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This Article Full Text Full Text (PDF) All Versions of this Article: 293/1/E355    most recent 00632.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Whaley-Connell, A. Articles by Sowers, J. R. Search for Related Content PubMed PubMed Citation Articles by Whaley-Connell, A. Articles by Sowers, J. R.

Angiotensin II-mediated oxidative stress promotes myocardial tissue remodeling in the transgenic (mRen2) 27 Ren2 rat

¹School of Medicine and ²Diabetes and Cardiovascular Laboratory, University of Missouri, and ³Harry S. Truman Veterans Affairs Medical Center, Columbia, Missouri; ⁴The University of Arizona Diabetes Center, Tucson, Arizona; and ⁵Wake Forest University School of Medicine, Winston-Salem, North Carolina

Submitted 21 November 2006 ; accepted in final form 12 April 2007

Angiotensin II (ANG II) contributes to cardiac remodeling, hypertrophy, and left ventricular dysfunction. ANG II stimulation of the ANG type 1 receptor (AT₁R) generates reactive oxygen species via NADPH oxidase, which facilitates this hypertrophy and remodeling. This investigation sought to determine whether cardiac oxidative stress and cellular remodeling could be attenuated by in vivo AT₁R blockade (AT₁B) (valsartan) or superoxide dismutase/catalase mimetic (tempol) treatment in a rodent model of chronically elevated tissue levels of ANG II, the transgenic (mRen2) 27 rat (Ren2). Ren2 rats overexpress the mouse renin transgene with resultant hypertension, insulin resistance, proteinuria, and cardiovascular damage. Young (6–7 wk old) male Ren2 and age-matched Sprague-Dawley rats were treated with valsartan (30 mg/kg), tempol (1 mmol/l), or placebo for 3 wk. Heart tissue NADPH oxidase (NOX) activity and immunohistochemical analysis of subunits NOX2, Rac1, and p22^phox, heart tissue malondialdehyde, and insulin-stimulated protein kinase B (Akt) activation were measured. Structural changes were assessed with cine MRI, transmission electron microscopy, and light microscopy. Increases in septal wall thickness and altered systolic function (cine MRI) were associated with perivascular fibrosis and increased mitochondria in Ren2 on light and transmission electron microscopy (P < 0.05). AT₁B, but not tempol, reduced blood pressure (P < 0.05); significant improvements were seen with both AT₁B and tempol on NOX activity, subunit expression, malondialdehyde, and insulin-mediated activation/phosphorylation of Akt (each P < 0.05). Collectively, these data suggest cardiac oxidative stress-induced structural and functional changes are driven, in part, by AT₁R-mediated increases in NADPH oxidase activity.

reduced nicotinamide adenine dinucleotide phosphate oxidase; malondialdehyde; Akt

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