Anti-inflammatory effect of dexmedetomidine combined with hypothermia on acute respiratory distress syndrome in rats

Abstract Background To investigate the protective effect of combination of dexmedetomidine and hypothermia on lipopolysaccharide (LPS) induced acute respiratory distress syndrome in rats. Methods Fifty male Wistar rats were randomly divided into five groups, with 10 rats in each group. The acute respiratory distress syndrome model was reproduced by LPS injected into the right external jugular vein (L group); only saline was injected into the right external jugular vein for control group (C group). In hypothermia group (T group), the body temperature was lowered to 32.5°C-33.0°C after 1 h of LPS injection, and 10 rats were sacrificed at 8 h. Group dexmedetomidine (D group) and dexmedetomidine combined with hypothermia group (DT group) received intraperitoneal dexmedetomidine 30 min before LPS was injected. The arterial blood gas was determined in all the groups before and 8 h after instillation of saline or LPS, and the oxygenation index (PaO2 /FiO2 ) was calculated. The TNF-α and IL-6 levels were determined by enzyme-linked immunosorbent assay. The expression of inflammatory signaling proteins in BALF was determined by Western blot. Results Compared with group L, TNF-α and IL-6 levels in serum of rats were significantly lower ( P