Angiotensin II studies in hypertension.

F OLLOWING the production of experimental hypertension through the alteration of intrarenal hemodynamics by Goldblatt in 1934, investigators have identified, isolated, described, and synthesized the active pressor octapeptide angiotensin II.'-" Others have described the metabolism and distribution of extracted and synthetic angiotensin II and have also suggested that this peptide is implicated in the etiology of primary hypertension.12-20 Concomitantly, the reactivity of the vascular bed of the digit to a variety of stimuli, including angiotensin II, was under study. 12 14, 21-24 The unique properties of the digital vascular bed made it possible to calculate pressure-flow ratios and radius equivalentS21-23, 25, 26 from which the work of vasoconstriction per unit of vasoactive substance administered per minute could be determined.25 26 Digital vascular reactivity to intravenously infused norepinephrine, after sympathetic blockade by indirect heat and the administration of a ganglionic blocking drug, was found to be increased in the primary hypertensive patient, compared to the normotensive subject.26 Vascular reactivity to angiotensin II was then also studied. Fifteen normotensive subjects and 15 patients with primary (untreated) hypertension were tested under 3 sets of conditions: at rest in the supine position, after ganglionic blockade, and after infusing sufficient angiotensin II to bring the blood pressure to approximately the recorded level before ganglionic blockade. The results are summarized in table 1 and