Moderate hypothermia attenuates lung in flammation inlipopolysaccharide- induced acute lung injury in rats

Objective To investigate the role of moderate h.vpothennia in the lung inflammation of rat acute lung injury induced by lipopolysaccharide(LPS). Methods A rat model of acute lung injury (ALl) was established by in-tin-tracheal instillation of lipopolysaccharide ( 1.5 mg/kg, 0.5 ml) at 16 h after LPS ( 1.0 mg/kg) intraperitoneal adrninis-tmtion. Thirty-four male Sprague Dawley rats were randomly divided into four groups: control group, receiving saline only;LPS group, receiving LPS; hypothennia group, treated with hypothennia without LPS; LPS + hypothennia group, treated with LPS and cooled to 32.5℃-33.0℃ as PaO2/FiO2. was below 300 mmHg. Hemodynamics and blood gases were record-ed every hour throughout the study. Rats were killed 4 h after ALl, and lung lavage was performed to measure the tumor ne-crosis factor α(TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) concentrations in bronchoalveolar lavage fluid (BALF) by using enzyme-linked immunosorbent assay (ELISA). Results PaO2/FiO2 was significantly decreased and PaCO2 was increased in the LPS group as compared to their baseline values( P＜0.01). Treatment with hypothermia inhib-ited the increase in PaCO2( P＜0.05) but had no effect on PaO2/FiO2 in the presence of LPS. The administration of LPS significantly increased the concentrations of TNF-α, IL-6 and IL-10 in BALF as compared to the control experiment( P＜0.05, P＜0.01 ). Moderate hypothermia reduced the expressions of TNF-α and IL-6 ( P＜0.01 ) but had no effect on the production of IL-10 ( P＞0.05). Conclusion Moderate hypothermia significantly inhibits proinflammatory cytokine ex-pressions in lipopolysaccharide-induced acute lung injury.