体外培养新生大鼠大脑皮层星形神经元钾通道的特性及膜外钾离子浓度对其影响

用膜片钳技术中的细胞贴附方式和内面向外方式，首次在新生大鼠大脑皮层星形神经元胞体膜上记录到一类电压依赖性钾通道。此通道可被２０ｍｍｏｌ／Ｌ ＴＥＡ，５ｍｍｏｌ／Ｌ Ｂａ＾２＋，１４０ｍｍｏｌ／Ｌ Ｃｓ＾＋阻断，不受２０ｍｍｏｌ／Ｌ４－ＡＰ影响，其激活不依赖Ｃａ＾２＋。膜外钾离子浓度对通道的特性有显著的影响，逆转电位随Ｋ＾＋的增大而增大，并表现出一定的饱和现象，两者的对数呈线性关系；同一驱动电位下，

PROPERTIES OF SINGLE POTASSIUM CHANNEL IN CULTURED NEW BORN RAT CORTICAL STAR-SHAPE NEURONS AND THE EFFECTS OF EXTRACELLAR POTASSIUM CONCENTRATION ON THEM

Using cell-attached and inside-out configuration of patch damp, we record a type of voltage-gated potassium channels in the cell membrane of cultured star-shape neurons of the new born rat cortex. The channel can be blocked by 20mmol/L TEA, 5mmol/L Ba2+ and 140mmol/L Cs+, but not by 20mmol/L 4-AP. No Ca2+ is reguired for activation. Extracellar potassium concentration (K+]0) has significant effects on the channel's properties. The relationship between the reserval potential and K+]0 is in accordance with the Nernst equation.The channel conductance increases with increasing K+]0 till it is saturted, and the relation of the double-logarithm of them are lined. Under the same driving potential, the mean open time and the open probability increase with increasing of K+]0, but the mean close time is just the opposite.