Investigation of the mechanisms by which chronic infusion of an acutely subpressor dose of angiotensin II induces hypertension

Abstract

The mechanisms by which chronic infusion of an initially subpressor low dose of angiotensin II (ANG II) causes a progressive and sustained hypertension remain unclear. In conscious sheep (n = 6), intravenous infusion of ANG II (2 μg/h) gradually increased mean arterial pressure (MAP) from 82 ± 3 to 96 ± 5 mmHg over 7 days (P < 0.001). This was accompanied by peripheral vasoconstriction; total peripheral conductance decreased from 44.6 ± 6.4 to 38.2 ± 6.7 ml·min-1·mmHg -1 (P < 0.001). Cardiac output and heart rate were unchanged. In the regional circulation, mesenteric, renal, and iliac conductances decreased but blood flows were unchanged. There was no coronary vasoconstriction, and coronary..