Effect of atorvastatin on cardiac function and HGF/c-Met signaling pathway after acute myocardial infarction in diabetic rats

AIM: To investigate the effect of atorvastatin on myocardial apoptosis, ventricular remodeling and cardiac function after acute myocardial infarction (AMI) in diabetic rats, and to explore whether the effect is mediated by hepatocyte growth factor (HGF)/c-Met signaling pathway. METHODS: Diabetes in 70 male SD rats was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). After 8 weeks, AMI was induced by the ligation of the left anterior descending coronary artery in the diabetic rats, and 32 surviving rats were divided into AMI group (n=16) and AMI＋atorvastatin group (n=16, 20 mg·kg-1·d-1) at random. The similar surgical procedure was completed in sham group (n=11) without coronary ligation. Atorvastatin was given daily by gavage from the first day after AMI. Two weeks later, the cardiac function, pathological changes of myocardial tissues, myocardial apoptosis, and the expression of HGF and c-Met were compared among groups. RESULTS: AMI significantly reduced cardiac function, increased collagen volume fraction (CVF) and myocardial apoptotic index, and up-regulated the expression of HGF and c-Met at mRNA and protein levels in AMI control group (P<0.05). The cardiac function was improved, and CVF and myocardial apoptotic index were reduced by the treatment with atorvastatin, which also up-regulated the expression of HGF and c-Met (P<0.05). CONCLUSION: Atorvastatin significantly attenuates myocardial apoptosis and cardiac remodeling, and improves cardiac function after AMI in diabetic rats by further enhancing the activation of HGF/c-Met pathway.     

MicroRNA profile analysis of ischemic myocardial tissues from rats with acute myocardial infarction

AIM：To identify differentially expressed microRNAs (miRNAs) in ischemic myocardial tissues from the rats with acute myocardial infarction (AMI) by miRNA array technique, and to predict their targets and analyze their functions using bioinformatics. METHODS：The rat models of AMI (n=3) were prepared by ligaturing the left anterior descending coronary artery (LAD) of Wistar rats. Electrocardiogram and blood pressure were detected during the operation, and the myocardial infarct size was measured by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Ischemic myocardial tissues were isolated from the infarct area 4 h after ischemia. The same procedure in sham group (n=3) was performed except for ligaturing LAD. Total RNA was extracted from ischemic and normal myocardial tissues. miRNA was isolated from total RNA, labeled with Cy3 and hybridized on miRNA array. Real-time PCR was applied to verify the reliability of miRNA array results. The targets of differentially expressed miRNAs were predicted and their functions were analyzed by bioinformatics. RESULTS：Rat model of AMI was successfully prepared and verified by electrocardiogram detection, blood pressure measurement and pathological observation. Compared with sham group, microarray screening showed that total 11 AMI-related miRNAs were selected, including 6 up-regulated and 5 down-regulated. Three of them (rno-miR-181c, rno-miR-146b and rno-miR-208) were related to the cardiovascular functions, while the functions of the others (rno-miR-672*, rno-miR-743b, rno-miR-128, rno-miR-138-1*, rno-miR-336, rno-miR-138-2*, rno-miR-325-3p and rno-miR-3572) were unknown and might be novel AMI-related biomarkers. Parts of the miRNA targets were also related to the cardiovascular functions. CONCLUSION：Differentially expressed miRNAs in AMI rats may serve as novel biomarkers for diagnosis of AMI and potential targets for treatment of AMI.     

