Pokrovskiĭ V G
Zh Evol Biokhim Fiziol. 1980 Jul-Aug;16(4):336-41.
Studies have been made on changes in Na and K concentrations in the lumen of the proximal tubule of the kidney of rat and newt during perfusion of the tubuli by solutions containing various concentrations of these ions. Intraluminar concentration of Na and K is rapidly changed and towards the end of the perfused region the ratio of Na and K concentration in the lumen to the concentration in the blood plasma approaches 1. Within the lumen of the perfused proximal tubuli of newt's kidney, Na and K concentrations are changed insignificantly as compared to the concentration of these ions in perfusion solutions. Proximal tubuli of the newt and rat exhibit low transepithelial potential, i. e. -0.27 +/- 0.15 and -3.59 +/- 0.16 mV correspondingly. The specific resistance of the wall of the proximal tubuli in the newt is 10 times higher than in rat. From changes in transepithelial diffusion potential, the following sequence of coefficients of ionic permeability for the proximal tubuli of the newt was calculated: PNa+:PK+:PCh+:PCl-:PNO3-=1 : 1.15: 0.96 : 2.86 : 3.21. The data obtained indicate that in rats as compared to the newt, proximal tubuli exhibit higher transepithelial conductivity, higher passive permeability for ions and different selectivity for anions and cations.
在通过含有不同浓度钠和钾离子的溶液对大鼠和蝾螈肾脏近端小管进行灌流期间，对近端小管管腔内钠和钾浓度的变化进行了研究。管腔内钠和钾的浓度迅速变化，在灌流区域末端，管腔内钠和钾的浓度与血浆中浓度的比值接近1。在蝾螈肾脏灌流的近端小管管腔内，与灌流液中这些离子的浓度相比，钠和钾的浓度变化不显著。蝾螈和大鼠的近端小管表现出较低的跨上皮电位，分别为-0.27±0.15和-3.59±0.16毫伏。蝾螈近端小管壁的比电阻比大鼠高10倍。根据跨上皮扩散电位的变化，计算出蝾螈近端小管离子通透系数的以下顺序：PNa+∶PK+∶PCh+∶PCl-∶PNO3- = 1∶1.15∶0.96∶2.86∶3.21。所获得的数据表明，与蝾螈相比，大鼠的近端小管表现出更高的跨上皮导电性、更高的离子被动通透性以及对阴离子和阳离子不同的选择性。
