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豚鼠I型前庭毛细胞胆碱能受体通道特性

朱云, 孔维佳, 夏交, 张宇, 程华茂, 郭长凯

华中科技大学同济医学院附属协和医院耳鼻咽喉科.湖北,武汉 430022

摘要

该文旨在探讨豚鼠I型前庭毛细胞上有无胆碱能受体存在，并对其相应的离子通道特性进行研究。应用全细胞膜片钳技术检测急性分离的豚鼠I型前庭毛细胞对乙酰胆碱(acetylcholine, ACh)的反应。结果显示，7.5% (21/279)的I型前庭毛细胞对10---1000 #mu#mol/L ACh敏感，引发明显的外向电流。该电流对ACh的反应呈浓度依赖性，半数激活浓度(EC_(50))为(63.78±2.31) #mu#mol/L，但该电流为非电压依赖性。在--50 mV钳制电压和正常细胞外液中，100 #mu#mol/L ACh激活一持久缓慢的外向电流，电流幅值为(170±15) pA，该电流幅值依赖于胞外钙离子浓度，可被胞外给予的钙依赖性钾通道拮抗剂TEA阻断。I型前庭毛细胞的再次激活时间不小于1 min。长时间暴露在ACh的情况下，受体离子通道不会发生自发性关闭。以上结果提示，部分豚鼠I型前庭毛细胞上存在胆碱能受体，胞外给予ACh可激活一持久缓慢的外向电流，其胆碱能受体通道对于ACh的作用呈浓度依赖性和外钙依赖性、非电压依赖性或失敏性。该研究结果对于阐明前庭传出神经的功能及其作用机制，证实并揭示I型前庭毛细胞上存在传出神经递质受体以及日后临床指导眩晕疾病的康复治疗具有重要的意义。

关键词： 乙酰胆碱; 前庭; 毛细胞; 内耳; 膜片钳技术

Properties of cholinergic receptor--mediated ion channels on type I vestibular hair cells of guinea pigs

Zhu Yun, Kong Weijia, Xia Jiao, Zhang Yu, Cheng Huamao, Guo Changkai

Department of Otorhinolaryngology,Union Hospital,Tongji Medical College,Huazhong University of Science and Technology.Wuhan 430022,Hubei

Abstract

To confirm the existence of cholinergic receptors on type I vestibular hair cells (VHCs I) of guinea pigs and to study the properties of the cholinergic receptor-mediated ion channels on VHCs I, electrophysiological responses of isolated VHCs I to external ACh were examined by means of whole-cell patch-clamp recordings. The results showed that 7.5% (21/279) VHCs I were found to be sensitive to ACh (10-1000 #mu#mol/L). ACh generated an outward current in a steady, slow, dose-dependent [EC_(50) was (63.78±2.31) #mu#mol/L] and voltage-independent manner. In standard extracellular solution, ACh at the concentration of 100 μmol/L triggered a calcium-dependent current of (170±15) pA at holding potential of -50 mV，whose amplitude could be depressed by calcium-dependent potassium channel antagonist TEA added extracellularly. The time interval for the next complete activation of ACh-sensitive current was no less than 1 min. The ion channels did not shut off even when they were exposed to ACh for an extended period of time (8 min). The results suggest that dose-dependent, calcium-dependent and voltage-independent cholinergic receptors were located on a few of the VHCs I investibular epithelium of guinea pigs. The cholinergic receptors did not show desensitization to ACh. This work reveals the existence of efferent neurotransmitter receptors on VHCs I and helps in understanding the function of vestibular efferent nervous system, and may provide some useful information on guiding the clinical rehabilitative treatment of vertigo.

Key words: Acetylcholine;vestibular;hair cell;inner ear;Patch-clamp techniques

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引用本文：

朱云, 孔维佳, 夏交, 张宇, 程华茂, 郭长凯. 豚鼠I型前庭毛细胞胆碱能受体通道特性[J]. 生理学报 2008; 60 (3): 375-381.

Zhu Yun, Kong Weijia, Xia Jiao, Zhang Yu, Cheng Huamao, Guo Changkai. Properties of cholinergic receptor--mediated ion channels on type I vestibular hair cells of guinea pigs. Acta Physiol Sin 2008; 60 (3): 375-381 (in Chinese with English abstract).