Relationship between NLRP3 inflammasome-IL-1β axis and End-MT after acute myocardial infarction in rats

AIM: To investigate whether activation of NLRP3 inflammasome-IL-1β axis is consistent with endothelial-mesenchymal transition (End-MT) during the process of myocardial fibrosis after acute myocardial infarction (AMI). METHODS: Adult male SD rats (n=30) were randomly divided into sham operation group (n=15) and AMI group (n=15). After 28 d, Masson staining was used to detect the level of myocardial fibrosis. The activation of NLRP3 inflammasome including NLRP3, ASC, pro-caspase-1 and caspase-1, the endothelial cell markers CD31 and VE-cadherin, and the mesenchymal cell markers α-SMA and FSP1 were analyzed by Western blot. The expression of IL-1β was measured by ELISA. RESULTS: The levels of myocardial fibrosis and End-MT, the activation of NLRP3 inflammasome, and the expression of caspase-1 and IL-1β were significantly increased in AMI group compared with sham operation group (P<0.05). CONCLUSION: The activation of NLRP3 inflammasome-IL-1β axis is significantly consistent with End-MT process, suggesting that NLRP3 inflammasome-IL-1β, as a potential target for the activation of End-MT, will provide a novel theoretical target for the treatment of myocardial fibrosis and heart failure after AMI.     

Salvia extract promotes angiogenesis of myocardium in rats with myocardial infarction

AIM: To determine the effect of salvia extract on angiogenesis of the myocardium in the rats with myocardial infarction (MI) and to analyze its possible mechanism. METHODS: Left coronary artery of Sprague-Dawley rats was ligated to establish a MI model. The rats were randomly divided into MI model group, 3 different dose groups of salvia (10, 20 and 40 mg·kg^-1·d^-1), and sham operation group. Each group consisted of 8 rats. The rats in all treatment groups were orally administered with the salvia extract, and the rats in MI group and sham operation group were fed with the same volume of saline. The rats were sacrificed 4 weeks later. The hemodynamic changes of the rats were determined, and the segmental heart samples were used for morphological observation by hematoxylin and eosin staining, Masson staining, or electron microscopic analysis. The expression of vascular endothelial growth factor (VEGF) and cluster of differentiation 34 (CD34) was analyzed according to immunohistochemistry. RESULTS: Compared with sham operation group, the morphological changes of the myocardium in MI group were disordered, part of myocardial cell outline disappeared, and obvious fibrosis in the necrosis myocardial tissue and fuzzy or disappearing microvascular ultrastructure were also observed. Compared with MI group, the number of new microvessels in all the treatment groups increased obviously, and the morphological changes of the endothelial cells were relatively complete according to electron microscopy. Compared with sham operation group, the protein expression of VEGF and CD34 in the cytoplasm of the myocardial tissues in MI group increased only a little. Compared with MI group, the protein expression of VEGF and CD34 in the cytoplasm of the myocardial tissues in all treatment groups increased significantly (P<0.01). CONCLUSION: Salvia extract obviously promotes angiogenesis of the myocardial tissues in the rats after myocardial infarction.     

Effects of stachydrine hydrochloride on experimental acute cerebral infarction in rats

AIM: To observe the therapeutic effect of stachydrine hydrochloride on experimental acute cerebral infarction in rats and to explore the underlying mechanisms. METHODS: SD rats (n=75) were randomly divided into 5 groups: sham group, cerebral infarction model group, and stachydrine hydrochloride (10 mg/kg, 20 mg/kg and 40 mg/kg) treatment groups. After the establishment of cerebral infarction model, the rats were given stachydrine hydrochloride at dose of 10 mg/kg, 20 mg/kg or 40 mg/kg by gavage daily for 14 d. The impairment of neurological function in each group was scored. The cerebral infarction volume and brain water content were measured. Moreover, the protein levels of β-catenin, cyclin D1, glycogen synthase kinase 3β (GSK-3β) and p-GSK-3β in the brain tissues were detected by Western blot. RESULTS: Compared with cerebral infarction group, the score of neurological function impairment, cerebral infarction volume and brain water content were significantly decreased in stachydrine hydrochloride treatment groups. In addition, the protein levels of β-catenin, cyclin D1 and p-GSK-3β were markedly increased after stachydrine hydrochloride treatment. CONCLUSION: Stachydrine hydrochloride protects against experimental acute cerebral infarction through activation of Wnt/β-catenin signaling pathway.     

