Lory P, Gilg A, Horster M
J Math Biol. 1983;16(3):281-304. doi: 10.1007/BF00276508.
A differential equation model of the renal countercurrent system has been developed and physiological data from nephron segments were incorporated together with recently suggested urea recycling from renal pelvis to inner medulla and, particularly, an exponential reduction in the number of collecting tubules towards the renal papilla. The role of these features for the countercurrent concentrating mechanism has been studied by simulation runs. The computations, using the multiple shooting method, provide predictions about concentration profiles for salt and urea in tubes (nephron segments) and in the central core along the entire medullary countercurrent system. The results indicate that this model, without active salt or urea transport in the inner medulla, yields concentration gradients along the medullary axis compatible with those measured in the tissue.
已经建立了肾逆流系统的微分方程模型，将来自肾单位各节段的生理数据与最近提出的从肾盂到髓质内层的尿素再循环，特别是集合小管数量朝着肾乳头呈指数减少的数据结合起来。通过模拟运行研究了这些特征对逆流浓缩机制的作用。使用多重打靶法进行的计算提供了关于沿整个髓质逆流系统的小管（肾单位节段）和中央核心中盐和尿素浓度分布的预测。结果表明，该模型在内髓质中没有主动盐或尿素转运的情况下，产生的沿髓质轴的浓度梯度与在组织中测量的浓度梯度相符。
