| Objective 1. To observe the changes of RhoA/Rock1 expression in rat myocardial with pressure overload;study the relationship between the left ventricular remodeling and the small GTP-bind protein Rho/Rock signaling pathway.2.To evaluate the intervention of Rho kinase selective inhibitor fasudil on the expression of RhoA/Rock1mRNA and the content of transforming growth factor-β2 and typeIII collagen in myocardial tissue.Study the effect of fasudil on the left ventricular remodeling after pressure overload state.Methods1. Sprague-Dawley rats(n=32) were randomly allocated into two groups: sham-operated(n=8);abdominal aortic banding(n=24).Cardiac hypertrophy (CH) was induced by suprarenal abdominal aorta constriction. All aorta binding rats were divided randomly into two groups: model(n=12),fasudil(n=12), fasudil (5 mg/kg),Bid i.p for 4 weeks starting from 1 weeks after surgery.Animals of the model and sham-operated groups were given with the same dose natria chloride Bid i.p .2. At terminal experiments,The degree of cardiac hypertrophy was estimated by measuring the wet weight of the whole hear(HW)and left ventricular free wall(LVFWW),and the LV hypertrophic index (LVHI) was indicated by heart weight to body weight(HW/BW) in mg per grams and left ventricular weight to body weight(LVFWW /BW) in mg per grams. LV remodeling morpholog was determined by light microscope and Cardiac fibrosis was confirmed by typeⅢcollagen immunohistology stained section. Measuring Rats' tail blood pressure, left ventricular end-diastolic pressure (LVDEP) and the left ventricular systolic pressure (LVSP) before the rat was killed. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect RhoA/Rock1mRNA's expression. Use the immunohistology to detect the myocardial transforming growth factor -β2 (TGF-β2) and calculate the intergal optical density (IOD).Results 1.Rats' general situation: Sham-operated rats act flexibly and response fast to the changes around; late the Model rats' color gradually lose luster, mental become sluggishness, act very slow, lying tired and Fasudil rats 'general state is better than the Model group. 2.Reconstruction of myocardial morphology and histological indicators: the Model group and Fasudil drug intervention group's HW,LVFWW,LVHI are general higher than Sham-operated group (p <0.01). Model group 's myocardial cell degenerated, large myocardial fiber fracture, myocardial nuclear pyknosis, interstitial edema, Fasudil drug intervention group' appears cardiac myocyte hypertrophy, mild degeneration, muscle fibers without fault crack, myocardial cells is not the whole shape slightly, and myocardial interstitial edema mildly. The typeⅢcollagen IOD (127.10±2.70) of the Model group 's rats typeⅢwere significantly increased, compared with the Sham-operated group (74.12±0.74) has a very significant difference; after the intervention, the typeⅢcollagen IOD (91.37±1.58) of the Fasudil dropped significantly.3.Detection of hemodynamic parameters: At terminal experiments, Model group's LVSP (149.80±8.40 VS 102.72±7.40), LVEDP (4.48±0.83 VS 1.85±0.92) was significantly increased compared with the Sham-operated group, and there existed significant difference (P <0.01) between them. Four weeks after the treatment, the Fasudil group's LVSP (121.20±7.60), LVEDP (3.70±0.72) was significantly decreased (P <0.01) compared to the Mode group's. Mode Model group rats' tail artery pressure has also increased and the Fasudil group 's tail artery were lower than the Model, but the difference between the two groups was not very obvious.4. Myocardial TGF-β2 detect: The content of TGF-β2 was significantly enhances in the model group compared(IOD 20.46±1.79 VS 5.02±0.14 p<0.01)with the Sham-operated group. The upregulation of TGF-β2 wad significantly inhibited in the fasudil group(IOD 12.17±0.82).5. Myocardial RhoA/Rock1mRNA's expression:β-actin control for the internal parameters, the Model group's RhoA,Rock1 expression was significantly increased contrast to Sham-operated group (RhoA mRNA 1.42±0.08 VS 0.69±0.05, Rock1mRNA 1.29±0.04 VS 0.58±0.02) and there is a difference between the two (P <0.01). Fasudil group, after four weeks of drug intervention, the RhoAmRNA(0.85±0.03) and Rock1mRNA(0.83±0.03) decreased significantly compared with the model group, the difference between the two is also very significant (P <0.01). Conclusion1: Rho / Rock signal transduction pathway is closely linked with the pressure overload rats' myocardial remodeling development.2: Rho kinase inhibitor fasudil can significantly reduce myocardial fibrosis, inhibit ventricular remodeling and the inhibition of TGF-β2 production is one of the important mechanisms. |
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