Oiki S, Okada Y
Department of Physiology, Faculty of Medicine, Kyoto University, Japan.
J Membr Biol. 1988 Oct;105(1):23-32. doi: 10.1007/BF01871103.
In giant fibroblastic L cells, penetration of a conventional microelectrode brought about marked decreases in the membrane potential and input resistance measured with a patch electrode under tight-seal whole-cell configuration, and repeated hyperpolarizations were often observed upon penetration. Therefore, the question arose whether such leakage artifact is a causal factor for generation of the membrane potential oscillation even in giant L cells. During whole-cell recordings, however, regular potential oscillations were observed in the cells that had not been impaled with a conventional microelectrode, as far as the Ca2+ buffer was not strong in the pipette solution. Oscillatory changes in the intracellular potential were detected by extracellular recordings with a tight-seal patch electrode in the cell-attached configuration. Thus, the potential oscillation occurs even in the absence of penetration-induced leakage or without rupture of the patch membrane. Withdrawal of a micropipette from one cell was often found to induce marked cell damage and elicit oscillatory hyperpolarizations in a neighboring cell with a certain time lag. The longer the distance between the injured and recorded cells, the greater was the time lag. Application of the cell lysate on the cell surface also gave rise to oscillatory hyperpolarizations. After repeated applications of the lysate, the membrane became unresponsive (desensitized), suggesting the involvement of receptors for the lysate factor. The lysates of different cell species (mouse lymphoma L5178Y cells or human epithelial Intestine 407 cells) produced similar effects. The effective component was heat stable and distinct from ATP. Lysate-induced hyperpolarizations were inhibited by deprivation of extracellular Ca2+ and by application of a Ca2+ channel blocker (nifedipine) or a K+ channel blocker (quinine) in the same manner as spontaneous oscillatory hyperpolarizations. It is concluded that the mouse fibroblast exhibits membrane potential oscillations, when the cell was activated, presumably via receptor systems, by some diffusible factors released from damaged cells.
在巨大的成纤维细胞样L细胞中，传统微电极的刺入会导致在全细胞封接配置下用膜片电极测量的膜电位和输入电阻显著降低，并且在刺入时经常观察到反复的超极化。因此，出现了这样一个问题，即这种泄漏伪迹是否是即使在巨大的L细胞中膜电位振荡产生的一个因果因素。然而，在全细胞记录过程中，只要移液管溶液中的Ca2+缓冲剂不强，在未被传统微电极刺入的细胞中也观察到了规则的电位振荡。通过在细胞贴附配置下用封接紧密的膜片电极进行细胞外记录，检测到细胞内电位的振荡变化。因此，即使在没有刺入引起的泄漏或膜片未破裂的情况下，电位振荡也会发生。经常发现从一个细胞中拔出微吸管会导致明显的细胞损伤，并在相邻细胞中引发振荡性超极化，且有一定的时间延迟。受损细胞与记录细胞之间的距离越远，时间延迟越大。将细胞裂解物应用于细胞表面也会引起振荡性超极化。在反复应用裂解物后，膜变得无反应（脱敏），这表明裂解物因子的受体参与其中。不同细胞种类（小鼠淋巴瘤L5178Y细胞或人上皮小肠407细胞）的裂解物产生了类似的效果。有效成分对热稳定且不同于ATP。裂解物诱导的超极化与自发振荡性超极化一样，可通过剥夺细胞外Ca2+以及应用Ca2+通道阻滞剂（硝苯地平）或K+通道阻滞剂（奎宁）来抑制。得出的结论是，当小鼠成纤维细胞被激活时，可能通过受体系统，被受损细胞释放的一些可扩散因子作用，从而表现出膜电位振荡。
