Karmakar N, Jayaraman G
Centre for Atmospheric and Fluids Sciences, Indian Institute of Technology, New Delhi.
IMA J Math Appl Med Biol. 1988;5(1):33-43. doi: 10.1093/imammb/5.1.33.
In this paper, the authors present a diffusion model of the intestinal wall to describe the transient overall uptake of lead ions across the epithelium of gastrointestinal mucosa and their subsequent diffusion in the underlying blood capillaries. The gastrointestinal mucosa is treated as a heterogeneous two-phase medium, consisting of a continuous extracellular phase and a dispersed cellular phase. The main mode of uptake is considered to be bulk diffusion, since transport of lead across the mucosal membrane occurs mainly by a passive diffusion process. The equations give the variation with time of concentrations of lead in both the phases across the intestinal wall. The mean concentration of lead available for absorption by the blood capillaries has been studied as a function of time. It is found that a steady state is reached in 19.45 min. It has been possible to estimate the intestinal membrane permeability for the lead molecule from this analysis: it is calculated to be 3.34 X 10(-3) s-1. Finally, the rate of lead uptake by the blood for different gut concentrations has been calculated.
在本文中，作者提出了一种肠壁扩散模型，以描述铅离子在胃肠道黏膜上皮的瞬时总体摄取及其随后在下层毛细血管中的扩散。胃肠道黏膜被视为一种非均质的两相介质，由连续的细胞外相和分散的细胞相组成。摄取的主要方式被认为是整体扩散，因为铅穿过黏膜膜的运输主要通过被动扩散过程发生。这些方程给出了肠壁两侧两相中铅浓度随时间的变化。已研究了可供毛细血管吸收的铅的平均浓度随时间的函数关系。结果发现，在19.45分钟时达到稳态。通过该分析有可能估算铅分子的肠膜渗透率：经计算为3.34×10⁻³ s⁻¹。最后，计算了不同肠道浓度下血液对铅的摄取速率。
