title: NADPH oxidase-derived superoxide anion mediates angiotensin II-induced cardiac hypertrophy.
abstract: Cardiac hypertrophy is an adaptive response to increases in blood pressure. Recent studies indicate that the hypertrophic process is associated with increases in intracellular oxidative stress in cardiomyocytes. We hypothesize that superoxide anion mediates the hypertrophic response and that antioxidant therapy may be effective in attenuating cardiac hypertrophy. Neonatal rat cardiac myocytes were stimulated with angiotensin II (AngII, 1 microM) with and without various antioxidants. N-acetylcysteine (NAC, 10 mM) and probucol (50 microM), and to a lesser extent, vitamin C (500 microM) and reduced glutathione (1 mM), inhibited AngII-induced [(3)H]-leucine uptake and atrial natriuretic factor (ANF) promoter activity. The hypertrophic response is mediated by superoxide anion (O(2)(-).) since cell-permeable polyethylene glycol (PEG)-conjugated superoxide dismutase (50 U/ml), but not PEG-catalase (500 U/ml), attenuated AngII-induced [(3)H]-leucine uptake and ANF promoter activity. Furthermore, NAC blocked AngII-induced increase in myocardial oxidative stress, decreased the expression of ANF and myosin light chain-2v, and inhibited the re-organization of cytoskeletal proteins, desmin and alpha-actinin. These effects of AngII were abolished by angiotensin type 1 receptor blocker, losartan, but not type 2 receptor blocker, PD123319. Indeed, co-administration of losartan (10 mg/kg/d, 14 d) or NAC (200 mg/kg/d, 14 d) inhibited AngII-induced O(2)(-). production and cardiac hypertrophy in rats without affecting blood pressure. These findings indicate that the generation of O(2)(-). contributes to oxidant-induced hypertrophic response and suggest that antioxidant therapy may have beneficial effects in cardiac hypertrophy.
authors.affiliation: Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Cambridge, MA 02139, USA.
authors.forename: Hironori
authors.initials: H
authors.lastname: Nakagami
authors.forename: Masao
authors.initials: M
authors.lastname: Takemoto
authors.forename: James K
authors.initials: JK
authors.lastname: Liao
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis / Q000235:genetics; D006332:Cardiomegaly / Q000188:drug therapy / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects; D019255:NADPH Oxidases / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D014662:Vasoconstrictor Agents; D013481:Superoxides; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D019255:NADPH Oxidases; D020830:rac1 GTP-Binding Protein