Effects of diltiazem hydrochloride on pressor and steroidogenic actions of angiotensins and norepinephrine in man.

The effect of diltiazem hydrochloride (DTZ), a calcium-antagonist, on pressor and steroidogenic action of angiotensin II (AII), angiotensin III (AIII) and norepinephrine (NE) was studied in 5 normal men. AII, AIII and NE were infused intravenously for 50 min from 0900 hr at a rate of 20 ng/kg/min, 100 ng/kg/min and 200 ng/kg/min, respectively. DTZ was infused intravenously alone or in combination with each of these pressor substances at a rate of 1 mg/min from 0910 hr to 0930 hr. DTZ alone did not cause significant changes in blood pressure (BP) and plasma aldosterone concentration (P1 Aldo). On the other hand, DTZ combined with AII, AIII or NE significantly inhibited the rise in BP induced by these pressor substances. DTZ also inhibited the NE-induced increase in P1 Aldo, whereas it did dot alter AII-, or AIII-induced increase in P1 Aldo. These results indicate that in normal men pressor actions of AII, AIII and NE are calcium-dependent and calcium ions are also involved in NE-induced increase in P1 Aldo.