Effects of pentoxifylline on ventricular remodeling and cardiac function of dilated cardiomyopathy rats

AIM: To explore the effects of pentoxifylline (PTX) on ventricular remodeling and cardiac function in dilated cardiomyopathy (DCM) rats.METHODS: Lewis rats were randomly allocated to a myocin-induced dilated cardiomyopathy (DCM) group receiving saline (n=10), a DCM group receiving PTX (PTX group; 25 mg·kg^-1·d^-1, ip, for 30 days, n=10) or healthy control group (n=10). The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-10 in the blood plasma were analyzed by ELISA. The extent of fibrosis was estimated using Massons staining and immunohistochemistry analyses. Cardiac structure and function were measured by echocardiography.RESULTS: PTX decreased plasma levels of TNF-α and IL-6, and increased IL-10 level in DCM animals compared with DCM group ［TNF-α: (7.21±0.24) μg/L vs (19.30±1.31) μg/L, P<0.01; IL-6: (119.60±36.58) ng/L vs (189.50±13.25) ng/L, P<0.05; IL-10: (41.26±3.27) μg/L vs (32.45±4.32) μg/L, P<0.05］. Collagen volume fraction (CVF), perivascular collagen area (PVCA) and collagen Ⅰ/Ⅲ ratio were lower in PTX group than those in DCM group ［CVF: (16.45±3.01)% vs (23.33±4.43)%, P<0.05; PVCA: 4.58±2.10 vs 13.74±4.29, P<0.05; Ⅰ/Ⅲ ratio: 2.84±0.67 vs 4.22±0.54, P<0.01］. Left ventricular end-diastolic dimension reduced ［(6.11±0.51) mm vs (6.46±0.28) mm, P<0.05］ and left ventricular ejection fraction elevated ［(77.29±5.20)% vs (62.73±10.11)%, P<0.01］ by PTX compared with DCM.CONCLUSION: PTX modulates plasma levels of inflammatory cytokines, delays the ventricle remodeling and improves the heart function in DCM rats.     

Protective effect of aFGF delivery by ultrasound-targeted microbubble destruction on left ventricular function in diabetic cardiomyopathy rats

AIM：To observe the protective effect of delivery of acidic fibroblast growth factor (aFGF) to myocardium by ultrasound-targeted microbubble destruction (UTMD) on left ventricular function in diabetic cardiomyopathy (DCM) rats and to investigate the possible mechanisms. METHODS：Twenty-four rats were intraperitoneally injected with streptozocin to induce DCM and were randomly divided into DCM group and aFGF treatment group. Twelve healthy rats served as normal controls. The rats in aFGF treatment group were infused with SonoVue-aFGF mixed fluid through tail vein and UTMD was simultaneously performed. Four weeks after intervention, all rats underwent cardiac catheterization to mea-sure left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP) and the maximal increase/decrease rate of left ventricular pressure (LV±dp/dtmax). The microvessel density (MVD) of rat myocardial tissues was measured by immunohistochemical staining for CD31. The myocardial collagen volume fraction (CVF) was determined by improved Masson staining. The apoptotic index (AI) was detected by TUNEL method. RESULTS：Four weeks after intervention, the LVESP and LV±dp/dtmax in aFGF treatment group were significantly increased compared with DCM group (P<0.01), while the LVEDP in aFGF treatment group was significantly lower than that in DCM group (P<0.01). The MVD in aFGF treatment group was significantly increased compared with DCM group (P<0.01), but the CVF and AI in aFGF treatment group were significantly lower than those in DCM group (P<0.01). CONCLUSION: Delivery of aFGF to diabetic myocardium by UTMD could improve the left ventricular function of DCM rats and may be a new feasible therapeutic method for DCM.     

