Effect Of Valsartan And Enalapril On Remodeling Of Myocardial Interstitial Collagen After Myocardial Infarction In Rabbits

Objective To investigate the effect of angiotensin II type I receptor blocker (AR1B) and angiotensin converting anzyme inhibitor (ACEI) on deposition of collagen in infarct zone (IZ) and non-infarct zone (NIZ) in myocardial infarction(MI) rabbits. Methods Twenty-four hours after left anterior descending coronary ligation, New Zealand White rabbits were randomized to four groups: V group (valsartan 10mg kg-1 d-1), E group (enalapril 5mg kg-1 d-1), C group (control group) and S group (Sham group). Ten weeks after administration, the heart and body weight, myocardial collagen content, procollagen type I carboxyl-terminal peptide (PICP) and procollagen type III amino-terminal peptide (PIIINP) in plasma, and left ventricular diastolic pressure (LVDP), left ventricular systolic pressure (LVSP) were measured. Myocardial total-collagen volume fraction(CVF-T),and nonvascular-collagen volume fraction(CVF-NV) were examined with histomorphometrical method. Results Ten weeks after operation, survivors were 8 in V group, 7 in E group, 7 in C group, 9 in S group,respectively. The ratio of left ventricle weight (LVW) to body weight, and that of right ventricle (RV) weight (RVW) to body weight, myocardial CVF-T, CVF-NV, and plasma contents of PICP and PIIINP significantly increased in C group compared with those of S group (P<0.01, or P<0.05). Above parameters were reduced by treatment with valsartan or enalapril(versus C group, P<0.05 or P<0.01). Plasma contents of PICP had a significant correlation with LVDP. NIZ collagen content had a significant correlation with LVDP and LVSP. Conclusion 1. Both ACEI and AR1B attenuate postinfarcted collagen remodeling, and improve hemodynamic parameters. There was no significant difference between two drugs. 2. NIZ collagen content is one of the important factors in worsing cardiac function. NIZ collagen content had a significant correlation with LVDP and LVSP. 3. Plasma contents of PICP and PIIINP could to some extent be used to evaluate the degree of myocardial collagen network remodeling and the outcome of therapy.