Effects of nitrendipine and atenolol on blood pressure and intracellular sodium in hypertensive blacks.

Thirty-five hypertensive black patients were randomized in a double-blind fashion to receive either atenolol 100 mg per day (n = 17) or nitrendipine 20 mg daily (n = 18) for six weeks. Atenolol and nitrendipine significantly reduced blood pressure (P less than 0.05 or less). However, the magnitude of the decrease in supine systolic blood pressure (SBP) and diastolic blood pressure (DBP), and in standing diastolic pressure was more pronounced (P less than 0.05 or less) in the nitrendipine than in the atenolol group. Neither of the drugs significantly affected the erythrocyte sodium and potassium concentrations or the ouabain-sensitive efflux of sodium. In multiple regression analysis the changes in supine SBP and DBP with nitrendipine were independently and negatively correlated with the patients' age and initial blood pressure, and positively with the change in supine pulse rate; the change in supine SBP was also negatively correlated with initial erythrocyte sodium concentration. Our results suggest that nitrendipine is more efficient than atenolol in hypertensive blacks and that besides older age and higher pre-treatment. BP levels, a higher intracellular sodium concentration could predict a greater response to nitrendipine.