Effects of pioglitazone on myocardial energy metabolism and hemodynamics in rats with myocardial infarction

AIM: To observe the effects of pioglitazone on myocardial energy metabolism and hemodynamics in rats with heart failure after myocardial infarction (MI). METHODS: The model of MI was established by ligation of left anterior descending artery. The 20 surviving rats were randomly divided into MI group (n=10) and pioglitazone intervention group (P group,n=10, pioglitazone 3 mg·kg^-1·d^-1 orally). The sham-operated rats (SH, n=10) served as controls. Hemodynamic parameters were measured. The ratio of left ventricular weight to body weight (LVW/BW) and the ratio of right ventricular weight to body weight (RVW/BW) were calculated after 8-week treatment. The expression of PPARγ was examined by Western blotting. Mitochondrial respiratory function was determined by Clark oxygen electrodes. The size of adenine acid pool (ATP, ADP and AMP) in mitochondria was measured by HPLC. The adenine nucleotide translocator(ANT) activity was detected by the atractyloside-inhibitor stop technique. RESULTS: Compared with SH group, the protein expression of PPARγ was significantly decreased in MI group (P<0.01). The mitochondrial respiratory activity, the transport activity of ANT and the high-energy phosphate content were decreased in MI group (P<0.01), and the hemodynamic parameters were in disorder (P<0.01). Compared with MI group, the protein expression of PPARγ in P group was significantly increased. The mitochondrial respiratory activity, the high-energy phosphate content, the transport activity of ANT were improved (P<0.01). However, the hemodynamic parameters were not significantly changed.CONCLUSION: Pioglitazone increases the protein expression of PPARγ and improves myocardial energy metabolism in the development of heart failure in the rat model of myocardial infarction, but dose not change the hemodynamic parameters significantly.     

Effects of atorvastatin on iopromide-induced apoptosis of renal tubular epithelial cells in diabetic rats

AIM：To investigate the protective effect of atorvastatin (ATO) against contrast medium (CM)-induced apoptosis of renal tubular epithelial cells in diabetic rats. METHODS：Streptozocin-induced diabetic Wistar rats were fed for 8 weeks and then randomly divided into 5 groups: diabetes mellitus (DM) group, DM with iopromide (a kind of CM) treatment group (DM+CM group), and groups of DM rats treated with ATO at 5 mg·kg-1·d-1 (ATO1 group), 10 mg·kg-1·d-1 (ATO2 group) and 30 mg·kg-1·d-1 (ATO3 group) before iopromide injection. Healthy Wistar rats served as normal controls (N group). Urine creatinine (UCr) and 24-hour urinary albumin (24 h-UAlb) were determined 24 h after iopromide injection. Serum creatinine (SCr) and blood urea nitrogen (BUN) were detected 48 h after iopromide injection, and then creatinine clearance (CCr) and 24-hour urinary albumin excretion rate (24 h-UAER) were calculated. The rats were sacrificed and both kidneys were removed 48 h after iopromide injection. For the left kidney, the morphology by HE staining, the renal tubular apoptosis by TUNEL and the expression of Bax and Bcl-2 by immunohistochemistry were detected. For the right kidney, the expression of Bax and Bcl-2 was measured by Western blotting. RESULTS：Compared with N and DM groups, the levels of SCr, BUN and 24 h-UAER, as well as the expression of Bax in the renal medulla were higher, the levels of Ccr and Bcl-2 expression in the renal medulla were lower and TUNEL-positive cells were more in DM+CM group. Compared with DM+CM group, ATO attenuated these changes, especially in ATO3 group. CONCLUSION: Iopromide could cause renal tubular apoptosis. Early application of ATO could dose-dependently attenuate the development of contrast-induced acute kidney injury, partly due to suppression of iopromide-induced renal tubular apoptosis.     

