Analysis of synaptic mechanisms in cochlear hair cells by measuring membrane capacitance

通过测量膜电容分析耳蜗毛细胞的突触机制

• 批准号: 13671789
• 负责人: KIMITSUKI Takashi
• 金额: $ 2.18万
• 依托单位: 宮崎医科大学
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13671789/
• 关键词: cochlea; inner hair cell; membrane capacitance; endocytosis; exocytosis; ion channel; potassium current; frequency analysis; トランスデューサー電流

We measured the membrane current possessing the properties of mechano-electric transducer current in isolated inner hair cells of guinea-pig cochlea. In free-standing hair bundle, depolarization to +80 mV evoked a stable outward current attributable to the opening of transducer channels and repolarization to -80 mV evoked a transient inward current indicating adaptation followed. Time constant of adaptation increased as the membrane potential depolarized. Dihydrostreptomycin diminished both the outward and inward currents.Cyclopiazonic acid (CPA) is a reticulum-like intracellular Ca^<2+> store depletory, which raises intracellular Ca^<2+> concentration. The effect of CPA on membrane currents in isolated inner hair cells (IHCs) from guinea-pig cochlea was investigated by the patch-clamp technique in the whole-cell configuration. Four out of eight IHCs showed an augmentation of the currents and the other four cells showed an inhibition of the currents by extracellular CPA application. The activation kinetics of outward currents were not changed by CPA. Three out of four IHCs obtained from the basal part of the cochlea demonstrated augmentation, whereas three out of four IHCs from the apical part demonstrated inhibition of the currents. This result suggests that Ca^<2+>-activated currents were dominant in the basal IHCs of the cochlea.

在离体豚鼠耳蜗内毛细胞上测量了具有机电转换器电流特性的膜电流。在独立的毛束中，去极化至+80 mV诱发了归因于换能器通道开放的稳定外向电流，并且复极化至-80 mV诱发了指示随后的适应的瞬时内向电流。适应时间常数随膜电位去极化而增加。环匹阿尼酸（Cyclopiazonic acid，CPA）是一种网状的细胞内钙库，可使细胞内Ca^2+浓度升高。用膜片钳技术研究了CPA对豚鼠耳蜗内毛细胞膜电流的影响。八个IHC中的四个显示出电流的增强，并且其他四个细胞显示出通过细胞外CPA应用的电流的抑制。CPA不改变外向电流的激活动力学。从耳蜗的基底部分获得的四个IHC中有三个表现出增强，而从顶端部分获得的四个IHC中有三个表现出电流抑制。这一结果表明，耳蜗基底毛细胞中Ca^<2+>激活电流占主导地位。

项目成果

Takashi Kimitsuki et al.: "Membrane current possessing the properties of a mechano-electric transducer current in inner hair cells of guinea-pig cochlea."Brain Research. 915.1. 101-103 (2001)

Takashi Kimitsuki 等人：“豚鼠耳蜗内毛细胞中的膜电流具有机电换能器电流的特性。”大脑研究。