A mechano-electrochemical model of radial deformation of the capillary glycocalyx
A mechano-electrochemical model of radial deformation of the capillary glycocalyx
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DOI：
10.1016/s0006-3495(02)75474-x
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发表时间：
2002-03-01
影响因子：
3.4
通讯作者：
Stace, TM
中科院分区：
文献类型：
--
作者：
Damiano, ER;Stace, TM
提出了毛细血管内皮细胞表面糖萼的机械电化学理论，该理论将结构建模为电解液中水合的带静电大分子的混合物。由机械变形引起的干扰被引入为远离近电中性平衡环境的扰动。在该层的机械压缩下，例如僵硬的白细胞通过毛细血管时可能发生的情况，该模型预测压缩层的电化学势梯度会导致糖萼内移动离子的重新分布以及该层的再水化和恢复到其平衡尺寸。由于通过的白细胞引起糖萼的大变形，因此在理论中考虑了与该层的有限变形相关的非线性运动学。移动离子的传输调用伪平衡近似，将耦合非线性积分微分方程组简化为单个非线性偏微分方程，在固定网格上使用有限差分法对糖萼的压缩和恢复进行数值求解。还获得了小应变的线性化模型作为有限差分解的验证。渐近分析的结果与层小变形极限下的非线性解非常吻合。使用现有的糖萼特性的实验和理论估计，通过分析估计糖萼固定电荷密度类似于 1 mEq/l，即，我们估计血液中每 100 个离子在糖萼上大约存在一个固定电荷。这样的电荷密度将导致未变形的糖萼和毛细管腔之间的电压差类似于0.1mV。除了提供对变形下层的机械电化学动力学的深入了解之外，该模型还提出了几种方法来获得体内糖萼固定电荷密度和渗透性的改进估计。
A mechano-electrochemical theory of the surface glycocalyx on capillary endothelial cells is presented that models the structure as a mixture of electrostatically charged macromolecules hydrated in an electrolytic fluid. Disturbances arising from mechanical deformation are introduced as perturbations away from a nearly electroneutral equilibrium environment. Under mechanical compression of the layer, such as might occur on the passing of stiff leukocytes through capillaries, the model predicts that gradients in the electrochemical potential of the compressed layer cause a redistribution of mobile ions within the glycocalyx and a rehydration and restoration of the layer to its equilibrium dimensions. Because of the large deformations of the glycocalyx arising from passing leukocytes, nonlinear kinematics associated with finite deformations of the layer are accounted for in the theory. A pseudo-equilibrium approximation is invoked for the transport of the mobile ions that reduces the system of coupled nonlinear integro-differential equations to a single nonlinear partial differential equation that is solved numerically for the compression and recovery of the glycocalyx using a finite difference method on a fixed grid. A linearized model for small strains is also obtained as verification of the finite difference solution. Results of the asymptotic analysis agree well with the nonlinear solution in the limit of small deformations of the layer. Using existing experimental and theoretical estimates of glycocalyx properties, the glycocalyx fixed-charge density is estimated from the analysis to be similar to1 mEq/l, i.e., we estimate that there exists approximately one fixed charge on the glycocalyx for every 100 ions in blood. Such a charge density would result in a voltage differential between the undeformed glycocalyx and the capillary lumen of similar to0.1 mV. In addition to providing insight into the mechano-electrochemical dynamics of the layer under deformation, the model suggests several methods for obtaining improved estimates of the glycocalyx fixed-charge density and permeability in vivo.