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Objective: To investigate the effect of maslinic acid (MA) on isoproterenol (ISO)-induced myocardial fibrosis in mice. Methods: ISO was used to induce myocardial fibrosis in adult male C57BL/6 mice, and MA was administered for two weeks to detect the effects of MA on cardiac function and fibrosis. Molecular changes of fibrosis markers and signaling pathways were detected by RT-PCR and western blotting. Phosphate buffer saline (PBS), PBS+SB203580 (p38 MAPK inhibitor), PBS+MA, ISO, ISO+SB203580, ISO+MA were added to the primary cultured rat fibroblasts. Cells were collected after 48 h for subsequent detection. Results: In this study, the mouse model of myocardial fibrosis was successfully established. The left ventricular faction shortening (FS) and maximum rate of rise and maximum rate of fall of pressure in left ventricular chamber (±dp/dt) of the ISO+MA group were significantly higher than those of the ISO group ((35.1±1.8)% vs (28.5±2.6)%, (7 256±153) mmHg/s vs (6 402±240) mmHg/s, (7 156±163) mmHg/s vs (6 319±219) mmHg/s, all P< 0.05). The levels of interstitial and perivascular collagen deposition in the ISO+MA group were higher than those in the ISO group ( P< 0.05), the relative mRNA levels of COL-1, COL-3 and TGF-β in the ISO+MA group were significantly lower than those in the ISO group, with the relative expression levels of 1.70±0.24 vs 3.69±0.34, 1.72±0.56 vs 4.84±0.82, 1.52±0.19 vs 2.64±0.29, respectively (all P< 0.05). The phosphorylation levels of p38 MAPK, Smad3 and protein expression level of TGF-β1 in ISO+MA group were lower than those in ISO group (relative expression levels were 1.67±0.35 vs 2.61±0.58, 1.68±0.23 vs 2.52±0.19,1.56±0.15 vs 2.48±0.26, respectively, all P< 0.05). The results of in vitro cell experiments showed that the mRNA levels of COL-1, COL-3 and TGF-β in the SB203580 and MA groups were significantly lower than those in the ISO group (relative expression levels were 2.25±0.51, 2.16±0.48 vs 5.29±1.21; 1.58±0.34, 1.69±0.29 vs 4.97±1.32; 1.41±0.31, 1.55±0.38 vs 3.53±0.56, respectively, all P< 0.05). The phosphorylation levels of p38 MAPK and Smad3 in the SB203580 MA groups was significantly lower than those in the ISO group, and the protein expression level of TGF-β1 was lower than that in the ISO group (1.81±0.18, 1.77±0.16 vs 2.56±0.32; 1.85±0.21, 1.81±0.17 vs 2.48±0.37; 1.84±0.24, 1.72±0.17 vs 2.52±0.29, all P< 0.05). Conclusion: Maslinic acid can inhibit the phosphorylation of p38 MAPK, thereby preventing the canonical TGF-β1/Smads fibrosis signaling pathway to achieve an anti-fibrosis role.

