Macromolecular transport through the deformable porous media of an artery wall

To determine the macromolecular transport properties of the tunica media of an artery wall deformed inhomogeneously by the transmural pressure, we combine a simple mechano-hydraulic model based on a two parameter strain-dependent permeability function, which was developed by Klanchar and Tarbell (1987), with a fiber matrix theory. The combined theory allows us to calculate the spatial distributions of porosity, solute partition, fiber radius and macromolecular solute concentration in the media and their dependence on the transmural pressure. The predictions from the combined theory are in good agreement with experimental measurements of sucrose space, albumin space and albumin concentration profiles in the media of rabbit aortas at transmural pressures of 70 and 180 mmHg. The predictions indicate that albumin transport through the aortic media is dominated by convection rather than diffusion. It is further demonstrated that the transport properties of unstressed planar tissue samples, which are often used in in vitro experiments, may be quite different from those of intact vessels in their natural cylindrical configuration because of variation in tissue deformation.