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目的 :观察豚鼠耳蜗单离外毛细胞 (OHC)的电生理特性 ,记录不同长度OHC的外向整流钾电流 ,分析区分外向整流钾电流所包含的通道电流成分 ,研究外向整流钾电流的动力学特征。方法 :采用酶消化法及机械分离OHC。运用全细胞膜片钳技术 ,在电压钳下记录K+ 通道电流。结果 :OHC的全细胞膜电容为 (30 .96±2 .79) pF(n =2 9) ,零电流电位 (30± 2 .1)mV(n =16 ) ,反转电位为 (- 5 1.6 7± 1.84 )mV(n =9)。不同长度OHC的外向整流钾电流存在系统差异 ,短OHC表现出大的钾电导 ,长OHC则相反。 10 0 μmol/L的氯化镉 (Cd Cl2 )抑制了OHC外向整流钾电流的最大电流幅度的 6 0 % ,且改变了电流的动力学特征 ,对峰电流的影响明显大于稳态电流 (P<0 .0 1,n =5 ) ;1mmol/L的四氨基吡啶 (4 AP)抑制了最大电流幅度的 4 3% ,没有改变电流的动力学特征。外向整流钾电流的激活符合Boltzmann方程 ,V1/ 2 =(- 11.0 7± 0 .2 6 )mV ,S =(6 .6 2± 1.74 )mV(n=13)。结论 :外向整流钾电流包含有钙离子激活的钾离子电流、外向延迟整流钾电流和A型电流
OBJECTIVE: To observe the electrophysiological characteristics of single isolated outer hair cells (OHCs) of guinea pig cochlea and record the outward rectifier potassium current of OHC with different length. The current components contained in outward rectifier potassium current were analyzed to study the kinetic characteristics of outward rectifier potassium current . Methods: The enzyme digestion and mechanical separation of OHC. Using whole-cell patch clamp techniques, K + channel current was recorded under voltage clamp. RESULTS: The whole cell membrane capacitance of OHC was (30.96 ± 2.79) pF (n = 29), the zero current potential was (30 ± 2.1) mV (n = 16) 7 ± 1.84) mV (n = 9). There are systematic differences in outward rectified potassium currents with different lengths of OHC, with short OHC showing large potassium conductance and long OHC being the opposite. CdCl 2 at 10 μmol / L inhibited the maximum current amplitude of outward rectification potassium current by 60%, and changed the kinetic characteristics of current, which greatly affected the peak current (P <0. 01, n = 5); 1 mmol / L tetraaminopyridine (4 AP) inhibited 43% of the maximum current amplitude and did not change the kinetic characteristics of the current. The activation of outward rectified potassium current is in accordance with the Boltzmann equation, V1 / 2 = (- 11.0 7 ± 0.26) mV, S = (6.26 ± 1.74) mV (n = 13). Conclusion: The outward rectifier potassium current contains potassium ion-activated potassium ion current, outward delayed rectifier potassium current, and type A current