INNER EAR--ION HOMEOSTASIS IN THE SENSORY EPITHELIUM

尽管所有细胞都调节它们的体积和细胞内 离子组成，内耳的细胞外环境是 可能呈现独特的毛细胞和相关的支持细胞 离子动态平衡的问题。听觉转导，它调节 离子流过毛细胞，对离子提出了额外的要求 这些细胞的动态平衡。相反，细胞内的离子组成 毛细胞的数量对它们的信号处理功能至关重要。因此， 毛细胞的动态平衡和信号处理特性是不可分割的 已链接。我们的总体目标是了解听觉中的离子动态平衡 感觉上皮及其与听觉传递的相互作用 耳蜗里的信号。动态平衡与信号处理之间的联系 可能具有重要的病理生理学意义。改变的细胞内 离子组成可能导致可逆和不可逆的变化 细胞。因此，它们可能在短期或长期内发挥关键作用 在许多情况下观察到听力损失，如梅尼埃病， 过度刺激，或耳毒性。 离子动态平衡及其与刺激诱导活动的关系 在鳄鱼相对简单的耳朵中进行了检查，其中 许多重要的变量都可以严格控制。感官 耳朵上皮将被放置在一个房间里，在这个房间里 细胞外液成分可以调节、控制刺激 接生，器官在显微镜下检查。离子敏感型 荧光染料将被用来测定细胞内的钠、钙、 以及毛细胞和支持细胞中的氢离子，在静止和 刺激。特定的离子传输过程很可能是 调节细胞内离子状态的重要因素也将是 通过观察激活或抑制个体的效果进行检查 离子进入和离子输出途径。这些研究将在 流体环境与完整动物相似，但不同 沐浴在感觉的内淋巴和外淋巴两侧的液体 上皮组织。结合对分离毛细胞的其他研究， 这些研究将帮助我们确定哪些离子动态平衡过程 依赖于毛细胞和支持细胞的组织 上皮组织。

Although all cells regulate their volume and their intracellular composition of ions, the extracellular environment of the inner ear is likely to present hair cells and associated supporting cells with unique problems for ion homeostasis. Auditory transduction, which modulates the flow of ions through hair cells, places additional demands on ion homeostasis by these cells. Conversely, the intracellular ion composition of hair cells is critical to their signal processing functions. Thus the homeostatic and signal processing properties of hair cells are inextricably linked. Our overall goal is to understand ion homeostasis in the auditory sensory epithelium and its interaction with transmission of auditory signals in the cochlea. The link between homeostasis and signal processing may have important pathophysiological implications. Altered intracellular ionic composition may lead to changes, both reversible and irreversible, in cells. Thus they may play critical roles in either short- or long-term hearing losses observed in many conditions such as Meniere's Disease, overstimulation, or ototoxicity. Ion homeostasis and its relation to stimulus-induced activity can be examined in the relatively simple ear of the alligator lizard, in which many important variables can be strictly controlled. The sensory epithelium of the ear will be placed in a chamber in which the extracellular fluid composition can be regulated, controlled stimuli delivered, and the organ examined microscopically. Ion-sensitive fluorescent dyes will be used to determine intracellular sodium, calcium, and hydrogen ions in hair cells and supporting cells, at rest and during stimulation. Specific ion-transport processes that are likely to be important in regulating intracellular ionic conditions will also be examined, by observing the effects of activating or inhibiting individual ion-entry and ion-export pathways. These studies will be performed in a fluid environment similar to that in the intact animal, with different fluids bathing the endolymphatic and perilymphatic sides of the sensory epithelium. In combination with other studies on isolated hair cells, these studies will help us to determine which ion-homeostasis processes depend on the organization of hair cells and supporting cells into an epithelium.