The Protective Role Of Qiliqiangxin Against Hypoxia Induced Apoptosis In Cardiac Myocytes And Cardiac Microvascular Endothelial Cells

Part One Role of Qiliqiangxin on hypoxia-induced cardiac myocytes apoptosisObjective: Cardiac myocytes apoptosis plays an important role in heart failure. Being a traditional Chinese medicine, plenty of studies have reported that Qiliqiangxin(QL) possesses therapeutic efficacy in chronic heart failure,but the underlying mechanism is not clear. Here we investigate whether QL can prevent cardiac myocytes apoptosis induced by hypoxia and the possible mechanisms.Methods: Isolated neonatal rat cardiac myocytes(NRCMs) were subjected to hypoxia with or without QL. Lentiviral-vector-mediated Erb B4-si RNA was introduced into cardiacmyocytes to knockdown the Erb B4 expression. PI3K/Akt pathway was blocked by a specific PI3 K inhibitor-LY294002. Cell apoptosis was detected by terminal deoxynucleotide transferase d UTP nick end labeling(TUNEL), flow cytometry and caspase-3activity assay. Protein expressions of Erb B4, p-Akt and total-Akt were examined by Western blot, and m RNA expression of Erb B4 was detected by real-time quantitative PCR.Results: Hypoxia induced a significant increase of apoptotic NRCMs compared to non-hypoxia treatment, which was significantly attenuated by the treatment of QL. In addition, we found that QL up-regulated the m RNA and protein expressions of Erb B4 and the phosphorylation level of Akt in NRCMsundergoing hypoxia. Importantly, knockdown of Erb B4 abolished the role of QL in preventing NRCMs apoptosis, and inhibited Akt phosphorylation.Furthermore, QL-mediated protection against NRCMs apoptosis was also abrogated by inhibition of PI3K/Akt signaling with LY294002.Conclusion: Our data suggest that QL protects cardiac myocytes against hypoxia induced apoptosis partially, via regulating Erb B4-dependent PI3K/Akt pathway.Part Two Investigation of Qiliqiangxin on hypoxia induced cardiac microvascular endothelial cells apoptosisObjective: To investigate the mechanism of Qiliqiangxin(QL) against hypoxia induced cardiac microvascular endothelial cells(CMVECs)apoptosis.Methods: CMVECs were cultured by the method of planting myocardium tissues. Cells were passaged to P2 and randomly divided into three groups: control group, hypoxia group and hypoxia + QL treatment group.Hypoxia circumstance was induced in a hypoxia generator filled with95% N2 and 5% CO2, and the intervention concentration of QL was selected at 0.5mg/ml. Caspase 3 activity was detected by caspase 3 activity kit. Cell apoptosis was measured by terminal deoxynucleotide transferase d UTP nick end labeling(TUNEL). Protein expressions of Bcl-2 and Bax were determined by Western Blot.Results: Compared to control group, CMVECs undergoing hypoxia exhibited significant apoptosis as evidenced by elevated activity of caspase 3,increased expression of proapoptotic protein Bax as well as decreasedantiapoptotic protein Bcl-2(all p<0.05), which were all effectively suppressed or retained by the treatment of QL(all p<0.05).Conclusions: QL suppressed CMVECs apoptosis under hypoxia by upregulation of Bcl-2 and downregulation of Bax.