Effects of Ginkgo biloba extract on myocardial TGF-β1 and collagen expression and interstitial fibrosis in type I diabetic cardiomyopathy rats

AIM:To study the effects of Ginkgo biloba extract (EGB) on myocardial TGF-β1 and collagen expression and interstitial fibrosis in type I diabetic cardiomyopathy rats. METHODS:Thirty male SD rats were randomly divided into normal control group (CON), diabetes mellitus group (DM) and EGB treatment group (EGB). Streptozocin was intraperitoneally injected into the animals in the latter 2 groups to induce type I diabetic rat model. The rats in EGB group were intraperitoneally injected with EGB. At the end of the 12th week, the body weight of each rat and its left ventri-cular weight, blood glucose, glycosylated hemoglobin and serum insulin concentration were measured. The left ventricular end-diastolic volume (LVEDV), the left ventricular end-systolic volume (LVESV), the left ventricular ejection fraction (LVEF) and the stroke volume (SV) were determined by echocardiography. The content of collagen in left ventricular myocardium, and the expression of transforming growth factor β1 (TGF-β1), procollagen type I and collagen type III were assayed by Sirius red staining, immunohistochemical staining and RT-PCR, respectively. Left ventricular myocardial cells of the neonatal SD rats were isolated and cultured in vitro with low-glucose culture medium (LG group), high-glucose culture medium (HG group) or high-glucose culture medium plus EGB (HG+EGB group). The mRNA levels of TGF-β1, procollagen type I and collagen type III were detected by RT-PCR. RESULTS:Compared with CON group, blood glucose, glycosylated hemoglobin, left ventricular weight index, the content of collagen, and the expression of TGF-β1, procollagen type I and collagen type III in left ventricular myocardial tissues of DM group were significantly increased, while the levels of blood insulin, LVEDV and SV were significantly decreased. However, compared with DM group, blood glucose, glycosylated hemoglobin, left ventricule weight index, the content of collagen, and the expression levels of TGF-β1, procollagen type I and collagen type III in the left ventricular myocardial tissues of EGB-treated rats were significantly decreased, while the levels of blood insulin, LVEDV and SV were significantly increased. Compared with LG group, the mRNA expression levels of TGF-β1, procollagen type I and collagen type III were significantly increased. However, compared with HG group, the mRNA expression levels of TGF-β1, procollagen type I and collagen type III were significantly decreased after treated with EGB. CONCLUSION: EGB retards the process of myocardial fibrosis and improves the cardiac functions in type I diabetic cardiomyopathy rats by down-regulating the expression of TGF-β1, reducing the synthesis and deposition of collagen type I and collagen type III.     

Valsartan protects a rat model of adriamycin-induced dilated cardiomyopathy from left ventricular remodeling and failure

AIM: To investigate whether and how AT1 receptor blocker， valsartan， attenuates left ventricular remodeling and failure in a rat model of adriamycin（ADR）-induced dilated cardiomyopathy. METHODS: Weight-matched adult male Wistar rats were randomly divided into 3 groups as follows: 1) the ADR group, in which 2.5 mg/kg of ADR was weekly injected via a tail vein for 10 weeks (n=25); 2) concomitant AT1 receptor blocker valsartan and ADR, in which valsartan was administered by daily gavage at a dose of 30 mg·kg-1·d-1 (n=10); 3) control group (n=10). Hemodynamics and echocardiographic measurements were obtained at 12 weeks after treatment. Finally, left ventricle (LV) samples were collected at 12 weeks. The hydroxyproline content was determined by the methods of chloramines T. The expression of MMP-2, MMP-9 and tissue inhibitors of metalloproteinase-1 (TIMP-1) were measured by Western blotting. MMP-2 and -9 gelatinolytic activities were measured by gelatin zymography. RESULTS: Mortality was significantly lower in valsartan -treated rats than that in ADR rats (20% versus 40%, P<0.01). The dilatation of LV cavity was significantly attenuated in ADR-induced dilated cardiomyopathy rats given valsartan. Valsartan partially normalized LV contractile function, which was significantly reduced in ADR rats. The hydroxyproline content was increased in ADR-DCM group and significantly reduced by valsartan treatment (P<0.01). The protein levels of LV MMP-2 and MMP-9 were increased in ADR rats and attenuated by valsartan treatment (both P<0.01). However, no change in TIMP-1 was observed (P>0.05). The activities of LV myocardial MMP-2 and -9 gelatinolytic were increased significantly in ADR rats (both P<0.01) and attenuated by valsartan treatment (both P<0.01). CONCLUSION: Pretreatment with AT1 receptor blocker valsartan attenuates left ventricular remodeling and failure in a rat model of adriamycin-induced dilated cardiomyopathy.     

