[Astragalus injection mediates autophagy and myocardial remodeling in rats with ischemic cardiomyopathy through calumenin].

OBJECTIVE: To study the effects of astragalus injection on myocardial remodeling, calumenin and autophagy in rats with ischemic cardiomyopathy. METHODS: Thirty-six male SD rats were divided into normal control group, ischemic cardiomyopathy group and astragalus injection group, 12 in each group. Electrocardiogram (ECG) and echocardiography were performed before operation in three groups. Rats in ischemic cardiomyopathy group and astragalus injection group underwent thoracotomy and ligation of coronary artery for 20 minutes, then thoracic cavity was closed after reperfusion. In the astragalus injection group,10 g/kg body weight of Astragalus injection was injected once a week, four times in total. Four weeks after operation, rats in three groups were executed by echocardiography and their hearts were collected for Hematoxylin-Eosin (HE) staining and Van Gieson (VG) staining to observe myocardial pathological changes. Calumenin, LC3-I, LC3-II expressions and LC3-I/LC3-II ratio were detected by Western blot. RESULTS: Compared with ischemic cardiomyopathy group, the echocardiography and myocardial pathology of rats in astragalus injection group changed obviously, and the expressions of calumenin, LC3-I, LC3-II and LC3-I/LC3-II ratio changed significantly (P＜0.01). CONCLUSION: Astragalus injection has apparent inhibitory effect on ventricular remodeling and autophagy of myocardial cells in rats with ischemic cardiomyopathy, which may be mediated by calumenin.

[The relationship between myocardial remodeling and endoplasmic reticulum stress and autophagy in rats with ischemic cardiomyopathy].

OBJECTIVE: To study the relationship between myocardial remodeling and endoplasmic reticulum stress and autophagy in rats with ischemic cardiomyopathy. METHODS: Thirty-six male SD rats were divided into normal control group, sham-operated group and ischemic cardiomyopathy group (n=12). Echocardiography was performed before operation in three groups. Rats in sham-operated group closed their thoracic cavity without ligation of coronary artery after thoracotomy. The rats in ischemic cardiomyopathy group were closed their thoracic cavity after ligating of coronary artery for 20 minutes and recovered reperfusion. After operation for 4 weeks, rats in three groups were killed after taking echocardiography. The myocardial tissues were taken for HE staining and Masson staining to observe the pathological changes of myocardium and the expressions of glucose-regulated protein 78 (GRP78), microtubule-associated protein 1 light chain 3- I (LC3-I), microtubule-associated protein 1 light chain 3- II (LC3-II), Bcl-2 interacting protein (Beclin-I) and the ratio of LC3-II/LC3-I were detected by Western blot. RESULTS: Compared with normal group and sham-operated group, ischemic cardiomyopathy rats had significant differences in echocardiography and myocardial pathology; the myocardial array was disordered, myocardial fibrosis was increased, mitochondrial vacuolation was serious. Mean while, the expressions of GRP78, LC3-I, LC3-II, Beclin-I and LC3-II/LC3-I ratio had significant changes. CONCLUSION: Autophagy and endoplasmic reticulum stress may play important roles in myocardial remodeling in rats with ischemic cardiomyopathy.

[Effects of total flavonids of astragalus on arrhythmia,endoplasmic reticulum stress in mice with viral myocarditis].

OBJECTIVE: To investigate the effects of total flavonids of astragalus(TFA) on arrhythmia, endoplasmic reticulum stress and connexcin in mice with viral myocarditis and to clarify the mechanisms of TFA against viral myocarditis complicated with arrhythmia. METHODS: Thirty-six male Balb/c mice were randomly divided into control group, viral myocarditis group and total flavonoids group (n=12). The mice of viral myocarditis were intraperitonealy injected with 0.1 ml/day 10-950 TCID CVB3 for 3 days. The mice of TFA group were intraperitoneal injected with 0.1 ml/day 10-950 TCID CVB3 for 3 days and treated with 0.1ml, 20 mg/L TFA by tail vein injection. At the end of the experiment, arrhythmia was detected by electrocardiogram, the heart of mice were stained by HE, the expressions of glucose-regulated protein 78(GRP78), endoplasmic reticulum stress signaling pathway factor activating transcription factor 4(ATF4) and connexcin 43(Cx43) were detected by Western blot. RESULTS: The expressions of GRP78 and ATF4 were increased and the expression of Cx43 was decreased in viral myocarditis, while TFA inhibited these effect of viral myocarditis in heart of mice. CONCLUSIONS: The antiarrhythmic effect of TFA may be related to the alleviation of endoplasmic reticulum stress and the increase of Cx43 expression.

[Effect of Astragalus injection on cardiomyocyte apoptosis, endoplasmic reticulum stress and expression of connexin in cardiomyopathy rats induced by adriamycin].

