Effects of chronic angiotensin I-converting enzyme inhibition on the relations between ventricular action potential changes and myocardial hypertrophy in aging rats.

We studied the effect of aging on cardiac hypertrophy and action potential duration (APD) in normotensive male WAG/Rij rats and evaluated the role of the renin-angiotensin system (RAS) in these effects. Cardiac hypertrophy occurs in 30-month-old rats, as indicated by an increase in heart weight, and APD gradually increases with aging in the epicardial region of the right and the left ventricle. Short-term treatment (1 month) with the angiotensin-converting enzyme inhibitor (ACEI) perindopril prevented age-related increase in heart weight/body weight ratio independent of its antihypertensive effects, but did not prevent changes in APD in 30-month-old rats. Our results show a dissociation of changes in cardiac mass from changes in APD during aging. The effect of ACEI on hypertrophy may be due in part to a direct angiotensin effect on cellular growth. Changes in APD are not related to hypertrophy but rather to the process of aging.