Induced hypothermia attenuates the acute lung injury in hemorrhagic shock

Background: In previous animal studies, induction of therapeutic hypothermia (HT) in hemorrhagic shock (HS) had beneficial effects on the hemodynamic and metabolic parameters and on the survival. However, the effect of induced HT on acute lung injury (ALI) in HS has not been investigated. We sought to determine the effects of HT on ALI in HS. Methods: Male Sprague-Dawley rats (350-390 g; n = 8 per group) were randomized to the normothermia (NT; 36-37°C) group or the moderate HT (27-30°C) group and were subjected to volume-controlled (2 mL/100 g weight) HS (90 minutes) followed by 90 minutes of resuscitation. ALI score, lung malondialdehyde content, and myeloperoxidase activity were measured. The expression of glycogen synthase kinase 3β (GSK-3β), phosphorylated GSK-3β, inducible nitric oxide synthase (iNOS), heat shock protein (HSP) 72, and nuclear factor-κB (NF-κB) in the lung were compared. Results: ALI score, lung malondialdehyde content, and myeloperoxidase were lower in the HT group. GSK-3β and iNOS gene expressions in lung tissue were significantly decreased in the HT group (p < 0.05). On the contrary, the expression of phosphorylated GSK-3β was increased in the HT group (p < 0.001). HSP 72 was expressed in the HT group but not in the NT group. The activated p65 NF-κB levels in lung nuclear extract were significantly lower in the NT group (p = 0.03). Conclusions: HT attenuates HS-induced ALI in rats by the modulation of GSK, HSP 72, iNOS, and NF-κB.