GIEBISCH G
J Gen Physiol. 1961 Mar;44(4):659-78. doi: 10.1085/jgp.44.4.659.
Stable electrical potential differences can be measured by means of conventional glass microelectrodes across the cell membrane of renal tubule cells and across the epithelial wall of single tubules in the doubly perfused kidney of Necturus. These measurements have been carried out with amphibian Ringer's solution, and with solutions of altered ionic composition. The proximal tubule cell has been found to be electrically asymmetrical inasmuch as a smaller potential difference is maintained across the luminal cell membrane than across the peritubular cell boundary. The tubule lumen is always electrically negative with respect to the peritubular extracellular medium. Observations on the effectiveness of potassium ions in depolarizing single tubule cells indicate that the transmembrane potential is essentially an inverse function of the logarithm of the external potassium concentration. The behavior of the peritubular transmembrane potential resembles more closely an ideal potassium electrode than that of the luminal transmembrane potential. From these results, and the effects of various ionic substitutions on the electrical profile of the renal tubular epithelium, a thesis concerning the origin of the observed potential differences is presented. A sodium extrusion mechanism is considered to be located at the peritubular cell boundary, and reasons are given for the hypothesis that the electrical asymmetry across the proximal renal tubule cell could arise as a consequence of differences in the relative sodium and potassium permeability at the luminal and peritubular cell boundaries.
利用传统玻璃微电极，可以测量美西螈双灌注肾中肾小管细胞的细胞膜以及单个肾小管上皮壁两侧的稳定电势差。这些测量是在两栖类任氏液以及离子成分改变的溶液中进行的。已发现近端肾小管细胞存在电不对称性，即跨管腔细胞膜维持的电势差小于跨肾小管周围细胞边界的电势差。相对于肾小管周围细胞外介质，肾小管管腔总是呈电负性。关于钾离子对单个肾小管细胞去极化作用的观察表明，跨膜电位本质上是外部钾离子浓度对数的反函数。肾小管周围跨膜电位的行为比管腔跨膜电位更类似于理想的钾电极。基于这些结果以及各种离子替代对肾小管上皮电分布的影响，提出了一个关于所观察到的电势差起源的论点。一种钠排出机制被认为位于肾小管周围细胞边界，并且给出了如下假设的理由：近端肾小管细胞的电不对称可能是由于管腔和肾小管周围细胞边界处相对钠和钾通透性的差异所致。
