53 research outputs found

    Oxidative DNA Damage in Kidneys and Heart of Hypertensive Mice Is Prevented by Blocking Angiotensin II and Aldosterone Receptors

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    <div><p>Introduction</p><p>Recently, we could show that angiotensin II, the reactive peptide of the blood pressure-regulating renin-angiotensin-aldosterone-system, causes the formation of reactive oxygen species and DNA damage in kidneys and hearts of hypertensive mice. To further investigate on the one hand the mechanism of DNA damage caused by angiotensin II, and on the other hand possible intervention strategies against end-organ damage, the effects of substances interfering with the renin-angiotensin-aldosterone-system on angiotensin II-induced genomic damage were studied.</p><p>Methods</p><p>In C57BL/6-mice, hypertension was induced by infusion of 600 ng/kg • min angiotensin II. The animals were additionally treated with the angiotensin II type 1 receptor blocker candesartan, the mineralocorticoid receptor blocker eplerenone and the antioxidant tempol. DNA damage and the activation of transcription factors were studied by immunohistochemistry and protein expression analysis.</p><p>Results</p><p>Administration of angiotensin II led to a significant increase of blood pressure, decreased only by candesartan. In kidneys and hearts of angiotensin II-treated animals, significant oxidative stress could be detected (1.5-fold over control). The redox-sensitive transcription factors Nrf2 and NF-κB were activated in the kidney by angiotensin II-treatment (4- and 3-fold over control, respectively) and reduced by all interventions. In kidneys and hearts an increase of DNA damage (3- and 2-fold over control, respectively) and of DNA repair (3-fold over control) was found. These effects were ameliorated by all interventions in both organs. Consistently, candesartan and tempol were more effective than eplerenone.</p><p>Conclusion</p><p>Angiotensin II-induced DNA damage is caused by angiotensin II type 1 receptor-mediated formation of oxidative stress <i>in vivo</i>. The angiotensin II-mediated physiological increase of aldosterone adds to the DNA-damaging effects. Blocking angiotensin II and mineralocorticoid receptors therefore has beneficial effects on end-organ damage independent of blood pressure normalization.</p></div

    Primer sequences used for real-time PCR.

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    <p>NADPH oxidase isoform 1,</p><p>Nox2  =  NADPH oxidase isoform 2, Nox4  =  NADPH oxidase isoform 4.</p><p>Primer sequences used for real-time PCR.</p

    Multiple reaction monitoring parameters for the analysis of oxidized bases and internal standard and optimized conditions of the mass spectrometry measurement with the Q-Trap 2000.

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    <p>Multiple reaction monitoring parameters for the analysis of oxidized bases and internal standard and optimized conditions of the mass spectrometry measurement with the Q-Trap 2000.</p

    Induction of reactive oxygen species in kidney and heart.

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    <p>ROS formation quantified after staining kidney <b>(a)</b> and heart <b>(b)</b> cryosections with the ROS-sensitive fluorescent dye dihydroethidium. Quantification was done with the free software Cell Profiler <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115715#pone.0115715-Lamprecht1" target="_blank">[15]</a>. Data are shown as mean ± SEM after normalization to control values. Western blot-analysis of the amount of one subunit of the ROS-generating enzyme NADPH-oxidase 4 (NOX4) in protein extracts of kidney <b>(c)</b> and heart <b>(d)</b>, related to the house-keeping protein glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Shown are representative blots and the quantification of band densities of proteins of all animals. Relative quantification of the transcripts of the NADPH-oxidase subunits 1 (NOX1), 2 (NOX2) and 4 (NOX4) in kidney tissue <b>(e)</b>. Western blot-analysis of the amount of xanthine oxidase in protein extracts of the heart <b>(f)</b> related to the house-keeping protein glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Shown is a representative blot and the quantification of band densities of proteins of all animals. * p≤0.05, ** p<0.01, *** p<0.001 vs. Control, °° p<0.01 vs. AngII-treatment.</p

    Correlation between phosphatidylserine exposure and dynamic adhesion of erythrocytes to endothelial cells under arterial shear stress.

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    <p>Arithmetic means ± SEM (n = 6−8) of the erythrocytes adhering to HUVEC as a function of the percentage erythrocytes binding annexin V. The erythrocytes from annexin7-deficient mice (<i>anx7<sup>−/−</sup></i>, closed symbols) and their wild type control mice (<i>anx7<sup>+/+</sup></i>, open symbols) were left without pretreatment (circles), or pretreated 30 minutes with 1 µM ionomycin (triangles), 12 hours with glucose-depleted Ringer (squares) or 2 hours with hyperosmotic shock by addition of 550 mM sucrose (diamonds).</p
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