豚鼠耳蜗血管纹周细胞电生理特性的研究

Study on the electrophsiological properties in the stria vascularis pericytes in cochlear of guinea pig

目的 了解豚鼠耳蜗血管纹毛细血管周细胞的电生理特性以及周细胞膜上钾通道的类型.方法 通过免疫荧光技术标记豚鼠耳蜗血管纹毛细血管周细胞相关蛋白,结合形态学特点进行单个周细胞的鉴定.利用全细胞膜片钳技术观察周细胞的基本电生理特性,并探讨给予钾通道阻断剂后周细胞外向电流的变化.结果 通过免疫荧光技术标记周细胞结蛋白desmin,结合形态学进行鉴定,发现豚鼠耳蜗血管纹存在周细胞,消化成单个周细胞后,形态保持完好.周细胞的膜电容为（5.9 ±0.3）pF,膜电阻为（2.2±0.3） GΩ,膜静息电位为（-30.9±1.2）mV;当指令电压为0 mV、＋ 20 mV、＋40 mV、＋60 mV时,周细胞的电流密度分别为（3.2±0.7）、（10.6±1.0）、（15.7±0.9）和（21.3±1.2）pA/pF.单个周细胞膜电流I/V关系呈明显的外向整流特性,并对1 mmol/L四乙胺和1 mmol/L 4-氨基吡啶敏感.给四乙胺前后的外向电流值分别为（296.2±35.9）pA和（163.7±16.8）pA,差异具有统计学意义（n=6,P＜0.01）;给4-氨基吡啶前后的外向电流值分别为（248.7±39.8）pA和（158.0±38.0） pA,差异具有统计学意义（n=6,P＜0.05）.结论 豚鼠耳蜗血管纹周细胞上的钾离子通道为大电导钙激活钾通道和电压依赖性钾通道.

Objective The purpose of this paper was to study the electrophysiological properties and the type of potassium channels on cell membrane in the stria vascularis pericytes in cochlear of guinea pig. Methods Firstly examined the expression of the stria vascularis pericytes by desmin, a marker of pericytes, in cochlear of guinea pig with immunofluorescent method. Using whole-cell patch clamp recording techniques to observe electrophysiological properties in the cochlear pericytes in stria vascularis of guinea pig. Results Pericytes were predominately distributed in the capillaries of cochlea. The average membrane capacitance, resistance, and potential of a single pericyte in stria vascularis were（5.9 ±0. 3 ） pF, （2. 2 ±0. 3 ） GΩ and （ - 30. 9 ±1.2） mV, respectively by using patch clamp technique. In addition, the average current density of cochlear pericyte was voltage-sensitive （ Vh from 0 to ＋ 60 mV, in 20 mV steps ）. The pericytes exhibited outward current and this property could be blocked by TEA （tetraethylammonium） 1 retool/L, a large-conductance calcium-activated potassium channel（ BKCa）inhibitor and 4-AP （4-aminopyridine） 1 mmol/L, a voltage-dependent K ＋ channels（ Kv ） channel blocker. TEA blocked the outward current from （296. 2± 35.9）pA to （163.7 ±16.8）pA and 4-AP blocked the outward current from （248.7±39.8）pA to （158.0±38.0）pA. Conclusion These results suggest that pericytes in stria vascularis have BKCa and Kv channels.