The Influence of Blocking Renin-Angiotensin System by Benazepril and Losartan on the Left Ventricular Remodeling of the Aged Spontaneously Hypertensive Rats

Aim To find out the effects of the combination of Benazepril and Losartan on improving and reversing left ventricular remodeling of the aged spontaneously hypertensive rats(SHR). Methods 18 WistarKyoto rats(WKY) and 54 SHR of 55 weeks old were chosen as the experiment animals.54 SHR were divided into 4 groups randomly: SHR-control group,SHR-Benazepril group [10mg/(kg·d)],SHR-Losartan group [30 mg/(kg·d)],SHR-Benazepril [10 mg/(kg·d)]+Losartan [15 mg/(kg·d)] group.After 12 weeks of treatment,all rats were drawn for detection,including observing systolic blood pressure(SBP) and left ventricular mass index(LVMI),myocardial pathologic changes and detecting the collagen protein level of left ventriculum by the immunohistochemical methods.TUNEL-method was used to detect the apoptosis rate of myocardial cells. Results Both SBP and LVMI of the SHR-control group were higher than those of drug-interfered groups(P0.01). And it was the combination that can lower the LVMI most notably.Compared with the SHR-control group,pathological changes were obviously improved in all three drug-interfered groups,with the combination group being the most.The expression levels of type Ⅰ and total collagen fibers of each treatment group were lower than those of SHR-control group(P0.01),especially for the combination group.The expression levels of type Ⅲ collagen fibers in each drug-interfered group were decreased slightly,and also with the combination group being the most(P0.01).Compared with the SHR-control group,the apoptosis rate of Benazepril group was significantly higher(P0.05),while that of Losartan group and the combination group were significantly lower(P0.01). Conclusions Compared with monotherapy,the combination of Benazepril and Losartan seems more efficient in improving and reversing the aging SHR's left ventricular hypertrophy,myocardial apoptosis and myocardial fibrosis.