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.     

Correlation between myocardial interstitial collagen remodeling and changes in hemodynamics in rats with myocardial infarction

AIM: To study the relationship between cardiac extracellular matrix remodeling and cardiac function after myocardial infarction. METHODS: We observed sequential changes in collagen contents and collagen Ⅰ/Ⅲ ratios in infarct zone (IZ) and non-infarct zone (NIZ) and their relationship to the parameters of left ventricular systolic and diastolic function in the rat model of myocardial infarction induced by ligation of left main coronary artery. RESULTS: Collagen conteants in IZ and NIZ after 3d of myocardial infarction were significantly higher than those in sham group at corresponding time (P<0.05, P<0.01). Collagen Ⅰ/Ⅲ ratio in IZ decreased on day 3, significantly increased after 7 d (P<0.01). Collagen Ⅰ/Ⅲ ratio in NIZ increased significantly afte14 d. Correlated analysis between collagen contents in IZ or NIZ and collagen type Ⅰ/Ⅲ ratio and maximal ascending velocity (+p'_max) or maximal descending velocity of the left ventricular pressure (-p'_max) was performed and the negative correlation between collagen contents in NIZ and +P'_max (r=-0.589, P>0.05) and -P'_max (r=-0.788, P<0.01) was found. Collagen content in IZ positively correlated to the +P'_max (r=0.70, P<0.50), but not to -P'_max (r=-0.29, P>0.05). Collagen type Ⅰ/Ⅲ ratios in NIZ correlated negatively to the +P'_max (r=-0.504, P>0.05) and -P'_max (r=-0.545, P>0.05), but there were no relationship between collagen type Ⅰ/Ⅲ ratios in IZ and +P'_max or -P'_max in IZ. CONCLUSION: Collagen deposition in IZ after myocardial infarction was of benefit to improvement of systolic function. Collagen deposition in NIZ was harmful to systolic and diastolic function.     

Experimental research on cardiac fibrosis induced by recombinant mouse interleukin-11 in mice

AIM To observe the effect of recombinant mouse interleukin-11 （rmIL-11）injected subcutaneously into mice on heart structure and function and to determine its pro-fibrotic effect. METHODS C57BL/6 mice were randomly divided into experimental group and control group.The mice in experimental group were injected subcutaneously with recombinant mouse IL-11 at the dose of 100 μg·kg^-1·d^-1 for 3 consecutive weeks, while the control group were given equal volume of normal saline in the same way. After the experiment was finished, the parameters of heart function were measured by echocardiography.The heart weight was weighed and the cardiac weight index (CWI) was calculated. HE staining and Masson's trichrome staining were performed to observe the pathological changes and the extent of myocardial fibrosis in mouse myocardia respectively, and the cardiac collagen volume fraction (CVF) was calculated. The expression levels of extracellular matrix proteins in the myocardial tissues of mice, including type Ⅰ collagen, type Ⅲ collagen and fibronectin, were determined by Western blot. RESULTS Left ventricular ejection fraction and left ventricular fraction shortening in experimental group were obviously lower than those in control group (P<0.01), however left ventricular end-diastolic diamension and left ventricular end systolic dimension were significantly higher than those in control group (P<0.05).Compared with control group, the CWI was increased (P<0.01), the myocardial arrangement was disorder, the necrosis of cardiac myocytes was increased, and excessive deposition of collagen was observed in the myocardial tissues in experimental group. Correspondingly, the CVF and protein levels of type Ⅰ collagen, type Ⅲ collagen and fibronectin in the left ventricle in experimental group were increased significantly (P<0.05). CONCLUSION Injection of rmIL-11 into the mice subcutaneously induces fibrogenesis in the heart, which implies that IL-11 is likely a novel pro-fibrotic factor.     

