Upregulation of p67phoxand gp91phoxin aortas from angiotensin II-infused mice

Abstract

Although NAD(P)H oxidase-derived superoxide (O₂⁻) is increased during the development of angiotensin II (ANG II)-dependent hypertension, vascular regulation at the protein level has not been reported. We have shown that four major components of NAD(P)H oxidase are located primarily in the vascular adventitia as a primary source of vascular O₂⁻. Here we compare vascular levels of O₂⁻ and NAD(P)H oxidase in normotensive and ANG II-infused hypertensive mice and show that, after 7 days of ANG II infusion (750 μg · kg⁻¹ · day⁻¹ ip) in C57B1/6 mice, systolic blood pressure was increased compared with that after sham infusion, concomitant with increased O₂⁻ in the thoracic aorta as measured using lucigenin (25 μM)-enhanced chemiluminescence. Both p67^phox and gp91^phox were detectable by Western blotting in aortic homogenates, and we observed increased protein levels of NAD(P)H oxidase subunits. These ANG II-induced increases were normalized by simultaneous treatment with the AT₁receptor antagonist losartan. Moreover, the primary location of these subunits was the adventitia as detected immunohistochemically. Our results suggest that ANG II-induced increases in O₂⁻are due to increased adventitial NAD(P)H oxidase activity, brought about by the heightened expression and interaction of its components.