TRANSDUCTION MECHANISM OF VERTEBRATE HAIR CELLS

最不了解内耳的过程，即内耳的转导 机械刺激转化为电反应，也是 最常见的是听觉和前庭系统的严重病理。 我们建议使用细胞生物学和膜生物物理学的技术 为了研究转导的正常运作方式以及它是如何受到 临床上一类重要的耳毒性药物氨基糖苷类 抗生素。这些研究将有助于理解 转导，从长远来看，将有助于合理设计 预防或治疗氨基糖苷类耳毒性， 听觉创伤、老年性耳聋和梅尼埃病。毛细胞来自于 牛蛙的内耳将在体外保持在球囊内 上皮细胞或被酶解离的孤立细胞。两国关系 在细胞对机械敏感的发束的偏转和 由此产生的受体电位和膜电导将发生变化 仔细研究各种频率、幅度和频率的刺激 波形。研究结果将对LESS的运行建模有一定的参考价值 可接近的器官，如哺乳动物的耳蜗器和前庭器官。 发生转导的亚细胞位置将由 测量毛束周围的电流模式并通过 激活转导定位钙离子内流 频道。换能器离子通道的渗透率将为 用放射性三(羟甲基)氨基甲烷填充的离子，其 细胞内蓄积也可以用来标记受刺激的毛细胞。 作为阐明氨基糖苷类药物作用机制的一步 抗生素损伤毛细胞、作用部位及结合动力学 这些药物将被确定。应该有可能了解到 耳毒性抗生素干扰细胞新陈代谢或发挥其作用 对膜受体结合的影响。电压钳实验 将在分离的毛细胞上进行，以估计 单个转导通道的电导和识别其他 影响受体形态的膜电导机制 潜力。

The least understood process of the inner ear, the transduction of mechanical stimuli into electrical responses, is also the stage at which severe pathology of the auditory and vestibular systems most often arises. We propose to employ the techniques of cell biology and membrane biophysics to investigate how transduction normally operates and how it is affected by a clinically important class of ototoxic agents, the aminoglycoside antibiotics. These studies will contribute to an understanding of transduction which, in the long term, will aid in the rational design of prophylaxis or treatment for conditions such as aminoglycoside ototoxicity, acoustic trauma, presbyacusis, and Meniere's disease. Hair cells from the bullfrog's inner ear will be maintained in vitro either within the saccular epithelium or as solitary cells dissociated by enzymes. The relationship between deflection of a cell's mechanosensitive hair bundle and the resultant receptor potential and membrane conductance changes will be carefully studied with stimuli of a variety of frequencies, amplitudes, and waveforms. The results will be of value in modeling the operation of less accessible organs such as the mammalian cochlea and vestibular apparatus. The subcellular site at which transduction occurs will be sought both by measuring the pattern of current flow around the hair bundle and by localizing the influx of calcium ion through activated transduction channels. The permeability of the transducer's ionic channel will be plumbed with radioactive tris(hydroxymethyl) aminomethane, an ion whose intracellular accumulation may also serve to label stimulated hair cells. As a step toward elucidation of the mechanism whereby aminoglycoside antibiotics damage hair cells, the site of action and binding kinetics of these drugs will be determined. It should be possible to learn whether ototoxic antibiotics interfere with cellular metabolism or exert their effects upon binding to a membrane receptor. Voltage-clamp experiments will be performed on isolated hair cells in order to estimate the conductance of individual transduction channels and to identify other membrane conductance mechanisms that affect the form of the receptor potential.