Flonta M L, Galter D, Frangopol P T, Mărgineanu D G
Pflugers Arch. 1987 Mar;408(3):215-9. doi: 10.1007/BF02181461.
Procaine has opposite effects on the active transport of Na+ when applied on the mucosal side of the frog skin [where it produces a stimulation of the short-circuit current (Isc)] or when added on the serosal side (where it produces an inhibition of Isc). In an attempt to reveal and localize the primary effect of procaine on either the apical or latero-basal membranes of the epithelial cells, we have tried to "chemically dissect" both membrane functions with inhibitors and ionophores. When applied on the apical side of the latero-basally depolarized epithelium, 25 mmol/l procaine increases Isc and Voc (transepithelial open-circuit potential), while decreasing the transepithelial resistance. The E1-E2 linearity domain of the I-V curves is narrowed. On the serosal side of the depolarized epithelium, the same concentration of procaine does not affect Isc and Voc (which are already inhibited) but it produces an increase in the transepithelial resistance (Rt). Procaine influence on the passive K+ permeability was studied by using the ionophore nystatin, which is assumed to form channels permeable to K+, when applied on the amiloride blocked apical membrane. In nystatin-treated epithelia, 25 mmol/l procaine on the apical side decreased Isc, Voc and Rt. In parallel experiments during Cl- substitution by SO2-(4), the procaine effects on Isc and Voc are no longer maintained, but transient.(ABSTRACT TRUNCATED AT 250 WORDS)
当将普鲁卡因应用于蛙皮黏膜侧（在此处它会刺激短路电流（Isc））或添加于浆膜侧（在此处它会抑制Isc）时，它对Na⁺的主动转运具有相反的作用。为了揭示并定位普鲁卡因对上皮细胞顶端或侧基底膜的主要作用，我们尝试用抑制剂和离子载体对这两种膜功能进行“化学剖析”。当将25 mmol/L的普鲁卡因应用于侧基底去极化上皮细胞的顶端侧时，它会增加Isc和跨上皮开路电位（Voc），同时降低跨上皮电阻。I-V曲线的E1-E2线性范围变窄。在去极化上皮细胞的浆膜侧，相同浓度的普鲁卡因不影响Isc和Voc（它们已被抑制），但会使跨上皮电阻（Rt）增加。通过使用离子载体制霉菌素研究了普鲁卡因对被动K⁺通透性的影响，当将制霉菌素应用于被氨氯吡咪阻断的顶端膜时，它被认为会形成对K⁺通透的通道。在制霉菌素处理的上皮细胞中，顶端侧25 mmol/L的普鲁卡因降低了Isc、Voc和Rt。在SO₂⁻(4)替代Cl⁻的平行实验中，普鲁卡因对Isc和Voc的作用不再维持，而是短暂的。（摘要截短于250词）
