Targeted Temperature Management Suppresses Hypoxia-Inducible Factor-1 alpha and Vascular Endothelial Growth Factor Expression in a Pig Model of Cardiac Arrest

Background The hypoxia-inducible factor-1 alpha (HIF-1 alpha)/vascular endothelial growth factor (VEGF)/VEGF receptor subtype 2 (VEGFR-2) pathway has been implicated in ischemia/reperfusion injury. The aim of this study was to clarify whether whole-body hypothermic targeted temperature management (HTTM) inhibits the HIF-1 alpha/VEGF/VEGFR-2 pathway in a swine model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods Twenty-four domestic male Beijing Landrace pigs were used in this study. CA was electrically induced with ventricular fibrillation and left untreated for 8 min. Return of spontaneous circulation (ROSC) was achieved in 16 pigs, which were randomly assigned either to normothermia at 38 degrees C or to HTTM at 33 degrees C (each group: n = 8). HTTM was intravascularly induced immediately after ROSC. The core temperature was reduced to 33 degrees C and maintained for 12 h after ROSC. The serum levels of HIF-1 alpha, VEGF, VEGFR-2, and neuron-specific enolase (NSE) were measured with enzyme immunoassay kits 0.5, 6, 12, and 24 h after ROSC. The expression of HIF-1 alpha, VEGF, and VEGFR-2 in cerebral cortical tissue was measured by RT-PCR and Western blot analysis 24 h after ROSC. Neurological deficit scores and brain cortical tissue water content were evaluated 24 h after ROSC. Results The serum levels of HIF-1 alpha, VEGF, and VEGFR-2 were significantly increased under normothermia within 24 h after ROSC. However, these increases were significantly reduced by HTTM. HTTM also decreased cerebral cortical HIF-1 alpha, VEGF, and VEGFR-2 mRNA and protein expression 24 h after ROSC (all p < 0.05). HTTM pigs had better neurological outcomes and less brain edema than normothermic pigs. Conclusion The HIF-1 alpha/VEGF/VEGFR-2 system is activated following CA and CPR. HTTM protects against cerebral injury after ROSC, which may be part of the mechanism by which it inhibits the expression of components of the HIF-1 alpha/VEGF/VEGFR-2 signaling pathway.