Modulation of left ventricular hypertrophy by dietary salt and inhibition of angiotensin converting enzyme

Abstract

The interactions of blood pressure, salt intake and angiotensin converting enzyme (ACE) inhibition were investigated in the Dahl salt-sensitive (DS) and salt-resistant (DR) strains of rats. Eight-week-old DS and DR (40 of each) were separately randomized to receive a low- (0.4% NaCl) or a high- (8% NaCl) salt diet for 3 weeks. Thereafter the rats were further separated randomly to receive the ACE inhibitor lisinopril (3-8 mg/kg per day) or no drug treatment for 11 weeks. In untreated DS rats blood pressure rose, paralleled by a higher left ventricular mass (ratio left ventricular weight/body weight) irrespective of salt intake. Lisinopril lowered blood pressure to normotensive levels in all groups except DS rats on a high-salt diet, despite doses of up to 100 mg/kg per day, although there was a significant fall in blood pressure. Lisinopril reduced left ventricular mass significantly on the low- but not on the high-salt diet. Plasma renin activity increased on lisinopril treatment in all groups except DS rats on the high-salt diet. Regression of an increased left ventricular mass by ACE inhibition seemed to be impaired by a high salt intake, even when blood pressure was lowered. Therefore, although for regression of left ventricular hypertrophy, reduction of afterload was the leading factor, this might be adversely affected by a high salt intake.