Effect of galectin-3 on ventricular remodeling in rabbits with ischemic cardiac insufficiency

AIM:To investigate the relationship between galectin-3(Gal-3) and myocardial fibrosis,and to clarify the role of Gal-3 in ventricular remodeling in rabbits with ischemic cardiac insufficiency.METHODS:A rabbit model of ischemic cardiac insufficiency was established by ligation of the anterior descending branch of the coronary artery.The 20 rabbits were randomly divided into sham operation group and cardiac insufficiency group by random number table method.After 4 weeks of coronary artery ligation,the cardiac function was measured by cardiac echocardiogram.Real-time PCR and Western blot were used to detect the expression of Gal-3,type I collagen and type Ⅲ collagen at mRNA and protein levels in the myocardium.The serum Gal-3 contents were measured by ELISA.HE staining and Masson staining were used to observe the degree of fibrosis development in myocardial tissues after infarction.RESULTS:Compared with sham operation group,the mRNA expression of Gal-3 in cardiac insufficiency group was significantly increased.At the same time,type I collagen,type Ⅲ collagen and collagen type I/Ⅲ ratio were also increased significantly.The protein contents of Gal-3,type I collagen and type Ⅲ collagen were increased significantly.The serum Gal-3 levels were significantly increased.The pathological changes were observed in cardiac insufficiency group as the myocardial cell morphological disorder and marked hyperplasia of fibrous tissue were seen.CONCLUSION:Gal-3 aggravates myocardial fibrosis in rabbits with ischemic cardiac insufficiency,and promotes the ventricular remodeling and the occurrence of heart failure.     

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.     

Effects of soluble transforming growth factor-β type Ⅱ receptor on cardiac functions after myocardial infarction in rats

AIM: To observe the effects of soluble transforming growth factor-β type Ⅱ receptor (sTGFβRⅡ) on cardiac functions after myocardial infarction (MI) in rats. METHODS: MI was induced in Sprague-Dawley (SD) rats by ligating the left anterior descending coronary artery. The rats surviving to the third day after MI were included in the study and randomly divided into MI group, pAd-sTGFβRⅡ group (transfected with recombinant adenovirus vector expressing the extracellular domain gene of TGF-βRⅡ), vector group and sham group. Four weeks later, the heart rate (HR), left ventricular end-diastolic dimension (LVEDD), left ventricular end-systolic dimension (LVESD) and ejection fraction (EF) were evaluated by echocardiograms. The expression of sTGFβRⅡ in myocardial tissues was observed under fluorescence microscope by frozen sectioning, and the expression of typeⅠ and Ⅲ collagens was observed by Sirius red-saturated picric acid staining. The expression of matrix metalloproteinase 9 (MMP-9) at mRNA and protein levels was determined by RT-PCR and immunohistochemical method. The activity of MMP-9 was assayed by gelatin zymography. RESULTS: Compared with sham group, HR, LVEDD, LVESD, typeⅠ and Ⅲ collagen, mRNA and protein of MMP-9, and the activity of MMP-9 increased significantly (P<0.01), and EF decreased (P<0.01) in MI group and vector group. Compared with MI group, EF was increased (P<0.01), but HR, LVEDD, LVESD, typeⅠ and Ⅲ collagen, mRNA and protein expression of MMP-9 and the activity of MMP-9 decreased significantly (P<0.01) in pAd-sTGFβRⅡ group, and all the parameters above were still higher than those in sham group. CONCLUSION: sTGFβRⅡ intervention improves the cardiac functions after MI by inhibiting TGF-β-mediated MMP-9 expression.     

Long-term effects of TCV116 on left ventricular remodeling and heart function after myocardial infarction in rats

