MECHANICS OF THE COCHLEAR OUTER HAIR CELL

本研究的目的是调查的力学外毛 细胞（OHC），并确定特定细胞器的贡献 （亚表面池，皮质晶格和细胞质膜的 侧壁）和细胞质对细胞的机械性能的影响。 这些知识对于理解OHC在以下方面的作用是必要的 耳蜗力学，特别是在被动和主动机械 过滤 该项目的一个具体目标是表征OHC轴向 力-位移函数;该函数对于评估 外毛细胞对周围环境施加的力的大小 结构作为OHC电运动的结果。 协调实验 和理论研究将针对调查的弹性 以及细胞的粘弹性。 高分辨率视频显微镜 将用于记录分离的豚鼠OHC对 通过贴片移液管进行微量移液管抽吸和细胞膨胀，以及 观察细胞质中珠子的热驱动运动。 位移 将从视频的时间推移分析中测量每个刺激 图像. 这项研究的大部分集中在横向的微观力学 墙 将采用多种药物治疗来改变 构成侧壁的亚细胞成分。 机械 未经处理的OHC的性能将与 经细胞培养处理的细胞。 OHC的理论模型作为一个 两端加盖的充满流体的粘弹性圆柱壳 将被开发来分析实验结果。 该模型将 将细胞的径向刚度与其压力膨胀响应联系起来 轴向力-位移函数。 理论分析将 也可用于分析直接测量的动态结果， 力-位移函数在孤立细胞的轴向加载期间。 的 结果将提供静态下的轴向力-位移函数， 动态条件，并允许精确确定OHC驱动 力对耳蜗力学，这将有助于描绘机械 OHC对无源和有源机械滤波的贡献。 这些研究的结果将量化OHC在 细胞和亚细胞水平，并作为研究的基础， OHC电活动的分子机制。 知识 微观结构要素及其在OHC力学中的作用意义 将提高我们对OHC如何促进哺乳动物 健康和疾病中的听力。

The goal of this research is to investigate the mechanics of outer hair cell (OHCs) and to determine the contribution of specific organelles (subsurface cisterna, cortical lattice and cytoplasmic membrane of the lateral wall) and the cytoplasm to the mechanical properties of the cell. This knowledge is necessary for understanding the role of the OHC in cochlear mechanics, specifically in passive and active mechanical filtering. A specific goal of the project is to characterize the OHC axial force-displacement function; this function is crucial for evaluating the magnitude of the forces that outer hair cells exert on the surrounding structures as the result of OHC electromotility. Coordinated experimental and theoretical studies will be directed towards investigating the elastic and viscoelastic properties of the cell. High resolution video microscopy will be used to record the response of isolated guinea pig OHCs to micropipet aspiration and cell inflation through a patch pipet, and to observe thermally driven movement of beads in the cytoplasm. Displacements from each stimulus will be measured from time-lapse analysis of video images. Much of this research focuses on the micromechanics of the lateral wall. A variety of pharmacological treatments will be applied to modify the subcellular components that make up the lateral wall. The mechanical properties of untreated OHCs will be compared with those of pharmacologically treated cells. A theoretical model of the OHC as a fluid-filled viscoelastic cylindrical shell that is capped at both ends will be developed to analyze the experimental results. The model will relate the radial stiffness of the cell and its pressure-inflation response to the axial force-displacement function. The theoretical analysis will also be applied to analyze the results of direct measurements of dynamic force-displacement function during axial loading of isolated cells. The results will provide the axial force-displacement function under static and dynamic conditions and permit a precise determination of the OHC driving force on cochlear mechanics, which will help delineate the mechanical contribution of the OHC to both passive and active mechanical filtering. The results of these studies will quantify the mechanics of the OHC at the cellular and subcellular level and serve as a basis for research on the molecular mechanisms of OHC electromotility. Knowledge of the microstructural elements and their functional significance in OHC mechanics will enhance our understanding of how the OHC contributes to mammalian hearing in health and disease.