Sajo I M, Goldstein M B, Sonnenberg H, Stinebaugh B J, Wilson D R, Halperin M L
Kidney Int. 1981 Sep;20(3):353-8. doi: 10.1038/ki.1981.146.
The purpose of this investigation was to determine in which nephron segments ammonia was added to or removed from the lumenal fluid of the rat. Ammonium was measured in proximal and distal tubular fluid samples obtained by micropuncture and in collecting duct fluid samples obtained by microcatheterization. Water abstraction was assessed by examining the tubular fluid-to-plasma inulin concentration, (TF/P)In. In normal or acidotic rats, the vast bulk of the final urine ammonium appeared in the proximal tubular fluid samples. Most of this ammonia was lost, however, in transit from the proximal to the distal tubule so that only 20 to 30% of the excreted ammonium was present at the distal site. Ammonia reentered the lumenal fluid primarily in the cortical collecting duct in acidotic rats and in the medullary collecting duct in normal rats. Although the pattern was qualitatively similar in both groups of rats, the absolute quantity of ammonium in each nephron segment of normal rats was about 10 to 20% of that in acidotic animals.
本研究的目的是确定大鼠肾单位的哪些节段向管腔液中添加氨或从管腔液中去除氨。通过微穿刺获得近端和远端肾小管液样本，并通过微导管插入术获得集合管液样本，测量其中的铵含量。通过检测肾小管液与血浆中菊粉浓度之比（TF/P）In来评估水的重吸收情况。在正常或酸中毒大鼠中，最终尿液中绝大部分铵出现在近端肾小管液样本中。然而，大部分氨在从近端小管转运到远端小管的过程中丢失，因此在远端部位仅存在20%至30%的排泄铵。在酸中毒大鼠中，氨主要在皮质集合管重新进入管腔液，而在正常大鼠中则在髓质集合管重新进入管腔液。尽管两组大鼠的模式在定性上相似，但正常大鼠每个肾单位节段中的铵绝对量约为酸中毒动物的10%至20%。