AIM: To investigate the effects of long-term TCV116 on left ventricular remodeling and heart function after myocardial infarction. METHODS: Myocardial infarction (MI) was caused by ligation of the left anterior descending coronary artery in rats. One week after the surgical performance, the surviving rats were randomly assigned to the following treatment protocols: (1) MI rats with no therapy; (2) MI rats treated with TCV116 2 mg/kg per day; (3) Sham-operated control; (4) Sham-operated rats, treated with TCV116 2 mg/kg per day. At 22 weeks, cardiac hemodynamic parameters such as MAP, LVSP, dp/dt_max and LVEDP, and histomorphometric parameters such as LVW/BW and LVCA/BW were measured, mRNA of cardiac genes such as βMHC, BNP, TGF-β₁, collagen I and III were quantified, and survival rates were calculated. RESULTS: Compared with sham-operated rats, MI rats without therapy showed significant increases in histomorphometric parameters as well as in mRAN expressions of cardiac genes (P<0.01); While their hemodynamic parameters were significantly impaired (P<0.01), and survival duration shortened (P<0.05). Compared with MI rats without therapy, MI rats treated with TCV116 showed significant attenuation of mRAN expression of cardiac genes (P<0.01); While their hemodynamic parameters were significantly improved (P<0.05 or P＜0.01), and survival duration extended (P<0.05). CONCLUSION: Treatment with long-term angiotensin II type 1 receptor antagonist may improve left ventricular remodeling and cardiac function after MI in rats.     

Changes of serum levels of inflammatory cytokines in elderly patients with heart failure

AIM: To investigate the relationship between serum levels of TNF-α, sTNFRI, IL-6, IL-10, TGF-β₁ and cardiac function in elderly patients with heart failure.METHODS: The serum levels of TNF-α, sTNFRI, IL-6, IL-10 and TGF-β₁ were determined by ELISA in 112 elderly patients with heart failure and 60 elderly normal subjects.The left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) were measured by color Doppler ultrasonic instrument.RESULTS: (1) Compared with normal subjects group, the serum levels of TNF-α, sTNFRI, IL-6, IL-10 and TGF-β₁ in elderly patients with heart failure were significantly elevated (P<0.05 or P<0.01), and increased gradually with upgrade of cardiac function according to cardiac function classification of New York Heart Association (P<0.05 or P<0.01).(2) The ratio of TNFα/sTNFRI and IL-6/IL-10 in patients with heart failure were notably higher than those in control (P<0.05, P<0.01) and increased gradually with upgrade of cardiac function classification (P<0.05, P<0.01).(3) In heart failure group, a significantly positive correlation was found between serum levels of TNF-α, IL-6 and LVEDD.A significantly negative correlation between serum levels of TNF-α, IL-6 and LVEF was also observed.CONCLUSION: The serum levels of pro-inflammatory cytokines are closely related with cardiac function in elderly patients with heart failure.The balances of TNFα/sTNFRI and IL-6/IL-10 shifted towards inflammatory side.Furthermore, the changes of them reflect the varieties of cardiac function.     

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.     

Transfection of rAAV1-SERCA2a improves cardiac function of beagles with heart failure

AIM:To study the effects of recombinant adeno-associated virus type 1 (rAAV1)-sarcoplasmic/endoplasmic reticulum calcium ATPase 2a (SERCA2a) transfection on the cardiac function of beagles with heart failure (HF). METHODS:The beagles were used to make an animal model with heart failure after rapid right ventricular pacing (230 beats/min) for 30 d. A reduced rate (180 beats/min) was continuously applied for another 30 d. The beagles were divided into 4 groups (n=4): control group, HF group, HF+EGFP group and HF+SERCA2a group. rAAV1-EGFP and rAAV1-SERCA2a (both 1×1012 viral genomes) were intramyocardially injected into the animals in the latter 2 groups, respectively. RESULTS:After transfection for 30 d, the left ventricular systolic function in HF+SERCA2a group was similar to that in control group, and significantly higher than that in HF group (P<0.05). The ratio of SERCA2a mRNA/GAPDH mRNA was significantly higher in HF+SERCA2a group than that in HF group (P<0.05). The expression level of SERCA2a in the myocardial tissues was higher in HF+SERCA2a group than that in HF group (P<0.05). The apoptotic index of the cardiomyocytes and the protein expression of MMP-9 were much lower in HF+ SERCA2a group than those in HF group (P<0.05). No significant difference of all parameters was observed between HF group and HF+EGFP group. The mRNA level of phospholamban was unchanged. CONCLUSION:Transfection of SERCA2a improves the expression of SERCA2a, restores the cardiac function and inhibits left ventricular remodeling by reducing the cardiac cell apoptosis and the MMP-9 expression in the heart failure beagles.     

