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Abstract: FR-PO332

NAD(P)H Oxidase 4 Modulates Generation of Hydrogen Peroxide in Rat Aorta and Kidney Glomerulus During High Salt Intake

Session Information

Category: Hypertension and CVD

  • 1403 Hypertension and CVD: Mechanisms

Authors

  • Li, Xingsheng, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Ying, Wei-zhong, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Sanders, Paul W., University of Alabama at Birmingham, Birmingham, Alabama, United States
Background

NAD(P)H Oxidase 4 (Nox4) is a unique member of a family of oxidoreductases, because it is a constitutively active enzyme that produces specifically hydrogen peroxide (H2O2). The purpose of present study is to test the hypothesis that high-salt intake increases H2O2 generation in the aorta and kidney glomerulus through Nox4.

Methods

Sprague-Dawley rats were randomly assigned to receive a low-salt (LS, 0.3% sodium chloride) or high-salt (HS, 8% sodium chloride) diet for 7 days. Additional groups of rats on the LS and HS diets received a Nox4 inhibitor (GKT136901, 60mg/g BW) by gavage in the final two days. Fresh aortic rings and kidney glomeruli were prepared for H2O2 measurement using Amplex Red ELISA or C2DCF fluorescence staining for confocal microscopy. Expression of kidney Nox4 protein was accessed by immunohistochemistry in fixed kidney tissue.

Results

Compared with animals maintained on the LS diet, HS enhanced H2O2 generation in the aorta (P=0.019); animals that received the HS diet had a 47.4% higher H2O2 production than animals on the LS diet. Serial scanning using confocal microscopy of aortic specimens stained with C2DCF demonstrated that intracellular levels of H2O2 in both endothelial and smooth muscle layers of the HS-treated animals were higher than the LS group. Treatment of rats with the Nox4 inhibitor reduced intracellular H2O2 levels remarkably in both low- and high-salt treated animals.
Production of H2O2 by kidney glomeruli in rats that received HS was also higher than LS animals (P<0.001), and co-incubation with the Nox4 inhibitor (50µM) inhibited H2O2 generation in glomeruli of animals receiving both the LS and HS diets (P<0.001). Immunohistochemistry of kidney sections showed that Nox4 protein expression was increased in animals that received HS diet, particularly in outer cortex and medulla.
CONCLUSION: In summary, rat aortae and kidney glomeruli from rats on a HS diet showed enhanced H2O2 generation, which was attenuated by introducing the Nox4 inhibitor. We conclude that Nox4 participated in the modulation of the salt-dependent increase in H2O2.

Conclusion

In summary, rat aortae and kidney glomeruli from rats on a high-salt diet showed enhanced H2O2 generation, which was attenuated by introducing the Nox4 inhibitor. We conclude that Nox4 participated in the modulation of the salt-dependent increase in H2O2.

Funding

  • Veterans Affairs Support