成年大鼠海马CA1区锥体细胞KATP通道的特性

为了解成年大鼠海马CA1区锥体细胞KATP通道的特性,实验采用膜片钳技术的内面向外式记录法,在急性分离的CA1区锥体神经元上,研究了可被胞浆侧ATP所抑制的钾离子单通道的特性,当细胞膜内外两侧的K^ 浓度均为140mmol/L时,通道的电导为63pS,翻转电位为1．71mV,通道呈弱向内向整流性,在负钳制电位时,通道开放时常被短时的关闭所打断,而在正钳制电位时,这种短时程的关闭状态明显少于负钳制电位时,但通道开放概率未见明显的电压依赖性,ATP对通道活动的抑制作用呈浓度依赖性,抑制通道活动50％的ATP浓度为0．1mmol/L.KATP通道的特异性阻断剂tolbutamide(甲糖宁,1mmol/L)可完全阻断通道的活动,而KATP通道开放剂diazoxide(二氮嗪,1mmol/L）则不增强通道的活动。

Properties of KATP channels in hippocampal CA1 pyramidal neurons from adult rats

Properties of KATP channels in acutely dissociated hippocampal CA1 pyramidal neurons of adult rats were studied with inside-out patch-clamp technique. With symmetrical 140 mmol/L K+ on both sides of the excised membrane, the single-channel conductance was approximately 63 pS and the reversal potential was 1.71 mV. These channels had a weak inward rectifying property. Channels' openings interrupted by shorter closed intervals were more frequently observed at negative holding potential than at positive holding potential. However, noticeable voltage dependence was not found in channel open probability. ATP applied at the cytosolic side inhibited channel activity in a concentration-dependent manner with an IC50 of 0.1 mmol/L. Sulphonyluren tolbutamide (1 mmol/L), a specific KATP channel blocker, added to the bath completely suppressed the channel activity, while diazoxide (1 mmol/L), a KATP channel opener, had no apparent effect.