A constitutively active, phagocyte-like NADPH oxidase localized in rabbit aortic adventitial fibroblasts produces superoxide anion, an activity that is enhanced by angiotensin II.
Identifies a constitutively active, phagocyte-like NADPH oxidase in the aortic adventitia that produces superoxide and is enhanced by angiotensin II, providing insight into the pathogenesis of hypertension.
Superoxide anion (O2-) plays a key role in the endogenous suppression of endothelium-derived nitric oxide (NO) bioactivity and has been implicated in the development of hypertension. In previous studies, we found that O2- is produced predominantly in the adventitia of isolated rabbit aorta and acts as a barrier to NO. In the present studies, we characterize the enzyme responsible for O2- production in the adventitia and show that this enzyme is a constitutively active NADPH oxidase with similar composition as the phagocyte NADPH oxidase. Constitutive O2--generating activity was localized to aortic adventitial fibroblasts and was enhanced by the potent vasoconstrictor angiotensin II. Immunohistochemistry of aortic sections demonstrated the presence of p22(phox), gp91(phox), p47(phox), and p67(phox) localized exclusively in rabbit aortic adventitia, coincident with the site of staining for O2- production. Furthermore, immunodepletion of p67(phox) from adventitial fibroblast particulates resulted in the loss of NADPH oxidase activity, which could be restored by the addition of recombinant p67(phox). Further study into the regulation of this adventitial source of O2- is important in elucidating the mechanisms regulating the bioactivity of NO and may contribute to our understanding of the pathogenesis of hypertension.
Pagano et al. (Tue,) conducted a other in Hypertension. Angiotensin II was evaluated on Superoxide anion (O2-) production and NADPH oxidase activity. A constitutively active, phagocyte-like NADPH oxidase localized in rabbit aortic adventitial fibroblasts produces superoxide anion, an activity that is enhanced by angiotensin II.