Brownell W E
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2195.
Ear Hear. 1990 Apr;11(2):82-92. doi: 10.1097/00003446-199004000-00003.
Outer hair cell electromotility is a rapid, force generating, length change in response to electrical stimulation. DC electrical pulses either elongate or shorten the cell and sinusoidal electrical stimulation results in mechanical oscillations at acoustic frequencies. The mechanism underlying outer hair cell electromotility is thought to be the origin of spontaneous otoacoustic emissions. The ability of the cell to change its length requires that it be mechanically flexible. At the same time the structural integrity of the organ of Corti requires that the cell possess considerable compressive rigidity along its major axis. Evolution appears to have arrived at novel solutions to the mechanical requirements imposed on the outer hair cell. Segregation of cytoskeletal elements in specific intracellular domains facilitates the rapid movements. Compressive strength is provided by a unique hydraulic skeleton in which a positive hydrostatic pressure in the cytoplasm stabilizes a flexible elastic cortex with circumferential tensile strength. Cell turgor is required in order that the pressure gradients associated with the electromotile response can be communicated to the ends of the cell. A loss in turgor leads to loss of outer hair cell electromotility. Concentrations of salicylate equivalent to those that abolish spontaneous otoacoustic emissions in patients weaken the outer hair cell's hydraulic skeleton. There is a significant diminution in the electromotile response associated with the loss in cell turgor. Aspirin's effect on outer hair cell electromotility attests to the role of the outer hair cell in generating otoacoustic emissions and demonstrates how their physiology can influence the propagation of otoacoustic emissions.
外毛细胞电运动是一种快速的、产生力的长度变化，它对电刺激作出反应。直流电脉冲可使细胞伸长或缩短，而正弦电刺激则导致在声学频率下的机械振荡。外毛细胞电运动的潜在机制被认为是自发性耳声发射的起源。细胞改变其长度的能力要求它在机械上具有柔韧性。与此同时，柯蒂氏器的结构完整性要求细胞沿其主轴具有相当大的抗压刚度。进化似乎已经找到了对外毛细胞所施加的机械要求的新解决方案。细胞骨架成分在特定细胞内区域的分离促进了快速运动。抗压强度由一种独特的液压骨架提供，其中细胞质中的正静水压力稳定了具有周向拉伸强度的柔性弹性皮质。为了使与电运动反应相关的压力梯度能够传递到细胞的两端，需要细胞膨压。膨压的丧失会导致外毛细胞电运动的丧失。与患者中消除自发性耳声发射的水杨酸盐浓度相当的水杨酸盐会削弱外毛细胞的液压骨架。与细胞膨压丧失相关的电运动反应会有显著降低。阿司匹林对外毛细胞电运动的影响证明了外毛细胞在产生耳声发射中的作用，并展示了它们的生理学如何影响耳声发射的传播。
