Changes in systemic and pulmonary vascular reactivity in hypertension following nifedipine and verapamil

Excessive vascular tone and overresponsiveness to adrenergic stimuli char acterize the hemodynamics of the greater and the lesser circulation in hyperten sion. We tested whether calcium entry blockade with verapamil (11 cases) or nifedipine (11 cases) may improve the vascular regulation in high blood pres sure. Mental arithmetic and cold were used as adrenergic activators. The former stimulus produced obvious elevation of epinephrine plasma concentra tion, increase of cardiac output (CO), slight systemic vasodilatation, pulmonary vasoconstriction, and rise of blood pressure in both circuits. After calcium an tagonists, the epinephrine reaction to the arithmetic test was significantly attenuated, variations in CO and systemic blood pressure were unchanged, pul monary vasoconstriction was abolished, and the pressure rise in the lesser cir cuit was halved. The cold pressor test increased norepinephrine plasma concen tration (NE pc), systemic and pulmonary blood pressure, and vascular resist ance and did not ...