中文摘要：

目的评价磷脂酰肌醇3-激酶／丝氨酸-苏氨酸蛋白激酶（PI3K／Akt）信号通路在异丙酚后处理减轻大鼠心肌细胞缺氧复氧损伤中的作用。方法体外培养SD乳鼠心肌细胞，接种于96孔板（细胞密度1×10^5／ml，200μl/孔）或6孔板（细胞密度5×10^5／ml，2ml／孔）中，采用随机数字表法，将细胞随机分为4组（n=24）：常规培养组（C组）细胞常规培养6h；缺氧复氧组（H／R组）细胞行缺氧2h，复氧4h；缺氧复氧＋异丙酚组（H／R＋P组）于缺氧结束时行异丙酚（终浓度50μmol／L）后处理；H／R＋异丙酚＋PI3K抑制剂组（H／R＋P＋W组）于缺氧结束时加入PI3K抑制剂渥曼青霉素（终浓度100nmol／L）和异丙酚（终浓度为50μmol／L）。复氧结束时，采用MTT法测定细胞活力，应用生化自动分析仪测定培养液LDH活性；流式细胞仪检测细胞凋亡情况；Western blot法检测心肌细胞磷酸化Akt（p-Akt）、Bcl-2及Bax表达水平。结果与C组相比，H／R组细胞活力降低，LDH活性和细胞凋亡牢升高，p-Akt和Bax表达上调，Bcl-2表达下调，Bcl-2／Bax降低（P〈0．05）。与H／R组比较，H／R＋P组细胞活力升高，LDH活性和细胞凋亡率降低，p-Akt和Bcl-2表达上调，Bax表达下调，Bcl-2／Bax升高（P〈0．05）。与H／R＋P组比较，H／R＋P＋W组细胞活力降低，LDH活性和细胞凋亡率升高，p-Akt和Bcl-2表达下调，Bcl-2／Bax降低（P〈0．05）。结论异丙酚后处理减轻心肌细胞缺氧复氧损伤的机制与激活PI3K／Akt信号通路有关。

英文摘要：

Objective To evaluate the role of Phosphatidylinositol 3-kinase/protein-sefine-threonine ki- nases （PI3K/Akt） signaling pathway in reduction of hypoxia-reoxygenation （H/R）-induced injury to cardiomyocytes by propofol postconditioning in rats.Methods Primary cardiomyocytes were obtained from neonatal rats aged 1-3 days and cultured in DMEM culture medium. The ceils were seeded in 96-well plates （density 1 × 10^5/ml, 200 μl/ well） or 6-well plates （density 5 × 10^5/ml, 2 ml/well） and randomly assigned into 4 groups （ n = 24 each） ： control group （C group）, H/R group, H/R ＋ propofol group （H/R ＋ P group） and H/R ＋ propofol ＋ wortmannin （a specific PI3K inhibitor） group （H/R ＋ P ＋ W group）. The cells were routinely cultured tot 6 h in group C. The cells were exposed to 2 h hypoxia followed by 4 h reoxygenation. Propofol with the final concentration of 50 μmol/L was added to the culture medium at the end of hypoxia in group H/R ＋ P. Wortmannin （final concentration 100 nmol/L） and propofol （final concentration 50μmol/L） was added to the culture medium at the end of hypoxia in group H/R ＋ P ＋ W. At the end of reoxygenation, the cell viability was measured by MTT assay, the lactic dehydrogenase （LDH） activity was detected in the culture medium, the cell apoptosis was assessed by flow eytometry, and the expression of phosphorylated Akt （p-Akt）, Bcl-2 and Bax in cardiomyocytes were determined by Western blot. The apoptotic rate and Bcl-2/Bax ratio were calculated. Results Compared with C group, the cellviability was significantly decreased, the LDH activity and apoptotic rate were increased, p-Akt and Bax expression was up-regulated and Bcl-2 expression was down-regulated in H/R group （ P〈 0.05）. Compared with H/R group, the cell viability and Bcl-2/Bax ratio were significantly increased, the LDH activity and apoptotic rate were decreased, p-Akt and Bcl-2 expression was up-regulated and Bax expression was down-regulated in H/R ＋ P group ?