Hebert S C
Am J Physiol. 1986 Jun;250(6 Pt 1):C920-31. doi: 10.1152/ajpcell.1986.250.6.C920.
Differential interference contrast microscopy and standard electrophysiological techniques were used to evaluate the transport processes involved in antidiuretic hormone (ADH)-dependent hypertonic cell volume regulation in the in vitro perfused mouse medullary thick ascending limb of Henle. Hypertonic cell volume regulation appeared to involve NaCl uptake into cells, since the cell volume increase after osmotic shrinkage in hypertonic media could be abolished either by symmetrical removal of Na+ from external solutions or by bath Cl- omission. The volume-regulatory process also required CO2/HCO3- in external media and could be abolished by the lipophilic carbonic anhydrase inhibitor, ethoxzolamide, in the presence of CO2/HCO3-. In addition, ADH-dependent hypertonic cell volume regulation was reduced or abolished by 10(-4) M amiloride, 10(-3) M ouabain, or 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2-disulfonic acid in peritubular media or by cooling to 15 degrees C. In contrast, lumen Cl- omission or 10(-4) M amiloride addition to the perfusate had no effect on cell volume regulation in hypertonic peritubular media. These data suggest that ADH-dependent, hypertonic cell volume regulation in the mouse medullary thick limb depends on cell NaCl uptake via a secondary active transport process involving parallel Na+-H+ and Cl(-)-HCO3- exchangers in basolateral cell membranes. Finally, luminal furosemide (10(-4) M) abolished bath ouabain-mediated, rapid cell swelling in isotonic media containing ADH. Thus these exchangers do not appear to be active in the resting, isotonic state. The specific role of ADH in this NaCl transport process remains to be defined.
利用微分干涉对比显微镜和标准电生理技术，评估了抗利尿激素（ADH）依赖性高渗细胞体积调节过程中，体外灌注的小鼠髓袢升支粗段所涉及的转运过程。高渗细胞体积调节似乎涉及细胞摄取NaCl，因为在高渗介质中渗透性收缩后细胞体积的增加，可通过从外部溶液中对称去除Na⁺或通过浴液中Cl⁻缺失来消除。体积调节过程还需要外部介质中的CO₂/HCO₃⁻，并且在存在CO₂/HCO₃⁻的情况下，可被亲脂性碳酸酐酶抑制剂乙氧唑胺消除。此外，在肾小管周介质中加入10⁻⁴ M氨氯吡脒、10⁻³ M哇巴因或10⁻⁴ M 4-乙酰氨基-4'-异硫氰基芪-2,2-二磺酸，或冷却至15℃，可降低或消除ADH依赖性高渗细胞体积调节。相比之下，管腔Cl⁻缺失或向灌注液中添加10⁻⁴ M氨氯吡脒，对高渗肾小管周介质中的细胞体积调节没有影响。这些数据表明，小鼠髓袢升支粗段中ADH依赖性高渗细胞体积调节，依赖于细胞通过涉及基底外侧细胞膜中平行Na⁺-H⁺和Cl⁻-HCO₃⁻交换体的继发性主动转运过程摄取NaCl。最后，管腔呋塞米（10⁻⁴ M）消除了浴液哇巴因介导的、在含有ADH的等渗介质中的快速细胞肿胀。因此，这些交换体在静息等渗状态下似乎不活跃。ADH在这种NaCl转运过程中的具体作用仍有待确定。
