Cohen B, Giebisch G, Hansen L L, Teuscher U, Wiederholt M
J Physiol. 1984 Mar;348:115-34. doi: 10.1113/jphysiol.1984.sp015102.
Amphiuma kidneys were isolated and perfused with modified Ringer solution and peritubular and transepithelial membrane potentials (p.d.s) in distal tubules measured with micro-electrodes during rapid changes of luminal electrolyte concentrations. Peritubular membrane potential and net fluid reabsorption (split-oil-droplet method) were also measured with and without application of various drugs known to alter transport. Raising the luminal sodium concentration from 10 to 100 mM reversibly increased the peritubular p.d. The magnitude of the peritubular p.d. was a saturable function of luminal sodium concentration. In the presence of chloride in the lumen the peritubular hyperpolarization following increased luminal sodium could be inhibited by luminal amiloride (10(-4)M). Sodium-induced hyperpolarization of the peritubular p.d. could be completely inhibited by 10(-5)M-ouabain. Adding amiloride (10(-4)M) to the luminal fluid rapidly and reversibly depolarized the peritubular p.d. and inhibited fluid reabsorption. Addition of amphotericin B (20 micrograms/ml) to the luminal perfusion solution had no effect on peritubular p.d. at 100 mM-luminal NaCl but at 10 mM-NaCl, peritubular p.d. hyperpolarized. Fluid reabsorption was stimulated (with 100 mM-NaCl in the lumen). Addition of amphotericin when the tubule was perfused on both sides with solutions containing a constant potassium concentration of 78 mM and a variable sodium concentration ranging from 7.8 to 34.5 mM revealed strong dependence of the peritubular hyperpolarization on the sodium concentration. Luminal furosemide (10(-4)M) and chlorothiazide (10(-4)M) and peritubular ethacrynic acid (10(-4)M) all reduced fluid reabsorption but hyperpolarized the peritubular p.d. The data suggest the presence of an electrogenic sodium transport process in the peritubular membrane that directly contributes to the generation of the peritubular potential. In addition, chloride transport has an important role in determining this potential.
分离美洲鳗螈的肾脏，用改良林格氏液进行灌注，并在管腔电解质浓度快速变化期间，用微电极测量远端小管的管周和跨上皮膜电位（p.d.s）。在使用和不使用已知会改变转运的各种药物的情况下，还测量了管周膜电位和净液体重吸收（分油滴法）。将管腔钠浓度从10 mM提高到100 mM可使管周p.d.可逆性增加。管周p.d.的幅度是管腔钠浓度的饱和函数。当管腔中存在氯离子时，管腔钠浓度增加后管周超极化可被管腔氨氯地平（10⁻⁴M）抑制。钠诱导的管周p.d.超极化可被10⁻⁵M哇巴因完全抑制。向管腔液中添加氨氯地平（10⁻⁴M）可使管周p.d.迅速且可逆地去极化，并抑制液体重吸收。向管腔灌注溶液中添加两性霉素B（20微克/毫升），在管腔氯化钠浓度为100 mM时对管周p.d.无影响，但在管腔氯化钠浓度为10 mM时，管周p.d.会超极化。液体重吸收受到刺激（管腔中为100 mM氯化钠）。当小管两侧用含有78 mM恒定钾浓度和7.8至34.5 mM可变钠浓度的溶液灌注时，添加两性霉素显示管周超极化强烈依赖于钠浓度。管腔速尿（10⁻⁴M）、氯噻嗪（10⁻⁴M）和管周依他尼酸（10⁻⁴M）均降低液体重吸收，但使管周p.d.超极化。数据表明管周膜中存在一种电生性钠转运过程，该过程直接有助于管周电位的产生。此外，氯离子转运在决定该电位方面具有重要作用。
