| Objectives 1 To clarify whether Ang-(1-7)regulates the activity of YAP through the Gprotein-coupled MAS receptor.2 To investigate the role of YAP in the course of Ang-(1-7)alleviates hypertensive cardiac remodeling by establishing the model of Ang Ⅱ-induced hypertensive mice.Methods 1 Grouping and molding: Twenty-four 6-month-old ICR mice were divided into 4 groups randomly(n=6): Control group,Ang Ⅱ group,Ang Ⅱ+Ang-(1-7)group,and Ang Ⅱ+Ang-(1-7)+A779 group.According to grouping,mice were subcutaneously infused with Ang Ⅱ(800 ng/kg/min),Ang-(1-7)(400 ng/kg/min),A779(400 ng/kg/min)and Control group received an infusion of saline.After 4 weeks of continuous infusion,the mice were euthanized and heart tissues were collected.2 Detecting: 1)Systolic blood pressure(SBP)was measured by the non-invasive tail cuff method.Basal SBPs of mice in each group were measured for 1 week before infusion and every 2 days after infusion.2)Body weight,heart weight and tibia length were measured,and the ratios of heart weight/body weight and heart weight/tibia length were calculated.3)Pathological changes of heart were observed by HE staining,and the cross-sectional area of myocardial cells was quantitated by Image J software.4)Cardiac fibrosis was observed by Masson trichromatic staining.5)The mRNA expression of ANP and BNP in heart tissue were determined by RT-qPCR.6)The expression of YAP and p-YAP in heart tissue were determined by Western Blot.Results 1 Changes in SBP: Compared with the SBPs before administration,the SBPs of Ang Ⅱ group,Ang Ⅱ+Ang-(1-7)group,and Ang Ⅱ+Ang-(1-7)+A779 group were increased significantly to 160 mm Hg after 4 weeks of administration(P<0.05),and the difference between the three groups was not statistically significant.2 Heart size,HW/BW and TL/BW: Compared with Control group,the heart size,HW/BW and HW/TL were increased in Ang Ⅱ group(P<0.05),and these changes were decreased in Ang Ⅱ+Ang-(1-7)group(P<0.05).The heart size and HW/TL were increased compared with Ang Ⅱ+Ang-(1-7)group(P<0.05),but HW/BW was not changed in Ang Ⅱ+Ang-(1-7)+A779 group.3 The relative expression of ANP and BNP mRNA in heart: Compared with Control group,the relative expression of ANP and BNP mRNA in Ang Ⅱ group were increased(P<0.05),and these changes were decreased in Ang Ⅱ+Ang-(1-7)group(P<0.05).The relative expression of ANP and BNP mRNA in Ang Ⅱ+Ang-(1-7)+A779 group were increased compared with Ang Ⅱ+Ang-(1-7)group(P<0.05).4 HE staining of heart: The arrangement of cardiomyocytes were regular,and it has no obvious pathological change in Control group.The cross sectional area of cardiomyocytes in Ang Ⅱ group was significantly increased compared with the Control group(P<0.05),connective tissue hyperplasia and the broken layer of muscle fibers were observed,the pathological changes were obvious.These pathological changes were improved in Ang Ⅱ+Ang-(1-7)group and the cross sectional area of cardiomyocytes was decreased(P<0.05).Compared with Ang Ⅱ+Ang-(1-7)group,the arrangement of myocardium cells were irregular,the space between cardiomyocytes and connective tissue hyperplasia were increased in Ang Ⅱ+Ang-(1-7)+A779 group.5 Masson staining of heart: There were no obvious blue collagen fibers in the heart of control mice.Compared with the Control group,the proportion of collagen fibers in the Ang Ⅱ group was increased(P<0.05),and there were obviously blue collagen fibers between myofibers and around blood vessels.These pathological changes were significantly alleviated in Ang Ⅱ+Ang-(1-7)group and the proportion of collagen fibers was decreased(P<0.05).Compared with Ang Ⅱ+Ang-(1-7)group,the proportion of collagen fibers in Ang Ⅱ+Ang-(1-7)+A779 group was increased(P<0.05),and blue collagen fibers could be seen between myofibers and around blood vessels.6 The expression of YAP,p-YAP and p-YAP/YAP in heart: In Ang Ⅱ group,the expression of YAP was not changed,but the expression of p-YAP and p-YAP/YAP were decreased compared with Control group(P<0.05).In Ang Ⅱ+Ang-(1-7)group,the expression of YAP was not changed,but the expression of p-YAP and p-YAP/YAP were increased compared with Ang Ⅱ group(P<0.05).Compared with Ang Ⅱ+Ang-(1-7)group,the expression of YAP,p-YAP and p-YAP/YAP were decreased in Ang Ⅱ+Ang-(1-7)+A779 group(P<0.05).Conclusions1 Subcutaneous infusion of Ang-(1-7)did not affect SBP in mice.It can alleviate cardiac remodeling by inhibiting Ang Ⅱ-induced cardiac changes directly,a process unrelated to the reduction of high afterload induced by high blood pressure.2 Ang-(1-7)can inhibit the activation of YAP through the G-protein-coupled MAS receptor,and may alleviate cardiac remodeling by inhibiting Ang Ⅱ-induced YAP activation.Figure 10;Table 11;Reference 108... |
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