Buerkert J, Alexander E, Purkerson M L, Klahr S
J Lab Clin Med. 1976 Mar;87(3):397-410.
Fluid reabsorption in surface nephrons was studied by micropuncture 3 hours after release of complete left ureteral ligation (LUL) or after unilateral release of bilateral ureteral ligation (BUL). In 11 rats with LUL, glomerular filtration rate (GFR) averaged 0.23 +/- 0.04 ml. per minute in the experimental vs. 1.25 +/- 0.11 ml. per minute in the control kidney. GFR averaged 0.18 +/- 0.02 ml. per minute in BUL. Single nephron glomerular filtration rate (SNGFR) was decreased in the experimental kidney of LUL or BUL when determined at proximal or distal sites as compared to the SNGFR determined in shams or the left kidney following right ureteral ligation (RUL). Fractional water excretion was increased after release of obstruction. LUL 2.72 +/- 0.66 per cent; BUL 12.3 +/- 2.82 per cent when compared to sham-operated rats (0.48 +/- 0.07 per cent) or to the untouched kidneys of the RUL group (0.60 +/- 0.09 per cent). Despite increased water and sodium excretion after release of unilateral ureteral ligation and BUL there were marked differences in tubular fluid reabsorption between these two groups. Following release of LUL there was increased fractional water reabsorption along the accessible length of surface nephrons of the experimental kidney. At 55 per cent of proximal tubular length TF/Pin averaged 4.02 +/- 0.02 in LUL vs. 2.18 +/- 0.06 in shams. The mean TF/Pin at 90 per cent of distal tubular length was 31.0 +/- 1.37 in LUL vs. 10.6 +/- 0.08 in sham-operated rats. In contrast, water reabsorption after BUL was slightly but significantly suppressed proximally (TF/Pin 1.95 +/- 0.02) and markedly depressed distally (TF/Pin 3.35 +/- 0.29). These results suggest that the change in fluid reabsorption observed after relief of LUL is located at a site beyond the accessible length of surface nephrons, most likely in the collecting duct. However, the data could also be explained by alterations in fluid reabsorption in deep nephrons. The changes in fluid reabsorption seen following release of BUL reflect the additive effects of release of obstruction and a marked reduction in functioning nephron mass.
在完全结扎左输尿管（LUL）解除3小时后或双侧输尿管结扎（BUL）单侧解除后，通过微穿刺术研究了浅表肾单位的液体重吸收情况。在11只接受LUL的大鼠中，实验侧肾脏的肾小球滤过率（GFR）平均为0.23±0.04毫升/分钟，而对照侧肾脏为1.25±0.11毫升/分钟。BUL组的GFR平均为0.18±0.02毫升/分钟。与假手术组或右侧输尿管结扎（RUL）后左侧肾脏相比，在近端或远端测定时，LUL或BUL实验侧肾脏的单肾单位肾小球滤过率（SNGFR）降低。梗阻解除后，水排泄分数增加。与假手术大鼠（0.48±0.07%）或RUL组未处理的肾脏（0.60±0.09%）相比，LUL组为2.72±0.66%；BUL组为12.3±2.82%。尽管单侧输尿管结扎和BUL解除后水和钠排泄增加，但这两组之间的肾小管液重吸收存在显著差异。LUL解除后，实验侧肾脏浅表肾单位可及长度范围内的水重吸收分数增加。在近端肾小管长度的55%处，LUL组的TF/Pin平均为4.02±0.02，而假手术组为2.18±0.06。在远端肾小管长度的90%处，LUL组的平均TF/Pin为31.0±1.37，而假手术大鼠为10.6±0.08。相比之下，BUL后近端水重吸收略有但显著受抑制（TF/Pin为1.95±0.02），远端则明显降低（TF/Pin为3.35±0.29）。这些结果表明，LUL解除后观察到的液体重吸收变化位于浅表肾单位可及长度之外的部位，很可能在集合管。然而，这些数据也可以用深部肾单位液体重吸收的改变来解释。BUL解除后液体重吸收的变化反映了梗阻解除的叠加效应以及功能性肾单位数量的显著减少。