Effects of Shenmai injection on myocardial fibrosis in rat model of diabe-tic cardiomyopathy

AIM：To explore the effects of Shenmai injection on myocardial fibrosis in a rat model of diabetic cardiomyopathy (DCM). METHODS：Wistar rats (n=30) were randomly divided into control group, diabetes group and treatment group. Single intraperitoneal injection of streptozotocin was utilized to establish a rat model of DCM. The rats with DCM in treatment group were intraperitoneally injected with Shenmai injection. Ventricular cannulation was applied to assess the cardiac functions. The formation of collagen in the cardiac tissues was assessed by Masson staining. The generation of reactive oxygen species (ROS) in the cardiac tissues was detected by dihydroethidium staining. The expression levels of matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinase 2 (TIMP-2) and collagen I in the cardiac tissues were determined by Western blotting. RESULTS：Compared with control group, the cardiac functions were deteriorated in diabetes group (P<0.05), which was improved in treatment group as compared with diabetes group (P<0.05). Compared with control group, the formation of collagen and ROS increased significantly in diabetes group (P<0.05), which was decreased in treatment group as compared with diabetes group (P<0.05). Compared with control group, the expression level of MMP-2 in the cardiac tissues was deceased and TIMP-2 was increased significantly in diabetes group (P<0.05), but reversed significantly in treatment group (P<0.05).CONCLUSION:Shenmai injection attenuates cardiac fibrosis in the rats with DCM by inhibiting the generation of ROS.     

Inhibitory effect of aerobic exercise on left ventricular remodeling and sympathetic neural remodeling in rats with heart failure after myocardial infarction

AIM: To investigate the effects of long-term aerobic exercise on the heart and sympathetic neural remodeling (structure and function remodeling) in heart failure rats induced by myocardial infarction. METHODS: Heart failure model after myocardial infarction was performed by ligating anterior descending coronary artery in the Wistar rats. Four weeks after operation, the rats were randomly divided into sham operation sedentary (S) group, heart failure sedentary (H) group and heart failure exercise (HE) group. The animals in HE group underwent 10-week treadmill running, while those in S group and H group were sustained in a resting state. The cardiac structure and function including left ventricular internal diameter at diastole (LVIDd), left ventricular internal diameter at systole (LVIDs), left ventricular anterior wall diameter at diastole (LVAWDd), left ventricular anterior wall diameter at systole (LVAWDs), left ventricular posterior wall diameter at diastole (LVPWDd) and left ventricular posterior wall diameter at systole (LVPWDs), and cardiac function parameters including fractional shortening (FS) and left ventricular ejection fraction (LVEF) were measured by echocardiography. The myocardium was collected for histopathological observation with Masson staining, and the collagen volume fraction (CVF) was determined. The concentrations of norepinephrine (NE) in the myocardium and plasma were measured by high-pressure liquid chromatography. The frequency domain analysis was applied for determining the heart rate variability (HRV) via subcutaneous recording electrode involving total power (TP), normalized low power (LFn), normalized high power (HFn) and LF/HF ratio. The mRNA expression of collagen type I (Col-I), collagen type III (Col-III), atrial natriuretic factor (ANF), α-myosin heavy chain (α-MHC), β-myosin heavy chain (β-MHC), sarcoplasmic endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) was detected by real-time PCR. The protein levels of nerve growth factor (NGF) and its receptor (TrkA), and tyrosine hydroxylase (TH) were measured by Western blotting. RESULTS: (1) Compared with S group, body weight (BW), LVIDd, FS, LVEF, TP, HFn, the mRNA expression of α-MHC and SERCA2a, and the protein levels of NGF, TrkA and TH decreased (P<0.05). Left ventricular weight (LVW), left ventricular mass index (LVMI), LVAWDd, LVAWDs, LVPWDd, LVPWDs, CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF, β-MHC, Col-I and Col-III increased (P<0.05) in H group. (2) Compared with H group, LVW, LVMI, LVIDd, FS, LVEF, TP, HFn, the mRNA expression of α-MHC and SERCA2a, and the protein levels of NGF, TrkA and TH were raised (P<0.05), while CVF, plasma and myocardial NE content, LFn, LF/HF, and the mRNA expression of ANF, β-MHC, Col-I and Col-III decreased (P<0.05) in HE group. CONCLUSION: Long-term aerobic exercise training leads to inhibition of heart and sympathetic neural remodeling and improvement of cardiac function and autonomic modulation in the rats after myocardial infarction.     

