1. The effect of the calcium antagonist nifedipine on the pressor and aldosterone responses to angiotensin II was studied in six normal subjects.
2. Blood pressure, pulse rate and plasma aldosterone, potassium and cortisol were measured during paired consecutive infusions of angiotensin II (5, 10 and 20 ng min−1 kg−1) on two separate occasions. Nifedipine (20 mg by mouth) was given, 30 min before the second set of infusions.
3. After nifedipine there were reciprocal changes in supine resting blood pressure (−7 mm Hg) and pulse rate (+18 min−1) and a significant decrease in the pressor response to angiotensin II (P < 0.05; Wilcoxon signed rank test).
4. Basal levels of aldosterone were not changed by nifedipine, but the response to angiotensin II was significantly attenuated (P < 0.05). Nifedipine had no effect on plasma potassium or cortisol.
5. Transmembrane movement of calcium is involved in the aldosterone response to angiotensin II in man. Calcium antagonists may lower blood pressure via decreased adrenal responsiveness to angiotensin II as well as by peripheral vasodilatation.