Clausen C, Dixon T E
J Membr Biol. 1986;92(1):9-19. doi: 10.1007/BF01869011.
Equivalent-circuit impedance analysis experiments were performed on the urinary bladders of freshwater turtles in order to quantify membrane ionic conductances and areas, and to investigate how changes in these parameters are associated with changes in the rate of proton secretion in this tissue. In all experiments, sodium reabsorption was inhibited thereby unmasking the electrogenic proton secretion process. We report the following: transepithelial impedance is represented exceptionally well by a simple equivalent-circuit model, which results in estimates of the apical and basolateral membrane ionic conductances and capacitances; when sodium transport is inhibited with mucosal amiloride and serosal ouabain, the apical and basolateral membrane conductances and capacitances exhibit a continual decline with time; this decline in the membrane parameters is most likely caused by subtle time-dependent changes in cell volume, resulting in changes in the areas of the apical and basolateral membranes; stable membrane parameters are obtained if the tissue is not treated with ouabain, and if the oncotic pressure of the serosal solution is increased by the addition of 2% albumin; inhibition of proton secretion using acetazolamide in CO2 and HCO3- -free bathing solutions results in a decrease in the area of the apical membrane, with no significant change in its specific conductance; stimulation of proton transport with CO2 and HCO3- -containing serosal solution results in an increase in the apical membrane area and specific conductance. These results show that our methods can be used to measure changes in the membrane electrophysiological parameters that are related to changes in the rate of proton transport. Notably, they can be used to quantify in the live tissue, changes in membrane area resulting from changes in the net rates of endocytosis and exocytosis which are postulated to be intimately involved in the regulation of proton transport.
为了量化膜离子电导和面积，并研究这些参数的变化如何与该组织中质子分泌速率的变化相关联，对淡水龟的膀胱进行了等效电路阻抗分析实验。在所有实验中，抑制了钠的重吸收，从而揭示了生电性质子分泌过程。我们报告如下：跨上皮阻抗可以用一个简单的等效电路模型非常好地表示，该模型可以估算顶端和基底外侧膜的离子电导和电容；当用黏膜阿米洛利和浆膜哇巴因抑制钠转运时，顶端和基底外侧膜的电导和电容随时间持续下降；膜参数的这种下降很可能是由细胞体积随时间的细微变化引起的，导致顶端和基底外侧膜的面积发生变化；如果不对组织使用哇巴因，并且通过添加2%白蛋白来增加浆膜溶液的胶体渗透压，则可获得稳定的膜参数；在无CO₂和HCO₃⁻的浴液中使用乙酰唑胺抑制质子分泌会导致顶端膜面积减小，其比电导无显著变化；用含CO₂和HCO₃⁻的浆膜溶液刺激质子转运会导致顶端膜面积和比电导增加。这些结果表明，我们的方法可用于测量与质子转运速率变化相关的膜电生理参数的变化。值得注意的是，它们可用于在活组织中量化由内吞作用和外排作用净速率变化引起的膜面积变化，据推测这些变化与质子转运的调节密切相关。