Expression and significance of thrombospondin-1 in myocardium of type 2 diabetic cardiomyopathy rats

AIM: To investigate the expression and significance of thrombospondin-1 (TSP-1) in left ventricular myocardium of type 2 diabetic cardiomyopathy (DCM).METHODS: The rat model of DCM was established by eating a high-fat diet together with injection of low dose streptozocin (30 mg/kg) intrapertoneally.After 12 weeks,the content of collagen was quantified by Masson staining.The mRNA level of TSP-1 was determined by quantification real-time RT-PCR,while the protein level of TSP-1 was analyzed by Western blotting and immunohistochemistry.RESULTS: Compared with the control group,the content of collagen in the DCM group was increased greatly (11.01±3.05 vs 16.92±3.18,P<0.01).The mRNA and protein expressions of TSP-1 were significantly higher than those in control group (0.0089±0.0034 vs 0.0141±0.0037,P<0.05；96.38±16.80 vs 129.98±16.96,P<0.05).In DCM group,the mRNA and protein expressions of TSP-1 showed significantly positive correlations with the levels of fasting blood glucose and collagen (r=0.762,P<0.01; r=0.717,P<0.05; r=0.735,P<0.01; r=0.750,P<0.01).There was a significantly positive correlation of TSP-1 mRNA level with LVEDP (r=0.658,P<0.05).In contrast,there was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.605,P<0.05; r=-0.694,P<0.05).There was a significantly positive correlation of TSP-1 protein with LVEDP (r=0.716,P<0.05).There was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.633,P<0.05; r=-0.669,P<0.05).CONCLUSION: The increased expression of TSP-1 may play an important role in the development of myocardial interstitial fibrosis in DCM.     

Pathological study of dilated cardiomyopathy

AIM: To study the pathological features of the dilated cardiomyopathy and the mechanisms involved. METHODS: The left ventricular myocardium specimens were obtained from 8 patients with dilated cardiomyopathy by BATISTA. The morphological changes was examined macropathologically and histopathologically. RESULTS: The dilated cardiomyopathy from 8 patients can be classified into two types macropathology. One of them showed hypertrophy of left ventricular wall and the other showed fatty infiltration on myocardium of the left ventricular. In the first type, swelling of the endothelial cells as well as luminal stenosis even occlusive of small arteries and arterioles were observed in the study. Electronical microscopical examination showed that there were a lot of homogeneous secretory granules in the endothelial cells. CONCLUSION: These results suggested that the secretory granules might be from the damaged myocardial cells and entered into the adjacent endothelial cells. The pathological changes mentioned above could aggravate the ischemia of myocardium. At the same time, the vicious cycle make the pathological changes more serious. Further study should be made to confirm the nature of the secretory granules.     

Therapeutic effect of neuregulin-1β on pressure overload-induced myocardial hypertrophy in rats

AIM：To investigate the therapeutic effect and the mechanism of neuregulin-1β (NRG-1β) on the rat model of myocardial hypertrophy induced by pressure overload．METHODS：Eight weeks after coarctation of abdominal aorta, the Wistar rats were randomly divided into 4 groups: myocardial hypertrophy (model) group, sham operation (sham) group, NRG-1β treatment group (intravenous injection of NRG-1β at dose of 10 μg/kg daily for 7 d) and NRG-1β+Herceptin (HERCE) treatment group ［intravenous injection of NRG-1β (10 μg/kg) plus HERCE (10 μg/kg) daily for 7 d］. The characteristics of heart functions were evaluated by the methods of hemodynamics and echocardiography. Masson staining was employed to observe the pathological changes of myocardial tissues. The concentration of angiotensin II (Ang II) in myocardial tissues was measured by radioimmunoassay. The level of tumor necrosis factor α (TNF-α) in myocardial tissues was detected by ELISA. The mRNA expression of B-cell lymphoma/leukemia-2 (bcl-2) and bcl-2-associated X protein (bax) in the myocardium was determined by RT-PCR. RESULTS：The left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS) were higher, while the left ventricular end-systolic diameter (LVESD) and left ventricular end-diastolic diameter (LVEDD) were smaller in NRG-1β group than those in model group. The left ventricular end-systolic pressure (LVESP) and maximal rate of increase/decrease in left ventricular pressure (±dp/dtmax) were higher, and left ventricular end-diastolic pressure (LVEDP) was significantly lower in NRG-1β group than those in model group. Compared with model group, treatment with NRG-1β decreased collagen volume fraction (CVF), reduced the Ang II and TNF-α, increased bcl-2 mRNA expression, and decreased bax mRNA expression in myocardial tissues. No difference of the above parameters between model group and NRG-1β+HERCE treatment group was observed. CONCLUSION：NRG-1 reduces the expression of Ang II and TNF-α in myocardial tissues in pressure-overload rats, thus reducing Ang II and TNF-α mediated myocardial interstitial remodeling. Increase in the mRNA expression of bcl-2 and decrease in the mRNA expression of bax by NRG-1 inhibit myocardial cell apoptosis, which is responsible for its role of improving cardiac function of myocardial hypertrophy induced by pressure overload.     

