THEORY OF SOLUTE AND WATER TRANSPORT ACROSS EPITHELIA

数学模型被公式化，其表示上皮 作为隔室和边界膜的系统， 正常和病理状态的计算机模拟。 这 项目还进行了简化，近似， 数学模型，可用于解释 实验数据 近似解析比较 模型与详细的计算机模拟是用来评估 简单模型的适用范围。 主要目标为 下一个调查阶段是完成一个模型， 近端肾血管单位-包括近端小管， 肾小球和管周毛细血管。 该模型跟踪 Na+、K+、H+、C1-、碳酸根离子的浓度和通量， 仲磷酸氢根离子，伯磷酸氢根 离子、葡萄糖和尿素。 此模拟的主要焦点是 近端小管钠重吸收的研究： 钠转运的跨上皮途径和驱动力 以及物理因素调节这一过程的机制 重吸收 特别是，这是一个量化的努力， 影响的管腔和周围的因素，介导的 肾小球滤过和近端重吸收之间的平衡。 第二个焦点是近端小管的表现 碳酸氢盐重吸收：细胞内确定的转运机制 膜系统将在小管的背景下进行检查 模型，在模拟酸碱紊乱。 特别 感兴趣的是近端肾单位在维持肾功能中的作用。 代谢性疾病-定义减少的 肾小球滤过率、细胞外容量耗竭，以及 增加肾小管周围的pH值。下一个目标的第二个目标 研究期是皮质的代表 集合小管 该模型将逐步开发 从蟾蜍和乌龟膀胱的模拟时尚。 它 将用于探索肾小管流动、酸碱 状态和钠亲合力对该肾单位钾转运的影响 片段

Mathematical models are formulated that represent an epithelium as a system of compartments and bounding membranes and permit the computer simulation of normal and pathological states. This project also undertakes the analysis of simplified, approximate, mathematical models, which may be used in the interpretation of experimental data. Comparison of the approximate analytical models with the detailed computer simulation is used to assess the range of applicability of the simpler models. The major aim for the next period of investigation is the completion of a model of the proximal nephrovascular unit - including proximal tubule, glomerulus, and peritubular capillary. The model tracks the concentrations and fluxes of Na+, K+, H+, C1-, carbonate ion, secondary hydrogen phosphate ion, primary hydrogen phosphate ion, glucose and urea. The primary focus of this simulation is the study of the proximal tubule sodium reabsorption: the transepithelial pathways and driving forces of sodium transport and the mechanisms by which physical factors modulate this reabsorption. In particular, this is an effort to quantify the effects of luminal and peritubular factors which mediate the balance between glomerular filtration and proximal reabsorption. The second focus is the representation of proximal tubule bicarbonate reabsorption: mechanisms of transport defined in cell membrane systems are to be examined in the context of a tubule model, in simulations of the acid-base disturbances. Of particular interest is the role of the proximal nephron in the maintenance of metabolic alkalosis - defining the interplay of decreased glomerular filtration rate, extracellular volume depletion, and increased peritubular pH. A second aim for the next investigational period is the representation of the cortical collecting tubule. This model will be developed in a step-wise fashion from simulations of toad and turtle urinary bladder. It will be used to explore the interaction of tubule flow, acid-base states, and sodium avidity on potassium transport by this nephron segment.