Vascular gp91 phox : beyond the endothelium. Circ. Res

In this issue of Circulation Research, Görlach et al1present compelling evidence for conventional gp91phox-containing NAD(P)H oxidase in the vascular endotheli-um and for the functional involvement of gp91phox in endo-thelial cell NAD(P)H oxidase superoxide anion (O2–) production and aberrant endothelium-dependent relaxation. Many studies have implicated reactive oxygen species in the impairment of endothelium-dependent vascular responses.2–10 Since their initial discovery in the vasculature and the suggestion of their importance in the modulation of endothe-lium-derived relaxing factor nitric oxide (EDRF/NO) bioac-tivity, phagocyte-like NAD(P)H oxidases have been under intense study in 3 major vascular cell types.11–18 Griendling et al19 showed the presence of angiotensin II (Ang II)–activat-able NAD(P)H oxidase in rat vascular smooth muscle, and Mohazzab-H and colleagues12,14 also made seminal discov-eries of endothelial and smooth muscle isotypes in bovin