MMP-7,MMP-10 and TIMP-4 expression in ventricular remodeling of human heart failure

AIM:To sieve matrix metalloproteinases (MMPs) and the tissue inhibitors of matrix metalloproteinases (TIMPs) closely associated with ventricular remodeling of human heart failure using antibody chip technology.METHODS:We performed cytokine-specific antibody array analysis using individual left ventricular myocardial samples from 6 patients with heart failure due to arrythmogenic right ventricular cardiomyopathy (ARVC) undergoing transplantation and matched samples from 6 non-failing subjects to screen differentially expressed MMPs and TIMPs associated with the ventricular remodeling of heart failure.The results were further validated by ELISA and immunohistochemical analysis.RESULTS:We identified high expression of MMP-7 and MMP-10 and low expression of TIMP-4 in ARVC failing hearts compared to non-failing hearts by hybridization with the cytokine-specific antibody arrays containing 17 MMPs and 4 TIMPs on the chips.ELISA and immunohistochemical analyses further confirmed that differentially expressed levels of MMP-7, MMP-10, and TIMP-4 were observed not only in ARVC failing heart, but also in failing hearts due to ischemic (ICM) and dilated cardiomyopathy (DCM).CONCLUSION:Highly expressed MMP-7 and MMP-10 and lowly expressed TIMP-4 may be involved in the ventricular remodeling of heart failure derived from cardiomyopathy of different etiology.     

Role of PPARα/PGC-1α in doxorubicin induced mouse dilated cardio-myopathy

AIM: To investigate the changes of peroxisome proliferator-activated receptors (PPAR)α/peroxisome proliferator activated receptor coactivator 1 alpha (PGC-1α) in doxorubicin (DOX) induced dilated cardiomyopathy (DCM) and its effect on the energy metabolism and myocardial function in mice. METHODS: Forty mice were randomly divided into 4 groups: control group, DOX group, PPARα inhibitor group and PPARα agonist group. The DCM model was established by injection of DOX. The protein levels of PPARα/PGC-1α were detected. The PPARα inhibitor and PPARα agonist were used 2 weeks beforeinjection of DOX. The contents of adenine acid and phosphocreatine (Pcr) in the mitochondria were measured by high-performance liquid chromatography (HPLC). The ANT activity was analyzed by the atractyloside-inhibitor stop technique. The changes of the echocardiography and hemodynamics were also observed. RESULTS: DOX induced DCM model was successfully established. The protein levels of PPARα and PGC-1α in control group were significantly higher than those in DOX group (P<0.05). Both of the high-energy phosphate contents and the transport activity of ANT were decreased in DOX group (P<0.05), and the hemodynamic parameters were disordered (P<0.01). Compared with DOX group, PPARα inhibitor pre-treatment significantly reduced the PPARα/PGC-1α expression. Meanwhile, high-energy phosphate contents in the mitochondria and the ANT transport activity of the mitochondria decreased, as well as the left ventricular function (P<0.05). On the other hand, PPARα agonist significantly increased the expression of PPARα and PGC-1α, and improved the transport activity of ANT. In addition, the hemodynamic parameters were ameliorated, but the high-energy phosphate contents of the mitochondria did not significantly change. CONCLUSION: PPARα/PGC-1α plays an important role in the regulation of ANT transport activity in dilated cardiomyopathy induced by DOX, and the activation of PPARα/PGC-1α has protective effects on the DCM induced by DOX.     

