Convective uphill transport of NaCl from ascending thin limb of loop of Henle.
Convective uphill transport of NaCl from ascending thin limb of loop of Henle.
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氯化钠从亨勒环上升细肢的对流上坡输送。
DOI：
10.1152/ajprenal.1995.268.4.f680
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Tewarson,RP
中科院分区：
文献类型：
--
作者：
Stephenson,JL;Jen,JF;Wang,H;Tewarson,RP
在本文中，我们描述了一个数学模型的基础上，以前提出的模型[A.S. Wexler，R.E. Kalaba和D.J. Marsh。Am. J.Physiol.260（Renal Fluid Electrolyte Physiol.29）：F368-F383，1991]，其中在髓内，Henle袢（ATL）和集合管（CD）的上升细肢与局部毛细血管结交换，其中再吸收的水和溶质径向流向中央血管束。我们的模型的不同之处在于，上升和下降的直血管和周围的间隙空间被中央核心所取代。我们的耦合ATL-CD系统的分析表明，它是理论上能够运输NaCl的ATL到中央血管空间（近似的中央核心）对浓度梯度，在没有径向扩散可以是任意大。通过数值求解NaCl的径向扩散系数D（r）为0的模型，我们发现ATL相对于核可以达到100 mosmol/l以上的低渗。我们还发现，限制扩散的CD在乳头的渗透压显着大于亨利环。当D（r）接近NaCl在自由溶液中的扩散系数时，环的渗透压增加，CD的渗透压降低。因此，总的来说，与直观的预期相反，NaCl的径向分离和向上输送不会使回路浓度显著增加，这主要取决于从CD再吸收的尿素的量。
In this paper we describe a mathematical model of the renal inner medulla based on a previously proposed model [A.S. Wexler, R.E. Kalaba, and D.J. Marsh. Am. J. Physiol. 260 (Renal Fluid Electrolyte Physiol. 29): F368–F383, 1991] in which in the inner medullary ascending thin limb of Henle's loop (ATL) and collecting duct (CD) exchange with a local capillary node with the reabsorbed water and solutes flowing radially toward a central vascular bundle. Our model differs in that ascending and descending vasa recta and surrounding interstitial space are replaced by a central core. Our analysis of the coupled ATL-CD system shows that it is theoretically capable of transporting NaCl out of the ATL into the central vascular space (approximated by the central core) against a concentration gradient, which in the absence of radial diffusion can be arbitrarily large. By numerical solution of the model with the radial diffusion coefficient (D(r)) for NaCl of 0, we find that the ATL can be more than 100 mosmol/l hypotonic with respect to the core. We also find that with restricted diffusion the osmolality of the CD at the papilla is significantly greater than that of the loop of Henle. As D(r) approaches the diffusion coefficient of NaCl in free solution, the osmolality of the loop increases and that of the CD decreases. Thus, overall, contrary to intuitive expectations, the radial separation and uphill transport of NaCl do not give any significant increase in loop concentration, which depends primarily on the quantity of urea reabsorbed from the CD.