Objective: To investigate the effect and specific mechanism of heat shock protein 47 (HSP47) on streptozotocin (STZ)-induced diabetic cardiomyopathy (DCM). Methods: A mouse model of type 1 diabetic cardiomyopathy was established by intraperitoneal injection of STZ. After 8 weeks of successful modeling, HSP47 was overexpressed by tail vein injection, and the heart of the mouse was harvested after 6 weeks. Hematoxylin-eosin (HE) staining and Sirius red (PSR) staining were used to detect the cross-sectional area of myocardial cells and myocardial fibrosis, respectively. Immunofluorescence staining with α-smooth muscle actin (α-SMA) and collagen Ⅰ was used to detect the degree of fibrosis activation. The expression level of fibrosis-related proteins was determined by Western blot. Results: The expression level of HSP47 in the myocardium of the diabetic group up-regulated (2.014±0.264 vs 1.004±0.064, P< 0.001). The area of myocardial cells in the diabetic group was increased compared with the control group [(235.3±20.7) μm(2) vs (172.8±13.6) μm(2), P< 0.001] and the cross-sectional area of myocardial cells in the HSP47 overexpression-diabetes group was further increased [(302.2±41.0) μm(2) vs (235.3±20.7) μm(2), P= 0.009], while the mRNA levels of mouse cardiac hypertrophic markers atrial natriuretic peptide (ANP), type B brain natriuretic peptide (BNP), myosin heavy chain β (β-MHC) further upregulated (all P< 0.001). Compared with the control group, the myocardial fibrosis content in the diabetic group increased [(7.333±1.127)% vs (4.837±0.775)%, P= 0.002] and the left ventricular fibrosis content of the HSP47 overexpressing diabetic group further increased [(9.175±1.008)% vs (7.333±1.127)%, P= 0.025] and the mRNA levels of fibrosis index collagenⅠ, collagen Ⅲ, connective tissue growth factor (CTGF) and transforming growth factor β (TGFβ) further up-regulated (all P< 0.001). Immunofluorescence results showed that compared with the control group, the expression of collagenⅠ up-regulated in the endothelial stroma of the diabetic group and the content of collagenⅠ in the HSP47 over-expressing diabetic group was higher ( P< 0.001). Western blot results indicated that the phosphorylation level of Smad3 and the protein levels of α-SMA and TGFβ in HSP47 overexpressing diabetic group increased, compared with those of diabetic group (all P< 0.001). Conclusion: HSP47 ameliorates STZ-induced diabetic myocardial fibrosis by activating the TGFβ/Smad3 signaling pathway.

Objective: The aim of this study is to investigate the underlying mechanism of cinnamaldehyde attenuating pressure overload-induced cardiac fibrosis. Methods: The mice were randomly divided into control group, model group and treatment group by random number table and each group had 8 mice.Cardiac hypertrophy was induced by aortic banding. Heart vascular density was detected by immunohistochemical staining of CD31.The expression level of stromal cells marker α-smooth muscle actin (α-SMA) was detected by immunofluorescence staining in different groups.The expression levels of endothelial cell associated markers and stromal cell associated markers were detected by using Western blotting.The possible molecular pathway was also screened by using Western blotting. Human umbilical vein endothelial cell (HUVECs) were stimulated with TGFβ1 and cultured with 10 nmol/L cinnamomum for 24 hour to further confirm the mechanism. Results: Eight weeks after operation, the vascular density was significantly decreased in model group mice heart.The expressions of stromal cells markers were increased (α-SMA: 2.57±0.38; Vimentin: 0.58±0.02) and endothelial cell markers were reduced (CD31: 0.58±0.29; CD34: 0.62±0.21). While cinnamicaldehyde treatment significantly increased the mouse heart vascular density, increased endothelial cell markers expression (CD31: 1.51±0.11; CD34: 2.37±0.44; P <0.05), and reduced stromal cells marker expression (α-SMA: 1.22±0.14; Vimentin: 0.35±0.03; P <0.05). Further studies showed that the anti-fibrosis effect of cinnamicaldehyde was mainly through the TGFβ /smad signaling pathway.10 nmol/L cinnamomum attenuated TGFβ1 induced endothelial mesenchymal transition in HUVECs. Conclusion: Cinnamaldehyde may be able to retard the progression of cardiac fibrosis, via blocking endothelial to mesenchymal transition, which, in verse, is through regulating TGFβ /smad signaling pathway.

