Effects Of Intermittent Hypoxic Preconditioning On Apoptosis-related Bcl-2and Bax Protein Expression In Rat Liver After Partial Hepatectomy Under Ischemia-reperfusion

ObjectiveBy establishing the rat model of residual liver ischemia-reperfusion injury after partial hepatectomy, this study aims to observe the effects of intermittent hypoxic preconditioning on the expression of apoptosis-related Bcl-2and Bax protein, and to explore the protective effect of hypoxic preconditioning against the residual liver ischemia-reperfusion injury, for which application in liver surgery to find a theoretical basis.MethodTwenty SD rats were used to understand anatomical structure of the liver and practices the model of residual liver ischemia-reperfusion injury after partial hepatectomy, the survival rate was calculated after one week. Other fifty-four SD rats were randomly divided into three groups (n=18):partial hepatectomy group(PH), ischemia reperfusion group(IR) and intermittent hypoxia preconditioning group(IHP). The left and middle liver lobes of rats in PH group, were resected after ligation of the roots of them, the resected of which is about the whole liver weight of70%. The left and middle liver lobes of rats in IR group were resected after clipping hepatoduodenal ligament and blocking the hepatic blood flow. The occlusion of the hepatoduodenal ligament lasted for20minutes, and the residual hepatic ischemia reperfusion injury was occureed. The rats of IHP group were exposed to hypoxic environment of10%oxygen for lh/day. After7consecutive days, the left and middle lobes of liver were resected (the same with IR group). At12,24and48hours after the surgery, the inferior vena venous blood and residual liver tissue were detected. The serum levels of ALT and AST, which indirectly reflect the degree of liver damage, were determined by automatic biochemical analyzer. The expression of Bcl-2and Bax protein in liver tissue were observed by immunohistochemistry and the intensity were measured by integral optical density Result1. The seven-day survival rate for the rats in the model is93.3%. The rats after anesthesia recovery were healthy, and they had no significant complications.2. At each time points after surgery, the serum levels of ALT and AST in IR group and IHP group were higher than in PH group, but in IHP group were lower than in IR group. All these differences were statistically significant.(P<0.05).3. Compared with PH group and IR group, the integral optical density of Bcl-2protein in IHP group significantly increased at each time points (P<0.05). The difference between PH group and IR group was not statistically significant at12and24hours after the operation (P>0.05), but was statistically significant at48hours after the surgery (P<0.05). In contrast to the expression of Bcl-2protein, at each time points, the integral optical density of Bax protein in IHP group was significantly lower than in IR group, but was significantly higher than in PH group. All these differences were statistically significant (P<0.05).ConclusionBy temporarily clipping the hepatoduodenal ligament, a stable and reliable rat model of residual liver ischemia-reperfusion injury after partial hepatectomy can be established. Intermittent hypoxic preconditioning might protect residual liver against ischemia reperfusion injury, through increasing the expression of Bcl-2protein and reducing the expression of Bcl-2protein to decrease liver cell apoptosis.