Furazolidone induces dilated cardiomyopathy in rats

AIM: To establish the Wistar rat model of furazolidone-induced dilated cardiomyopathy (Fz-DCM). METHODS: The Wistar rat model of Fz-DCM was established by feeding the animals with furazolidone. The left ventricular dimension and cardiac function were detected by echocardiogram. Aortic and right atrial pressure were measured by invasive catheter. Left ventricular interior diameter and the thickness of left ventricular free wall were measured after the rats were killed. Myocardial collagen network remodeling was observed and collagen volume fraction (CVF) was calculated by Van Gieson stain. RESULTS: ①The total incidence rate of DCM was 66.6% (20/30) in DCM group. ②Compared the corresponding subgroups to control group, the left ventricular end-diastolic diameter (LVED), left ventricular end-systolic diameter (LVES), the right atrial pressure, the left ventricular interior diameter and the ratio of left ventricle weight and body weight were increased significantly. The fraction shortening (FS), the left ventricular ejection fraction (LVEF) and the thickness of left ventricular free wall were decreased significantly. ③In FZ-DCM rat, the myocyte hypertrophy and degeneration, interistial fibrous tissue hyperplasia, the quantity of typeⅠand type Ⅲ collagen fibers and the collagen volume fraction (CVF%) were increased significantly. CONCLUSIONS: The rat model of DCM can be induced successfully by feeding the animals with furazolidone. In the rats with Fz-DCM, there are left ventricular dilation, the thinness of ventricular wall, the interistial fibrous tissue hyperplasia, and the decrease in left ventricular contractic function, indicating that the Fz-DCM rat model represents the pathophysiological characters of dilated cardiomyopathy.     

Effects of cardiac contractility modulation applied to different locations of heart on cardiac functions in rabbits with heart failure

AIM: To investigate the effects of cardiac contractility modulation (CCM) applied to different locations of the heart on cardiac functions and cardiac dys-synchrony in the rabbits with chronic heart failure, and to explore the best pattern of CCM.METHODS: Forty rabbits were divided into 4 groups according to the location of receiving CCM: heart failure (HF) group, left ventricular anterior wall (LVAW-CCM) group, left ventricular posterior lateral wall (LVPLW-CCM) group and right ventricular apex (RVA-CCM) group. The model of chronic heart failure was made by ligating ascending aortic root of the rabbits. After 12 weeks, the electrical stimulations during the absolute refractory period were delivered in different locations of the heart, lasting 6 h everyday for 7 days. The changes of cardiac functions and cardiac dys-synchrony were observed by cardiac ultrasonic cardiogram before and after CCM stimulation. The plasma level of brain natriuretic peptide (BNP) was detected by ABC-ELISA method. Pulsed-wave Doppler was used to acquire aortic pre-ejection interval (APEI) and pulmonary pre-ejection internal (PPEI), and inter-ventricular mechanical delay (IVMD) was calculated to evaluate the cardiac dys-synchrony.RESULTS: Compared with HF group, left ventricular end-systolic dimension (LVESD) and left ventricular end-diastolic dimension (LVEDD) in LVAW-CCM group, LVPLW-CCM group and RVA-CCM group were significantly decreased (P<0.05), while left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were significantly increased (P<0.05), especially in LVAW-CCM group. Interventricular septal thickness (IVS) and left ventricular posterior wall thickness (LVPW) were similar among groups. No significant difference of plasma BNP level before CCM delivery among the 4 groups was observed. However, the plasma BNP level in control group was the highest, followed by LVPLW-CCM group and RVA-CCM group, and LVAW-CCM group was the lowest after CCM delivery. No change of IVMD was observed among groups before and after CCM delivery.CONCLUSION: The effect of CCM applied to different locations of the heart on cardiac functions is different.The optimal site of CCM delivery is left ventricular anterior wall. No influence of interventricular dys-synchrony was observed during application of CCM.     

