PHYSIOLOGY OF RETINAL MULLER CELLS AND ASTROCYTES

视网膜米勒细胞和星形胶质细胞的生理学

• 批准号: 2158990
• 负责人: ERIC A NEWMAN
• 金额: $ 25.07万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-07-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2158990
• 关键词: Muller's cell; Urodela; acid base balance; acidity /alkalinity; adenosinetriphosphatase; antiport; astrocytes; carbonates; confocal scanning microscopy; electroretinography; glia; laboratory rat; membrane potentials; membrane transport proteins; retina; vitreous body; voltage /patch clamp

The long term objectives of this research are to characterize the membrane properties of Muller cells and retinal astrocytes and to relate these properties to possible glial cell functions in the retina, including the regulation of extracellular pH and [K]o, the control of retinal blood flow, and the generation of the electroretinogram. Specific aims for the project period differ from previous periods and examine, primarily, pH regulation in retinal glial cells. The aims are; (1) Characterize the acid/base transport systems of amphibian and mammalian Muller cells. Hypotheses to be tested include; (i) Muller cells possess an electrogenic Na+/HCO-3 cotransport system and a Cl-/HCO-3 exchanger which are both localized tot he cell endfoot. (ii) Muller cells possess a Na+/H+ exchanger and a H+-ATPase. (2) Test the hypothesis that muller cells modulate extracellular pH (pHo) by the action of the electrogenic Na+/HCO-3 cotransporter. The hypothesis will be tested in two preparations; (i) dissociated Muller cells (Salamander and rat) and (ii) Muller cells in situ in the isolated rat retina. (3) Test the hypothesis that Muller cells regulate pHo in the retina by functioning as CO2 buffers, transporting CO2, in the form of H- and HCO-3, to the vitreous humor. (4) Characterize the acid/base transport systems of mammalian astrocytes in situ. Specific hypotheses to be tested include: (i) the acid/base transport systems of mammalian astroytes in situ have properties similar to those found in Muller cells and cultured astrocytes. (ii) the Na+/HCO-3 cotransport system of mammalian astrocytes in situ is localized in cell endfeet. (5) Test the hypothesis that glial cells regulate blood flow in the mammalian retina. Blood vessel diameter will be monitored in the isolated rat retina as the membrane potential of glial cells is modulated by current injection. Acid/base transport systems will be characterized by monitoring intracellular and extracellular pH with ratio imaging of pH-sensitive indicator eyes. Measurements in dissociated salamander and rat muller cells will be made by imaging the dye BCECF with inverted fluorescence microscopy. In situ measurements in the isolated rat retina will be made by confocal imaging of the dye SNARF-1. Elucidating the basic membrane properties of Muller cells and retinal astrocytes is necessary for understanding the ole that these cells play in retinal function under normal and pathological condiitons, including retinitis pigmentosa and macular dystrophy.

这项研究的长期目标是表征膜 Muller 细胞和视网膜星形胶质细胞的特性并将它们联系起来 视网膜中可能的神经胶质细胞功能的特性，包括 调节细胞外 pH 值和 [K]o，控制视网膜血流， 以及视网膜电图的生成。 该项目的具体目标 周期与之前的周期不同，主要检查 pH 调节 在视网膜神经胶质细胞中。 目标是； (1) 表征酸/碱传输系统 两栖动物和哺乳动物的 Muller 细胞。 要测试的假设包括： （我） Muller 细胞具有产电 Na+/HCO-3 共转运系统和 Cl-/HCO-3 交换器均位于细胞末端。 (二) Muller 细胞拥有 Na+/H+ 交换器和 H+-ATP 酶。 (2) 测试 假设 Muller 细胞通过以下作用调节细胞外 pH (pHo) 产电 Na+/HCO-3 协同转运蛋白。 假设将被检验 分两种制剂； (i) 解离的 Muller 细胞（蝾螈和大鼠）和 (ii) 离体大鼠视网膜原位 Muller 细胞。 (3) 测试 假设 Muller 细胞通过以下功能调节视网膜中的 pHo： CO2 缓冲剂，将 CO2 以 H- 和 HCO-3 的形式输送至玻璃体 幽默。 (4) 表征哺乳动物的酸/碱运输系统 原位星形胶质细胞。 需要检验的具体假设包括： (i) 哺乳动物星形细胞的酸/碱原位运输系统具有以下特性 与穆勒细胞和培养的星形胶质细胞中发现的相似。 (二) 哺乳动物星形胶质细胞原位Na+/HCO-3共转运系统的定位 在细胞末端足中。 (5)检验神经胶质细胞调节血液的假设 在哺乳动物视网膜中流动。 血管直径将被监测 离体大鼠视网膜神经胶质细胞膜电位为 通过电流注入调制。 酸/碱传输系统将通过监测来表征 细胞内和细胞外 pH 值的 pH 敏感比率成像 指示眼。 分离蝾螈和大鼠穆勒的测量 细胞将通过使用倒置荧光对染料 BCECF 进行成像来制备 显微镜。 将在离体大鼠视网膜中进行原位测量 通过染料 SNARF-1 的共焦成像。 阐明米勒细胞和视网膜的基本膜特性 星形胶质细胞对于理解这些细胞所发挥的作用是必要的 正常和病理条件下的视网膜功能，包括 视网膜色素变性和黄斑营养不良。