Interference of dexamethasone with leukocyte blood volume and albumin movements in lungs from endotoxemic guinea-pigs

Using radioactive tracers, we measured blood volume, albumin exchanges and blood leukocyte sequestration within lungs, following an intravenous injection of lipopolysaccharide (0.1–1 mglkg). Neutrophil infiltration into the airways was followed in parallel experiments. Dexamethasone pretreatment (20 mg/kg, subcutaneous) failed to prevent early pulmonary changes induced by lipopolysaccharide as decreased blood volume, leukocyte sequestration, leukopenia or the increased trans-endothelial albumin exchanges. However, dexamethasone provided a significant protection against the later albumin leakage through the endothelial/epithelial barrier and the neutrophil accumulation in the airways observed in lipopolysaccharide-treated guinea-pigs. Our results indicate that the protective effect of dexamethasone in lipopolysaccharide-induced lung injury might derive from an initial reduction of leukocyte adhesion and a later decrease in alveolo-capillary permeability.