Spenney J G, Flemstrom G, Shoemaker R L, Sachs G
J Gen Physiol. 1975 May;65(5):645-62. doi: 10.1085/jgp.65.5.645.
The magnitude of cellular and shunt conductance of Necturus gastric antral mucosa was studied by (a) comparing the cellular PD response to transepithelial PD response during changes of ionic activity in the serosal bathing solution and (b) by measurement of current spread within the epithelial sheet. Using constant product KCl changes cellular resistance was 6,788 omegacm2 and shunt resistance was 1,803 omegacm2. Deletion of HCO3- from the serosal solution produced similar but quantitatively smaller changes in PD. Using HCO3- deletion cellular resistance was 7,338 omegacm2 and shunt resistance was 1,973 omegacm2. Measurement of current spead within the mucosa avoids changing ionic gradients yet gave very similar results; cellular resistance was 8,967 omegacm2 and shunt resistance was 2,947 omegacm2. The shunt contribution to transepithelial conductance ranged from 75.2 to 79.0%. Shunt selectivity was assessed using KCl dilution potentials, where mucosal dilution gave a small change in tissue PD compatible with an anion/cation selectivity ratio of 1.16 across the shunt, whereas serosal dilution effect was dominated by a PD change across the serosal membrane of the cell.
（a）在浆膜浴液离子活性变化期间，比较细胞电位差（PD）对跨上皮PD反应的变化；（b）测量上皮片层内的电流扩散。使用恒定乘积的氯化钾变化时，细胞电阻为6788Ω·cm²，旁路电阻为1803Ω·cm²。从浆膜溶液中去除碳酸氢根离子（HCO₃⁻）会使PD产生相似但数量上较小的变化。使用去除HCO₃⁻的溶液时，细胞电阻为7338Ω·cm²，旁路电阻为1973Ω·cm²。测量黏膜内的电流扩散避免了改变离子梯度，但得到了非常相似的结果；细胞电阻为8967Ω·cm²，旁路电阻为2947Ω·cm²。旁路对跨上皮电导的贡献范围为75.2%至79.0%。使用氯化钾稀释电位评估旁路选择性，其中黏膜稀释使组织PD产生小的变化，与跨旁路的阴离子/阳离子选择性比1.16相符，而浆膜稀释效应主要由细胞浆膜上的PD变化主导。
