摘要
为了研究耳蜗外毛细胞的基本电生理特性，应用细胞膜片钳制技术对豚鼠耳蜗外毛细胞底侧膜的高电导的钾通道进行了初步研究。结果显示，其高电导钾通道有以下典型特征：①具有明显的电压依赖性。在膜去极化时，通道被激活，其去极化程度越高，通道活动越强。在非对称性钾浓度梯度下，其反转电位为－３０ｍＶ，斜率电导约１３３±３ｐＳ（ｎ＝５）；②通道活动能被特异性阻断剂四乙胺（ＴＥＡ）在较高浓度下（＞１０ｍｍｏｌ／Ｌ）阻断，ＴＥＡ的阻断效应呈浓度依赖性；③胞浆内钙浓度的增高，能显著激活该通道，增加其开放概率和平均开放时间。上述结果表明：豚鼠耳蜗外毛细胞存在着高电导的电压依赖的钙激活的钾通道。该研究为进一步开展通道活动的调控，以及药物等因素对通道活动影响的研究，提供了有价值的资料。
The basic electrophysiological characteristics of large conductance K + channels in the basolateral cell membrane of outer hair cells (OHC) from the guinea pig cochlea were studied with patch clamp technique. Acutely isolated OHC preparations were obtained by enzymatic digestion and excised patches were made in cell attached configuration to record single channel currents led by patch clamp micropipette and fed to patch clamp amplifier. Data were sampled and analyzed on line with a computer. The result showed that the typical properties of single channels of large conductance K + channels were: 1. The channel was activated by depolarization of membrane and it showed a marked voltage dependence. The channel had a unitary conductance of about 133 pS and the channel current reversed at about -30mV under asymmetrical K + concentration gradient. 2. Tetraethylammonium (TEA, >10 mmol/L), a potas sium channel blocker, dose dependently abolished the outward current. 3. The openprobability (Po) and mean open time of this channel was markedly increased with elevation of cytoplasmic Ca 2+ concentration. These results suggest that a population of voltage dependent and Ca 2+ activated K + channel exists in the basolateral membrane of OHC of the guinea pig; it is characterized by a very high unitary conductance and high sensitivity to Ca 2+ and is blocked by K + channel blocker. This work provided valuable basic materials for further study on the regulation and drug influence of the type of single channels.
出处
《华西医科大学学报》
CSCD
1996年第4期362-366,共5页
Journal of West China University of Medical Sciences
关键词
耳蜗
外毛细胞
钾通道
膜片钳
电生理
Cochlea outer hair cell
K + activated potassium channel
Patch clamp technique
