Analysis of electrokinetic effects in transcapillary exchange

An idealized model of electrokinetic and convective exchange is used to investigate contributions of solute and barrier charge to capillary permselectivity. The exchange barrier is modelled with parallel plates representing endothelial cell surfaces and a bridging hexagonal array of posts representing glyco-calyx fibers. To construct a general solution of transport through this array, we first derive analytical expressions for electrostatic potential and electroosmotic velocity for transport around a single bounded post. For the negative zeta potential of the interen-dothelial cleft surfaces, we find electroosmotic velocity enhances (diminishes) transport of cationic (anionic) molecules compared to uncharged molecules. This agrees with and may provide a theoretical basis for experimental observations.