The role of renin-angiotensin-aldosterone system in cardiac remodelling was studied in isoproterenol-induced cardiac hypertrophy in rats. The effects of captopril and spironolactone were compared. Isoproterenol treatment increased ventricular to body weight ratio (4.6 vs 3.7) and collagen area (22.6 vs 8.2%), and reduced systolic (89.93 vs 107.5 mm Hg) and diastolic (59.6 vs 70.8 mm Hg) pressure. In these animals, captopril decreased systolic (67.4 mm Hg) and diastolic pressure (31.9 mm Hg), whereas spironolactone regressed systolic pressure to control values (101.2 mm Hg). Captopril and spironolactone prevented cardiac hypertrophy (4.01 and 3.95). However, only spironolactone prevented myocardial fibrosis (11.3%). (C) 2001 Academic Press.