ABSTRACT
Objective:Through phosphatidylinositol 3-kinase（PI3K）/protein kinase B （Akt）/mammalian rapamycin target protein （mTOR） signaling pathway， explore the effect of Zhigancao Tang on myocardial ischemia-reperfusion injury（MIRI）The role and mechanism of arrhythmia（ventricular tachycardia and ventricular fibrillation）. Method:The 72 SD rats were randomly divided into sham operation group，model group， Zhigancao Tang low，medium and high dose group（11.43，22.86，45.72 g·kg-1），Wenxin granule group（2.43 g·kg-1），continuous drug intervention for 10 days. Two hours after the last administration，the MIRI model of rat was prepared by ligating the left anterior descending coronary artery，and the changes of electrocardiogram were recorded. After successful modeling，blood and heart tissue were collected to detect the content of creatine creatine（CK），lactate dehydrogenase（LDH）and aspartate aminotransferase（AST）in the serum, the enzyme-linked immunoassay（ELISA） method was used to detect cardiac troponin（CtnI）content, immunohistochemical detection of myocardial PI3K，Akt，mTOR expression. Western blot was used to detect the myocardial autophagy-related protein microtubule-associated protein 1 light chain 3（LC-3），autophagy markers Beclin1 and PI3K/Akt/mTOR signaling pathway related protein expression and phosphorylated p-PI3K，p-Akt，p-mTOR levels. Result:In model group， 100% of ventricular tachycardia and 91.67% of ventricular fibrillation occurred. Compared with sham operation group， the serum levels of CK，LDH，AST，and CtnI in the model group were significantly increased（P<0.01），PI3K，Akt，mTOR AOD values in myocardial tissue were significantly increased （P<0.01），the relative expression of the ratio of LC3-Ⅱ/LC3-Ⅰ and Beclin1 was significantly increased（P<0.01），p-PI3K/PI3K，p-Akt/Akt，and p-mTOR/mTOR were significantly reduced （P<0.01）. Compared with model group， the incidence of ventricular tachycardia and ventricular fibrillation in the high-dose Zhigancao Tang group was significantly reduced （P<0.01），and the duration was the shortest compared with other administration groups（P<0.01）， CK，LDH，AST level and CtnI content were significantly reduced（P<0.01）， the expression of PI3K，Akt and mTOR of Zhigancao Tang group was significantly decreased with increasing dose（P<0.01）， the expression of LC-3 and Beclin1 was accompanied by Zhigancao Tang increase of each dose group of soup had different degrees of decrease （P<0.01），while the expression ratio of PI3K/Akt/mTOR-related protein was significantly increased （P<0.05，P<0.01）. Conclusion:Pretreatment of Zhigancao Tang can reduce the abusually elevated cardiac enzymes CK, LDH, AST and CtnI, inhibit excessive autophagy of cells, and up-regulate the expression of PI3K, Akt and mTOR, indicating that the anti-MIRI arrhythmia effect of Zhigancao Tang may be related to the PI3K/Akt/mTOR signaling pathway.