Effect of nifedipine on blood pressure and adrenocortical responses to trophic stimuli in humans

Abstract

The effect of nifedipine on blood pressure and aldosterone and cortisol responses to both angiotensin II and adrenocorticotrophin (ACTH) was studied in two groups of normal male subjects. Nifedipine (20 mg by mouth) caused a significant fall in diastolic blood pressure in both groups, from 71 +/- 8 (SEM) to 60 +/- 10 mm Hg after 30 min (p greater than 0.005; n = 15; paired t test), and a reflex tachycardia. During graded infusion of angiotensin II at 5, 10, and 20 ng/kg/min each for 30 min, there was a significant decrease in both the pressor and aldosterone responses after administration of nifedipine (p less than 0.05; n = 6; paired Wilcoxon test); the pressor and aldosterone response ratios at 10 ng/kg/min were 0.5 and 0.25, respectively. However, in a second study, no inhibition of either cortisol or aldosterone responses to ACTH (250 microgram intramuscularly) was observed. These data indicate that aldosterone release in humans is calcium dependent, and that nifedipine decreases the sensitivity of the zona glomerulosa to angiotensin II, but has no effect on the aldosterone or cortisol responses to ACTH.