McLarnon J G
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Pflugers Arch. 1989 Apr;413(6):604-9. doi: 10.1007/BF00581809.
In this work the cell-attached and the excised membrane patch configurations have been used to determine properties of voltage-dependent K+ channels in cultured rat hypothalamic neurons. With inside-out patches and 140 mM K+ in the bath and 5 mM K+ in the pipette step depolarizations, in excess of 20 mV, elicited channel activity with at least two independent current levels. The larger current level was studied presently and current-voltage plots showed the conductance of the channel to be 48 pS; measurements of the changes in reversal potential with 140 mM or 5 mM K+ in the bathing solution indicated the channel to be selective for K+. The 48 pS channel was blocked when the bathing solution contained 140 mM Cs+. A concentration of 10 mM TEA applied to the outside of the patch in the outside-out configuration caused a loss of channel activity whereas 4-AP had no obvious effect on channel conductance or kinetics. Changes in the bath concentration of Ca2+ had no apparent effect to alter the frequency or duration of channel openings for inside-out patches. In some instances obvious changes in channel kinetics were observed during the course of an experiment; these included long periods where no channel opening events occurred and on a few other occasions progressive increases in mean open time. In cell-attached patch experiments with no TTX in the bathing medium to block sodium channels, action potentials could be recorded through capacitive coupling between the cell and the pipette.(ABSTRACT TRUNCATED AT 250 WORDS)
在这项研究中，采用细胞贴附式和膜片切除式配置来测定培养的大鼠下丘脑神经元中电压依赖性钾通道的特性。在膜片外翻式配置中，浴槽中为140 mM K⁺，移液管中为5 mM K⁺，阶跃去极化超过20 mV时，引发了通道活性，且至少有两个独立的电流水平。目前对较大的电流水平进行了研究，电流-电压图显示通道电导为48 pS；测量浴槽溶液中140 mM或5 mM K⁺时反转电位的变化表明该通道对K⁺具有选择性。当浴槽溶液含有140 mM Cs⁺时，48 pS通道被阻断。在膜片向外式配置中，将10 mM TEA施加到膜片外部会导致通道活性丧失，而4-AP对通道电导或动力学没有明显影响。浴槽中Ca²⁺浓度的变化对膜片外翻式配置中通道开放的频率或持续时间没有明显影响。在某些实验过程中观察到通道动力学有明显变化；这些变化包括长时间没有通道开放事件发生，以及在其他一些情况下平均开放时间逐渐增加。在浴槽培养基中没有TTX阻断钠通道的细胞贴附式膜片实验中，可以通过细胞与移液管之间的电容耦合记录动作电位。（摘要截取自250字）
