Draheim H, Repp H, Malettke N, Dreyer F
Rudolf-Buchheim-Institut für Pharmakologie der Justus-Liebig-Universität Giessen, Germany.
Pflugers Arch. 1994 May;427(1-2):17-23. doi: 10.1007/BF00585937.
Ion channels in normal and Rous sarcoma virus (RSV)-transformed chicken embryo fibroblasts (CEFs) were examined by using the patch-clamp technique. Three different types of ion channels were observed with single-channel conductances in symmetrical 140 mM KCl (with frequencies of occurrence in parentheses) of 186 pS (70%), 110 pS (10%), and 65 pS (20%), which are identical in normal and RSV-transformed CEFs. The total channel density in both cell types is about 0.13 per micron2. All three types of channels are highly selective for K+ ions, they are Ca(2+)- and voltage-dependent, and they can be completely blocked by external tetraethylammonium (10 mM) in both normal and RSV-transformed cells. Some channel properties, however, are different in normal and RSV-transformed CEFs. The K186 channel of normal CEFs is almost completely activated in the presence of about 1 nM free internal Ca2+ and is insensitive to charybdotoxin (100 nM). In contrast, the K186 channel of RSV-transformed CEFs has an EC50 value for activation by internal Ca2+ of about 100 nM and is highly sensitive to charybdotoxin (IC50 = 9 nM). In normal CEFs, the K186 channel activity starts at membrane potentials more positive than -50 mV and reaches a high open state probability of 0.94 at +50 mV. In RSV-transformed CEFs, the threshold of K186 channel activity is also -50 mV but the maximal open state probability is only 0.70 at +50 mV membrane potential. Averages of current traces of K186 channels show the typical features of the macroscopic K+ currents described previously for normal and RSV-transformed CEFs.(ABSTRACT TRUNCATED AT 250 WORDS)
利用膜片钳技术检测了正常和劳斯肉瘤病毒（RSV）转化的鸡胚成纤维细胞（CEF）中的离子通道。在对称的140 mM KCl中观察到三种不同类型的离子通道，其单通道电导分别为186 pS（出现频率70%）、110 pS（10%）和65 pS（20%），正常和RSV转化的CEF中的这些通道相同。两种细胞类型中的总通道密度约为每平方微米0.13个。所有三种类型的通道对K+离子具有高度选择性，它们依赖于Ca(2+)和电压，并且在正常和RSV转化的细胞中均可被外部四乙铵（10 mM）完全阻断。然而，正常和RSV转化的CEF中的一些通道特性有所不同。正常CEF的K186通道在约1 nM游离内部Ca2+存在时几乎完全激活，并且对大蝎毒素（100 nM）不敏感。相比之下，RSV转化的CEF的K186通道被内部Ca2+激活的EC50值约为100 nM，并且对大蝎毒素高度敏感（IC50 = 9 nM）。在正常CEF中，K186通道活性在膜电位比 -50 mV更正时开始，在 +50 mV时达到0.94的高开放状态概率。在RSV转化的CEF中，K186通道活性的阈值也是 -50 mV，但在 +50 mV膜电位时最大开放状态概率仅为0.70。K186通道电流迹线的平均值显示了先前描述的正常和RSV转化的CEF的宏观K+电流的典型特征。（摘要截断于250字）
