Puro D G, Roberge F, Chan C C
Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, FL 33101.
Invest Ophthalmol Vis Sci. 1989 Mar;30(3):521-9.
Under a variety of pathological conditions, glial cells of the retina proliferate. Although glial cell proliferation may play a role in a number of important retinal disorders, the regulation of this proliferative response is understood poorly. We examined the possibility that the function of certain ion channels in retinal glial cells may be linked with the induction of proliferation. Experiments were performed on glial cells derived from the adult rat retina and maintained in culture. The cells stained positively by immunocytochemistry with antibodies specific for glial fibrillary acidic protein and for Muller cells. Patch clamp studies of these retinal glial cells demonstrated the presence of a large conductance, calcium-activated potassium channel that is sensitive to tetraethylammonium, a classical blocker of potassium channels. The activity of this type of potassium channel was monitored by patch clamp recordings in the cell-attached configuration before and after exposure of the glial cells to a mitogenic conditioned medium. Exposure to this conditioned medium was associated with a marked increase in the activity of the ion channel. A possible link between the activity of potassium channels and the action of mitogens was suggested further by the finding that tetraethylammonium significantly blocked the proliferative response of retinal glial cells to the conditioned medium. Our findings support the hypothesis that there is a link between the biophysical processes involved in ion channel activity and the proliferation of retinal glial cells.
在多种病理条件下，视网膜神经胶质细胞会增殖。尽管神经胶质细胞增殖可能在许多重要的视网膜疾病中起作用，但对这种增殖反应的调节了解甚少。我们研究了视网膜神经胶质细胞中某些离子通道的功能可能与增殖诱导相关的可能性。实验在源自成年大鼠视网膜并在培养中维持的神经胶质细胞上进行。这些细胞通过免疫细胞化学用针对神经胶质纤维酸性蛋白和穆勒细胞的特异性抗体呈阳性染色。对这些视网膜神经胶质细胞的膜片钳研究表明存在一种大电导、钙激活钾通道，该通道对钾通道的经典阻滞剂四乙铵敏感。在神经胶质细胞暴露于促有丝分裂条件培养基之前和之后，通过膜片钳记录在细胞贴附模式下监测这种类型钾通道的活性。暴露于这种条件培养基与离子通道活性的显著增加相关。四乙铵显著阻断视网膜神经胶质细胞对条件培养基的增殖反应这一发现进一步表明了钾通道活性与促有丝分裂原作用之间可能存在联系。我们的研究结果支持这样一种假设，即离子通道活性所涉及的生物物理过程与视网膜神经胶质细胞的增殖之间存在联系。