Effect of cell transplantation for the treatment of acute myocardial infarction using vascular endothelial growth factor gene transferred neonatal cardiomyocytes

AIM:To observe the secretion of vascular endothelial growth factor (VEGF) when adenovirus induced VEGF165 (AdVEGF165) gene transferred into neonatal cardiomyocytes in vitro,and to investigate the impact on heart function after transplanted the transferred cardiomyocytes into infarct myocardium in rats.METHODS:Neonatal cardiomyocytes were cultured in vitro and labeled with BrdU,then transferred by AdVEGF165.ELISA was applied to assay the expression and secretion of VEGF.Wistar rats,in which left descending branch of coronary artery was ligated,were randomly divided into four groups and transplanted into MI area with transferred cardiomyocytes (group Ⅰ),untransferred cardiomyocytes (group Ⅱ),AdVEGF165 (group Ⅲ) and culture medium (group Ⅳ),respectively.The echocardiograph was applied to evaluate the heart function before and after cell transplantation.Then the rats were executed and the hearts were harvested for histological (hematoxylin-eosin) and immunohistological (anti-BrdU dyeing) examinations.The vessels were also counted in injected area.RESULTS:ELISA indicated that the expression and secretion of VEGF in groupⅠwere higher than those in the rest (P<0.01).Echocardiograph revealed that the improvement of ejection fraction (EF) in groupⅠwas greater than that in other groups (P<0.01).Immunohistological study showed that the implanted cardiomyocytes survived in MI area.More blood vessels in groupⅠthan other groups were observed (P<0.01) by vessel-counting.CONCLUSIONS:AdVEGF165 gene transfer increased the VEGF-production,accelerated neovascularization in MI area and increased the blood flow.The method makes favor for the survival of implanted cells and greatly improves the heart function.     

Combinational effects of trimetazidin and parecoxib on acute myocardial infarction in rats

AIM: To investigate the protective effects and mechanisms of combinational use of trimetazidine(TMZ) and parecoxib sodium on acute myocardial infarction (AMI) in rats. METHODS: Sixty-six Sprague-Dawley rats were randomly divided into 5 groups: sham group; AMI group; AMI+TMZ group; AMI+parecoxib group; AMI+TMZ+parecoxib group. All rats were sacrificed and cardiac functions (HR, LVSP, LVEDP, +dp/dt_max,-dp/dt_max) were measured with a Pclab-3804 biological signal processing system on the 8th day. The infarct size in each group was checked up by TTC staining method. RT-PCR was employed to detect the bax mRNA and bcl-2 mRNA. The protein levels of COX-2, Bax, Bcl-2 and cleaved caspase-3 in myocardium were determined by Western blotting. The activity of caspase-3 in each group was measured by colorimetric assay kit, and the apoptotic rates were detected with DNA ladder kit.RESULTS: Compared with sham group, increased expression of COX-2 protein (P<0.01) was observed in AMI group. The expression of COX-2 protein in parecoxib group was lower than that in AMI group (P<0.01). Compared with AMI group, the combinational use of trimetazidin and parecoxib improved contractile functions (LVSP and +dp/dt_max), reduced the infarct size and lowered the apoptotic rates remarkably. Specifically, the combinational use of trimetazidin and parecoxib showed better effects than use of trimetazidin or parecoxib alone. Reduced expression of Bax/Bcl-2 mRNA and protein, the reduced caspase-3 activity and cleaved caspase-3 expression were also found in combinational group as compared with other groups (P<0.05).CONCLUSION: The combinational use of trimetazidin and parecoxib effectively improves cardiac functions and reduces infarct size. The mechanism of the protective effect is probably associated with inhibiting apoptosis of cardiac myocytes.     

