Increased microvascular permeability in canine endotoxic shock: protective effects of ibuprofen.

The ability of sodium ibuprofen to prevent endotoxin-induced changes in vascular permeability was examined in an anesthetized canine model. Ibuprofen was administered i.v. (3.75 mg/kg) in two pretreatment doses before the administration of Escherichia coli endotoxin (0.5 mg/kg). Serum and left thoracic duct lymph samples were collected for measurement of total protein and separation by polyacrylamide gel electrophoresis. Four protein fractions with molecular weights (MW) ranging from 60,000 to 1,000,000 were consistently analyzed. Administration of endotoxin alone resulted in hypotension and was accompanied by an increase in microvascular permeability as evidenced by increases in lymph flow rate, protein flux, lymph/plasma protein ratio (L/P), and permeability-surface area product (PS). Pretreatment with ibuprofen attenuated the increase in permeability as reflected by significantly lower lymph flow rate, protein flux, L/P, and PS. Electrophoretic data illustrate partial to complete protection for all four MW fractions. These results suggest that endotoxin damages microvascular integrity and increases extravasation of macromolecules as great as 1,000,000 MW. This damage is attenuated significantly by pretreatment with ibuprofen.