European journal of clinical pharmacology vol:36 issue:6 pages:567-73
The effects of acute calcium entry blockade by isradipine (IS) and placebo (P) on the haemodynamic and humoral responses to angiotensin II (A II) have been compared in two groups of 9 patients with essential hypertension. During 4 sequential periods each of 20 min, an i.v. infusion of A II 0, 2, 4 and 8 ng.kg-1.min-1 was given before (control) and 30 min after the oral administration either of IS or P. After IS, both the blood pressure and the angiotensin II-induced pressor effect were significantly reduced. Isradipine increased the heart rate and this cardio-acceleration was potentiated by A II. In contrast, when A II was infused in the absence of IS, heart rate tended to decrease. IS stimulated plasma renin activity and reduced plasma aldosterone. However, it did not affect either the inhibition of plasma renin activity or the rise in plasma aldosterone in response to A II. In conclusion, acute calcium entry blockade in patients with essential hypertension reduces the pressor response to A II, but not the A II-induced inhibition of renin and increase in plasma aldosterone.