双氢链霉素改变适应性并阻断鸡耳蜗毛细胞的机械电换能器。

Dihydrostreptomycin modifies adaptation and blocks the mechano-electric transducer in chick cochlear hair cells.

作者信息

Kimitsuki T, Ohmori H

机构信息

National Institute for Physiology Sciences, Okazaki, Japan.

出版信息

Brain Res. 1993 Oct 8;624(1-2):143-50. doi: 10.1016/0006-8993(93)90072-u.

DOI:10.1016/0006-8993(93)90072-u

PMID:7504569

Abstract

Block of the mechano-electric transduction (MET) channel by dihydrostreptomycin (DHSM) and its effects on adaptation were investigated in dissociated cochlear hair cells of the chick with a whole-cell patch-electrode voltage clamp technique. DHSM reversibly blocked the MET channel in a dose- and voltage-dependent manner. At -50 mV, DHSM blocked the MET channel with a Hill coefficient of approximately 1 and a dissociation constant (Kd) of 2 x 10(-5) M. Rate constants for the DHSM to bind and to unbind to and from the channel were estimated, and could be larger than 5 x 10(7) M-1.s-1 and 1 x 10(3) s-1, respectively. The amplitude of MET current decreased during a constant displacement of the hair bundle. This current decay, the adaptation, disappeared in the DHSM medium. The disappearance and the emergence of adaptation did not have a simple relationship with the block of MET channel by DHSM, but appeared with some delay.

摘要

采用全细胞膜片钳电压钳技术，在雏鸡分离的耳蜗毛细胞中研究了二氢链霉素（DHSM）对机械电转导（MET）通道的阻断作用及其对适应性的影响。DHSM以剂量和电压依赖性方式可逆地阻断MET通道。在-50 mV时，DHSM以约1的希尔系数和2×10⁻⁵ M的解离常数（Kd）阻断MET通道。估算了DHSM与通道结合和解离的速率常数，分别可能大于5×10⁷ M⁻¹·s⁻¹和1×10³ s⁻¹。在毛束持续位移期间，MET电流的幅度减小。这种电流衰减即适应性，在DHSM介质中消失。适应性的消失和出现与DHSM对MET通道的阻断没有简单的关系，而是有一定延迟出现。