Cardiac collagen metabolism in murine viral heart diseases

AIM：To investigate the dynamic alteration of cardiac collagen metabolism in mice with acute,chronic myocarditis and dilated cardiomyopathy (DCM).METHODS：BALB/c mice infected with coxsackievirus B3 were used to establish animal models of acute,chronic myocarditis and dilated cardiomyopathy,while uninfected animals were also prepared and served as controls.After verification of models by histopathological methods and echocardiography,serum concentration of aminoterminal propeptide of type Ⅲ procollagen (PIIINP),aminoterminal propeptide of type Ⅰ procollagen (PINP) and carboxyterminal propeptide of type I procollagen (PICP) in each group of mice were detected by enzyme linked immunosorbent assay (ELISA).The expression of matrix metalloproteinase 1 (MMP-1) and its tissue inhibitor (TIMP-1) were determined by Western blotting analysis.The MMP-1 activity was also detected.RESULTS：Marked myocardial fibrosis was observed in all groups of CVB3-infected mice.Reparative fibrosis,promotion of synthesis and degradation of cardiac collagens were presented in heart tissue of acute myocarditis mice.Both reparative and reactive fibrosis,enhanced synthesis and lightened degradation of collagen were present in chronic myocarditis,while reactive fibrosis and excess collagen synthesis were confirmed in DCM.Expression and activity of MMP-1 was progressively decreased.TIMP-1 showed unchanged.The ratio of MMP-1/TIMP-1 was progressively descended.CONCLUSION：Collagen metabolism was special in different phase of viral heart diseases,which may play different roles in the progression and prognosis of these kinds of disease.     

Electrical heterogeneity of transient outward current in thyroxine induced ventricular myocytes of cardiomyopathy rat

AIM: To study the electrical heterogeneity of transient outward potassium current (Ito) in left and right ventricular myocytes of cardiomyopathy rat. METHODS: The rats were peritoneally injected with L-thyroxine 0.5 mg/kg for 10 d to establish the model of ventricular hypertrophy. The right and left ventricular parts of the heart were separated and the ventricular myocytes were prepared by step digestion using enzyme solution. Ito was recorded by using whole cell patch clamp technique. The change of the electrical heterogeneity was determined. RESULTS: The electrical heterogeneity of Ito existed in the normal myocytes of left and right ventricles. In the myocytes of left and right ventricles isolated from the cardiomyopathy rats, the electrical heterogeneity was enhanced obviously and showed statistical difference. At +40 mV depolarizing test potential, the current density of Ito in the myocytes of right ventricle was increased from (9.23±0.84) pA/pF to (11.19±1.73) pA/pF, while the current density of Ito in the myocytes of left ventricle was decreased from (6.99±1.14) pA/pF to (4.95 ±1.84) pA/pF and the dispersion was increased. The V1/2 of right ventricle steady inactivation was increased significantly ［from (-68.85±1.37) mV to (-49.86±0.69) mV］. The time constant τ of de-inactivation changed significantly ［τleft=(79.16±7.04) ms,τright=(53.19±3.72) ms］. CONCLUSION: Enhanced electrical heterogeneity of Ito in the left and right ventricular myocytes of cardiomyopathy rat may represent one of the important ionic mechanisms for some arrhythmia caused by myocardial hypertrophy.     

Role of nucleolin on myocardial hypertrophy and fibrosis in type Ⅱ diabetic cardiomyopathy mice

AIM:To investigate the effect of nucleolin on diabetic cardiomyopathy in mice.METHODS:A type Ⅱ diabetic cardiomyopathy mouse model was prepared using a cardiac-specific nucleolin-overexpressing transgenic mice.The mice were divided into wild-type mouse control group,nucleolin transgenic mouse control group,wild-type mouse diabetes group and nucleolin transgenic mouse diabetes group.Wheat germ agglutinin (WGA) fluorescent dye,Masson staining and PowerLab system detection were used to further clarify the role of nucleolin on cardiac hypertrophy,fibrosis and cardiac function in type Ⅱ diabetic cardiomyopathy mice.RESULTS:Compared with wild-type mouse control group,no significant increase in blood glucose level was found,while genetical myocardial cell hypertrophy was significantly attenuated in nucleolin transgenic mouse diabetes group.The collagen fibers were also significantly reduced,and hemodynamic indexes±dp/dt_max,left ventricular end-diastolic pressure,left ventricular systolic pressure and heart rate were also improved.The above differences were statistically significant.CONCLUSION:Nucleolin may reduce the occurrence of myocardial hypertrophy and fibrosis,thus improving the cardiac function of diabetic cardiomyopathy mice.     

