Upregulation of the vascular NAD(P)H-oxidase isoforms Nox1 and Nox4 by therenin-angiotensin system in vitro and in vivo

In different cardiovascular disease states, oxidative stress decreases the bioavailability of endothelial NO, resulting in endothelial dysfunction. An important molecular source of reactive oxygen species is the enzyme family of NAD(P)H oxidases (Nox). Here we provide evidence that the vascular Nox isoforms Nox1 and Nox4 appear to be involved in vascular oxidative stress i n response to risk factors like angiotensin II (Ang II) in vitro as well as in vivo. Nox mRNA and protein levels were quantified by real-time RT-PCR a nd Western blotting, respectively. Nox1 and Nox4 were expressed in the vasc ular smooth muscle cell (VSMC) fine A7r5 and aortas and kidneys of rats. Up on exposure of A7r5 cells to Ang II (1 muM, 4 h), Nox1 and Nox4 mRNA levels were increased 6-fold and 4-fold, respectively. Neither the vasoconstricto r endothelin 1 (up to 500 nM, 1-24 h) nor Lipopolysaccharide (up to 100 ng/ ml, 1-24 h) had any effect on Nox1 and Nox4 expression in these cells. Cons istent with these observations made in vitro, aortas and kidneys of transge nic hypertensive rats overexpressing the Ren2 gene [TGR(mRen2)27] had signi ficantly higher amounts of Nox1 and Nox4 mRNA and of Nox4 protein compared to tissues from normotensive wild-type animals. In conclusion, Nox4 and Nox 1 are upregulated by the renin-angiotensin system. Increased superoxide pro duction by upregulated vascular Nox isoforms may diminish the effectiveness of NO and thus contribute to the development of vascular diseases. Nox1 an d Nox4 could be targeted therapeutically to reduce vascular reactive oxygen species production and thereby increase the bioavailability of NO. (C) 200 1 Elsevier Science Inc.