title: RNA silencing in vivo reveals role of p22phox in rat angiotensin slow pressor response.
abstract: The angiotensin II (Ang II) slow-pressor response entails an increase in mean arterial pressure and reactive oxygen species. We used double-stranded interfering RNAs (siRNAs) in Sprague Dawley rats in vivo to test the hypothesis that an increase in the p22phox component of NADPH oxidase is required for this response. Reactive oxygen species were assessed from excretion of 8-isoprostane prostaglandin F2alpha and blood pressure by telemetry. Two siRNA sequences to p22phox (sip22phox) reduced mRNA >85% in cultured vascular smooth muscle cells. Rats received rapid (10 second) IV injections (50 to 100 microg) of 1 of 2 different sip22phox, control siRNA, or vehicle (TransIt in saline) during 14 day SC infusions of Ang II (200 ng.kg(-1).min(-1)) or sham infusions. In both groups, sip22phox, relative to control siRNA, led to significant (P<0.001; approximately 50%) reductions in expression of p22phox mRNA and protein and of NADPH oxidase activity in the kidney cortex. In Ang II-infused rats, sip22phox decreased protein expression for Nox-1, -2, and -4 but increased p47phox. Three days after sip22phox, conscious rats infused with Ang II had a reduced excretion of 8-isoprostane (10+/-1 versus 19+/-2 pg.24 h(-1); P<0.01) and a reduced mean arterial pressure (142+/-5 versus 168+/-4 mm Hg; P<0.005). An increase in p22phox is required for increased renal NADPH oxidase activity, expression of Nox proteins and oxidative stress, and contributes < or =50% to hypertension during an Ang II slow-pressor response.
authors.affiliation: Division of Nephrology and Hypertension, Georgetown University, Washington, DC, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Modlinger
authors.forename: Tinatin
authors.initials: T
authors.lastname: Chabrashvili
authors.forename: Pritomhinder S
authors.initials: PS
authors.lastname: Gill
authors.forename: Margarida
authors.initials: M
authors.lastname: Mendonca
authors.forename: David G
authors.initials: DG
authors.lastname: Harrison
authors.forename: Kathy K
authors.initials: KK
authors.lastname: Griendling
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Julie
authors.initials: J
authors.lastname: Raggio
authors.forename: Anton
authors.initials: A
authors.lastname: Wellstein
authors.forename: Yifan
authors.initials: Y
authors.lastname: Chen
authors.forename: William J
authors.initials: WJ
authors.lastname: Welch
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Wilcox
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002478:Cells, Cultured; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D007668:Kidney / Q000201:enzymology; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D019255:NADPH Oxidases / Q000235:genetics* / Q000378:metabolism*; D018384:Oxidative Stress; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D026901:Membrane Transport Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D000804:Angiotensin II; D019255:NADPH Oxidases; C086986:CYBA protein, human