Corman B, Di Stefano A
Pflugers Arch. 1983 Apr;397(1):35-41. doi: 10.1007/BF00585165.
Coupling of salt and water movements across kidney proximal tubules was studied in the presence of an induced transepithelial osmotic water flux. Convoluted proximal tubules from rabbit kidney were perfused in vitro with a control solution, with or without 50 mM/l of mannitol or raffinose in the both. Osmolalities of the perfused and collected fluids as well as the net water flux Jv were measured in each experiment. The net solute flux Js was calculated from the difference between the amount of total solutes delivered and collected at each end of the tubule. No apparent net transepithelial solute movements were detected in the presence of an osmotic water flux when active solute transport was inhibited either by an external to of 26 degrees C or by ouabain in the bath. The water flux observed was similar to that calculated assuming that only water crossed the epithelium, and no streaming potential was measured, whether or not active transport was blocked. It is concluded that the osmotic water flux through kidney proximal tubule does not drag a significant amount of solutes, probably because of the absence of convective solvent flux. This suggests the existence of different pathways for water and salt movement.
在存在诱导的跨上皮渗透水通量的情况下，研究了肾近端小管中盐和水运动的耦合。用对照溶液在体外灌注来自兔肾的曲部近端小管，对照溶液中分别添加或不添加50 mM/l的甘露醇或棉子糖。在每个实验中测量灌注液和收集液的渗透压以及净水通量Jv。净溶质通量Js根据在小管两端输送和收集的总溶质数量之差计算得出。当通过将浴温外部调节至26℃或在浴中加入哇巴因抑制主动溶质转运时，在存在渗透水通量的情况下未检测到明显的跨上皮净溶质运动。观察到的水通量与假设仅水穿过上皮时计算得出的水通量相似，并且无论主动转运是否被阻断均未测量到流动电位。得出的结论是，通过肾近端小管的渗透水通量不会携带大量溶质，这可能是因为不存在对流溶剂通量。这表明水和盐的运动存在不同途径。