Objective: To explore the relationship among heart rate turbulence (HRT), QT dispersion (QTd) and heart function in patients with dilated cardiomyopathy (DCM) and assess its clinical value., Methods: A total of 81 DCM patients with ventricular premature contraction (VPC) were divided into two groups according to heart function: Group A (NYHA class I-II, n=34) and Group B (NYHA class III-IV, n=47). Thirty out-patient control cases were chosen from those undergoing regular physical examination. 24 hour holter was performed to monitor turbulence onset (TO) and turbulence slope (TS). Electrocardiogram (ECG) was used to assess QTd. Meanwhile left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD), E and A-wave peak velocities, E/A were measured by echocardiogram. After a comparison of all indicators in each group, an investigation was conducted to discern the relationship among HRT, QTd and heart function., Results: Compared with normal group, TO significantly increased in DCM A and B group: [0.38 (-0.99-1.85)% vs 1.82 (0.02-3.92)% vs (-4.03±3.48)%, P<0.01]. TS significantly decreased while QTd increased. The trend of QTd addition was apparent along with heart failure. TO was negatively correlated with LVEF (r=-0.701, P<0.05) but positively correlated with LVEDD (r=0.621, P<0.05). There was no correlation with E and A-wave peak velocities. TS and QTd also had an obvious correlation with LVEF and LVEDD (all P<0.05)., Conclusions: HRT is dramatically blunted in DCM patients and has a certain correlation with cardiac dysfunction. A combined test of HRT and QTd is a sensitive and indirect index in assessing autonomic nerve functions. It has a high clinical value of predicting the prognosis.

Objective: To investigate the properties of electrophysiology and effects of ouabain upon transient outward potassium current (I(to)) and L-type calcium current (I(Ca-L)) of left atrium posterior wall (LAPW) and left atrium appendage tissue (LAA)in rabbit so as to provide the scientific explanations that LAPW and ouabain can enhance atrial fibrillation (AF) vulnerability through increasing electrophysiological heterogeneity and electrical remodeling of different regions of left atrium in rabbits., Methods: Atrial myocytes from LAPWs and LAAs of rabbits on an in vitro heart perfusion system were obtained by enzymatic dissociation. The whole-cell patch-clamp technique was used to assess the effects of ouabain upon I(to) and I(Ca-L). The current-voltage (I-V) curves of I(to) and I(Ca-L) in LAPW and LAA myocytes were fitted before and after ouabain administration., Results: (1) With holding potential +50 mV and commanding potential +50 mV, the current densities of LAPW I(to) decreased slightly less than that of LAA I(to) in control groups (P > 0.05). After ouabain administration, the current densities of LAPW I(to) were significantly larger than that of LAA I(to) [(10.97 +/- 0.58) pA/pF vs (9.39 +/- 0.83) pA/pF, P < 0.05]. The I-V curve of LAPW I(to) was slightly lowered to I-V curve of LAA I(to) in control groups. But with perfusion of ouabain, the I-V curve of LAPW I(to) opposed to I-V curve of LAA I(to) significantly changed from the bottom to the top with the same upward direction. (2) With the voltage clamp protocol of I(Ca-L), the current densities of LAPW I(Ca-L) markedly decreased compared with that of LAA I(Ca-L) in control groups (P < 0.05). With the addition of ouabain, the peak of amplitude of LAPW I(Ca-L) at +20 mV obviously increased to that of LAA I(Ca-L) [(-11.13 +/- 0.99) pA/pF vs (-8.86 +/- 0.51) pA/pF, P < 0.01]. In the control groups, the I-V curve of LAPW I(Ca-L) was shifted to the bottom of all I-V curves of I(Ca-L). Through the effects of ouabain, the I-V curve of LAPW I(Ca-L) was completely upgraded to the top of other I-V curves of I(Ca-L). However, all shapes and directions of current peak of I-V curves of I(Ca-L) remained unchanged in both groups., Conclusion: The distribution properties of I(Ca-L) have significant difference in LAPW. Ouabain can accentuate the electrophysiological heterogeneity and electrical remodeling of I(to) and I(Ca-L) in LAPW of rabbits. It may become the triggering factor and persisting basis of AF vulnerability.

