ROS在乳化异氟醚后处理激活大鼠心肌细胞Nrf2／ARE信号通路中的作用

Role of ROS in emulsified isoflurane postconditioning-induced activation of Nrf2/ARE signalingpathway in rat cardiomyocytes

目的评价活性氧（Ros）在乳化异氟醚后处理激活大鼠心肌细胞转录因子NF-E2相关因子2（Nrf2）／抗氧化反应元件（ARE）信号通路中的作用。方法原代培养大鼠心肌细胞，采用随机数字表法分为4组（n=20）：对照组（C组）、缺氧／复氧组（H／R组）、乳化异氟醚后处理组（EIP组）、乳化异氟醚后处理＋ROS清除剂N．2-巯基丙酰．甘氨酸（MPG）组（EIP＋MPG组）。采用混合气体培养法制备心肌细胞缺氧／复氧损伤模型。EIP组缺氧45min时加入乳化异氟醚（终浓度1．68mmol／L）。孵育5min。随后复氧60min；EIP＋MPG组于乳化异氟醚孵育5min时加入MPG（终浓度2mmol／L），孵育10min．其余步骤同EIP组。于复氧末观察心肌细胞超微结构，行线粒体损伤评分；测定细胞内游离Ca^2＋水平及Nrf2活性；采用RT．PCR法及Westernblot法分别检测Nrf2及血红素加氧酶-1（HO-1）、超氧化物歧化酶1（SODl）、醌氧化还原酶（NQ01）的mRNA及蛋白表达水平。结果与C组比较，其余3组线粒体损伤评分和细胞内游离Ca^2＋水平升高，Nrf2活性增强，Nrf2、HO-1、SODl及NQ01及其mRNA表达下调（P〈0．05）；与H／R组比较，EIP组与EIP＋MPG组线粒体损伤评分和细胞内游离Ca^2＋水平降低，Nrf2活性增强，Nff2、HO-1、SODl及NQ01及其mRNA表达上调（P〈0．05），心肌细胞病理学损伤减轻；与EIP组比较，EIP＋MPG组线粒体损伤评分和细胞内游离Ca^2＋水平升高，Nrf2活性减弱，Nrf2、HO-1、SODl及NQ01及其mRNA表达下调（P〈0．05），心肌细胞病理学损伤加重。结论乳化异氟醚后处理激活大鼠心肌细胞Nrf2／ARE信号通路的机制可能与ROS有关。

Objective To evaluate the role of reactive oxygen species （ROS） in emulsified isoflurane postconditioning-induced activation of nuclear factor erythroid 2-related factor 2 （Nrf2）/antioxidant response element （ARE） signaling pathway in rat eardiomyocytes. Methods Primarily cultured cardiomyo- cytes of rats were divided into 4 groups （n= 20 each） using a random number table： control group （group C） , hypoxia/reoxygenation （H/R） group, emulsified isoflurane postconditioning group （ group EIP） , and emulsified isoflurane postconditioning plus ROS scavenger N-2-mercaptopropionyl glycine （MPG） group （group EIP＋MPG）. Cardiomyocytes were exposed to the mixed air to establish the cardiomyocyte H/R dam- age model. Emulsified isoflurane （ final concentration 1.68 retool/L） was added at 45 min of hypoxia, andthe ceils were incubated for 5 min followed by restoration of oxygen supply for 60 min in group EIP. In group EIP＋MPG, MPG （final concentration 2 mmol/L） was added at 5 min of incubation with emulsified isoflu- rane, the cells were incubated for 10 min, and the other treatments were similar to those previously de- scribed in group EIP. At the end of reoxygenation, the ultrastructure of cardiomyocytes was observed, and the damage to mitochondria was evaluated and scored, the intracellular free Ca2＋ level and Nrf2 activity were measured, and the expression of Nrf2, heme oxygenase-1 （HO-1）, superoxide dismutase 1 （SOD1） and quinine oxidoreductase 1 （NQO1） protein and mRNA was detected using real-time polymerase chain reaction and Western blot. Results Compared with group C, the mitochondrial damage score and intracellular free Ca2＋ level were significantly increased, the Nrf2 activity was enhanced, and the expression of Nrf2, HO-1, SOD1 and NQO1 protein and mRNA was down-regulated in the other three groups （P〈O. 05 ）. Compared with group H/R, the mitochondrial damage score and intraeellular free Ca2＋ level were significantly decreased, the Nrf2 activity was enhanced, and the expression of Nrf2, HO-1, SOD1 and NQO1 protein and mRNA was up-regulated in group EIP and group EIP＋MPG （P〈0. 05）. Compared with group EIP, the mitochondrial damage score and intracellular free Ca2＋ level were significantly increased, the Nrf2 activity was weakened, and the expression of Nrf2, HO-1, SOD1 and NQO1 protein and mRNA was down-regulated in group EIP＋MPG （P〈0. 05）. Conclusion The mechanism by which emulsified isoflurane postconditioning activates Nrf2/ARE signaling pathway may be related to ROS in rat cardiomyocytes.