Article

Intrarenal artery superoxide is mainly NADPH oxidase-derived and modulates endothelium-dependent dilation in elderly patients.

Department of Physiology, University Clinics of Greifswald, Greifswald, Germany.
Cardiovascular research (impact factor: 5.8). 10/2009; 85(4):814-24. DOI:10.1093/cvr/cvp346 pp.814-24
Source: PubMed

ABSTRACT The present study was performed to investigate the contribution of NADPH oxidases (Nox) to superoxide formation in human renal proximal resistance arteries and to test whether superoxide formation contributes to acute vasoconstrictor responses and endothelium-dependent vasodilation in these vessels.
Arcuate and proximal interlobular artery segments were from patients who underwent nephrectomy because of a renal tumour. Vessels were dissected from tumour-free parts of the kidneys. Additional intrarenal arteries were obtained from rats. Superoxide formation was measured by lucigenin-enhanced chemiluminescence, expression of Nox isoforms was analysed by RT-PCR, and functional studies were performed by small vessel wire myography. Sixty per cent of superoxide formation in human arcuate and proximal interlobular arteries was due to Nox activity. mRNA expression analyses revealed the presence of Nox2 and Nox4 but not Nox1. Phenylephrine and endothelin-1 induced powerful concentration-dependent vasoconstrictions that were unaffected by superoxide scavengers. Vasopressin elicited small and variable vasoconstrictions with signs of tachyphylaxis. Endothelium-dependent vasodilation was blunted by tiron and Nomega-nitro-L-arginine methyl ester but not by superoxide dismutase or catalase. Exogenous hydrogen peroxide elicited vasoconstriction.
Nox activity is the major source of superoxide formation in renal proximal resistance arteries from elderly patients. Acute vasoconstrictor responses to alpha1-adrenoreceptor activation and to endothelin-1 do not depend on superoxide formation, while endothelium-dependent vasodilation in intrarenal arteries is reactive oxygen species-dependent.

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    Article: Arterial flow reduces oxidative stress via an antioxidant response element and Oct-1 binding site within the NADPH oxidase 4 promoter in endothelial cells.
    Claudia Goettsch, Winfried Goettsch, Melanie Brux, Claudia Haschke, Coy Brunssen, Gregor Muller, Stefan R Bornstein, Nicole Duerrschmidt, Andreas H Wagner, Henning Morawietz
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    ABSTRACT: The main sources of oxidative stress in the vessel wall are nicotine adenine dinucleotide phosphate (NADPH) oxidase (Nox) complexes. The endothelium mainly expresses the Nox4-containing complex; however, the mechanism by which shear stress in endothelial cells regulates Nox4 is not well understood. This study demonstrates that long-term application of arterial laminar shear stress using a cone-and-plate viscometer reduces endothelial superoxide anion formation and Nox4 expression. In primary human endothelial cells, we identified a 47 bp 5'-untranslated region of Nox4 mRNA by 5'-rapid amplification of cDNA ends (5'-RACE) PCR. Cloning and functional analysis of human Nox4 promoter revealed a range between -1,490 and -1,310 bp responsible for flow-dependent downregulation. Mutation of an overlapping antioxidative response element (ARE)-like and Oct-1 binding site at -1,376 bp eliminated shear stress-dependent Nox4 downregulation. Consistent with these observations, electrophoretic mobility shift assays (EMSA) demonstrated an enhanced shear stress-dependent binding of Nox4 oligonucleotide containing the ARE-like/Oct-1 binding site, which could be inhibited by specific antibodies against the transcription factors nuclear factor erythroid 2-related factor 2 (Nrf2) and octamer transcription factor 1 (Oct-1). Furthermore, shear stress caused the translocation of Nrf2 and Oct-1 from the cytoplasm to the nucleus. Knockdown of Nrf2 by short hairpin RNA (shRNA) increased Nox4 expression twofold, indicating a direct cross-talk between Nrf2 and Nox4. In conclusion, an ARE-like/Oct-1 binding site was noticed to be essential for shear stress-dependent downregulation of Nox4. This novel mechanism may be involved in the flow-dependent downregulation of endothelial superoxide anion formation.
    Archiv für Kreislaufforschung 03/2011; 106(4):551-61. · 7.35 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

acute vasoconstrictor responses
 
Additional intrarenal arteries
 
alpha1-adrenoreceptor activation
 
endothelin-1 induced powerful concentration-dependent vasoconstrictions
 
Endothelium-dependent vasodilation
 
Exogenous hydrogen peroxide elicited vasoconstriction
 
human renal proximal resistance arteries
 
intrarenal arteries
 
lucigenin-enhanced chemiluminescence
 
mRNA expression analyses
 
Nomega-nitro-L-arginine methyl ester
 
proximal interlobular arteries
 
proximal interlobular artery segments
 
renal proximal resistance arteries
 
small vessel wire myography
 
superoxide dismutase
 
Superoxide formation
 
superoxide formation contributes
 
superoxide scavengers
 
Vasopressin elicited small