Effects of celecoxib on cardiac myocyte apoptosis after myocardial infarction

AIM: To investigate the effects of celecoxib, a selective cyclooxygenase-2 inhibitor, on antioxidative capability and apoptosis of cardiac myocytes after myocardial infarction. METHODS: 24 New Zealand rabbits were divided into three groups randomly (8 in each group): sham-operated group (sham group), myocardial infarction group (MI group), celecoxib group (Cele group, 10 mg kg^-1·d^-1, qd, with the drugs gastric gavage for six weeks). The NO concentration, total antioxidative capability (T-AOC), the activity of constitutive nitric oxide synthase (cNOS) and inducible NOS (iNOS) in cardiac tissue homogenate, adjacent to the infracted area, were detected. The pathological changes were observed by light microscope and electron microscopy. The expressions of Bcl-2 and Bax protein in myocytes were observed using immunohistochemistry, and the degree of apoptosis were examined by TUNEL. RESULTS: Cardiac tissue in MI group presented interstitial edema, fibroplastic proliferation, inflammatory cellular infiltration, and vacuolar degeneration in cardiac myocytes. The results of electron microscopy showed that myocytes presented more changes caused by ischemic injury: widened interspace of myofibril, disordered myofibrillae, focal lysis of myofilament, ectasia of sarcoplasmic reticulum. In Cele group, the pathological changes were light, the NO^-₂/ NO^-₃ concentration, the activity of iNOS were lower (P<0.05), while the activity of cNOS and T-AOC were higher (P<0.05) than those in MI group. The expression rate of Bcl-2 protein in Cele group was higher than that in MI group, while the Bax was lower (P<0.01). The number of apoptotic myocytes was lower than that in MI group (P<0.01).CONCLUSION: Celecoxib decreases the number of apoptotic cardiomyocytes and increases the antioxidative capability after myocardial infarction.     

Short-term cardioprotective effects of trimetazidine on acute myocardial infarction in rats

AIM: To observe the myocardial protective effects of trimetazidine on myocardial infarction (MI) in Sprague-Dawley (SD) rats. METHODS: Ninety SD rats were randomly assigned to 3 groups (n=30 each): myocardial infarction group (MI group), MI+trimetazidine group (MT group) and sham group (S group). By permanently ligating the left anterior descending artery, the MI model was set up in the rats in MI group and MT group. Before and after setting up the MI model, normal saline was given to the rats in MI and S group by gavage. On the other hand, trimetazidine (3 mg/kg,twice per day) was given to the rats in MT group by gavage. At 8 h, 24 h and 48 h after applying trimetazidine, the serum level of cardiac troponin I (cTnI) was measured. At the 1st week, 2nd week and 4th week after treated with trimetazidine, the size of myocardial infarction, the maximum rising rate of the left ventricular systolic pressure (+dp/dt_max) and the maximum descending rate of the left ventricular diastolic pressure (-dp/dt_max) were measured. Also at the 1st week after applying trimetazidine, the cardiomyocyte apoptotic index was detected. RESULTS: Compared with MI group 2 weeks after applying trimetazidine, +dp/dt_max significantly increased in MT group , and -dp/dt_max also significantly increased in MT group . Four weeks after applying trimetazidine, +dp/dt_max significantly increased in MT group , and -dp/dt_max also significantly increased in MT group . At 8 h and 48 h after applying trimetazidine, no statistically significant difference (P＞0.05) of serum cTnI between MI group and MT group was observed. However, at 24 h after applying trimetazidine, the serum level of cTnI decreased in MT group as compared with MI group . Aditionally, trimetazidine significantly decreased the infarction size of myocardium in MT group (0.248±0.052) as compared with MI group (0.362±0.082, P<0.01). CONCLUSION: Trimetazidine has short-term cardioprotective effects on the rats with acute MI by improving myocardial systolic and diastolic functions, reducing infarct size and inhibiting apoptosis.     

Effects of atorvastatin on the experimental autoimmune myocarditis in Lewis rats

AIM:To test the hypothesis that atorvastatin affects T cell-mediated autoimmunity through modulating the balance of Th1/Th2 and reduces the severity of EAM. METHODS:Myocarditis was induced in Lewis rats by injection of porcine cardiac myosin. High-dose (10 mg·kg^-1·d^-1) or low-dose (1 mg·kg^-1·d^-1) atorvastatin or vehicle was administered orally for 3 weeks. On day 21, echocardiography was examined and the severity of myocarditis was detected by histopathological evaluation. Levels of serum IFN-γ, IL-2, IL-4 and IL-10 were measured by ELISA. RESULTS:Cardiac function and histological severity of myocarditis were improved in the two atorvastatin-treated groups. Treatment with atorvastatin decreased the levels of Th1 cytokine (IFN-γ, IL-2) and increased the levels of Th2 cytokine (IL-4, IL-10). CONCLUSION:These results suggest that HMG-CoA reductase blockade may be a promising new strategy for the treatment of autoimmune myocarditis.     

