The Experimental Study Of Correlation Between PAI-1 And Fibrosis Of Myocardium In Old Rats And Intervention With Losartan

Object:This experiment discussed of myocardial fibrosis in old rats by studying changes of cardiac structure and PAI-1 in rats with aging,and observed change of myocardial interstitial in old rats after Losartan.It could provide a sound theoretical basis for preventing and reversing myocardial fibrosis with aging and recovering heart normal structure and clinical medication.Methods:Thirty Wistar rats were divided into three groups:10 young rats(3 months old); 20 old rats(20 months old)were randomly divided into 2 groups,10 rats were in the old group, 10 rats were given Losartan(20mg/kg/d in 2-3ml ditilled water)for 10 weeks.In the young and the old group rats were given the same dose distilled water for 10 weeks.Weighing rats, abdominal anesthesia by 20%Urethane(1000mg/kg),opening chests,taking hearts out,weighing left ventricle(LVW)and calculating left ventricular mass index:(LVMI).The left ventricle tissues were divided two piece(1)To take epimere of left ventricle make into paraffin imbedding slice on the cross section:The sections were stained with 1%acid fuchsin and 0. 5%saturated picric acid(Van-Gieson staining,VG staining).Collagen Volume Fraction(CVF) and perivascular Circumferential Area(PVCA)were examined with computer-based video analysis system and analysis software package.CVF=the area of collagen/the total area,the area of collagen didnt include the area of perivascular collagen;PVCA=the area of collagen around the small artery/the area of the small arterial antrum.Immunohistochemical staining of PAI-1: Immunohistochemical staining of PAI-1 were performed with the method of SP.The expressions of PAI-1 were quantified with computer-based video analysis system and analysis software package.Calulate ratio of masc areae with computer-based video analysis system and analysis software package.(2)Detection of hydroxyproline concentration(HC):The content of hydroxyproline in the collagen is fixed,so it can show the extent of myocardial fibrosis.After myocardial tissue were digested and hydrolyzed,absorbencies(OB)of the solution were detected with spectrophotometer(550nm).HC(μg/100mg)=[(OB of myocardial tissues—OB of blank tube)÷(OB of standard tube—OB of blank tube)]×concentration of standard tube×[bulk volume of digest(10ml)÷humid weight of tissue(mg)].To compare the difference of HC CVF PVCA and the express of PAI-1 between in the old group and the young group and in the old group and the Losartan group,to analyze the correlation of between PAI-1 and CVF HC and PVCA.All data were expressed as mean±standard deviation.Statistical comparisons were made by t-test,and the relativity was made by linear correlation analysis.All the statistical analyses were done with statistical software(SPSS 13.0).Statistical significance was defined at P＜0.05.Results:1.Comparisons of LVMI in rats:Compared to those in the young group,LVMI in the old group decreased,and the differences were significant(P＜0.05);Compared to those in the old group,LVMI in the Losartan group show up the tendency of reducing.2.Comparison of HC,CVF and PVCA:Compared to those in the young group,HC, CVF and PVCA in the old group increased significantly,and the differences were significant(P＜0.01);Compared to those in the old group,HC,CVF and PVCA in the Losartan group decreased,and the difference were significant(P＜0.01,P＜0.01,P＜0.05).3.Immunohistochemical staining of PAI-1:In the young group,few fine granules expressed in myocardial plasma,scattered,weak staining.In the old group,the expression of PAI-1 in myocardial plasma increased obviously,and many coarse granules were seen,diffusely. Semiquantitative analysis:the expression of PAI-1 in the old group was much stronger than that in the young group(P＜0.05).Compared to those in the old group,expression of PAI-1 in the Losartan group was thinner(P＜0.05).4.Linear correlation analysis between PAI-1 and HC,CVF and PVCA:The expression of PAI-1 was positively correlated to HC,CVF and PVCA(r_S=0.693,0.738,0.672;P＜0.01, P＜0.01,P＜0.01)。Conclusions:1.With aging,myocardial collagen contents in the old group increased gradually,gathered in myocardial interstitial and around vessels abnormally,and then contributed to the formation of myocardial fibrosis.2.Compared to those in the young group,the expression of PAI-1 increased gradually in the old group,and PAI-1 might participate in the formation of myocardial fibrosis in old rats.3.Losartan could inhibit the formation of myocardial fibrosis in old rats with an extent,decrease of the express of PAI-1 in rats muscular tissues may be the one of its mechanism...