A Model of NO/O2Transport in Capillary-perfused Tissue Containing an Arteriole and Venule Pair

The goal of this study was to investigate the complex co-transport of nitric oxide (NO) and oxygen (O₂) in a paired arteriole-venule, surrounded by capillary-perfused tissue using a computer model. Blood flow was assumed to be steady in the arteriole and venular lumens and to obey Darcy's law in the capillary-perfused tissue. NO consumption rate in the arteriolar and venular lumen was assumed to be constant in the core of the arteriolar and venular lumen and to decrease linearly to the endothelium. Average NO consumption rate by capillary blood in a unit tissue volume was assumed proportional to the blood flux across the volume. Our preliminary results predict that: 1) The capillary bed, which connects the arteriole and venule, facilitates the release of O₂ from the vessel pair to the surrounding tissue; 2) Decreasing the distance between arteriole and venule can result in a higher NO concentration in the venular wall than in the arteriolar wall; 3) In the absence of capillaries in the surrounding tissue, diffusion of NO from venule to arteriole contributes little to NO contents in the arteriole; and 4) when capillaries are added to the simulation, a significant increase in arteriole NO content is observed.