Effects of carvedilol,cilazapril and their combination on left ventricular remodeling after acute myocardial infarction in rats

AIM:To compare the effects of carvedilol, cilazapril and their combination on left ventricular remodeling(LVRM) after acute myocardial infarction(AMI) in rats. METHODS: Twenty-four hours after AMI operation, 100 surviving rats were randomly assigned to: ①AMI control(n= 25), ②AMI+carvedilol(1 mg·kg^-1 ·d^-1, n= 25)(C1), ③AMI+cilazapril(1 mg·kg^-1 ·d^-1, n= 25)(Z1), and ④ AMI+combination(n= 25) groups. Sham-operated group(n= 17) were selected randomly. After 4 weeks of therapy with the drugs gastric gavage, hemodynamic and pathological studies were performed. RESULTS: There were no significant differences in MI size among the four AMI groups(all P> 0.05) Left ventricular(LV) end diastolic pressure(LVEDP), volume(LVV), weight(LVW) and septal thickness(STh) were all higher and left ventricular pressure maximal rate of rise and fall(±d p /d t) were lower(all P< 0.01) in AMI group than sham-operated group. The LVEDP, LVV, LVW and STh were all lower and ±dp /dt were higher in Z1, C1, and combination groups than those in AMI group(P< 0.05, P< 0.01), with LVEDP and STh were more lower in the combination group than in the two monotherapy group(P< 0.05, P< 0.01), but there were no significant differences in other variables among the three therapy groups. CONCLUSION: Carvedilol, cilazapril and their combination all can prevent from LVRM after AMI in rats, improve hemodynamics and LV function, with the combination superior.     

Mechanism of endothelial microparticle generation in hypertension and its pathophysiological roles

Hypertension is closely related to many target organ damage. Endothelial microparticles (EMPs), derived from endothelial cells in response to endothelial cell activation or apoptosis, are complex vesicular structures with a membrane skeleton and express various antigens specific to parental endothelial cells. EMPs circulate in human plasma and show elevated levels in many vascular damage diseases, such as hypertension, atherosclerotic vascular diseases, sepsis and diabetes. Recent studies have shown that EMPs could be a comprehensive index for endothelial homeostasis monitoring, such as vasomotor activity, anti-inflammatory status and so on. Especially, more and more evidence suggests that EMPs play an important role in hypertension. Patients with hypertension show higher circulating levels of EMPs compared with healthy controls. Furthermore, increasing evidence demonstrates that EMPs can induce endothelial dysfunction in vitro and in vivo, and then further promote the development of hypertension and its complications. This review will summarize the progress in the definition and formation mechanisms of EMPs, levels of EMPs and their phenotypes in patients with hypertension, and the pathophysiological roles of EMPs in hypertension.     

Cardiomyocyte apoptosis and related gene expression after acute myocardial infarction in rats

