Abstract
The procedures described below are for producing gastric aspiration pneumonitis in mice with alterations for rats and rabbits described parenthetically. We use 4 different injury vehicles delivered intratracheally to investigate the inflammatory responses to gastric aspiration:1) Normal saline (NS) as the injury vehicle control2) NS + HCl, pH = 1.25 (acid)3) NS + gastric particles, pH ≈ 5.3 (part.)4) NS + gastric particles + HCl, pH = 1.25 (acid + part.)The volume, pH, and gastric particle concentration all affect the resulting lung injury. In mice, we generally use an injury volume of 3.6 ml/kg (rat: 1.2 ml/kg, rabbit: 2.4 ml/kg), an injury pH (for the acid-containing vehicles) of 1.25, and a gastric particulate concentration (in the particulate-containing vehicles) of 10 mg/ml (rat: 40 mg/ml). In our hands this results in a maximal, non-lethal lung injury with ≤ 10% mortality for the most injurious vehicle (i.e., acid + part.) The maximum tolerable particulate concentration needs to be determined empirically for any new strains to be used, especially in genetically-altered mice, because an altered inflammatory response may have detrimental affects on mortality.We have extensive experience utilizing these procedures in the outbred strain, CD-1, as well as many genetically-altered inbred stains on the C57BL/6 background. Choice of strain should be carefully considered, especially in terms of strain-specific immune bias, to assure proper data interpretation. The size of the mouse should be ≥ 20 g at the time of injury. Smaller mice can be attempted, if necessary, but the surgical manipulation becomes increasingly more difficult and the surgery survival rate decreases substantially. There are no size or strain constraints for rat and rabbit models, but we generally use Long-Evans rats at 250-300 g and New Zealand White rats at ≈ 2 kg at the time of initial injury.
Keywords: Pneumonitis, Acute lung injury (ALI), Acute respiratory distress syndrome (ARDS), Inflammation, Rodent models
Materials and Reagents
Note: All salts and other chemicals are from Sigma-Aldrich unless otherwise noted (however, any source for such chemicals is probably okay to use).
Equipment
Procedure
Recipes
Acknowledgments
The work presented here was supported by NIH grant HL048889, “Pathogenesis of Aspiration Pneumonitis” to Paul R Knight, M.D., Ph.D. and Bruce A. Davidson, Ph.D. To cite this protocol please also use the following reference: Davidson et al. (2013).
References
Mouse models
Rat models
Rabbit model
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