Myocardial gene expression profiling of rewarming shock in a rodent model of accidental hypothermia

BackgroundSevere accidental hypothermia represents a cardiovascular emergency associated with high mortality and poor recovery of cardiac function. The biochemical changes occurring within the heart during the development of hypothermia and subsequent resuscitation are not known.MethodsBy mRNA expression profiling, we have characterized gene expression changes occurring within the myocardium in an intact rat model of accidental hypothermia during cooling to a core temperature of 15 °C and subsequent rewarming to 37 °C. During the rewarming phase, these animals develop a profound low-output cardiac failure.ResultsHypothermia induces expression of known mediators of thermotolerance, including heat-shock protein 70 and several factors involved in protection against apoptotic cell death. Upregulation of genes involved in autophagy and increased abundance of autophagosomal vesicles suggest involvement of autophagic degeneration in the development of myocardial dysfunction occurring during rewarming from hypothermia. Rewarming from hypothermia also induces expression of several pro-inflammatory genes involved in the nuclear factor kappa B (NFκB) signaling cascade.ConclusionsOur data demonstrate that rewarming from hypothermia is associated with the induction of a cellular stress–response, including upregulation of autophagy and activation of pro-inflammatory signaling cascades. These data provide a framework for understanding the molecular changes that occur during induction of and rewarming from severe hypothermia, and identifies potential targets for cardioprotective interventions in resuscitation of victims of hypothermia.

► The pathophysiology of rewarming shock in hypothermia victims is poorly understood. ► Rewarming from deep hypothermia commonly induces myocardial contractile dysfunction. ► Rewarming from hypothermia causes distinct changes in myocardial gene expression. ► Rewarming induces autophagy and activation of pro-inflammatory signaling pathways.