Plasma Vasoconstrictor Activity in Patients with Renal, Malignant, and Primary Hypertension

Polypeptide vasoconstrictor activity was assayed in the peripheral venous blood of 45 hypertensive patients and 20 normal subjects. The average activity was significantly increased in all hypertensive groups, and activity tended to be much higher in patients with renovascular and malignant hypertension than in primary hypertension. In confirmation of previously reported results by Helmer and Judson, there was no correlation between vasoconstrictor activity and renal excretory function. The plasma level of vasoconstrictor activity did not correlate with mean arterial pressure except when malignant or renovascular hypertension was present. A significant inverse relationship was found between the serum potassium concentration and vasoconstrictor activity: as activity levels increased, the potassium fell. The data suggest that a renin-like substance may be present in various hypertensive states in amounts sufficient to depress serum potassium, presumably by activation of the renin-angiotensin-aldosterone mechanism.