OBJECTIVES: To investigate the effect of Astragalus injection on cardiomyocyte apoptosis, endoplasmic reticulum stress and connexin protein in cardiomyopathy rats induced by adriamycin. METHODS: Thirty-six male Wister rats were randomly divided into control group (n=12), adriamycin(ADR) group (n=12) and Astragalus group (n=12). The normal saline (10 ml/kg body weight) was injected intraperitoneally in control group rats, ADR (2 mg/kg body weight) was injected intraperitoneally in ADR group rats, ADR (10 ml/kg body weight) and Astragalus injection (10 ml/kg body weight) were injected intraperitoneally in rats of astragalus group, one time a week, totle 3 times. By the end of the 7th week, the left ventricular end-diastolic diameter(LVEDD), left ventricular end-systolic diameter (LVESD) and left ventricular ejection fraction (LVEF) were measured by echocardiography. Then the rats in the three groups were sacrificed and the left ventricle section was stained by HE, Masson, uranyl acetate/lead citrate respectively, the cardiomyopathy and ultrastructural changes were observed under light microscope and transmission electron microscope. The apoptosis of rat cardiomyocyte were analyzed by TUNEL. The expression of connexin Cx43 and p-Cx43 was detected by immunohistochemistry. The expression of glucose-regulated protein 78 (Grp78),activating transcription factor 4 (ATF-4) and C/EBP homologous protein (CHOP) were detected by real time PCR. RESULTS: Compared with control group, LVEDD, LVESD increased and LVEF decreased, myocardial fibers were disordered and edematous, infiltrated by lymphocytes, the mitochondria were destroyed and vacuolized, and the number of cardiomyocyte apoptosis was increased(P<0.01) in ADR group. The expression of Grp78, ATF-4, CHOP and p-Cx43 were increased, and the expression of Cx43 was decreased in ADR group. However, compared with ADR group, LVEDD, LVESD decreased and LVEF increased, the cardiomyopathy and ultrastructural changes were significantly improved, the number of cardiomyocyte apoptosis was significantly decreased (P<0. 01); the expression of Grp78, ATF-4, CHOP and p-Cx43 decreased (P<0.01); the expression of Cx43 increased in Astragalus group (P<0.01). CONCLUSIONS: Astragalus injection may effectively improve the myocardial damage induced by adriamycin, its mechanism may be related to the inhibition of endoplasmic reticulum stress (ERS) and the decrease of phosphorylation of CX43 in cardiomyopathy rats induced by adriamycin.

Calumenin relieves cardiac injury by inhibiting ERS-initiated apoptosis during viral myocarditis.

Viral myocarditis (VMC) is a common disease causing heart failure (HF) for which no specific treatments are available. As apoptosis of cardiomyoctes is a hallmark of VMC and HF, strategies targeting apoptosis are an effective way of prevention and treatment of HF. Recent studies found endoplasmic reticulum stress (ERS) reaction is a new signal transduction pathway mediating apoptosis. Calumenin protein (CP) is located within the endoplasmic reticulum Ca2+ binding proteins, and is important in ER-initiated apoptosis. The aim of this study was to investigate whether the function of CP was influenced in cardiomyocytes infected by coxsackievirus B3. The expression of CP was down-regulated in cardiomyocytes infected by coxsackievirus B3. TUNEL studies showed that apoptosis was increased in CP-deficient and ΔCP-mutant cardiomyocytes infected by coxsackievirus B3. Additionally, ERS-associated proteins (GRP78, p-PERK, p-eIF2α, ATF4 and CHOP) were up-regulated in coxsackievirus B3-infected CP-deficient and ΔCP-mutant cardiomyocytes compared to wild type control cells. These results suggested ER-initiated apoptosis was induced by coxsackievirus B3-infected cardiomyocytes and caused apoptosis through ER stress. CP can relieve ERS-initiated apoptosis in viral myocarditis.

[Effect of total flavonoids of astragalus on endoplasmic reticulum chaperone, calumenin and connecxin 43 in suckling mouse myocardium with myocarditis caused by coxsackievirus B3].

OBJECTIVE: To investigate the effect of total flavonoids of astragalus on the expression of endoplasmic reticulum chaperone, calumenin and connecxin 43 (CX43) in suckling mouse myocardium with myocarditis caused by coxsackievirus B3 (CVB3). METHODS: The primary culture of suckling mouse myocardium cells were randomly divided into control group, CVB3 infected group and total flavonoids of astragalus group. Firstly, to confirm the identity of the suckling mouse myocardium, α-SMA was monitored by immunohistochemistry method. Then the protein expression changes of endoplasmic reticulum chaperone-glucose regulatory protein 78 ( GRP78), calumenin and CX43 were detected by Western blot. RESULTS: (1) Compared with that of the control group, the GRP78 expression level in CVB3 infected group was improved, the expression levels of calumenin and CX43 were all reduced. (2) Compared with that of CVB3 infected group, GRP78 expression level was decreased, and the expression levels of calumenin and CX43 were increased in total flavonoids of astragalus group. CONCLUSION: CVB3 infection may cause endoplasmic reticulum stress of rat myocardium cells by increasing the expression of GRP78 and decreasing the expression of calumenin and CX43. On the other hand, total flavonoids of astragalus can reduce the expression of GRP78 and increase the expression of calumenin and CX43.The results of this experiment may be closely related to the effects of anti-arrhythmia with viral myocarditis caused by CVB3.