HIF-1α signaling activation by post-ischemia treatment with astragaloside IV attenuates myocardial ischemia-reperfusion injury.

Jingwen Si,Hui Yi,Lifang Yang,Junchang Li,Huan Wang,Zixuan Shi,Shiqiang Yu,Jian Yang,Wen Wang,Juan Xie,Ning Wang,Jing Ma,Meijing Wang

doi:10.1371/journal.pone.0107832

Abstract

In this study, we evaluated the effect of astragaloside IV (Ast IV) post-ischemia treatment on myocardial ischemia-reperfusion (IR) injury (IRI). We also examined whether hypoxia inducible factor-1α (HIF-1α) and its downstream gene-inducible nitric oxide (NO) synthase (iNOS) play roles in the cardioprotective effect of Ast IV. Cultured cardiomyocytes and perfused isolated rat hearts were exposed to Ast IV during reperfusion in the presence or absence of the HIF-1α inhibitor 2-methoxyestradiol (2-MeOE2). The post-ischemia treatment with Ast IV protected cardiomyocytes from the apoptosis and death induced by simulated IRI (SIRI). Additionally, in cardiomyocytes, 2-MeOE2 and HIF-1α siRNA treatment each not only abolished the anti-apoptotic effect of post-ischemia treatment with Ast IV but also reversed the upregulation of HIF-1α and iNOS expression. Furthermore, after treatment with Ast IV, post-ischemic cardiac functional recovery and lactate dehydrogenase (LDH) release in the coronary flow (CF) were improved, and the myocardial infarct size was decreased. Moreover, the number of apoptotic cells was reduced, and the upregulation of the anti-apoptotic protein Bcl2 and downregulation of the pro-apoptotic protein Caspase3 were reversed. 2-MeOE2 reversed these effects of Ast IV on IR-injured hearts. These results suggest that post-ischemia treatment with Ast IV can attenuate IRI by upregulating HIF-1α expression, which transmits a survival signal to the myocardium.

Highlights

Ischemia and reperfusion (IR) injury (IRI) is a primary cause of cardiac failure, morbidity, mortality after cardiac operations [1] or heart infarctions [2]
simulated ischemia reperfusion (SIR) induced significant decreases in cell viability to 18.761.9% compared with control cells (P,0.01), while astragaloside IV (Ast IV) treatment resulted in a significant increase in cell survival, restoring the cell survival rate to 39.762.4% (12.5 mM), 44.163.1%(25 mM), 50.463.4%(50 mM), 41.762.1%(100 mM), and 19.261.7% (200 mM)
The AST IV protective effects were abolished by hypoxia inducible factor-1a (HIF-1a) siRNA. This is the first study to demonstrate that post-ischemia treatment with Ast IV conferred a cardioprotective effect on isolated rat hearts and cardiomyocytes, as evidenced by improved post-ischemic cardiac functional recovery, decreased myocardial infarct size, diminished lactate dehydrogenase (LDH) release into the coronary effluent, and a reduced number of apoptotic cardiomyocytes

Summary

Introduction

Ischemia and reperfusion (IR) injury (IRI) is a primary cause of cardiac failure, morbidity, mortality after cardiac operations [1] or heart infarctions [2]. There are many powerful strategies to limit IRI [4,5,6]. Alternative methods have been explored, including protective drug delivery at the beginning of reperfusion [7,8]. Active compounds have been isolated from this plant, including astragalosides, polysaccharides, and flavones. The protective effects against myocardial IRI have been reported in different animal models in which Ast IV was administered before ischemia (Ast IV pre-treatment) [15,16,17]. Whether post-ischemia treatment with Ast IV has a potential protective effect against IRI in the heart has not been well investigated

Methods

Results

Conclusion