Abstract
Effects of SITS (4-acetamido-4'-isothiocyano-2, 2'-disulfonic stilbene) on a $Na^+$ transport, tissue oxygen consumption and Na-K-ATPase activity were studied in isolated frog skin preparations. $Na^+$ transport was estimated by measuring the short-circuit current(SC) across the skin; oxygen consumption was measured in separated epidermis as well as in intact skin; and Na-K-ATPase was assayed in $24,000{\times}g$ fraction of epidermal homogenates. The SCC across the skin Was rapidly and substantially reduced in the presence of 10 mM SITS in the medium bathing the outside(mucosal) surface of the skin. When the drug was added to the inside(serosal) bathing medium, there was about 20 min delay for inhibition of SCC and the effect was less pronounced. The above effect of SITS was independent of the presence of $Cl^-$ in the bathing medium. The oxygen consumption of the skin tissue was not affected by SITS, but the Na-K-ATPase activity of a subcellular fraction of the skin was significantly inhibited. These results suggest that SITS retards $Na^+$ transport across the frog skin primarily by interfering $Na^+$ entry across the mucosal membrance of the epithelial cell, although an effect on $Na^+$ pump can not be ruled out completely.
적출된 개구리 피부에서 $Na^+$이동, 산소소모량 및 Na-K-ATPase활성도에 대한 SITS(4-acetamido-4'-isothiocyano-2, 2'-disulfonic stilbene)의 영향을 연구하였다. 피부를 통한 능동적$Na^+$이동을 추정하기 위하여 short-circuit current(SCC)를 측정하였으며, 산소소모량은 피부조직 및 분리된 표피조직에서 측정하였으며, Na-K-ATPase활성도는 표피조직의 $24,000{\times}g$분획에서 측정하였다. 피부를 통한 SCC는 10 mM SITS가 피부외측용액에 첨가될 때 급격히 하강하였으며, 내측용액에 첨가될 때는 20분정도 지난후 하강하기 시작하였으나 그 하강정도는 전자에 비해 약했다. SITS에 의한 SCC억제현상은 용액내에 $Cl^-$이 없을때도 나타났다. SITS에 의하여 피부 및 표피조직의 산소소모량은 억제되지 않았으나 표피조직분획내 Na-K-ATPase활성도는 심하게 억제되었다. 이상과 같은 성적은 SITS가 개구리 피부에서 능동적 $Na^+$이동을 강력히 억제함을 나타내는데, 이러한 억제작용은 이 약물이 주로 상피세포의 외측막에 작용하여 나타나는 것으로 사료되지만 $Na^+$펌프를 억제할 가능성을 전연 배제할 수는 없다.