THE MECHANICAL-PROPERTIES OF CILIARY BUNDLES OF TURTLE COCHLEAR HAIR-CELLS
THE MECHANICAL-PROPERTIES OF CILIARY BUNDLES OF TURTLE COCHLEAR HAIR-CELLS
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DOI：
10.1113/jphysiol.1985.sp015750
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发表时间：
1985-01-01
影响因子：
5.5
通讯作者：
FETTIPLACE, R
中科院分区：
文献类型：
--
作者：
CRAWFORD, AC;FETTIPLACE, R
在细胞内同时记录细胞膜电位的过程中，通过用已知顺应性的柔性玻璃纤维偏转毛细胞的纤毛束来检查海龟耳蜗毛细胞的机械行为。通过连接的光纤部分遮挡入射在光电二极管阵列上的光束来监测束运动。假设光电流的变化与束位移成比例。对于朝向动纤毛的1-100 nM的偏转，睫状束的刚度为约100 nm。6倍。10-4 N/m，纤维附着在束的顶部。当纤维被放置在纤维束的不同位置时，刚度降低了约。与距睫状体基部的距离的平方成反比。这表明束绕着靠近细胞顶极的轴旋转，并且具有约2 × 104的旋转刚度。10-14 Nm/rad。柔性纤维固定端的阶跃位移导致毛细胞膜电位执行阻尼振荡;不同细胞的振荡频率范围为20至320 Hz。朝向动纤毛的位移总是产生膜去极化。初始振荡的振幅随着位移增加到100 nm，然后饱和。对于几个纳米的小位移，毛细胞的机电灵敏度为. apprx。0.2 mV/nm。由柔性纤维传递的力阶导致束位置与受体电位同步地经历阻尼振荡。大的去极化电流可减弱受体电位，从而消除机械振荡。当放置对束，纤维的自发运动增加，成为准正弦的振幅几倍，从系统的顺应性预期。毛束明显地驱动纤维。海龟耳蜗毛细胞具有主动力产生机制。
The mechanical behavior of the ciliary bundles of hair cells in the turtle cochlea was examined by deflecting them with flexible glass fibers of known compliance during simultaneous intracellular recording of the cell''s membrane potential. Bundle motion was monitored through the attached fiber partially occluding a light beam incident on a photodiode array. The change in photocurrent was assumed to be proportional to bundle displacement. For deflexions of 1-100 nM towards the kinocilium, the stiffness of the ciliary bundles was .apprx. 6 .times. 10-4 N/m, with the fiber attached to the top of the bundle. When the fiber was placed at different positions up the bundle, the stiffness decreased .apprx. as the inverse square of the distance from the ciliary base. This suggests that the bundles rotate about an axis close to the apical pole of the cell and have a rotational stiffness of about 2 .times. 10-14 Nm/rad. Step displacements of the fixed end of the flexible fiber caused the hair cell''s membrane potential to execute damped oscillations; the frequency of the oscillations in different cells ranged from 20 to 320 Hz. Displacements towards the kinocilium always produced membrane depolarization. The amplitude of the initial oscillation increased with displacements up to 100 nm and then saturated. For small displacements of a few nanometres, the hair cell''s mechanoelectrical sensitivity was .apprx. 0.2 mV/nm. Force steps delivered by the flexible fiber caused the bundle position to undergo damped oscillations in synchrony with the receptor potential. The mechanical oscillations could be abolished with large depolarizing currents that attenuated the receptor potential. When placed against a bundle, a fiber''s spontaneous motion increased and became quasi-sinusoidal with an amplitude several times that expected from the compliance of the system. The hair bundle evidently dirves the fiber. Turtle cochlear hair cells contain an active force generating mechanism.