Vesicle Transport in Arterial Endothelium and the Influence of Mechanical Factors on Macromolecular Permeability

Abstract

The time-dependent transport of labeled vesicles in arterial endothelium has been modeled, taking into account the space-varying electrodynamic and hydrodynamic forces and the steric hindrance of vesicle attachment by the already attached vesicles. With the aid of laboratory model experiments to assess the steric hindrance effect, theoretical computation has been made on time-dependent labeled vesicle concentration profiles, and the results agree reasonably well with the published experimental data. Oscillatory length variations (5–10 Hz for 15 min) and elevation of transmural pressure (from 0–100 and 200 mmHg) caused increases in 125 I-albumin uptake by the canine common carotid artery. Theoretical computations based on ultrastructural determination of free vesicle density indicate that there was negligible enhancement of vesicle diffusion by these mechanical disturbances. The increases in albumin uptake following length oscillation and pressure elevation to 100 mmHg were accompanied by increases in luminal surface area, and the albumin permeability remained unchanged. The albumin permeability was elevated following pressure elevation to 200 mmHg, and this was attributable to (a) a decrease in transendothelial diffusion distance, and (b) facilitation of vesicle loading into the vesicles.