ANALYSIS OF SOLUTE AND WATER TRANSPORT IN THE KIDNEY

本项目的具体目标是：(1)确定 骨髓浓度梯度与终末尿液渗透压的关系 哺乳动物肾脏对肾小管和血管的通透性、流量和 建筑。(2)建立了电解质迁移的数学模型。 在整个肾脏中，包括电解质(钠、钾、氯、HC03、H_2P_04、 H)、葡萄糖、尿素、蛋白质催化力、静水压力和 电势。(3)识别单向膜 基于时间和空间分布的渗透性和区域血流 由CAT扫描确定的放射性核素排泄量。 发展非电解质溶液的一般方法学 将使用全肾模型来解决扩展模型。 也就是说，对的“全局”变量进行了初步估计 浓度、静水压力和电势 皮质和髓质间质。描述流动的方程式， 的浓度、压力、电势和透尿量 然后溶解沿小管和毛细血管的溶质和水，以及 测试了质量守恒和电荷守恒。据估计， 然后，通过适当的数学方法迭代地改进全局变量 和计算方法，直到某些选定的守恒性得到满足 宽容。这一全球解决方案战略开启了 反馈在整个器官功能中循环，并允许我们跟踪任何选定的 变量作为任何选定模型参数或边界的函数 条件。 这项研究的长期目标是开发出与 正常和病理肾功能对基础微观转运的影响 肾小管膜和细胞内的突起及其相互作用 伴生的血管系统。更具体地说，该项目侧重于因素 对尿钠排泄浓度和稀释度的影响 完整和分离的灌流(大鼠)肾，目的是 理解体液渗透压的控制和调节 细胞外液容量。它与每种疾病都有关联 任何一种都不受干扰。

The specific aims of this project are: (1) To determine the relation of medullary concentration gradients and the osmolality of final urine in the mammalian kidney to tubular and vascular permeabilities, flows and architecture. (2) To develop a mathematical model of electrolyte transport in the whole kidney, which includes electrolytes (Na, K, Cl, HC03, H2P04, H), glucose, urea, protein oncotic forces, hydrostatic pressure, and electrical potential. (3) To identify unidirectional membrane permeabilities and regional blood flows from temporal and spatial patterns of radionuclide excretion as determined from CAT scans. The general methodology developed for the solution of non-electrolyte models of the whole kidney will be used to sovle the extended models. Namely, an initial estimate is made of the "global" variables of concentrations, hydrostatic pressure, and electrical potential in the cortical and medullary interstitium. The equations describing flow, concentration, pressure, electric potential, and transmureal fluxes of solutes and water along the tubules and capillaries are then solved, and conservation of mass and electric charge is tested. The estimates of the global variables are then iteratively improved by appropriate mathematical and computational methods until conservation is satisfied to some selected tolerance. This global solution strategy opens the network of interacting feedback loops in whole organ function and allows us to follow any selected variable as a function of any selected model parameter or boundary condition. The long term objective of the research is to develop models that relate normal and pathological renal function to underlying microscopic transport processes in the membranes and cells of the renal tubules and their associated vasculature. More specifically the project focuses on factors affecting the concentration and dilution of urine and sodium excretion in intact and isolated perfused (rat) kidney with the objective of understanding the control of body fluid osmolality and the regulation of extracellular fluid volume. It is relevant to every disease with a disturbance of either.