Pennell J P, Bourgoignie J J
Am J Physiol. 1982 Jun;242(6):F657-63. doi: 10.1152/ajprenal.1982.242.6.F657.
Water transport by terminal papillary collecting ducts was examined by micropuncture of the renal papilla in 15 rats with a solitary remnant kidney (RK) and in 27 normal rats, 10 of which had undergone sham operation. Before papillary exposure, urinary osmolality was significantly (P less than 0.001) lower in RK rats (685 vs. 1,722 mosmol/kg H2O in normal rats). After papillary exposure, urinary osmolality decreased by 50% in normal rats but did not change in RK rats. In RK rats, a greater percentage of filtered water was delivered to (5.74% vs. 2.29% in normal rats, P less than 0.001) and reabsorbed by (1.94% vs. 0.94% in normal rats, P less than 0.005) the terminal millimeter of papillary collecting ducts. Fractional water reabsorption by terminal papillary collecting ducts correlated directly (r = 0.83, P less than 0.001) with fractional water delivery, suggesting load dependence of water reabsorption. Estimated absolute water reabsorption by terminal collecting ducts was equivalent for remnant and normal kidneys and increased two-to fourfold in remnant kidneys when analyzed per functioning papillary collecting duct. There was an inverse relationship between urinary osmolality and fractional water delivery to papillary collecting ducts (r = 0.65, P less than 0.001). Although the data do not exclude functional alterations of papillary collecting ducts, the events underlying the reduction of urinary osmolality in remnant kidneys appear to involve physiological processes based on a high delivery and reabsorption of water.
通过对15只单肾残端大鼠（RK）和27只正常大鼠（其中10只接受过假手术）的肾乳头进行微穿刺，研究终末乳头集合管的水转运情况。在暴露乳头之前，RK大鼠的尿渗透压显著低于正常大鼠（P<0.001）（RK大鼠为685mOsmol/kg H₂O，正常大鼠为1722mOsmol/kg H₂O）。暴露乳头后，正常大鼠的尿渗透压降低了50%，而RK大鼠的尿渗透压没有变化。在RK大鼠中，更大比例的滤过水被输送至终末乳头集合管的最后1毫米（正常大鼠为2.29%，RK大鼠为5.74%，P<0.001）并被重吸收（正常大鼠为0.94%，RK大鼠为1.94%，P<0.005）。终末乳头集合管的水重吸收分数与水输送分数直接相关（r=0.83，P<0.001），提示水重吸收依赖于负荷。根据每个有功能的乳头集合管分析，终末集合管的估计绝对水重吸收在残肾和正常肾中相当，在残肾中增加了2至4倍。尿渗透压与输送至终末乳头集合管的水分数呈负相关（r=0.65，P<0.001）。虽然这些数据不排除乳头集合管的功能改变，但残肾中尿渗透压降低的潜在机制似乎涉及基于高水输送和重吸收的生理过程。
