VASOPRESSIN EFFECTS ON UREA AND H2O TRANSPORT IN INNER MEDULLARY COLLECTING DUCT SUBSEGMENTS
VASOPRESSIN EFFECTS ON UREA AND H2O TRANSPORT IN INNER MEDULLARY COLLECTING DUCT SUBSEGMENTS
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DOI：
10.1152/ajprenal.1987.253.5.f823
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发表时间：
1987-11-01
影响因子：
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通讯作者：
KNEPPER, MA
中科院分区：
文献类型：
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作者：
SANDS, JM;NONOGUCHI, H;KNEPPER, MA
内髓集合管（IMCD）被广泛视为具有均质特性的单个肾小管段。然而，最近的形态学和功能研究提出了 IMCD 的起始部分和末端部分可能不同的可能性。为了进一步测试这种可能性并定位精氨酸加压素 (AVP) 沿 IMCD 的作用位点，我们测量了离体灌注大鼠 IMCD 的渗透水渗透率 (Pf) 和尿素渗透率 (Purea)。在 IMCD 的最初三分之一中，10 nM AVP 将 Pf 从 16 .+- 增加。 8 至 148.+-。 50μm/秒。 IMCD 末端三分之二的基础 Pf 显着升高 (70.+-.12.mu.m/s)，增加至 186.+-. 25 μm/s，带 AVP。初始IMCD具有相对较低的基础Purea（3±1×10-5cm/s），其不随AVP改变。终端 IMCD 具有显着较高的基础 Purea (17.+-.4×10-5 cm/s)，使用 AVP 后增加至非常高的值 (69.+-.15×10-5 cm/s)。结果支持这样的前提：（从加压素对水和尿素运输的影响的角度来看）内髓集合管有两个功能不同的部分：类似于哺乳动物集合管的皮质或外髓部分的初始部分和类似于蟾蜍膀胱的末端部分。讨论了这些发现对于尿液浓缩机制的意义。
The inner medullary collecting duct (IMCD) is widely viewed as a single renal tubule segment with homogeneous properties. However, recent morphological and functional studies have raised the possibility that the initial and terminal parts of the IMCD may differ. To test this possibility further and to localize sites of action of arginine vasopressin (AVP) along the IMCD, we measured osmotic water permeability (Pf) and urea permeability (Purea) in isolated perfused rat IMCDs. In the initial third of the IMCD, 10 nM AVP increased Pf from 16 .+-. 8 to 148 .+-. 50 .mu.m/s. The terminal two-thirds of the IMCD had a significantly higher basal Pf (70 .+-. 12 .mu.m/s), which increased to 186 .+-. 25 .mu.m/s with AVP. The initial IMCD had a relatively low basal Purea (3 .+-. 1 .times. 10-5 cm/s), which did not change with AVP. The terminal IMCD had a significantly higher basal Purea (17 .+-. 4 .times. 10-5 cm/s), which increased to a very high value (69 .+-. 15 .times. 10-5 cm/s) with AVP. The results support the premise that (from the point of view of vasopressin effects on water and urea transport) there are two functionally distinct parts of the inner medullary collecting duct: an initial part that resembles the cortical or outer medullary portions of the mammalian collecting duct and a terminal part that resembles the toad urinary bladder. The significance of these findings for the urinary concentrating mechanism is discussed.