Narvarte J, Finn A L
Am J Physiol. 1983 Jan;244(1):C11-6. doi: 10.1152/ajpcell.1983.244.1.C11.
Conventional microelectrode and tracer flux techniques were used to study the effects of reduction in serosal chloride concentration ([Cl]s) on the electrical properties of toad urinary bladder epithelium. Reduction in [Cl]s resulted in a transient change in transepithelial potential (Vms) (and of apical and basolateral membrane potentials) that was inversely dependent on the base-line values of those potentials. In all cases, however, there was a decrease in transepithelial resistance (Rt) that was explained by an increase in the sodium conductance of the apical membrane. In tissues in which the transepithelial potential increased, there was a rise in the active mucosal-to-serosal sodium flux. The increase in conductance was directly related to the increase in short-circuit current. The changes in Vms and Rt brought about by reduction in [Cl]s were prevented by agents known to modify sodium transport, including low mucosal sodium concentration, addition of amiloride or amphotericin B to the mucosal solution, or of ouabain to the serosal solution. The results are best explained by a primary effect of chloride reduction on sodium extrusion across the basolateral membrane, with a secondary increase in apical sodium conductance. In addition, the data provide new evidence for the existence of a basolateral chloride conductance pathway.
采用传统的微电极和示踪剂通量技术，研究浆膜氯化物浓度（[Cl]s）降低对蟾蜍膀胱上皮细胞电特性的影响。[Cl]s降低导致跨上皮电位（Vms）（以及顶端和基底外侧膜电位）出现短暂变化，这种变化与这些电位的基线值呈负相关。然而，在所有情况下，跨上皮电阻（Rt）均降低，这是由顶端膜钠电导增加所致。在跨上皮电位升高的组织中，主动的黏膜到浆膜的钠通量增加。电导增加与短路电流增加直接相关。已知可改变钠转运的试剂可阻止因[Cl]s降低而引起的Vms和Rt变化，这些试剂包括低黏膜钠浓度、向黏膜溶液中添加氨氯吡脒或两性霉素B，或向浆膜溶液中添加哇巴因。这些结果最好用氯化物减少对通过基底外侧膜的钠排出的主要作用来解释，同时顶端钠电导会继发性增加。此外，这些数据为基底外侧氯化物电导途径存在提供了新证据。
