Study On The Protective Effect Of Selective Cerebral Perfusion Of Exogenous Pyruvate On Cerebral Hypothermic Circulatory Arrest In Rabbits

Objective:1. To explore the feasibility of establishing a modified lower body circulatory arrest and selective cerebral perfusion model in rabbits.2. To explore the effect that whether a combination of sodium pyruvate(Pyr) and blood for antegrade selective cerebral perfusion(ASCP) during deep hypothermic circulatory arrest(DHCA) could amilorate oxidative stress, improve energy metabolism and inhibit neuronal apoptotic pathway meadiated by PARP-1activation.Methods:1. Twenty-six rabbits were selected randomly. The mean weight and age of the rabbits were3.0kg and15-20weeks respectively. Half of them were used to model establishment, the rest blood donation. Cardiopulmonary bypass (CPB) was established via right subclavian artery and right artrium cannulation. Right femoral artery was cannulated for invasive blood pressure monitoring. Catheter was cannulated from left subclavian artery to arotic root for St. Thomas solution perfusion at28℃. Rabbits underwent60min of the lower body circulatory arrest and selective cerebral perfusion at a rectal temperature of20℃. Blood gas and hemodynamic parameters were measured in four time points during cardiopulmonary bypass.2. Fourty-five rabbits were selected randomly. The mean weight and age of the rabbits were3.0kg and15-20weeks respectively. Twenty-seven of them were used to model establishment, the rest blood donation. The rabbits used to model establishment were divided into three groups:Sham group (n=9), ASCP group (n=9) and Pyr group (n=9). The Sham group underwent anesthesia and thoracotomy but no CPB establishment. A combination of154mmol/L isotonic solution of sodium pyruvate and blood was used to selective cerebral perfusion for Pyr group after the onset of DHCA. A combination of154mmol/L Nacl solution and blood was used to selective cerebral perfusion for ASCP group after the onset of DHCA. Blood gas and hemodynamic parameters were measured in five time points peri-cardiopulmonary bypass. The rabbits ended with euthanasia at120min after CPB, and their brain tissue were preserved in-80℃refrigerator. All specimens and samples were used to measure ATP content, glycogen content, malondialdehyde (MDA) content, superoxide dismutase(SOD) activity,[Poly(ADP-ribose)polymerase-1](PARP-1) content, cysteinyl aspartate specific proteinase-3(Caspase-3) content、S100B content、 neuron specific enolase (NSE) content and pathological examination.Results:1. Of the thirteen rabbits, one died of aortic rupture and the others survived during the experiment. Blood gas and hemodynamic parameters were in accordance with the pathophysiological process of cardiopulmonary bypass generally.2. The ATP content of ASCP group is lower than Sham group and Pyr group (P<0.05).The glycogen content of ASCP group is lower than Sham group and Pyr group (P<0.05).The MDA content of ASCP group is higher than Sham group and Pyr group (P<0.05). The SOD activity of ASCP group is lower than Sham group and Pyr group (P<0.05). The Caspase-3content of ASCP group is higher than Sham group and Pyr group (P<0.05). The PARP-1content of ASCP group is higher than Sham group and Pyr group (P<0.05). The S100B concentration of ASCP group and Pyr group at T3, T4and T5point is higher than T1point at the same groups (P<0.05). The S100B concentration of ASCP group at T3, T4and T5point is higher than Sham group and Pyr group at the same points (P<0.05). The S100B concentration of Pyr group at T3, T4and T5point is higher than Sham group at the same points (P<0.05). The NSE concentration of ASCP group and Pyr group at T3, T4and T5point is higher than T1point at the same groups (P<0.05). The NSE concentration of ASCP group at T3, T4and T5point is higher than Sham group and Pyr group at the same points (P <0.05). The NSE concentration of Pyr group at T3, T4and T5point is higher than Sham group at the same points (P<0.05). The form and structure of neurons in Sham group is normal. While in ASCP group and Pyr group are basically normal, and swelling and vacuolation appear occasionally. The mitochondria dysfunction grading between Sham group and Pyr group has no statistical significance(P=0.452). While ASCP group is higher than Sham group and Pyr group (P=0.005and P=0.031)Conclusion:1. A modified model in rabbits arrested by cardiopledia has been established successfully. The model is safe and stable and it could be used to study the protective mechanism of heart, brain and the other organs under lower body circulatory arrest and selective cerebral perfusion.2. The combination of blood and sodium pyruvate for selective cerebral perfusion during DHCA could exert a better protective effect by amilorating oxidative stress, improving energy metabolism and inhibiting neuronal apoptotic pathway meadiated by PARP-1activation.