AIM: To investigate cardiomyocyte apoptosis and the expression of caspase-3, Bcl-2 and Bax after acute myocardial infarction (AMI) in rats.METHODS: AMI model was established with the ligation of left coronary artery in 78 randomly selected female SD rats.Twenty-four hours after operation, 43 survivors were randomly divided into 48-hour and 4-week two groups according to the time points: MI 48 h (n=11) and MI4 weeks (n=13) groups, sham-operated rats (S, n=27) were also randomly selected and reassigned to S48 h (n=10) and S4 weeks (n=10) groups.Cardiomyocyte apoptosis was detected with in situ terminal deoxynucleotidyl transferase (TdT)-dUTP nick-end labeling (TUNEL staining) and DNA gel electrophoresis.Caspase-3, Bcl-2 expression and Bax expression were detected with immunohistochemistry and Western blotting analysis.RESULTS: Compared with sham-operated group, after AMI, systolic, diastolic, and mean arterial blood pressures (SBP, DBP, MAP), left ventricular systolic pressure (LVSP) and the maximum change rate of left ventricular pressure rise and fall (±dp/dt) were significantly decreased (P<0.05, P＜0.01), while left ventricular end diastolic pressure (LVEDP) was significantly increased (P<0.05) in MI 48 h group.All the above indices in MI 4 weeks group had the same change as that in MI48h group, with the LVEDP significantly higher (P<0.01), except for a non-significantly change in SBP, DBP and MAP (all P>0.05).In both MI 48 h and MI 4 weeks groups, myocyte apoptotic index was significantly increased in the infracted/scar, border and non-infarcted areas (P<0.05,P＜0.01) with caspase-3 and Bax expressions increased significantly (P<0.05, P＜0.01) in myocytes of the above three areas and Bcl-2 expression increased only in myocytes of the infracted area in MI 48 h group.Western blotting indicated that Bcl-2/Bax ratio was also decreased in MI 48 h subgroup.CONCLUSIONS: After AMI in rats, cardiomyocyte apoptosis happened in the infarction/scar, border and non-infarcted areas, with caspase-3 and Bax expression in myocytes increased, and with Bcl-2 expression increased in myocytes of infracted area and Bcl-2/Bax ratio decreased only early after AMI.     

Effects of granulocyte colony-stimulating factor on the myocardial infarction in experimental rats

AIM: To investigate the effects of granulocyte colony-stimulating factor (G-CSF) on the myocardial infarction in experimental rats. METHODS: Rats were randomly divided into GT group and saline control group (SC).The rats of GT group were treated with G-CSF (10 μg/kg) once a day subcutaneously for 5 days and those of SC group were received saline.On the third day, both groups were injected with isoprenaline (ISO) interaperitoneally to develop acute ischemic model. The hearts were harvested from 2 weeks to 4 weeks after administration of ISO for histopathological examination. RESULTS: Compared with saline control group, G-CSF treatment group significantly reduced the scar size (P<0.05). We also found the regeneration of myocytes, smooth muscle and endothelial cells. CONCLUSION: G-CSF treatment could be benefical to the regeneration of infarcted myocardium and significantly reduce scar size and it could be used for therapeutic intervention of the acute myocardial infarction.     

Panax quinquefolium saponin attenuates ventricular remodeling after acute myocardial infarction in rats by inhibiting endoplasmic reticulum stress-related apoptosis

AIM: To investigate the effect of Panax quinquefolium saponin (PQS) on ventricular remodeling after acute myocardial infarction (AMI) in rats and its mechanism. METHODS: Ninety healthy male SD rats were randomly divided into sham group, AMI group, taurine 300 mg·kg-1·d-1 group, PQS 50 mg·kg-1·d-1 group, PQS 100 mg·kg-1·d-1 group and PQS 200 mg·kg-1·d-1 group. AMI models were produced by ligating the left coronary arteries in SD rats. The rats in each treatment group were gavaged with drugs dissolved in water (10 mL·kg-1·d-1), and the rats in sham group and AMI group received equal volume of water. Four weeks after MI, the left ventricle fractional shortening, ejection fraction and structure were evaluated by echocardiography. Myocardial infarct size was measured by 2,3,5-triphenyltetrazolium chloride staining. The hydroxyproline level was measured by colorimetric method. Apoptosis of the cardiomyocytes was detected by TUNEL. In addition, the expression of endoplasmic reticulum stress-related molecules in the noninfarcted myocardium was determined by Western blotting. RESULTS: Compared with AMI group, the left ventricular end-systolic dimension in PQS 50 mg·kg-1·d-1 group, PQS 100 mg·kg-1·d-1 group and PQS 200 mg·kg-1·d-1 group decreased by 17.2%, 20.3% and 38.8% respectively,and the left ventricular end-diastolic dimension decreased by 8.91%, 8.95% and 17.20%, respectively.The left ventricular end-systolic volume decreased by 31.4%, 38.5% and 67.0%, respectively, and the left ventricular end-diastolic volume decreased by 18.2%, 18.8% and 34.2%, respectively.The left ventricular ejection fraction increased by 44.9%, 60.1% and 118.0%, respectively,and the fractional shortening increased by 55.4%, 71.0% and 148.0%, respectively.The infarction size decreased by 4.6%, 39.5% and 55.8%, respectively,and the hydroxyproline level in noninfarcted myocardium decreased by 34.5%, 35.9% and 48.7%, respectively. Compared with AMI group, the myocardial apoptotic index in PQS 200 mg·kg-1·d-1 group decreased by 27.3%, the protein expression of Bcl-2 increased by 114.0%, and that of Bax, GRP78, CRT and CHOP decreased by 53.1%, 79.9%, 80.8% and 42.5%, respectively. The above mentioned protective effects in PQS 200 mg·kg-1·d-1 group and taurine group were similar. The Spearman correlation analysis revealed that CHOP expression had significant positive correlation with apoptotic index (r=0.797, P<0.01). CONCLUSION: PQS attenuates ventricular remodeling in rats. The underlying mechanism may be associated with the inhibition of CHOP-mediated endoplasmic reticulum stress-related cardiomyocyte apoptosis.     

