Acute Changes in Rat Tissue Gene Expression Following Exposure to Flight Relevant Hypobaria

Aeromedical evacuation (AE) is an invaluable tool for the transport of critically injured patients to care facilities. There is increasing evidence obtained from animal models and human patients that exposure to AE-relevant hypobaria within a few days of injury can worsen outcomes. The cause of this secondary injury is not well understood but it may be related to changes in gene expression induced by exposure to evacuation-relevant conditions. In order to explore the causes of secondary injury, gene expression induced by AE-relevant flight conditions was analyzed. Adult male rats were exposed to flight cabin-relevant hypobaria (8000 or 4000 ft equivalents) and/or different oxygen concentrations (21% or 100%) for 5 or 10 hr. At the end of the exposures, RNA was isolated from lung, blood, heart, and brain (hippocampus), levels of gene expression were measured via microarray analysis, and canonical pathway analysis identified the primary gene pathways enriched by the exposures. This information should be useful to not only optimize the health status of trauma patients undergoing aeromedical evacuation but also help determine which gene expression pathways could be modulated to optimize the therapeutic efficacy of the body's endogenous protection and repair mechanisms.