Nagel W, Pope M B, Peterson K, Civan M M
J Membr Biol. 1980 Dec 30;57(3):235-41. doi: 10.1007/BF01869591.
Skins from the frog Rana pipiens pipiens were studied under short-circuited conditions during the course of removing and replacing potassium in the inner bathing media in 14 experiments. The intracellular potential (Vsc), fractional resistance (FR), short-circuit current (Isc) and total tissue conductance (gr) were constantly monitored during impalements of the epithelial cells. The mean value (+/- SE) for Vsc was --79 (+/- 3) mV under baseline conditions. Removal of potassium from the inner bathing solution transiently stimulated the short-circuit current and hyperpolarized the basolateral membrane; with sufficiently long incubations, the basolateral membrane was eventually depolarized. Restoration of potassium to the inner solution within 43 min after initiating the perfusion with K+-free solution depolarized the basolateral membrane. However, restoration of potassium after at least 1 1/2 hr of incubation hyperpolarized the membrane. Ouabain consistently depolarized the basolateral membrane, even after extended periods of potassium depletion as long as 320 min. In the presence of ouabain, restoration of potassium depolarized the basolateral membrane. The data provide further evidence for the concept that the Na--K exchange pump of frog skin is rheogenic. Furthermore, the results suggest that the pump continues to be active even during prolonged periods of potassium depletion, reaccumulating potassium which has leaked out of the epithelial cells.
在14项实验中，研究了豹蛙（Rana pipiens pipiens）皮肤在短路条件下，于内部浴液中去除和重新添加钾的过程。在刺入上皮细胞期间，持续监测细胞内电位（Vsc）、分数电阻（FR）、短路电流（Isc）和总组织电导（gr）。在基线条件下，Vsc的平均值（±SE）为-79（±3）mV。从内部浴液中去除钾会短暂刺激短路电流，并使基底外侧膜超极化；经过足够长的孵育时间后，基底外侧膜最终会去极化。在用无钾溶液开始灌注后43分钟内将钾恢复到内部溶液中，会使基底外侧膜去极化。然而，在孵育至少1.5小时后恢复钾会使膜超极化。哇巴因始终使基底外侧膜去极化,即使在长达320分钟的长时间钾耗竭后也是如此。在存在哇巴因的情况下，恢复钾会使基底外侧膜去极化。这些数据为蛙皮的钠钾交换泵是生电的这一概念提供了进一步的证据。此外，结果表明，即使在长时间的钾耗竭期间，该泵仍保持活跃，重新积累从上皮细胞中泄漏出来的钾。
