Qiliqiangxin Protects Against Cardiac Ischemia-Reperfusion Injury via Activation of the mTOR Pathway

Abstract

Background/Aims: Qiliqiangxin (QL) has been used for the treatment of chronic heart failure in China. Accumulating evidence suggests QL's cardio-protective effects on continuous myocardial ischemia. However, it is unclear whether QL has beneficial effects on cardiac ischemia-reperfusion (I/R) injury. Methods: A mouse model of cardiac I/R was established by ligation of the left anterior descending coronary artery for 45 minutes followed by reperfusion. The mice were treated with QL for three days before surgery and continually after I/R. Triphenyltetrazolium chloride staining, echocardiography and Masson's trichrome staining were used to determine infarct size, cardiac function, and fibrosis, respectively. Expression levels of phospho-mTOR (Ser2448), mTOR, phospho-4EBP (Ser65), 4EBP, phospho-Akt (Ser473) and Akt were detected by Western blotting. Results: At 1 day after I/R, QL treatment significantly reduced the infarct size of mice exposed to I/R. At 7 days after I/R, mortality was reduced in QL treated animals in comparison with the control group. In addition, QL treated mice showed increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) at 1 and 7 days after I/R. In agreement, Masson's trichrome staining demonstrated that interstitial fibrosis was less pronounced in QL treated mice compared with controls, suggesting that adverse left ventricular remodeling is attenuated in QL treated mice. Moreover, western blotting analysis demonstrated that QL activated the mTOR pathway, while mTOR inhibition via Rapamycin abolished the protective effects of QL against I/R injury. Conclusion: This study suggests that QL attenuates the progression of cardiac remodeling after I/R likely via mTOR activation. This represents a new application for QL in the prevention of I/R injury.