Influence of Transepithelial Potential Difference on the Sodium Uptake at the Outer Surface of the Isolated Frog Skin
Influence of Transepithelial Potential Difference on the Sodium Uptake at the Outer Surface of the Isolated Frog Skin
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跨上皮电位差对离体蛙皮肤外表面钠吸收的影响
DOI：
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发表时间：
1973
期刊：
影响因子：
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通讯作者：
Molly L. Sanders
中科院分区：
文献类型：
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作者：
T. Biber;Molly L. Sanders
在跨上皮电位差（Δψ）范围为+100至-100 mV的情况下，测量了离体青蛙皮肤外表面的单向钠吸收（J 12 Na）。当沐浴溶液中钠浓度为 115 mM 时，当自发 Δψ 通过皮肤短路降低至零时，J 12 Na 显着增加。当 Na 浓度为 6 mM 时，当 Δψ 从 +100 到 -100 mV（浆膜侧分别为正和负）分几步减少时，可以观察到 J 12 Na 逐渐增加。观察到的 J 12 Na 变化仅相当于根据 Δψ 变化预测的变化的一小部分。结果表明，在开路条件下，穿过外表面的电势阶跃最多为 Δψ 的一半，并且穿过皮肤外部和内部屏障的电阻是欧姆的。这与青蛙皮肤中细胞内电位的测量以及蟾蜍皮肤中进行的电阻测量一致。数据强烈支持 J ψ 的饱和分量通过带电载流子系统进行的观点。暴露于50mV或更高的Δψ负值持续24分钟或更长的时间导致J 12 Na显着降低，其仅表现出部分可逆性或无可逆性。
The unidirectional uptake of sodium across the outer surface of the isolated frog skin (J 12 Na) was measured in the presence of transepithelial potential difference (Δψ) ranging from +100 to -100 mV. With a sodium concentration of 115 mM in the bathing solutions J 12 Na increases significantly when the spontaneous Δψ is reduced to zero by short-circuiting the skin. With an Na concentration of 6 mM a progressive increase J 12 Na can be observed when Δψ is decreased in several steps from +100 to -100 mV (serosal side positive and negative, respectively). The observed change J 12 Na amounts to a fraction only of that predicted from the shift in Δψ. The results suggest that under open circuit conditions the potential step across the outside surface is at most one half of Δψ and that the resistance across the outside and inside barrier of the skin is ohmic. This is in agreement with measurements of intracellular potentials in the frog skin and with resistance measurements carried out in the toad skin. The data strongly support the view that the saturating component of J ψ proceeds via a charged carrier system. Exposure to negative values of Δψ of 50 mV or more for times of 24 min or more result in a marked reduction of J 12 Na which shows only partial or no reversibility.