Effect of fluvastatin on left ventricular remodeling and caspase-3 expression after myocardial infarction in rats

AIM: To observe the effect of fluvastatin (FV) on left ventricular remodeling and expression of caspase-3 after myocardial infarction (MI) in rats. METHODS: Rats were divided into 4 groups: group Ⅰ (sham), group Ⅱ (sham+FV), group Ⅲ (MI) and group Ⅳ (MI+FV). group Ⅱ and Ⅳ were treated with FV (10 mg·kg^-1·d^-1) for 4 weeks. The left ventricular structure, echocardiography and hydroxyproline were observed. The expression of caspase-3 was measured by immunohistochemistry and RT-PCR. RESULTS: Compared with MI group, there was a improvement of ultrastructure and index of left ventricular remodeling, and decrease in hydroxyproline in MI+FV group (all P<0.05). The number of caspase-3 positive cells also decreased in MI+FV group, and RT-PCR showed the level of caspase-3 mRNA expression was lower than that in MI group (P<0.05). CONCLUSION: Fluvastatin improves left ventricular remodeling after myocardial infarction, decreases the expression of caspase-3 and inhibits apoptosis.     

Adrenomedullin gene transfection enhances the therapeutic effects of transplantation of bone marrow mesenchymal stem cells on cardiac function and ventricle remodeling in acute myocardial infarction rats

AIM: To investigate adrenomedullin gene transfection enhances the therapeutic effects of homogeneous transplantation of bone marrow mesenchymal stem cells (MSCs) on cardiac function and ventricle remodeling in acute myocardial infarction rats. METHODS: MSCs were isolated and expanded using the preplating method. The infection efficiency of adenovirus vector to MSCs was tested by X-gal staining. Ad-ADM expression in MSCs and its secretion in culture medium were measured by ELISA. The left anterior descending branch of rats was ligated to establish a myocardial infarction model. The MSCs were labeled by DAPI, and were directly implanted into the acute infarct site via focal injection. Four weeks later, cardiac function was evaluated using physiological recorder. Hearts were harvested and sliced to be analyzed by immunohistochemistry (factor Ⅷ and ADM) and the DAPI-labeled cells were identified. Sirius red staining was used to identify interstitial collagen on slides. Analysis of collagen type I and III was performed using a polarized filter on sections stained for collagen with Sirius red, and the ratio of collagen type I and III were detected. RESULTS: With X-gal staining, MSCs were effectively transfected by adenovirus in vitro. The transfection efficiency showed the dose-effect relationship with multiplicities of infection (MOI). When MOI was 150, the infection efficiency was 95.4%. The expression of ADM was traced in culture medium and expressed in the time-dependent manner. A maximum production of ADM was observed at 7 d after infection ［(26.53±1.42) ng/L vs (1.34±0.08) ng/L, P<0.05］, and ADM secretion reduced to normal level at 15 d ［(2.20±1.44) ng/L vs (1.52±0.33) ng/L, P>0.05］. DAPI-labeled MSCs transplantation was found in the hearts of the recipients. Immunohistochemical studies demonstrated that intense immunostaining for ADM was higher in Ad-ADM plus MSCs group, compared to other groups. Compared with control, MSCs transplantation significantly increased capillary density in infarct area (P<0.01). A combination of Ad-ADM trensfection and MSCs transplantation demonstrated a further increase in capillary density compared with Ad-ADM or MSCs alone. MSCs transplantation decreased the ratio of collagen type I and III, obviously improved the left ventricular functions. Furthermore the combination treatment resulted in further decrease in the ratio of collagen type I and III, and significantly improved the left ventricular functions. CONCLUSION: Ad-ADM transfection enhances the angiogenic potency of MSCs transplantation and decreases the ratio of collagen type I and III through increasing ADM expression in infarct area, thus contributes to reverse the ventricular remodeling and improves the cardiac function.     

