ABSTRACT To test concepts developed in our ovine model of
acute respiratory distress syndrome, specifically the roles of
neuropeptides and other
peptide mediators, a recently developed murine model of combined
smoke inhalation and
burn (SB) injury was extended by applying methods for quantitative assessment of acute
inflammation in the lung. Mice received SB injury per protocol, n = 5 to 7 per group. Mice were anesthetized with i.p.
ketamine/
xylazine, endotracheally intubated, and exposed to cooled cotton
smoke (4 x 30 sec for Balb/C, 2 x 30 sec for C57BL/6). After s.c. injection of 1 mL
0.9% saline, each received a 40% total body surface area (TBSA) flame
burn.
Buprenorphine (0.1 mg/kg) was given i.p. for postoperative
analgesia;
0.9% saline was given i.p. at 4 mL/kg per %TBSA
burn.
Evans Blue dye (EB) was injected i.v. 15 min before sacrifice.
Lung wet/dry weight ratio was measured. In other animals, after vascular perfusion with buffered saline, lungs were sampled and analyzed for
myeloperoxidase (MPO), using an EIA kit, and for their content of EB
dye. There was a significant (p < 0.05) increase in EB
dye content, wet/dry weight ratio, and MPO 24 h after injury in Balb/C mice. Similar increases were seen in C57BL/6 mice 48 h after SB injury, but not at 24 h. C57 mice tolerated less
smoke inhalation than Balb/C mice, due to postexposure
apnea, and required 48 h to show significant increases in these variables. Direct comparison between animals injured by 40% TBSA
burn and 2 x 30 sec
smoke exposure and sacrificed after 48 h showed significantly greater abnormality in the C57BL/6 mice. The mouse model can be used effectively to assess acute
inflammation in the lung.