Muto S, Ebata S, Asano Y
Department of Nephrology, Jichi Medical School, Tochigi, Japan.
J Clin Invest. 1994 Jan;93(1):286-96. doi: 10.1172/JCI116958.
Microelectrode techniques were used to assess the electrical properties of the collecting duct cell in the isolated perfused cortical collecting duct from remnant kidneys 3, 6, and 24 h after uninephrectomy (UNX); results were compared with those from sham-operated kidneys. Plasma aldosterone levels did not change during the time course after UNX. The lumen-negative transepithelial voltage was elevated significantly 3 h after UNX, and was increased further 24 h after UNX. The basolateral membrane voltage (VB) was elevated 6 h after UNX, and then was increased further at 24 h. Although the tight junction conductance and the fractional apical membrane resistance (fRA) were not altered at any time points after UNX, the apical membrane conductance as well as the transepithelial (GT) and basolateral membrane conductances increased 6 and 24 h after UNX. The changes in apical membrane voltage, GT, and fRA upon addition of luminal amiloride increased just 3 h after UNX, and then remained elevated at 6 and 24 h. The changes in apical membrane voltage and GT upon addition of luminal Ba2+, the changes in VB upon addition of bath ouabain, and the changes in VB, GT, and fRA upon raising bath K+ were not influenced 3 h after UNX, but increased at 6 and 24 h. At these latter periods after UNX, the transference number of Cl- of the basolateral membrane decreased significantly, whereas the transference number of K+ of the basolateral membrane increased significantly. Simultaneously, addition of Ba2+ to the bath caused the VB to hyperpolarize in parallel with decreases in GT and fRA. We conclude: (a) the initial effect of UNX (3 h) in the collecting duct cell is an increase in apical membrane Na+ conductance; (b) the delayed effects of UNX (6 and 24 h) are increases in apical membrane K+ conductance as well as basolateral membrane Na(+)-K+ pump activity and K+ conductance; (c) the hyperpolarization of VB at 6 and 24 h after UNX may result in the decrease of the ratio of the relative Cl- conductance to the relative K+ conductance of the basolateral membrane and also may increase passive K+ entry into the cell across the basolateral membrane; (d) these time-dependent electrical changes occur independently of plasma aldosterone levels.
采用微电极技术评估单侧肾切除（UNX）后3、6和24小时残余肾分离灌注皮质集合管中集合管细胞的电特性；将结果与假手术肾脏的结果进行比较。UNX后血浆醛固酮水平在整个时间段内未发生变化。UNX后3小时管腔负跨上皮电压显著升高，24小时后进一步升高。基底外侧膜电压（VB）在UNX后6小时升高，然后在24小时进一步升高。尽管UNX后任何时间点紧密连接电导和顶端膜电阻分数（fRA）均未改变，但顶端膜电导以及跨上皮（GT）和基底外侧膜电导在UNX后6和24小时增加。加入管腔阿米洛利后顶端膜电压、GT和fRA的变化在UNX后仅3小时增加，然后在6和24小时保持升高。加入管腔Ba2+后顶端膜电压和GT的变化、加入浴槽哇巴因后VB的变化以及升高浴槽K+后VB、GT和fRA的变化在UNX后3小时未受影响，但在6和24小时增加。在UNX后的这些后期，基底外侧膜Cl-的迁移数显著降低，而基底外侧膜K+的迁移数显著增加。同时，向浴槽中加入Ba2+导致VB超极化，同时GT和fRA降低。我们得出结论：（a）UNX（3小时）对集合管细胞的初始作用是顶端膜Na+电导增加；（b）UNX的延迟作用（6和24小时）是顶端膜K+电导以及基底外侧膜Na(+)-K+泵活性和K+电导增加；（c）UNX后6和24小时VB的超极化可能导致基底外侧膜相对Cl-电导与相对K+电导之比降低，也可能增加K+通过基底外侧膜被动进入细胞；（d）这些时间依赖性电变化独立于血浆醛固酮水平发生。
