| Objective:To explore the effect of recombinant human relaxin(rh-RLX)on its heart function in the rabbits with DHF.Methods:1.Thirty-six adult New Zealand rabbits were randomly divided into operated group(n=30)and sham operated group(n=6),respectively.Operated group was established DHF model with abdominal aorta constriction(constriction rate about 50%-60%).The sham operated group just open free abdominal aorta without constricting.According to the echocardiography results at the 8th weeks after the operation,we established the successful DHF rabbits model according to the diagnostic criteria that is left ventricular ejection fraction﹥50% and E/A ratio<1.2.At the 8th weeks after the operation,the successful DHF model rabbits were divided randomly into four groups: DHF group(n=6),Benazepril group(n=8,dose:3mg·kg-1·d-1),rh-RLX low-dose group(n=8,dose:30 ug·kg-1·d-1),rh-RLX high-dose group(n=8,dose:98 ug·kg-1·d-1).The DHF group and sham operated group were fed by normal foods as the same as that in control group,each group was fed continuously for a week 3.Echocardiography was performed in all rabbits before operation、at the 8th weeks and the 9th weeks after the operation,we compared the changes of heart function among those groups by the way of independent sample T-test and Paired-sample T-test.4.At the 9th weeks after the operation,when the above 5 groups rabbits finished echocardiography,among those group we cut a piece of left ventricular myocardium by the way of air embolism,manufactured pathological section and the rabbits myocardial interstitial fibrosis changes was observed by the way of myocardial Masson staining in the pathology department of our hospital.Result:1.The results of echocardiography:(1)At the 8th weeks after the operation,Compared with the sham operated group,the operated group had normal systolic function namely LVEF(Left Ventricular Ejection Fraction)(76.97±3.61 vs 75.90±1.67,p﹥0.05),however,the diastolic function had following changes: LVPW(Left Ventricular Posterior Wall)(2.48±0.25 mm vs 4.86±0.17 mm,p﹤0.01)、IVS(Interventricular Septal Thickeness)(2.72±0.31 mm vs 3.20±0.10 mm,p﹤0.01)、LVEDP(Left Ventricular End-Diastolic Pressure)(4.09±0.42 mm Hg vs 11.7±1.26 mm Hg,p﹤0.01)all increased significantly,and E/A ratio(1.55±0.31 vs 0.84±0.07,p﹤0.01)decreased significantly.(2)At the 9th weeks after the operation,Compared respectively with DHF group,the diastolic function changed significantly in the rh-RLX high-dose group:E/A increased significantly(1.36±0.10 vs 0.83±0.06,p﹤0.01))、 LVPW(3.71±0.21 mm vs 4.87±0.08 mm,p﹤0.01)、IVS(3.10±0.08 mm vs3.23±0.08 mm,p﹤0.05)、LVEDP(8.74±1.16 mm Hg vs 12.07±1.31 mm Hg,p﹤0.01)all decreased significantly,However no significantly changes was observed at the rh-RLX low-dose group or at the Benazepril group;(3)At the 9th weeks after the operation,Compared respectively with Benazepril group,the rh-RLX high-dose group had following changes: E/A increased significantly(1.36±0.10 vs 0.87±0.05,p﹤0.05)、LVPW(3.71±0.21 mm vs 4.75±0.18 mm,p﹤0.01)、LVEDP(8.74±1.16 mm Hg vs12.07±1.31 mm Hg,p﹤0.01)all decreased significantly.However,no significantly changes was observed at the rh-RLX low-dose group.2.Myocardial Masson staining showed: Myocardial fibrosis was all improved in the differently degree among the Benazepril group、rh-RLX low-dose group and rh-RLXhigh-dose group,among these groups,the most significant improvement was observed at the rh-RLX high-dose group,which in the group myocardial interstitial fibrosis significantly reduced merely a little residual fiber,chronic inflammatory cells completely disappeared,cardiomyocyte and cytoplasm completely backed to normal.Conclusion: The treatment with the high-dose rh-RLX treatment can significantly improve the myocardial diastolic function of the rabbits with DHF.The potential mechanism may be relate to the rh-RLX inhibition effect on myocardial fibrosis remodeling. |
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