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 poten tial duration (APD) in normotensive male WAG/Rij rats and evaluated th e 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 epicard ial region of the right and the left ventricle. Short-term treatment ( 1 month) with the angiotensin-converting enzyme inhibitor (ACEI) perin dopril prevented age-related increase in heart weight/body weight rati o independent of its antihypertensive effects, but did not prevent cha nges in APD in 30-month-old rats. Our results show a dissociation of c hanges 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.