髓袢升支段对 NaCl 的主动重吸收,既是造成外髓部高渗状态的直接原因,也是使尿素浓缩并经远曲小管、集合管向内髓间隙扩散从而形成内髓部高渗的原始动力。关于升支粗段对 NaCl 的重吸收方式,曾一度认为是由于上皮细胞主动重吸收 Cl-后造成跨上皮细胞电位差而将 Na~+被动重吸收的,但随着近年来分子生物学研究的不断深入,业已证明髓袢升支粗段上皮细胞对 NaCl 的重吸收属 Na~+-Cl~-同向偶联转运,并对某些药 Mucous or ascending branch of the active reabsorption of NaCl is not only the cause of extramedullary hyperosmolar state of the direct cause, but also to enrich the urea and the distal convoluted tubules, collecting tube spread to the medullary space to form the end of the original medullary hypertonic power. Regarding the reabsorption of NaCl in the ascending branch, it was once thought that the Na ~ + passively reabsorbed Na ~ + after the epithelial cells actively reabsorbed Cl-, resulting in the trans-epithelial cell potential difference. However, in recent years, molecular biology research Of the deepening, it has been shown that the medulla oblongata branch of crude epithelial cells of NaCl reabsorption Na ~ + -Cl ~ - isotropic coupled transport, and certain drugs