Bradykinin-(1–9) mitigates autophagy through upregulating PI3K/Akt in rats with myocardial infarction

The cardioprotective mechanisms of bradykinin-(1-9) in myocardial infarction were unclear. We investigated the effect of bradykinin-(1-9) on cardiac function, fibrosis, and autophagy induced by myocardial infarction and identified the mechanisms involved. To investigate the cardioprotective effect of bradykinin-(1-9), various doses of bradykinin-(1-9), its B2 receptor blocker HOE140, or their combination were administered to rats via subcutaneous osmotic minipump implantation before myocardial infarction. After 2 days, myocardial infarction was induced by ligation of the left anterior descending coronary artery. After 2 weeks, echocardiographic measurements and euthanasia were performed. Bradykinin-(1-9) treatment attenuated left ventricular dysfunction, fibrosis, and autophagy in rats with myocardial infarction, which was partially reversed by HOE140 administration. Moreover, the downregulatory effect of bradykinin-(1-9) on autophagy was partially reversed by combination with the PI3K inhibitor LY294002. Thus, bradykinin-(1-9) inhibits myocardial infarction-induced cardiomyocyte autophagy by upregulating the PI3K/Akt pathway.