摘要
把血-肾关系看成是水和溶质在它们之间的循环流动,据此对各成分建立物质守恒方程。如果再假设神经一激素调节已足以使 Na^+浓度稳定在标准值附近,则可由此方程式组把肾滤液流(GFR)、血液 pH 值和其他各溶质的浓度都定解为 Na^+浓度和各回收流动力学参数的函数。由定态解可导出以下与传统理论不同的结论:①肾滤液流是被 Na^+回收流按等渗关系决定的,不可能是被血流动力学因素独立决定的。②肾小管钠泵的生理功能是驱动 Na^+-水循环流而不是建立钠浓度。③血液 pH 值是由诸共轭酸离解速度之和为零这一 H^+守恒方程决定的,与缓冲容量无关。④各成分的排泄流都只决定于其摄入流,与肾的调控功能无关等等。
The matter exchange between the blood pool and kidney is mode- lled as via cyclic flows of water and solutes between them.Equations are esta- blished for every component based on the dynamical mass balance of them in the flow-system.If we additionally assume that the neural hormonal mecha nisms in the distal parts of tubels were effective enough to keep the Na^+ concentration nearby its standard value without demand on the proximal parts, then GFR as well as pH value and concentrations of all solutes in blood can be explained by the steady state solutions of the equation set.Model leads to con clusions remarkably different from some traditional notions.Following are examples:1)The glomerular filtration rate(GFR)is determined by the rate of Na^+ reabsorption,and can't be by hemodynamic mechanisms.2)The physiolo- gical role of Na^+-K^+ATPase is to drive a large Na^+-water flow rather than to build up the Na^+concentration.3)The pH value of blood is determined by a constraint that the summation of dissociation rates of all conjugate acids must be zero,and is not related to the buffer capacity.4)The balance of exc retion rate to the input rate for every component is not influenced by the renal regularatory functions,etc.Physiological significances of these conclutions are in discussed the article.
关键词
肾脏
内环境稳定
数学模型
kidney
homeostasis
model
acid-base regulation
