Zajac Miroslaw, Lewenstam Andrzej, Bednarczyk Piotr, Dolowy Krzysztof
Institute of Biology, Department of Physics and Biophysics, Warsaw University of Life Sciences-SGGW, 159 Nowoursynowska St., 02-776 Warsaw, Poland.
AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza 30, 30-059 Krakow, Poland.
Membranes (Basel). 2020 Mar 12;10(3):43. doi: 10.3390/membranes10030043.
We measured concentration changes of sodium, potassium, chloride ions, pH and the transepithelial potential difference by means of ion-selective electrodes, which were placed on both sides of a human bronchial epithelial 16HBE14σ cell line grown on a porous support in the presence of ion channel blockers. We found that, in the isosmotic transepithelial concentration gradient of either sodium or chloride ions, there is an electroneutral transport of the isosmotic solution of sodium chloride in both directions across the cell monolayer. The transepithelial potential difference is below 3 mV. Potassium and pH change plays a minor role in ion transport. Based on our measurements, we hypothesize that in a healthy bronchial epithelium, there is a dynamic balance between water absorption and secretion. Water absorption is caused by the action of two exchangers, Na/H and Cl/HCO, secreting weakly dissociated carbonic acid in exchange for well dissociated NaCl and water. The water secretion phase is triggered by an apical low volume-dependent factor opening the Cystic Fibrosis Transmembrane Regulator CFTR channel and secreting anions that are accompanied by paracellular sodium and water transport.
我们通过离子选择性电极测量了钠、钾、氯离子浓度变化、pH值以及跨上皮电位差，这些电极放置在生长于多孔支持物上的人支气管上皮16HBE14σ细胞系两侧，且处于离子通道阻滞剂存在的情况下。我们发现，在钠或氯离子的等渗跨上皮浓度梯度中，氯化钠等渗溶液在细胞单层两侧进行双向的电中性转运。跨上皮电位差低于3 mV。钾和pH值变化在离子转运中起次要作用。基于我们的测量结果，我们推测在健康的支气管上皮中，水的吸收和分泌之间存在动态平衡。水的吸收是由两种交换体Na/H和Cl/HCO的作用引起的，它们分泌弱解离的碳酸以交换完全解离的NaCl和水。水分泌阶段由顶端低容量依赖性因子触发，该因子打开囊性纤维化跨膜传导调节因子CFTR通道并分泌阴离子，同时伴有细胞旁的钠和水转运。
