Early Fluid Resuscitation by Lactated Ringer’s Solution Alleviate the Cardiac Apoptosis in Rats with Trauma-Hemorrhagic Shock

Cardiac trauma has been recognized as a complication associated with blunt chest trauma involving coronary artery injury, myocardium contusion and myocardial rupture. Secondary cardiac injuries after trauma supposed to be a critical factor in trauma patients, but the mechanism is not fully explored. Overproduction of TNF-alpha had been reported in multiple trauma animals, this induces oxidative stress resulting in cardiac apoptosis. Apoptosis gradually increases after trauma and reaches to a maximum level in 12 h time. TNF-alpha increases the expression of NFkB, and induces the expression of caspase-3 and resulted in cell apoptosis. The effect can be attenuated by non-selective caspase inhibitor and IL10. Fas induced cardiac apoptosis and hypertrophy in ischemic heart disease. In this study, we demonstrated a trauma-hemorrhagic shock (THS) model in rats and resuscitated rats by lactated Ringer's (L/R) solution after shock in different hours (0 hour, 4 hours, 8 hours). NFkB gradually increased after the first 8 hours of shock, and can be reduced by fluid resuscitation. NFkB is known as a downstream pathway of Fas related apoptosis, we found Fas ligand, caspase-8 levels elevate after shock, and can be reduced by resuscitation. In addition, resuscitation can activate insulin-like growth factor (IGF-1)/Akt pathway, at the same time. It can block mitochondrial damage by decrease the effect of tBid. In conclusion, THS can induce secondary cardiac injury. Fas showed to be an important element in caspase cascade induced myocardium apoptosis. By L/R fluid resuscitation, the suppression of caspase cascade and activation of IGF-I/Akt pathway showed antiapoptotic effects in traumatic heart of rats.