Altered activity and expression of MMPs/TIMPs are associated with functional and structural left ventricular remodeling in hypertensive rats

AIM: To investigate the relationship between matrix metalloproteinases and tissue inhibitors of matrix metalloproteases imbalance with functional and structural left ventricular (LV) remodeling in the hypertensive rats.METHODS: 6-week-old male stroke-prone spontaneously hypertensive rats (SHR-SPs,n=40) served as the hypertensive heart disease model,and age-matched male Wistar-Kyoto (WKY) rats (n=10) were used as control.After 6 months,the rats in two groups were anesthetized for invasive hemodynamic measurement by Millar pressure-volume (P-V) conductance catheter.Then the rats were sacrificed and hearts were dissected for morphological analysis,gelatin-zymography and Western blotting analysis.RESULTS: Left ventricular (LV) hemodynamic parameters showed the systolic and diastolic dysfunction in SHR-SPs compared with that in control group (P<0.05).Collagen volume fraction,ratio of perivascular collagen area to luminal area,myocardial cross-sectional area and the medial area to luminal area ratio of the SHR-SPs were all increased remarkably (P<0.05).LV matrix metalloproteinase-2 (MMP-2) activities,MMP-2 and tissue inhibitors of matrix metalloprotease-1 (TIMP-1) protein level in SHR-SP were notably higher than those in control group (P<0.05).CONCLUSION: Chronic pressure-overload is capable of inducing imbalances of cardiac ECM and MMPs/TIMPs system,both imbalances induce LV dilation,cardiac systolic and diastolic dysfunction.     

Effects of ERK1/2 on pressure overload-induced cardiomyopathy and heart failure in mice

AIM: To explore the changes in extracellular regulated protein kinase (ERK1/2) in the hypertrophic myocardium induced by pressure overload at the different time courses and to determine the molecular mechanism in the myocardium from hypertrophy to heart failure. METHODS: C57/BL mice, aged 12 week old, were subjected to sham-operation (SH) or transversing aortic constriction (TAC) to establish left ventricular hypertrophy. Echocardiographic assessments, hemodynamic determination, organ weight measurement, morphological and histological examination were performed at 1, 4, 8, 12 and 16 weeks after surgery. Meanwhile mRNA levels of atrial natriuretic peptide (ANP), α-myosin heavy chain (α-MHC), bcl-2 and bax were measured by RT-PCR, and ERK1/2 levels were detected by Western blotting. The animals in SH group were performed the same tests then sacrificed at 16 weeks. RESULTS: (1) Compared to SH group, LVESd, LVEDd, Awsth, Awdth, Pwsth and Pwdth progressively increased after TAC. Meanwhile, ejection fraction (EF%) significantly decreased at 16th week (P<0.05). LVSP, dp/dtmax and dp/dtmin in TAC group were progressively increased after 4 weeks. From 8-12 weeks these parameters maintained stable and then sharply decreased at 16th week (all P<0.05). However, LVEDP was statistically increased at 8th week. These echocardiographic and hemodynamic changes indicated a development of LVH and eventually progressing towards to heart failure. (2) Histologically, cardiac collagen measured by percentage of Sirius red positive stained area and apoptosis index showed progressive increases from 4 to 16 weeks. (3) Compared to SH group, mRNA levels of ANP was time-dependently increased while α-MHC and Bcl-2 were time-dependently decreased. The ratio of Bcl-2 /Bax was decreased. Phosphorylation of ERK1/2 was increased at 4th week, then decreased with age of TAC (all P<0.05). CONCLUSION: Pressure-overload induced by TAC results in a development of LVH from early concentric hypertrophy to late eccentric hypertrophy, and eventually toward cardiac dysfunction or heart failure. Those changes are associated with increase in cell size and cardiac fibrosis. ERK1/2 signaling pathway may involve in the regulation of myocardial cell apoptosis in hypertrophic and failure heart.     

