MODEL FOR PROTEIN-TRANSPORT ACROSS THE ENDOTHELIAL MEMBRANE

A mathematical model for convective and diffusive transport of protein across the capillary membrane is developed for a radioisotope-labeled species, the protein 113In-transferrin. Body tissue is modeled as a two-compartment porous medium with liquid and solid phases. In normal human subjects, labeled autologous blood is reinfused as an intravenous bolus, and blood samples are drawn periodically during the study. Gamma emissions detected in a well counter are fed automatically to a PDP- 11 10 computer for collection and analysis, and a transport parameter, r, which represents the ratio of convective to diffusive protein fluxes, is calculated for each subject. The range of r is 0.20-0.46 with an average ratio of 0.287. The results suggest that diffusion plays a dominant role in systemwide protein transport in the body. © 1979.