This protocol studies salt-sensitive hypertensive patients through the use of dietary sodium intake as validated by 24 hour urine collection. The GCRC dietitian does the dietary counseling. Once identified as salt sensitive, subjects receive either enalapril, isradipine, or placebo, and the antihypertensive effectiveness of these three regimens on a low versus a high dietary salt intake is compared, testing the null hypothesis of no superior effect of isradipine.