大鼠肾脏近曲小管细胞基侧膜钾离子通道特性的离体研究

目的 探讨大鼠肾脏近曲小管细胞基侧膜钾离子通道生理学特性及其意义。方法 在体视显微镜直视下，从大鼠肾脏冠状切片中机械分离出肾小管，采用膜片钳单通道实验技术，探讨大鼠近曲小管基侧膜钾离子通道的生理学特性。结果 大鼠近曲小管细胞基侧膜上容易记录到一类低电导、有内向整流性的钾离子通道，该通道在多数膜片(81％)中自发性开放，无自发性开放的通道在压力增加时可被激活。在inside-out膜片，通道活动出现rn-down现象。通道开放时间常数分别为0．524ms与5．087ms,通道关闭的两个时间常数分别为1．029ms与16．500ms。结论 大鼠近曲小管细胞基侧膜广泛分布一类低电导的钾离子通道，具有牵张敏感性和化学敏感性双重特性，呈现两个开放状态与两个关闭状态的动力学特征。

A study of a K+ channel in the basolateral membrane of renal proximal tubule recorded from single rat nephron in vitro

Objective To study the physiological properties of a potassium channel in the basolateral membrane (BLM) of proximal tubule. Methods Nephrons were dissected from rat kidney under a stereoscopic microscope. The standard configuration for single channel tight seal patch clamp technique was used to record channel currents from the BLM. Results A kind of potassium channel with low conductance and inward rectification was easily recorded in the BLM of the proximal tubule. The channel current occurred spontaneously in 81% seals made on the BLM. In the patches, with no spontaneous channel activity, the channel current occurred when the pressure increased. In the inside out configuration, run down was present in channel activity. The open dwelling time constants of the potassium channel were 0.524 ms and 5.087 ms, while the closed dwelling time constants were 1.029 ms and 16.500 ms. Conclusion A type of potassium channels with low conductance, stretch sensibility and chemistry sensibility, presenting kinetic properties as two opening and two closing states, are widely distributed in the basolateral membrane of proximal tubule.