Dynamic expression of S-adenosyl-L-homocysteine hydrolase under intervention of fimasartan in early stage of type 2 diabetic cardiomyopathy rats

AIM: To detect the changes of S-adenosyl-L-homocysteine hydrolase (SAHH) signaling pathway and related proteins under the intervention of fimasartan (FIM) in rats with diabetes mellitus (DM), and to explore the pathological mechanism of the occurrence and development of diabetic cardiomyopathy (DCM). METHODS: The type 2 diabetic rat model was established by injection of streptozocin after 5-week high-fat diet. The rats were randomly divided into control group, DM group, and DM+FIM group. Fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and fasting insulin (FINS) levels were tested. M-mode echocardiography was performed for determining the heart functions. High-performance liquid chromatography (HPLC) was used to detect homocysteine (Hcy), S-adenosylmethionine (SAM) and S-adenosyl-L-homocysteine (SAH). The alteration of SAHH in myocardium was determined by Western blot. RESULTS: The success rate of type 2 diabetic rat modeling was 84%. Compared with DM group, the body weight of the rats in DM+FIM group increased significantly (P<0.05), while cardiac index, left ventricular index, FBG and LDL-C were significantly reduced (P<0.05). The results of echocardiography showed that ejection fraction increased (P<0.05) in DM+FIM group. HPLC detection showed that the level of Hcy and the ratio of SAM/SAH were significantly reduced (P<0.05). The results of Western blot showed that the expression of SAHH in DM group was increased compared with control group, while that in DM+FIM group declined (P<0.01). CONCLUSION: The expression of SAHH, Hcy and other related factors may be important during the occurrence and development of early DCM, and FIM may play a role in this process as an inhibitor of SAHH.     

Effect of fluvastatin on left ventricular remodeling after myocardial infarction in rats

AIM: To clarify the protective effect of long-term administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor fluvastatin on ventricular remodeling after myocardial infarction (MI) in rats and its mechanisms. METHODS: Myocardial infarction were established by ligated left coronary anterior artery in SD rats, 24 hours after the operation, the survival rats were treated by gavage fluvastatin (20 mg·kg^-1·d^-1) or distilled water for 8 weeks. Doppler echocardiography, homodynamic and cardiac histomorphometry were used to assess the ventricular remodeling and cardiac function. The plasma levels of total cholesterol (Tch), creatinine (Cr), glutamic-oxal (o) acetic transaminase (AST), lipid peroxidation (LPO), glutathione perioxidase (GSH-PX), nitrogen monoxide (NO₂^-/NO₃^-) were detected. RESULTS: The Tch, Cr and AST were not significant difference in groups. Left ventricular end-diastole pressure, right relative weight, left ventricular posterior wall thickness, collagen volume fraction and the lung weight were decreased in AMI+fluvastatin group compared to AMI group (P＜0.05, P<0.01); The levels of LPO, NO₂^-+NO₃^- in plasma and LPO in myocardium decreased, but plasma GSH-PX level increased in AMI+fluvastatin group (P＜0.05). CONCLUSION: Fluvastatin ameliorates the ventricular structural remodeling in a rat model of infarction, and delays the development of heart failure. The anti-oxidation mechanism of fluvastatin may take part in this process.     

Expression of angiogenic factors in myocardial tissue of diabetic rats

AIM：To observe the expression of angiogenesis factors in the myocardial tissue of streptozotocin-induced diabetic rats. METHODS：The diabetic rat model was induced by intraperitoneal injection of streptozotocin. After 12 weeks, the cardiac function was measured by MPA cardiac function analysis system. The myocardial collagen volume fraction (CVF) was assessed by Masson staining. The capillary vessels was quantified as the ratio of capillary to myocyte (C/M) using CD31 immunostaining. The expression levels of vascular endothelial growth factor (VEGF), angiopoietin (Ang)-1, endostatin and Ang-2 were observed by Western blotting. RESULTS：Compared with normal control group, the left ventricular end-diastolic pressure (LVEDP) was evidently increased (P<0.01), but left ventricular pressure rise maximum rate (+dp／dtmax), left ventricular pressure decrease maximum rate (-dp／dtmax) and the ratio of capillary/myocyte (C/M) were significantly decreased (P<0.05). The CVF and the expression level of endostatin were significantly increased, whereas the expression levels of VEGF and Ang-1 evidently decreased (both P<0.05) in diabetic rats. However, no marked difference in the expression of Ang-2 between the 2 groups was observed (P>0.05). CONCLUSION：Imbalances between the angiogenic factors (VEGF and Ang-1) and anti-angiogenic factors (endostatin) may play an important role in the pathogenesis of diabetic cardiomyopathy.     

