Blast overpressure exposure

The Walter Reed Army Institute of Research (WRAIR) shock tube at the Naval Medical Research Center (NMRC, Silver Springs, MD, USA) was used to expose rats to overpressure injury. This apparatus, which simulates the effects of air blast exposure under experimental conditions, has been used in our prior studies to deliver blast overpressure injury to rats [4, 20–22, 25, 30, 39, 40]. As in previous studies, anesthetized rats were randomly assigned to sham or blast conditions with the head facing the blast exposure without any body shielding, resulting in a full body exposure to the blast wave. The physical characteristics of the blast wave and further details of the blast exposure have been described in detail [4]. Blast-exposed animals received a total of three 74.5-kPa (10.8 psi) exposures, with one exposure administered daily for 3 consecutive days. Control animals were anesthetized and placed in the blast tube but not subjected to a blast exposure. Within 10 days after the last blast exposure, the animals were transferred to the James J. Peters VA Medical Center (Bronx, NY, USA) where all other procedures were performed. Control and experimental cohorts were euthanized at 48 h (n = 6 per group), 6 weeks (n = 6 per group) and 13 months (n = 4 blast-exposed rats and n = 5 control rats) post-blast for observation of acute, subacute and chronic effects, respectively.