Weinstein F C, Rosowski J J, Peterson K, Delalic Z, Civan M M
J Membr Biol. 1980 Jan 31;52(1):25-35. doi: 10.1007/BF01869003.
Application of voltage pulses of 10 mV for periods of 9 sec across toad urinary bladder elicits a rapid deflection in transepithelial current. Frequently, the current decays back towards its baseline value during the course of the polarizing pulse. This transient phenomenon can be induced, or its magnitude increased, by raising the mucosal or serosal Na+ concentration. The transient can be abolished by sufficiently hyperpolarizing the tissue (rendering serosa positive to mucosa), by inhibiting transcellular Na+ transport with amiloride or ouabain, and by increasing the serosal K+ concentration. Vasopressin increases net Na+ movement across toad bladder but does not elicit these transients. It is proposed as a working hypothesis for further study that the transient behavior characterized in this study reflects: (1) the partition of Na+ between the apical plasma membrane and contiguous fluid layers, (2) the partition of K+ between the basolateral plasma membrane and adjacent submucosal fluid layer, and (3) the negative feedback interaction between intracellular Na+ activity and Na+ permeability of the apical plasma membrane of the transporting cells.
在蟾蜍膀胱上施加持续9秒的10毫伏电压脉冲会引起跨上皮电流的快速偏转。通常，在极化脉冲过程中，电流会衰减回到其基线值。通过提高黏膜或浆膜的钠离子浓度，可以诱发这种瞬态现象，或者增大其幅度。通过使组织充分超极化（使浆膜相对于黏膜呈正电）、用氨氯吡咪或哇巴因抑制跨细胞钠离子转运以及提高浆膜钾离子浓度，可以消除这种瞬态现象。抗利尿激素会增加钠离子跨蟾蜍膀胱的净移动，但不会引发这些瞬态现象。作为进一步研究的一个可行假设，本研究中所描述的瞬态行为反映了：（1）钠离子在顶端质膜和相邻液层之间的分配；（2）钾离子在基底外侧质膜和相邻黏膜下液层之间的分配；（3）细胞内钠离子活性与转运细胞顶端质膜钠离子通透性之间的负反馈相互作用。
