EFFECTS OF RENIN-ANGIOTENSIN SYSTEM BLOCKADE AND DIETARY SALT INTAKE ON LEFT-VENTRICULAR HYPERTROPHY IN DAHL SALT-SENSITIVE RATS

We studied the effects of chronic blockade of the renin-angiotensin sy stem on hypertension and cardiac left ventricular hypertrophy (LVH) in Dahl salt-sensitive (DS) rats given a high-salt or low-salt diet. [Ex periment 1] Twelve-week-old male DS rats were fed an 8% NaCl diet and received the angiotensin II receptor (AT(1)) antagonist, candesartan ( 3 mg/kg/d), the angiotensin converting enzyme inhibitor enalapril (30 mg/kg/d), or vehicle for 6 wk after 3 wk of 8% salt-loading. Neither c andesartan nor enalapril with concomitant high salt-loading attenuated the blood pressure (BP) elevation. LVH was also not attenuated signif icantly by these treatments. [Experiment 2] After 8 wk of 8% salt-load ing, the rats were given a 0.3% NaCl diet and concurrently received ca ndesartan, enalapril, or vehicle for 5 wk. Switching from the high-sal t to low-salt diet significantly decreased BP and left ventricular mas s in the vehicle-treated animals. Both candesartan and enalapril norma lized BP during salt-depletion; the blockade of the renin-angiotensin system produced an additive reduction in LVH. These findings suggest t hat sodium intake and hemodynamic load, but not the renin-angiotensin system, may be major determinants of the development of LVH in DS rats .