Isolated frog skin was bathed with a dilute solution containing 1 mm NaCl on the outside and with normal Ringer’s solution on the inner surface. Net Na flux was determined by simultaneous measurement of unidirectional fluxes with Na22 and Na24 and intracellular electrical potentials were examined with microelectrodes. There was a net inward transport of Na under both open-circuit and short-circuit conditions. The short-circuit current was approximately 15% greater than the net Na flux; the discrepancy could be accounted for by a small outward flux of Cl. The electrical potential profile did not differ greatly from that observed in skins bathed on the outside with normal Ringer’s solution. Under open-circuit conditions, there were usually several potential steps and under short-circuit conditions the cells were negative relative to the bathing solutions. Estimates of epithelial Na concentrations utilizing radioactive Na suggested that if all epithelial Na were in a single compartment, an active entry step would be necessary to allow a net inward Na transport. The results could also be explained by a series arrangement of Na compartments without necessarily postulating an active Na entry. The behavior of the potential profile suggested that this latter alternative was more likely.
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机译：离体的蛙皮在外部用含有1 mm NaCl的稀溶液沐浴，在其内表面用普通的林格氏溶液沐浴。通过同时测量Na 22 和Na 24 的单向通量来确定净Na通量，并用微电极检查细胞内电位。在开路和短路条件下，Na都净向内迁移。短路电流大约比净Na通量大15％。差异可能是由于Cl的较小向外通量引起的。电位分布与在正常的林格氏溶液中沐浴在皮肤上的皮肤没有太大差异。在开路条件下，通常存在多个潜在步骤，在短路条件下，电池相对于沐浴液为负值。利用放射性Na对上皮Na浓度的估计表明，如果所有上皮Na都在单个隔室中，则必须进行主动进入步骤以允许净内向Na转运。结果也可以通过Na隔室的一系列排列来解释，而不必假定活动的Na进入。潜在特征的行为表明，后者的可能性更大。
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