MEMBRANES PROPERTIES OF CELLS COMPRISING THE OHC SYSTEM

本项目的总体目标是分析膜的性能， 使用全细胞电压从内耳分离几种细胞类型 钳位技术 细胞类型（外毛细胞[OHC]，II型螺旋 选择神经节细胞和Deiter细胞），因为它们在功能上都是 直接或间接地与OHC系统有关。 该系统最近 对正常的耳蜗功能非常重要。 OHCs的几个特性将被研究，包括它们的内向Ca+2 电流，钆诱导阻断电压诱导OHC的机制 运动，和OHC运动的频率响应。 这些评价 将通过测量这些电流的电压依赖性来进行， 运动阻滞效应，通过比较运动特性， 牵张感受器，并通过测量OHC机械反应 由AC刺激引起的幅度。 II型螺旋线的离子电导 将分析神经节细胞和Deiter细胞以确定它们的作用 在OHC系统中。 具体地说，Deiter细胞，其与其他细胞偶联， 通过间隙连接支持细胞，将通过电压钳进行评估， 确定它们是否具有机制（例如，内向K+ 电流），这可能有助于Corti器官的离子稳态。 II型螺旋神经节细胞将以类似的方式评价， 确定它们是否具有所需的离子电导， 将声音信息传递到中枢神经系统。 由于没有 电生理学信息可在这种细胞类型上获得，这是一种 重要的问题。 了解这些现象将有助于了解OHC所发挥的作用 通过机械反馈在Corti器官内进行精细的频率调谐 机制等 他们也将有助于阐明的病理影响， 外毛细胞系统，包括离子失衡（例如，梅尼埃 疾病）、噪声引起的听力损失和耳鸣。

The overall aim of this project is to analyze the membrane properties of several isolated cell types from the inner ear using the whole cell voltage clamp technique. The cell types (outer hair cells [OHCs], Type II spiral ganglion cells, and Deiter cells) were chosen because they all functionally relate (directly or indirectly to the OHC system. This system has recently been shown to be very important for normal cochlear function. Several properties of OHCs will be studied, including their inward Ca+2 currents, the mechanism of gadolinium induced block of voltage induced OHC motility, and the frequency response of OHC motility. These evaluations will be made by measuring the voltage dependence of these currents and motility blocking effects, by comparing the motility characteristics to those of stretch receptors, and by measuring OHC mechanical response magnitude induced by AC stimuli. The ionic conductances of Type II spiral ganglion cells and Deiter cells will be analyzed to determine their roles in the OHC system. Specifically, Deiter cells, which are coupled to other supporting cells via gap junctions, will be evaluated via voltage clamp to determine whether they possess mechanisms (e.g., inwardly directed K+ currents) which might aid in the ionic homeostasis of the organ of Corti. Type II spiral ganglion cells will be evaluated in similar fashion to determine whether they possess the ionic conductances necessary for the transfer of acoustic information to the central nervous system. Since no electrophysiological information is available on this cell type, this is an important issue. Understanding these phenomena will shed light upon the role that OHCs play in fine frequency tuning within the organ of Corti via mechanical feedback mechanisms. They will also help elucidate the effects of pathologies of the outer hair cell system, including ionic imbalances (e.g., Meniere's disease), noise induced hearing loss, and tinnitus.