CHRONIC EFFECTS OF ENALAPRIL AND AMLODIPINE ON CARDIAC REMODELING IN CARDIOMYOPATHIC HAMSTER HEARTS

This study examined the effects of long-term treatments with the angio tensin-converting enzyme inhibitor, enalapril, and the calcium antagon ist, amlodipine, on the morphologic changes, progressive left ventricu lar dysfunction, and gene expression of the ryanodine receptor (RyR) a nd phospholamban (PLN) in dilated cardiomyopathy. From the ages of 5 t hrough 20 weeks, dilated cardiomyopathic hamsters, BIO53.58 (BIO), and control hamsters, F1b, orally received either enalapril or amlodipine . Cardiac function was assessed by echocardiography. At the age of 20 weeks, the collagen volume fractions were analyzed by the stereologic method. RyR and PLN messenger RNAs (mRNAs) were examined by Northern b lot in the amlodipine group. In BIG, the reduction of left ventricular percent age of fractional shortening was attenuated in the enalapril group (p < 0.05) and amlodipine group (p < 0.001), and the increase in the collagen volume fraction and the loss of myocytes were suppressed in the amlodipine group compared with the unheated group. RyR mRNA le vel decreased in BIO (p < 0.01) compared with F1b, but PLN mRNA level was unchanged. RyR and PLN mRNA levels were unaffected by the treatmen t with amlodipine, Enalapril and amlodipine prevent progressive remode ling and reduce cardiac dysfunction in BIG. Amlodipine prevents fibros is and cell death without modifying RyR and PLN mRNA levels in BIO.