MEMBRANE PHYSIOLOGY AND FUNCTION OF RETINAL MULLER CELLS

视网膜米勒细胞的膜生理学和功能

基本信息

批准号：
3258564
负责人：
ERIC A NEWMAN
金额：
$ 22.2万
依托单位：
UNIVERSITY OF MINNESOTA
依托单位国家：
美国
项目类别：
财政年份：
1990
资助国家：
美国
起止时间：
1990-07-01 至 1995-03-31
项目状态：
已结题

项目摘要

The long-term objectives of this research project are to characterize the membrane properties of muller cells of the vertebrate retina and to relate these properties to possible Muller cell functions, including the regulation of extracellular K+ and pH within the retina and the generation of the electroretinogram. Studies conducted during previous grant periods have demonstrated that the membrane conductance of Muller cells is distributed in a highly non-uniform manner over the cell surface. Conductance is localized to cell endfeet and, perhaps, to cell processes in contact with retinal blood vessels. Specific aims for the coming grant period are as follows: 1) Describe the types and spatial distribution of ion channels present in muller cells. This research will test the hypothesis that the high K+ conductance of the Muller cell endfoot is mediated by the same K+ channel(s) that are present in other cell regions.. 2) Describe changes in the ion channels of Muller cells during development, during retinal degeneration, and following retinal injury. This research will test two hypotheses: (i) That blood vessels induce "endfoot-like" properties in Muller cell processes contacting them. (ii) That significant changes occur in Muller cell ion channels and transport processes during retinal degeneration and following retinal injury produced by a penetrating wound. 3) Characterize the electrogenic Na+-HCO3- cotransport system of Muller cells. The stoichiometry of this transport system and its distribution over the cell surface will be studied. 4) Test the hypothesis that K+ and HCO3- are released preferentially from Muller cell endfeet and from processes in contact with blood vessels. Such ion fluxes may help regulate K+ and pH levels in the retina. 5) Test the hypothesis that glial cells regulate blood flow in the retina. 6) Test hypotheses of Muller cell function using computer simulations of Muller cells and retinal K+ dynamics. Electrophysiological investigations on mouse (normal and retinal degeneration mutant), rabbit, salamander and dogfish Muller cells will be conducted using the following preparations: (i) enzymatically dissociated Muller cells, (ii) retinal slices, and (iii) isolated retinas. Whole-cell voltage-and current-clamp, patch-clamp, and ion-selective microelectrode recording techniques will be employed. Elucidating Muller cell membrane properties is critical for understanding the role that these cells play in retinal function. Knowledge of the changes that occur in Muller cells during retinal degeneration and injury will help us understand such clinical conditions as retinitis pigmentosa and retinal trauma.

该研究项目的长期目标是表征脊椎动物视网膜穆勒细胞的膜特性并与之相关这些属性可能具有 Muller 胞功能，包括视网膜内细胞外 K+ 和 pH 值的调节及其生成的视网膜电图。之前资助期间进行的研究已证明 Muller 细胞的膜电导为以高度不均匀的方式分布在细胞表面。电导局限于细胞末端，也许还局限于细胞过程与视网膜血管接触。下一个资助期的具体目标如下： 1) 描述 Muller 细胞中离子通道的类型和空间分布。这项研究将检验以下假设： Muller 细胞尾足由存在的相同 K+ 通道介导其他细胞区域.. 2) 描述 Muller 离子通道的变化细胞在发育过程中、视网膜变性过程中以及随后的过程中视网膜损伤。这项研究将检验两个假设：（i）血液血管在 Muller 细胞过程中诱导“端足样”特性联系他们。 (ii) Muller 细胞离子发生显着变化视网膜变性及后续过程中的通道和运输过程穿透伤造成的视网膜损伤。 3）表征 Muller 细胞的产电 Na+-HCO3- 共转运系统。这该运输系统的化学计量及其在细胞内的分布将研究表面。 4) 检验 K+ 和 HCO3- 的假设优先从穆勒细胞端脚和过程中释放与血管接触。这种离子通量可能有助于调节 K+ 和 pH 值视网膜中的水平。 5）检验神经胶质细胞调节的假设视网膜中的血液流动。 6) 使用以下方法检验 Muller 细胞功能的假设 Muller 细胞和视网膜 K+ 动力学的计算机模拟。小鼠电生理学研究（正常和视网膜变性突变体）、兔、蝾螈和角鲨 Muller 细胞将使用以下制剂进行：（i）酶解 Muller 细胞，(ii) 视网膜切片，和 (iii) 分离的视网膜。全细胞电压和电流钳、膜片钳和离子选择性微电极将采用录音技术。阐明米勒细胞膜特性对于理解至关重要这些细胞在视网膜功能中发挥的作用。的知识视网膜变性和损伤过程中 Muller 细胞发生的变化将帮助我们了解色素性视网膜炎等临床病症和视网膜外伤。