Preinduction of heat shock proteins protects cardiac and hepatic functions following trauma and hemorrhage

Abstract

Although studies have shown that induction of the heat shock proteins (HSPs), such as HSP-70, has various beneficial effects after ischemia-reperfusion, it remains unknown whether prior induction of HSP-70 has any salutary effects on cardiovascular and hepatocellular functions after trauma-hemorrhage and resuscitation. Male rats were exposed to heat stress (41°C, 15 min) and then allowed to recover for 24 h at room temperature (21°C). The rats then underwent laparotomy (i.e., trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of the maximal shed blood volume was returned in the form of Ringer lactate. Animals were then resuscitated with four times the volume of shed blood with Ringer lactate over 60 min. The maximal rate of the left ventricular pressure increase or decrease was measured up to 4 h after resuscitation. Cardiac output, hepatocellular function, plasma levels of tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were determined at 4 h after resuscitation. Cardiac and hepatic tissue were examined for HSP-70 by Western blot analysis. Left ventricular performance, cardiac output, and hepatocellular function decreased significantly following trauma-hemorrhage. Plasma levels of TNF-α and IL-6 were also significantly increased. However, prior heat stress attenuated cardiovascular and hepatocellular dysfunction, decreased circulating levels of proinflammatory cytokines following trauma-hemorrhage, and was associated with an increased abundance of HSP-70 in the heart and liver. Our data, therefore, suggest that preinduction of HSP-70 protects cardiovascular and hepatocellular functions following trauma-hemorrhage and resuscitation.