Role of p47 in Vascular Oxidative Stress and Hypertension Caused by Angiotensin II

Hypertension caused by angiotensin II is dependent on vascular superoxide (O2 ) production. The nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase is a major source of vascular O2 and is activated by angiotensin II in vitro. However, its role in angiotensin II–induced hypertension in vivo is less clear. In the present studies, we used mice deficient in p47, a cytosolic subunit of the NADPH oxidase, to study the role of this enzyme system in vivo. In vivo, angiotensin II infusion (0.7 mg/kg per day for 7 days) increased systolic blood pressure from 105 2 to 151 6 mm Hg and increased vascular O2 formation 2to 3-fold in wild-type (WT) mice. In contrast, in p47 mice the hypertensive response to angiotensin II infusion (122 4 mm Hg; P 0.05) was markedly blunted, and there was no increase of vascular O2 production. In situ staining for O2 using dihydroethidium revealed a marked increase of O2 production in both endothelial and vascular smooth muscle cells of angiotensin II–treated WT mice, but not in those of p47 mice. To directly examine the role of the NAD(P)H oxidase in endothelial production of O2 , endothelial cells from WT and p47 mice were cultured. Western blotting confirmed the absence of p47 in p47 mice. Angiotensin II increased O2 production in endothelial cells from WT mice, but not in those from p47 mice, as determined by electron spin resonance spectroscopy. These results suggest a pivotal role of the NAD(P)H oxidase and its subunit p47 in the vascular oxidant stress and the blood pressure response to angiotensin II in vivo. (Hypertension. 2002;40:511-515.)