A Charge-Diffusion-Filtration Model for Endothelial Surface Glycocalyx

Endothelial surface glycocalyx plays an important role in the regulation of microvessel permeability by possibly changing its charge and configuration. To investigate the mechanisms of how surface properties of the endothelial cells control the changes in microvessel permeability, we extended the electrodiffusion model developed by Fu et al. (Am. J. Physiol. 284:H1240-1250, 2003), which is for the interendothelial cleft with a negatively charged surface glycocalyx layer, to include the filtration due to hydrostatic and oncotic pressures across the microvessel wall as well as the electrical potential across the glycocalyx layer. On the basis of the hypotheses proposed by Curry (Microcirculation 1(1): 11–26, 1994), the predictions from this electrodiffusion-filtration model provide a remarkably good agreement with experimental data for permeability of negatively charged α-lactalbumin summarized in Curry (Microcirculation 1(1): 11–26, 1994) under various conditions. In addition, we applied this new model to describe the transport of negatively charged macromolecules, bovine serum albumin (BSA), across venular microvessels in frog mesentery. A very interesting prediction is that the convective component of albumin transport is greatly diminished by the presence of a negatively charged glycocalyx under both normal and increased permeability conditions.