中文摘要：

目的为最终揭示大鼠背根神经节神经元上天然瞬时外向钾通道的结构与功能调节提供依据。方法采用双极电压钳技术记录非洲爪蟾卵母细胞上表达的Kv4．2电流，用全细胞膜片钳技术记录大鼠背根神经节神经元上瞬间外向钾电流（IA），并对二者进行动力学特征的比较。结果背根神经节神经元上IA和Kv4．2通道电流①均具有明显的A型电流特征；②半数最大激活电位分别为（-29．5±3．1）mV和（-3．9±1．0）mV；③半数最大失活电位分别为（-78．5±3．4）mV和（-48．5±0．6）mV,④失活后再激活恢复时间常数（τ）分别为（32．0±4．8）ms和（71．4±13．2）ms。结论Kv4．2通道电流可能是背根神经节神经元上IA电流的主要成分，但不是唯一成分。

英文摘要：

Objective To determine the functional properties of Kv4.2 expressed in Xenopus oocytes in comparison with native transient potassium outward current （IA） in the DRG neurons of rats. Methods Two-electrode voltage clamp and whole cell voltage clamp techniques were used to record Kv4.2 current and IA respectively. Results IA in DRG neurons and Kv4.2 expressed in Xenopus oocytes both displayed ＂A＂-type current properties. The activation curves of IA and Kv4.2 were better fitted by simple Boltzmann function with V1/2 （-29.5±3.1） mV for IA and V1/2 （-3.9±1.0） mV for Kv4.2. The steady-state inactivation curves of IAhad a midpoint of （-78.5±3.4） mV. The voltage-dependence of inactivation for Kv4.2 exhibited a midpoint of （-48.5±0.6） mV. The time constants （τ） of recovery from inactivation of IA and Kv4.2 were （32.0±4.8） ms and （71.4±13.2） ms, respectively. Conclusion Kv4.2 is probably a major component contributing to IA in DRG neurons.