Study of the Myocardial Interstitial Fibrosis and Effect of Small Dose of Benazepril with Spironolactone on Spontaneously Hypertensive Rats by Integrated Backscatter Technique

Objective To investigate the effect of small dose of benazepril with spironolactone on the left ventricular myocardial fibrosis accessed by integrated backscatter(IBS)technique in spontaneously hypertensive rats(SHR).MethodsTwenty-one male SHRs were divided equally into three groups: benazepril [SHR-B, given benazepril 10 mg/(kg·d)], low dose of benazepril with spironolactone[SHR-BS, 5 mg/(kg·d) benazepril with 10 mg/(kg·d) spironolactone] group and control (SHR) group.WKYs served as the normal control(WKY). Drugs were administered by gavage.WKY and SHR control received 2 mL distilled water.After 12 weeks, AII%, PPI were determined by ultrasonography.The myocardial hydroxyproline concentration (HPC) were determined, Masson staining and Argyrophilic staining were used to access 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.ResultsThe AII% and fibrosis index (including HPC, CVF,PVCA,T/D, APFVF, CTGF) were significantly higher and PPI was lower in SHR group than those in WKY group.The AII% and fibrosis index were decreased, and PPI was increased both in SHR-B and SHR-BS groups after treatment, but it did not return to baseline levels of WKY group.There was no difference between SHR-B group and SHR-BS group after treatment(P0.05).The correlation between AII% and fibrosis index was significant.ConclusionsThe myocardial interstitial fibrosis in SHR was accompanied by the upregulation of CTGF in myocardium of rat.There were no difference of CTGF expression and left ventricular myocardial interstitial fibrosis between the groups of small dose of benazepril with spironolactone and the group of benazepril, small dose group has a better cost-effective ratio.