GATZY J T, CLARKSON T W
J Gen Physiol. 1965 Mar;48(4):647-71. doi: 10.1085/jgp.48.4.647.
The spontaneous transtissue potential and the DC conductance of the isolated toad bladder were measured when the tissue was exposed to sulfate Ringer's solutions of modified ionic composition. Na(+) was replaced to varying extents by (C(2)H(5))(3)NH(+), (C(2)H(5))(4)N(+), Li(+), Cs(+), K(+), or Rb(+). Reversible and irreversible changes were observed. The reversible changes were consistent with equations derived from the Nernst-Planck diffusion equation, and gave the following functional description of the bladder: (a) the potential measurements were compatible with two membranes in series; (b) the mucosal surface was more permeable to Na(+) than to other monovalent cations; (c) the serosal surface was permeable to both K(+) and Na(+) but preferentially to K(+); (d) the rate of Na(+) diffusion across the mucosal membrane appeared to approach a maximum but two alternative interpretations are discussed; (e) the conductance data were consistent with the assumption of a constant concentration gradient for the penetrating ions within the membrane (Henderson's assumption) provided suitable hypotheses are made concerning the Na(+) distribution between the membrane surfaces and the bulk phases of the adjacent solutions; (f) the conductance and spontaneous potential data suggested that the mucosal membranes of a small fraction of the epithelial cells were more permeable than the mucosal membranes of the majority of these cells. The irreversible changes were almost entirely associated with cation substitution in the serosal solution. However, Li(+) produced an irreversible fall in voltage when added to either side of the tissue.
当将离体蟾蜍膀胱暴露于离子组成改变的硫酸林格氏溶液中时，测量其自发跨组织电位和直流电导。用（C₂H₅）₃NH⁺、（C₂H₅）₄N⁺、Li⁺、Cs⁺、K⁺或Rb⁺不同程度地替代Na⁺。观察到了可逆和不可逆的变化。可逆变化与从能斯特 - 普朗克扩散方程导出的方程一致，并对膀胱给出了以下功能描述：（a）电位测量结果与串联的两个膜相符；（b）黏膜表面对Na⁺的通透性高于其他单价阳离子；（c）浆膜表面对K⁺和Na⁺均有通透性，但优先通透K⁺；（d）Na⁺跨黏膜膜的扩散速率似乎接近最大值，但讨论了两种不同的解释；（e）如果对膜表面与相邻溶液本体相中Na⁺的分布做出合适的假设，电导数据与膜内穿透离子浓度梯度恒定的假设（亨德森假设）一致；（f）电导和自发电位数据表明，一小部分上皮细胞的黏膜膜比大多数这些细胞的黏膜膜通透性更高。不可逆变化几乎完全与浆膜溶液中的阳离子替代有关。然而，Li⁺添加到组织的任一侧时都会导致电压不可逆下降。