Objective: To investigate the effects of recombinant BmKIM (poly-peptide derived from Asian Scorpion Buthus martensi Karsch) on the sodium current (I(Na)) of isolated ventricular myocytes, transmembrane action potential and aconitine induced arrhythmia in vivo in rabbits., Methods: Ventricular myocytes were enzymatically dissociated from adult rabbits. Whole-cell patch-clamp technique was used to record voltage-dependent I(Na). Standard transmembrane action potentials in rabbit hearts in vivo were recorded by using floating glass microelectrodes. Incidence of arrhythmias, the early after depolarization (EAD) and/or delay after depolarization (DAD) were measured in vivo in rabbits post aconitine (100 microg/kg, iv) in the absence or presence of BmKIM (50 microg/kg iv)., Results: (1) BmKIM significantly inhibited I(Na) in a voltage-dependent manner and significantly shifted the I-V curves of I(Na) upward. BmKIM left shifted the inactivation curve of I(Na) and voltages at 50% inactivation of I(Na) were changed from (-70.8 +/- 2.6) mV to (-84.8 +/- 3.5) mV (P < 0.05). BmKIM prolonged the recovery of inactivation of I(Na). In the presence of BmKIM, the time constants of recovery (both tau(f) and tau(s)) of I(Na) were significantly prolonged from (28.9 +/- 6.1) ms and (107 +/- 21.6) ms in control group to (54.2 +/- 7.9) ms (P < 0.05) and (211.1 +/- 34.6) ms (P < 0.01), respectively. (2) BmKIM significantly shortened 50% and 90% of action potential duration (APD(50) and APD(90)), and reduced action potential amplitude (APA), declined maximum up stroke velocity of action potential (V(max)) in vivo. The Q-T duration was shortened and heart rate significantly increased post BmKIM injection. (3) Incidence of aconitine induced ventricular arrhythmias (77.8%) was significantly reduced by BmKIM (22.2%, P < 0.01)., Conclusions: BmKIM significantly blocked I(Na) through affecting the inactivated state of I(Na) in rabbit ventricular myocytes. BmKIM could attenuate the influx of I(Na), therefore shorten action potential duration and reduce action potential amplitude and reduce the incidence of aconitine induced arrhythmias.

Objective: To investigate the relationship between the changes of the L-type calcium current (I(Ca, L)) and the calcium-activated transient outward chloride current (I(Cl, Ca)), and the repolarization characteristic of action potential in phase 1 under isoprenaline (ISO) stimulation in atrium myocytes of rabbit., Methods: Atrium myocytes were obtained by enzymatic dissociation from a section of atrial free wall. The membrane currents and action potential were recorded by the whole-cell patch-clamp technique., Results: After recording I(Ca, L), atrium myocytes were perfused with ISO (1 micromol/L) immediately. Five minutes later, a transient outward current (I(to)) was significantly induced, and the peak of I(to) was gradually increased while I(Ca, L) gradually decreased with increasing in clamp voltage. The I(to) was resistant to 4-AP (3 mmol/L) but sensitive to DIDS (150 micromol/L, Cl(-) channel blocker). This current was blocked by CdCl(2) (200 micromol/L, Ca(2+) channel blocker). The elicited rate of I(to) was 91.67% (P < 0.05). (2) The shape of AP was like an inverse triangle with no plateau in Phase 2 after ISO (1 micromol/L) perfusion. Moreover, compared to the parameters of control group, APD(50) and APD(90) were significantly shortened from (65.4 +/- 4.2) ms and (95.8 +/- 3.8) ms to (12.8 +/- 3.8) ms and (27.0 +/- 4.7) ms, and reduced to 80.46% and 71.87%, respectively (P < 0.01, n = 12). 4-AP (3 mmol/L) had on obvious effect on the shape of AP, however, the plateau of AP in phase 2 was recovered by DIDS (150 micromol/L) perfusion, APD(50) and APD(90) were (41.1 +/- 4.5) ms and (79.6 +/- 3.4) ms respectively. Compared to the parameters of control group, there were no significant differences (P > 0.05, n = 12). These results indicated that ionic transport were changed by ISO perfusion in atrium myocytes and I(to) played an important role in the phase 1 repolarization of AP., Conclusions: Before ISO administration, we could only observe I(Ca, L) in atrium myocytes of rabbit. After isoproterenol intervention, certain intracellular ionic consistency and membrane ionic channels were changed. Calcium activated chloride channel and I(to2) revealed obvious predominance which shorten APD significantly. Action potential showed a triangle with no plateau, suggesting an electrical remodeling in atrium myocytes. The remodeling of ionic channel is related possibly with the opening of Ca(2+)-activated Cl(-) current, which maybe the electrophysiological base of reentrant atrial tachycardia.