豚鼠耳蜗单离外毛细胞外向钾电流的特性

目的：探讨豚鼠耳蜗单离外毛细胞（ＯＨＣ）钾电流（Ｉｋ）的正常值及其特性。方法：应用膜片钳全细胞记录技术及多种辅助方法,测试在不同细胞内、外液和电压刺激条件下的Ｉｋ、钾尾电流（Ｉｋｔａｉｌ）和反转电位。结果：Ｉｋ具有明显的电压依赖性和时间依赖性,在２０ｍｓ内达峰值,平均激活电压约为－３２．７ｍＶ,从激活电压至０电压时Ｉｋ增长最快,在４０ｍＶ时接近饱和。正常条件下Ｉｋ无明显“ｒｕｎ－ｄｏｗｎ现象”。细

Characteristics of outward potassium currents of outer hair cell isolated from the guinea pig cochlea

Objective:To study the normal values and characteistics of potassium currents (I k) of outer hair cell (OHC) isolated from the guinea pig cochlea.Method:With the patch clamp whole cell recording technique and several supplementary methods,the I k potassium tail current (I ktail ) and reverse potential were recorded under the conditions of the various intra and extracellular solutions and various command voltage stimuli.Result:I k possessed evident voltage and time dependence. The peak current appeared within 20 ms. The average activated potential was approximately - 32.7 mV. I k increased fastestly and greatestly in the voltage range from the activating voltage to 0 mV,and it approached saturation approximately at 40 mV. In normal status,no distinct "run down phenomenon" of I k appeared. When 10 mmol/L KCl was put in extracellular solution,I k would increased. Nevertheless,when K + was substituted by Cs + in the intracellular solution,I k would disappear. The reversal potential, - 64.0 mV in average approximately,could be measured by means of I ktail . Futhermore,by means of slope command voltage stimuli,the processes of I k activation,increment or decrement and saturation could be observed.Conclusion:As showing by the above described features,I k possessed the characteristics of both an inward rectifier and rapid element of a delay rectifier,which would play important role in frequency tuning,mechanic electrical transduction,maintenance of resting potential and excitement in OHC.