Oxygen radicals, enzymes, and fluid transport through pericardial interstitium

The interstitium is the final link in the transportation of nutrients from the bloodstream to the individual cells of an organism. To assess interstitial fluid transport in normal and inflamed tissue, the hydration (H, ml H2O/g dry wt) and hydraulic conductivity (Kp, 10(-8) cm2.s-1.cmH2O-1) of bovine pericardial stroma were determined. The effect of enzymes and neutrophil-derived products of inflammation on the properties of the interstitial model were determined. Samples of the pericardium were exposed separately to trypsin, elastase, hyaluronidase, collagenase, superoxide radicals, and hydrogen peroxide. After exposure, the tissues were washed repeatedly in physiological saline and equilibrated in transport chambers heated to 37 degrees C and pressurized to 50 cmH2O. Fluid flow across the tissues was monitored. A section of tissue was removed and weighed. The tissue section was subsequently dried and reweighed. Tissue thickness, H, and Kp were calculated. H and Kp of the control tissues were 2.82 +/- 0.04 and 1.71 +/- 0.07, respectively. Hydration was significantly increased (22-38%) by exposure to trypsin, elastase, collagenase, and superoxide radicals. Kp increased significantly (30-1055%) in the groups treated with trypsin, hyaluronidase, collagenase, and superoxide radicals. The inflammatory mediators generally increased the hydration and/or the hydraulic conductivity of the model. These results indicate that neutrophil-derived products could be involved in the development of interstitial edema during the inflammatory process.