Protective effect of curcumin on myocardium in diabetic rats

AIM: To study the effects of curcumin (Cur) on diabetic cardiomyopathy (DCM) in rats. METHODS: Male Wistar rats (n=75) were divided into control group and diabetes model group, in which the rats were fed with high-fat diet and then intraperitoneally injected with streptozotocin (STZ, 40 mg/kg). Fasting blood glucose was measured 72 h and 1 week after STZ injection. The diabetic rats were diagnosed when sustained fasting blood glucose levels ≥ 11.6 mmol/L. The diabetic rats were randomly divided into DCM group, DCM+Cur 100 mg/kg group and DCM+Cur 200 mg/kg group. After treatment for 16 weeks, glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) level were measured, and the level of cardiac troponin I (cTnI) in the serum was determined by enzyme-linked immunosorbent assay. The protein expression of protein kinase C (PKC) was detected by Western blotting. RESULTS: Curcumin significantly decreased the blood glucose level, increased the body weight, inhibited MDA content and up-regulated the GSH-Px activity in the diabetic rats. Furthermore, curcumin treatment inhibited the diabetes-induced protein expression of PKC. CONCLUSION: Curcumin may have a protective effect on diabetic cardiomyopathy by attenuating oxidative stress.     

Xinshuaikang inhibits myocardial autophagy and MAPK/ERK1/2 signaling pathway in rats with chronic heart failure

AIM:To explore the effect of Xinshuaikang on myocardial autophagy in the rats with chronic heart failure and its relationship with the MAPK/ERK1/2 signaling pathway. METHODS:The rats were divided into sham group, model group (rat model of chronic heart failure was established by ligation of anterior descending branch of left coronary artery), low-, middle-, and high-dose Xinshuaikang treatment (TL, TM and TH) groups and captopril group (treated with captopril as positive control), with 12 in each group. Doppler echocardiography was used to evaluate the cardiac function. The morphological changes of the myocardium were observed by HE staining. TUNEL staining was used to detect cardiomyocyte apoptosis. The expression of microtubule-associated protein 1 light chain 3-Ⅱ (LC3-Ⅱ) in the myocardium was detected by immunofluorescence labeling. The protein levels of p-ERK, p-p38 MAPK, LC3-Ⅱ, beclin-1 and p62 in the myocardium were determined by Western blot. RESULTS:Compared with sham group, left ventricular end-diastolic dia-meter (LVEDD) and left ventricular end-systolic diameter (LVESD) in model group were increased, while left ventricular posterior wall thickness at end-diastole (LVPWTd), left ventricular posterior wall thickness at end-systole (LVPWTs), left ventricular ejection fraction (LVEF), cardiac output (CO), left ventricular diastolic pressure (LVDP), left ventricular systolic pressure (LVSP) and maximum rate of rise/decrease of left ventricular pressure (+dp/dt_max/-dp/dt_max) were decreased (P<0.05). The myocardial cells were deformed and necrotic, and the myocardial fibers were broken, with inflammatory cell infiltration. The apoptotic rate, the positive rate of LC3-Ⅱ, and the protein levels of p-ERK, p-p38 MAPK, LC3-Ⅱ/LC3-I and beclin-1 were increased, and the protein expression of p62 was decreased (P<0.05). Compared with model group, the levels of LVEDD and LVESD were decreased, LVPWTd, LVPWTs, LVEF, CO, LVSP, LVDP, +dp/dt_max and -dp/dt_max were increased in Xinshuaikang groups and captopril group (P<0.05). The morphological changes of myocardial cells were gradually returned to normal, and inflammatory cell infiltration, the apoptotic rate and the positive rate of LC3-Ⅱ were decreased. The protein levels of p-ERK, p-p38 MAPK, LC3-Ⅱ/LC3-I and beclin-1 were decreased, and the protein expression of p62 was increased (P<0.05). CONCLUSION:Xinshuaikang inhibits myocardial auto-phagy to play a role of cardiac protection in the rats with chronic heart failure, and its mechanism may be related to inhibition of MAPK/ERK1/2 signaling pathway.