Zacopride attenuates pressure overload-induced ventricular remodeling in rats

AIM:To investigate the protective effect of zacopride (ZAC) on the pressure-overload left ventricular remodeling in the rats induced by coarctation of abdominal aorta. METHODS:Male Sprague-Dawley (SD) rats with pressure overload were induced by the coarctation of abdominal aorta. The model rats were intraperitoneally administered with ZAC, chloroquine (Chlor), and zacopride+chlorquine (ZAC+Chlor). The study duration was 8 weeks. The cardiac structure and function were assessed by echocardiography. The heart weight/body weight (HW/BW) ratio and the left ventricular weight/body weight (LVW/BW) ratio were calculated. The changes of structure and shape in myocardial tissue were observed with HE staining. The ultrastructure of the myocytes was observed under transmission electron microscope. The inward rectifier potassium channel (I_K1) protein expression was determined by Western blot. The mRNA expression of Kir2.1 was detected by RT-PCR. RESULTS:Compared with vehicle group, ZAC improved cardiac function, as indicated by the decreased left ventricular end-diastolic dimension (LVEDD) and left ventricular end systolic dimension (LVESD) (P<0.05), and the increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) (P<0.01). The HW/BW and LVW/BW ratios were significantly decreased, and the cross-sectional area of the cardiomyocytes was significantly less in ZAC group than that in vehicle group (P<0.01). The ultrastructure of the myocytes was significantly improved. Chlor blocked the protective effect of zacopride on the pressure-overload left ventricular remodeling. The protein level of I_K1 and mRNA expression of Kir2.1 in the cardiac tissues in ZAC group were significantly increased compared with vehicle group (P<0.01). CONCLUSION:I_K1 agonist ZAC significantly attenuates pressure overload-induced ventricular remodeling in rats.     

Effects of fluvastatin on the left ventricular function,MHC gene expression and collagen remodeling after myocardial infarction

AIM: To observe the effects of fluvastatin (FV) on the left ventricular (LV) function, MHC mRNA and collagen remodeling of non-infarcted area after acute myocardial infarction (AMI). METHODS: Six hours after ligating left coronary artery, survivors of AMI female SD rats were randomly assigned to: ①AMI control; ②FV; ③sham-operated groups. After 8 weeks of therapy, the LV function, hemodynamics, expression of non-infarcted myocardial MHC mRNA, collagen volume fraction (CVF) and the ratio of type Ⅰ/Ⅲ collagen of non-infarcted area were assessed. RESULTS: Compared with sham-operated group, E wave, E wave deceleration, E/A ratio, LV end diastolic pressure (LVEDP), β MHC mRNA, CVF and the ratio of type Ⅰ/Ⅲ collagen were all significantly increased in AMI group, while fractional shortening (FS), ejection fraction (EF), mean arterial pressure (MAP) and α MHC mRNA were all significantly decreased. In comparison with AMI group, E wave, E wave deceleration, E/A, LVEDP, β MHC mRNA, CVF and the ratio of type Ⅰ/Ⅲ collagen were all significantly decreased, while FS, EF, MAP and α MHC mRNA were all significantly increased in FV group. CONCLUSION: FV improves the LV function after AMI and has beneficial effects on reversing LV myocardial pathologic switching of MHC isoform and collagen remodeling.     

Changes of cytokine and collagen in the myocardial remodeling after acute myocardial infarction in rats

AIM:To clarify the relationship between the cytokine and collagen in myocardial remodeling after acute myocardial infarction (MI) in rats. METHODS:In MI group, Wistar rats were undergone acute myocardial infarction by ligation of the anterior descending coronary artery. Sham operation was made in rats as control. The mRNA expression of collagen and cytokines such as TNF-α and TGF-β1 in infract and non-infarct region of left myocardium were detected by RT-PCR at different time point (3 d, 1 and 4 weeks). RESULTS:Collagen type Ⅰ and Ⅲ elevated as well as the TNF-α and TGF-β1 in the MI group at 3th day. Expression of collagen type Ⅰ and Ⅲ were higher in the infarct region than that in the non-infarct region even at 4 weeks. TNF-α and TGF-β1 peaked at 1 week and declined gradually to the baseline, which was still higher than those in control group (P<0.01). Correlation analysis revealed that expressions of TNF-α and TGF-β1 were positively correlated with the collagen type Ⅰand Ⅲ (P<0.01). CONCLUSION:Cytokines participate in the myocardial remodeling after MI. Interfering with expression of cytokines may be the potentially preventative method in the myocardial remodeling.