The exchange of substances between the blood and tissue compartments can be analyzed at both a structural and a functional level. Much remains to be learned concerning the participation of the several components of the capillary wall in the movement of substances to and from the bloodstream. Previous interpretations of the capillary wall as a biologic membrane with fixed structural features are...

The distribution of red blood cells in alveolar capillaries is typically nonuniform, as shown by intravital microscopy and in alveolar tissue fixed in situ. To determine the effects of red cell distribution on pulmonary diffusive gas transport, we computed the uptake of CO across a two-dimensional geometric capillary model containing a variable number of red blood cells. Red blood cells are spa...

Blood losses are usually corrected initially by the restitution of volume with plasma expanders and subsequently by the restoration of oxygen-carrying capacity using either a blood transfusion or possibly, in the near future, oxygen-carrying plasma expanders. The present study was carried out to test the hypothesis that high-plasma viscosity hemodilution maintains perfused functional capillary ...

BACKGROUND One of the central physiological functions of the lungs is to transfer inhaled gases from the alveoli to pulmonary capillary blood. However, current measures of alveolar gas uptake provide only global information and thus lack the sensitivity and specificity needed to account for regional variations in gas exchange. METHODS AND PRINCIPAL FINDINGS Here we exploit the solubility, hig...

A mathematical model for solute distribution within the tissue due to combined processes of diffusion and convective transport through the tissue, through the capillary wall, and by lymphatic absorption, during the exchange of the solute between an organ and external medium is applied for the description of the transport of small, middle and macro molecules. The analytical solutions of the tran...

A mathematical model for nutritional transport in capillary tissues exchange system in the presence of magnetic field has been studied. In this case, the cell is deformed. Due to concentration gradients, the dissolved nutrient in substrate diffuses into surrounding tissue. The analytical method is based on perturbation technique while the numerical simulation is based on finite difference schem...

The escape of solutes from the blood during passage along capillaries in heart and skeletal muscle occurs via diffusion through clefts between endothelial cells and, for some solutes, via adsorption to or transport across the luminal plasmalemma of the endothelial cell. To quantitate the rates of permeation via these two routes of transport across capillary wall, we have developed a linear mode...

Various indices of capillary supply to the rat heart were studied in neonatal rats injected for 2 or 4 weeks with protamine sulfate in saline (subcutaneously, 60 mg/kg body weight, 2 times/day). Cardiac capillarization was evaluated not only by traditional indices for the capillary supply, such as mean capillary density and myocyte-to-capillary ratio, but also by a more advanced morphometric me...

To determine whether all-trans retinoic acid (RA) enhances compensatory lung growth in fully mature animals, adult male dogs (n = 4) received 2 mg x kg(-1) x day(-1) po RA 4 days/wk beginning the day after right pneumonectomy (R-PNX, 55-58% resection). Litter-matched male R-PNX controls (n = 4) received placebo. After 4 mo, the remaining lung was fixed by tracheal instillation of fixatives at a...