新生大鼠大脑皮层神经元胞体ATP激活的离子通道及其特性

用膜片箝技术的细胞贴附式和内面向外式，在机械分离的新生ＳＤ大鼠的大脑皮层神经元上，记录到ＡＴＰ激活的离子通道。此通道的电导为３２ｐＳ，对Ｎａ~＋，Ｋ~＋和Ｃｓ~＋无选择性通透，而对Ｃｌ~－不通透。通道开放时间分布直方图多数需用双指数拟合，少数可用单指数拟合；通道关闭时间分布直方图均需用双指数拟合。通道的平均开放时间和开放概率均不依赖于膜电位；但通道的开放概率随着激动剂ＡＴＰ浓度的增加而增大。当电极内液无ＡＴＰ时，无通道电流。六烃季胶和美加明不能阻断此通道。上述结果表明，新生大鼠的大脑皮层神经元胞体可能存在ＡＴＰ激活的离子通道。

ATP-ACTIVATED SINGLE ION CHANNEL AND ITS PROPERTIES IN CEREBRAL CORTICAL NEURONS OF NEONATAL RAT

In the present study, single channel currents were recorded from single neurons dissociated from the cerebral cortex of neonatal SD rat by the cell-attsched and inside-out modes of patch clamp technique. ATP-activated channels with a conductance of 32 pS were often recorded and permeable to Na , K and Cs , hilt not to Cl-. Most of open time distribution histograms were fitted by two exponential components and few by one, whereas closed time distribution histograms were fitted by two exponential components. Both mean open time and open probability were independent of membrane potential,but the latter increased with increasing ATP concentration. The channel activity was recorded only in the presence of pipette solution containing ATP, and its conductanceand open probability were not affected by ACh N-receptor antagonist hexamethoniumand mecamylamine. It is suggested that ATP-activated ion channels probably existin the cerebral conical neurons of neonatal rat.