Interstitial water and solute recovery by inner medullary vasa recta.
Interstitial water and solute recovery by inner medullary vasa recta.
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内髓直肠血管间质水和溶质的回收。
DOI：
10.1152/ajprenal.2000.278.2.f257
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Pallone,TL
中科院分区：
文献类型：
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作者：
Edwards,A;Delong,MJ;Pallone,TL
最近的一个肾髓质体积和溶质微血管交换模型通过模拟NaCl、尿素和水从Henle袢和收集管进入髓质间质的沉积而得到扩展，其生成速率在髓质间质内发生空间变化。根据Koepsell等人（H. Koepsell， W. E. A. P. Nicholson， W. Kriz和H. J. Höhling）的建议，在髓质内建立指数渗透压梯度。pflgers Arch.350: 167-184, 1974)，间隙小溶质的面积加权生成率与水的生成率的比值必须沿皮质-髓轴增加。通过保持水的面积加权生成速率不变，同时增加NaCl和尿素的面积加权生成速率，或者随着髓质深度的增加而减小水的输入速率，来满足这一条件。特别是后一种情况，在乳头尖端产生更高的溶质浓度。假设经髓内直血管过滤后的水、NaCl和尿素的回收率分别为1%、1%和40%，当单位体积间质尿素生成量和NaCl生成量分别呈指数和线性增加时，乳头尖渗透压为1470 mosmol/kgH2O。当1)髓血流量减少，2)降直血管（DVR）的水力导率降低，3)直血管对NaCl和尿素的渗透性最大化时，髓内渗透压梯度进一步增加。在DVR中，水通道蛋白-1介导的跨细胞通量导致水和小溶质运输之间的耦合也增强了尖端渗透压。
A recent model of volume and solute microvascular exchange in the renal medulla was extended by simulating the deposition of NaCl, urea, and water into the medullary interstitium from the loops of Henle and collecting ducts with generation rates that undergo spatial variation within the inner medullary interstitium. To build an exponential osmolality gradient in the inner medulla, as suggested by Koepsell et al. (H. Koepsell, W. E. A. P. Nicholson, W. Kriz, and H. J. Höhling.Pflügers Arch.350: 167–184, 1974), the ratio of the interstitial area-weighted generation rate of small solutes to that of water must increase along the corticomedullary axis. We satisfied this condition either by holding the area-weighted generation rate of water constant while increasing that of NaCl and urea or by reducing the input rate of water with medullary depth. The latter case, in particular, yielded higher solute concentrations at the papillary tip. Assuming that the fraction of the filtered load recovered by inner medullary vasa recta for water, NaCl, and urea is 1%, 1%, and 40%, respectively, papillary tip osmolality is 1,470 mosmol/kgH2O when urea generation and NaCl generation per unit volume of interstitium increase exponentially and linearly, respectively. The inner medullary osmolar gradient also increases further when1) medullary blood flow is reduced,2) hydraulic conductivity of descending vasa recta (DVR) is lowered, and3) vasa recta permeability to NaCl and urea is maximized. The coupling between water and small solute transport, resulting from aquaporin-1-mediated transcellular flux in DVR, also enhances tip osmolality.