Effects of Converting Enzyme Inhibitor on the Left Ventricular Remodeling after Coronary Artery Reperfusion in Rats

Oh, Byung Hee; Seo, Jung Don; Lee, Young Woo

Abstract

BACKGROUND
Angiotensin convertiong enzyme inhibitors have been shown to exert favorable effects on the left ventricular remodeling process associated with ventricular dilation after coronary occlusion. However, the effects of such therapy on global and regional left ventricular remodeling after coronart artery reperfusion have not been characterized, nor have such effects been assessed after exercise training.
METHODS AND RESULTS
Female Sprague-Dawley rats(n=80) were randodmized into 4 groups at 5 days after 45 minutes of left coronary artery occlusion followed by reperfusion. Animals completion the experiment included : Untreated Sedentary group(n=20), Untreated with Swimming Exercise group(n=21), Captopril Treated Sedentary group(n=18) and Captoril Treated with Exercise group(n=21). At 3 weeks after randomization, global and regional morphologic changes of the left ventricle(LV) were examined from mid-ventricular transverse slices which were perfusion-fixed at a constant aortic pressure of 60mmHg and a left ventricular cavity pressure of 10mmHG. At rest and during exercise, compared to untreated rats, the captopril treated animals showed significantly decreased LV weight/tibial length ratio(LV/TL)(p<0.01),increased LV cavity area and dimension(both p<0.01), decreased total myocardial area and noninfarcted area(both p<30.001) and reduced wall thicknesses in the noninfarcted and infarcted regions(both p<0.001). Compared to treated and untreated dsedentary rats, exercise significantly increased LV/TL(p<0.05) and epicardial and endocardial areas in the infarcted zone(both p<0.05) and decreased transmurality(p<0.01). Exercise decreased LV cavity area in the captopril treated groups(42.3+/-10.4 vs. 40.4+/-6.0mm2),whereas exercise increased LV cavity area in the untreated groups(33.5+/-8.9 vs. 39.1+/-6.2mm2)(p<0.05).
CONCLUSION
These findings provide evidence in rats for evidence in rats for exaggerated left ventricular dilation and supperssion of compensatory myocardial hypertrophy globally and in the infarct zone with 3 weeks of captopril treatment following coronary artery reperfusion with acute nontransmural myocardial infarction. In addition, the effects of captopril on LV dilation and suppression of global and regional hypertrophic response were partially reversible by swimming exercise.