Bar-Code Computers Ltd., POB 2065, Tirat-Carmel 39120, Israel.
J Theor Biol. 2010 Apr 7;263(3):295-302. doi: 10.1016/j.jtbi.2009.12.010. Epub 2009 Dec 16.
The factors that affect and govern the glucose transfer from maternal blood to the fetus are not completely deciphered. We present a steady state, one dimensional mathematical simulation which integrates the main mechanisms that have been shown to exist: metabolic consumption of the placenta, simple and facilitated diffusion via the two membranes of the microvillous and simple diffusion within the placenta. The model uses all available physiologic data we could collect. Numerical results indicate that the most crucial factor in determining the fetal glucose concentration is the facilitated diffusion process at the basal membrane or, more specifically: the permeability of the basal membrane and the density of the transporter GLUT1 on its faces. The gradient between the maternal and the fetal glucose concentration is important as is the metabolic consumption of the placenta. The diffusion within the placenta and the conditions that prevail at the apical microvillous plasma membrane are much less significant. Intrasyncytial concentration of glucose is close to that of maternal blood. The adjustment of the fetal glucose concentration to abrupt changes of its surrounding is estimated to be quite rapid hence for all practical purposes this steady state model can serve as a reasonable approximation. Parameters that await experimental determination are identified.
影响和控制母体血液中葡萄糖向胎儿转移的因素尚未完全阐明。我们提出了一个稳态、一维的数学模拟，该模拟整合了已证明存在的主要机制：胎盘的代谢消耗、通过微绒毛的两层膜的简单扩散和易化扩散以及胎盘内的简单扩散。该模型使用了我们能够收集到的所有可用生理数据。数值结果表明，决定胎儿葡萄糖浓度的最关键因素是基底膜的易化扩散过程，或者更具体地说，是基底膜的通透性和其表面上的转运蛋白 GLUT1 的密度。母体和胎儿葡萄糖浓度之间的梯度很重要，胎盘的代谢消耗也是如此。胎盘内的扩散以及在顶端微绒毛质膜上的条件则不那么重要。细胞内葡萄糖浓度接近母体血液。胎儿葡萄糖浓度对周围环境的突然变化的调整估计相当迅速，因此对于所有实际目的而言，这个稳态模型可以作为一个合理的近似。需要进行实验确定的参数已经确定。
