老年大鼠耳蜗核钾离子通道在爪蟾卵母细胞中的表达

Potassium channel expression in Xenopus oocytes by messenger RNA from aged rat cochlear nucleus

目的观察爪蟾卵母细胞表达的老年大鼠耳蜗核电压依赖性离子通道电流的变化，为研究感音神经性聋听觉中枢离子通道的变化建立方法学基础。方法分别自青年和老年大鼠耳蜗核提取多聚腺嘌呤信使核糖核酸（ｍＲＮＡ），注入非洲爪蟾卵母细胞表达有功能的钾离子通道，并利用电压钳方法记录电压依赖性的离子通道电流。结果在注射老年大鼠耳蜗核ｍＲＮＡ的卵母细胞膜上记录到电压依赖性的钾离子通道电流最大幅度（２７８±３７ｎＡ，１６只），明显小于青年组（３６４±４２ｎＡ，１７只，Ｐ＜０００１）。

Objective To detect the change of voltage dependent on channels expressed in Xenopus oocytes by mRNA from aged rat cochlear nucleus so as to establish a methodological foundation for studying the changes of ion channels in auditory centre with sensorineural hearing loss. Methods Poly (A) +mRNAs isolated from the cochlear nucleus of the adolescent(2 3 months) and aged (20 36 months) rats by acid guanidinum thiocyanate phenol chloroform (AGPC) method and Promega's new magesphere technique were microinjected into Xenopus laevis oocytes to express functional ion channels. Voltage clamp technique was used to record the current of voltage dependent ion channels. Results Voltage dependent potassium channel was detected from oocytes injected with adolescent and aged rat cochlear nucleus mRNA. The maximum amplitude of potassium current detected in aged group was lower than that in adolescent group ( P <0 001). Conclusions The result indicates that the decrease of potassium channel function in aged rat cochlear nucleus may be related to presbycusis.