Study of the left ventricular myocardial interstitial fibrosis and effect of benazepril in spontaneous hypertension rats by integrated backscatter technique

Objective To assess left ventricular myocardial interstitial fibrosis and effects of benazepril on spontaneous hypertension rat(SHR)by integrated backscatter(IBS)technique.Methods Fourteen SHRs were divided equally into two groups: intervening subject(SB)group and control subject(SHR)group.Other 7 WKYs were as the normal subjects(WKY).SB group were given 10 mg·kg-1·d-1 body weight of benazepril by intragastric administrstion,and WKY group and SHR group received 10 mg·kg-1·d-1 of distilled water.The animals were weighed once week to adjust for drug dosage.After 12 weeks,IBS%,CVIB,left ventricular ejection(LVEF)were determined.Masson staining and argyrophilic staining were used in the study of collagen volume fraction(CVF),perivascular collagen area(PVCA),ratio of small coronary artery wall thickness to external diameter(T/D)and argyrophilic fibers volume fraction(APFVF)in heart tissue.The expression of CTGF was evaluated by qualitative and semiquantitative immunohistochemical staining.Results IBS% was greater in SHR group than SB group(P0.01)and SB group greater than WKY group(P0.05),while CVIB was lower in SHR group than SB group and SB group less than WKY group(P0.05).CTGF,CVF,PVCA,T/D,APFVF were increased in SHR group than SB group,while SB group greater than WKY group(all P0.01).The correlations between IBS% and CTGF,CVF,PVCA,APFVF,T/D were significant.Conclusions The myocardial interstitial fibrosis in SHR is obvious.Hypertension induced the upregulation of CTGF in myocardium of rat.Benazepril can decrease the expression of CTGF and has good a effect on left ventricular myocardial interstitial fibrosis which contributes to reserve left ventricular systolic function.It is feasible to assess this change by IBS technique.