Trube G, Hescheler J
Pflugers Arch. 1984 Jun;401(2):178-84. doi: 10.1007/BF00583879.
Inward rectifying potassium single-channel currents were studied in the membrane of guinea pig cardiac myocytes. In isolated inside-out patches two different channels were observed: a channel of 25 pS conductance ([K+]o = 147 mM, T = 21 degrees C), if the solution at the cytoplasmic face of the patch contained 4 mM ATP and a channel of 80 pS conductance without ATP. The 25-pS-channel was also regularly seen in cell-attached patches (Sakmann and Trube 1984a,b), but the 80-pS-channel appeared only after inhibiting cellular metabolism by DNP. The percentage of time which the 25-pS-channel spent in the open state was 3.3 times larger in isolated patches compared to cell-attached patches. However, both types of single channel currents disappeared several minutes after the isolation of the patches. In contrast to the 25-pS-channel, the 80-pS-channel, which is activated by the lack of ATP, carried measurable outward currents saturating at 1.5 pA (inward rectification). It is suggested that the 80-pS-channel mediates part of the increase in potassium current during metabolic inhibition. The openings of this channel appeared in bursts. The mean open time was 1.6 ms and the mean duration of the gaps within bursts 0.33 ms at -80 mV.
对豚鼠心肌细胞膜上的内向整流钾单通道电流进行了研究。在分离的内面向外膜片中观察到两种不同的通道：一种是电导为25 pS的通道（[K⁺]ₒ = 147 mM，T = 21℃），前提是膜片胞质面的溶液含有4 mM ATP；另一种是无ATP时电导为80 pS的通道。25 pS通道在细胞贴附膜片中也经常可见（萨克曼和特鲁贝，1984a，b），但80 pS通道仅在通过二硝基苯酚抑制细胞代谢后出现。与细胞贴附膜片相比，分离膜片中25 pS通道处于开放状态的时间百分比大3.3倍。然而，两种类型的单通道电流在膜片分离后几分钟内均消失。与25 pS通道不同，由ATP缺乏激活的80 pS通道携带可测量的外向电流，在1.5 pA时达到饱和（内向整流）。有人提出，80 pS通道介导了代谢抑制期间钾电流增加的一部分。该通道的开放呈簇状出现。在-80 mV时，平均开放时间为1.6 ms，簇内间隙的平均持续时间为0.33 ms。
