Nielsen R
August Krogh Institute, University of Copenhagen, Denmark.
Acta Physiol Scand. 1995 Dec;155(4):351-61. doi: 10.1111/j.1748-1716.1995.tb09985.x.
The coupling between net transepithelial Cl- influx and net water flow was investigated. Experiments were performed on isolated frog skin bathed in isotonic Cl- Ringer's solution in the presence of the Na+ channel blocking agent amiloride in the mucosal solution. The skins were voltage-clamped at -80 or -100 mV (with the serosal solution as reference). Under these conditions the current across the skin is carried by an influx of Cl-. In the absence of antidiuretic hormone the correlation between current and net water flow was low, but in the presence of the antidiuretic hormone, arginine vasotocin, there was a highly significant correlation between current and net water flow. The data presented here indicate that under steady state conditions about 70 molecules of water follow each Cl- ion across the skin. If the water influx is driven by electroosmosis one would expect that a change in current should result in an immediate change in the water flow. There was, however, a considerable time delay between the change in current and water flow. This indicates that the observed coupling between Cl- flux and water flow is caused by current-induced local osmosis and not electroosmosis.
研究了净跨上皮氯离子内流与净水流之间的耦合关系。实验在分离的蛙皮上进行，蛙皮浸浴在等渗氯离子林格氏溶液中，黏膜溶液中存在钠离子通道阻滞剂氨氯吡脒。将皮肤电压钳制在-80或-100 mV（以浆膜溶液为参照）。在这些条件下，通过皮肤的电流由氯离子内流携带。在没有抗利尿激素的情况下，电流与净水流之间的相关性较低，但在存在抗利尿激素精氨酸血管加压素的情况下，电流与净水流之间存在高度显著的相关性。此处呈现的数据表明，在稳态条件下，每一个氯离子穿过皮肤时约有70个水分子随之通过。如果水的内流是由电渗作用驱动的，那么人们会预期电流的变化会导致水流立即改变。然而，电流变化和水流变化之间存在相当长的时间延迟。这表明观察到的氯离子通量与水流之间的耦合是由电流诱导的局部渗透作用而非电渗作用引起的。
