owl monkey) the K+ conductance of the end-foot is greater than the conductance of the proximal process of the cell. In these species, however, the K+ conductance of the soma and distal process is equal to, or greater than, the end-foot conductance. Müller cells also possess four voltage-dependent ion channels, including an inward rectifying K+ channel. These membrane specializations may aid in the regulation of extracellular K+ levels by Müller cells in the retina. High end-foot conductance shunts excess K+ out through the end-foot, where it diffuses into the vitreous humor. In vascularized retinae, excess K+ may also be transferred to the ablumenal wall of capillaries, where it could be transported into the blood.
缪勒细胞是脊椎动物视网膜的主要神经胶质细胞，其膜特性已在一系列对新鲜解离细胞的生理学实验中得到了表征。在缺乏视网膜循环的物种（虎螈、兔子、豚鼠）中，缪勒细胞的终足具有比其他细胞区域高得多的钾离子电导率。在具有视网膜循环的物种（小鼠、猫、猫头鹰猴）中，终足的钾离子电导率大于细胞近端突起的电导率。然而，在这些物种中，胞体和远端突起的钾离子电导率等于或大于终足电导率。缪勒细胞还拥有四种电压依赖性离子通道，包括一个内向整流钾离子通道。这些膜特化可能有助于缪勒细胞调节视网膜细胞外的钾离子水平。高终足电导率通过终足将多余的钾离子分流出去，钾离子在终足处扩散到玻璃体液中。在有血管的视网膜中，多余的钾离子也可能转移到毛细血管的无腔壁，在那里它可以被转运到血液中。
