Angiotensin converting enzyme inhibitor (ACEI) and angiotensin receptor 1 antagonists (ARB) ameliorate oxidative stress and fibrosis of myocardium through inhibiting the renin angiotensin system (RAS) in different ways, but if there is difference between this two kind of agents in protection to organ damages remains controversial. The purpose of this study is to study if irbesartan and benazepril alone and in combination would have different protective effects on left ventricular structure, systolic and diastolic function.Design and method:
Sixteen-weeks old female spontaneously hypertensive rats (SHR) (n = 8) were treated with irbesartan (Irb,), benazepril (Ben), combination of low irbesartan and benazepril (Irb+Ben) and vehicle for 12 weeks. Wistar Kyoto (WKY) rats (n = 8) receive vehicle. Echocardiography was performed for evaluation of left ventricular structure, systolic and diastolic function at 12 weeks.Results:
Systolic blood pressure were significantly lower in Irb+Ben rats than in untreated SHR, and demonstrated greater improvement than irbesartan or benazepril alone. IVSd was significantly lower in the Irb+Ben rats, Irb rats and Ben rats than untreated SHR (P = 0.010, P = 0.035, P = 0.028, separately). There was no difference in the LVEDD, LVEF and FS between SHR in each group and WKY. E/A showed no statistical difference between groups. E/E’ decreased in Irb+Ben rats, Irb rats and Ben rats compared with untreated SHR (P = 0.007, P = 0.020, P = 0.039, separately). E’/A’ increased in Irb+Ben rats, Irb rats and Ben rats compared with untreated SHR (P = 0.019, P = 0.032, P = 0.041, separately). Irb+Ben combination resulted in better outcomes of IVSd, E/E’ and E’/A’ than irbesartan or benazepril alone (P < 0.05 for all).Conclusions:
Hypertension associated with diastolic dysfunction. Irbesartan, benazepril and dual therapy provide therapeutic benefit in the blood pressure control, as well as improvement of left ventricular hypertrophy and diastolic dysfunction. The combination of these two RAS antagonists significantly attenuating development of hypertension and reducing left ventricular hypertrophy than monotherapy, however, this result could be related to the better antihypertensive effect of combination treatment. There was no evidence of differential effects of irbesartan and benazepril on the outcomes of left ventricular structure and function.