Effect of Shenshuguanxin granula on coronary circulation in rats with myocardial infarction

AIM：To explore the effect of traditional Chinese medicine Shenshuguanxin granula on coronary circulation in a rat model of myocardial infarction (MI). METHODS：SD rats (n=50, SPF grade) were randomly divided into 5 groups (n=10):sham group, MI group, and high-dose, middle-dose and low-dose Shenshuguanxin granula treatment groups. The rat MI model was established by ligation of the coronary artery. The cardiac markers, small and medium-sized blood vessels ［microvessel count (MVC) value］ in the infarct zone, and platelet endothelial cell adhesion mo-lecule 1 (PECAM-1) and vascular endothelial growth factor (VEGF) expression in the infarct border zone were measured. RESULTS：After 4 weeks of coronary artery ligation, the significant increases in MVC in the infarct zone, and the expression of PECAM-1 and VEGF in the infarct border zone were detected compared with sham group (P<0.05). The differences of cardiac markers between MI group and other groups were insignificant (P>0.05). CONCLUSION:Shenshuguanxin granula improves coronary circulation in the rats with myocardial infarction by increasing the expression of PECAM-1 and VEGF, and promoting small and medium-sized angiogenesis.     

Effects of Tongxinluo on connexin 43 remodeling and ventricular arrhythmia after myocardial infarction in rats

AIM: To determine the effects of Tongxinluo(TXL) on connexin 43(Cx43) remodeling and ventricular arrhythmia(VA) after myocardial infarction(MI) in rats. METHODS: Male SD rats were randomly divided into sham-operated(sham) group(n=25) and operation group(n=75). The left anterior descending(LAD) was ligated in operated group, while the rats in sham group only underwent pericardiotomy. The rats in operation group which survived for 3 d after operation were randomly assigned to TXL group and MI group. The rats in TXL group was administrated with TXL(2 g·kg^-1·d^-1, intragastric administration) for 4 weeks, while normal saline was applied to the rats in sham group and MI group. The levels of interleukin-1β(IL-1β) and endothelin-1(ET-1) in the tissue from the border zone were measured by ELISA after treatment. The distribution and the mRNA and protein expression of Cx43 were detected by immunohistochemical staining, RT-PCR and Western blotting, respectively. The burst pacing was used to induce ventricular arrhythmia(VA). RESULTS: Compared with sham group, the levels of IL-1β and ET-1 and the incidence of VA were significantly increased, while the mRNA and protein expression of Cx43 was markedly reduced with irregular distribution in MI group(P<0.05). Compared with MI group, the levels of IL-1β and ET-1 and the incidence of VA were significantly reduced, while the expression of Cx43 at mRNA and protein levels was markedly increased with augmented linear distribution in the myocardial cell intercalated disc in TXL group(P<0.05). CONCLUSION: TXL reduces the incidence of VA after MI via inhibiting the Cx43 remodeling.