Kidney Week

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

• Hypertension and CVD: Mechanisms - I
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

• 1403 Hypertension and CVD: Mechanisms

Authors

• Li, Xingsheng, University of Alabama at Birmingham, Birmingham, Alabama, United States

Xingsheng Li,

• Ying, Wei-zhong, University of Alabama at Birmingham, Birmingham, Alabama, United States

Wei-zhong Ying,

• Sanders, Paul W., University of Alabama at Birmingham, Birmingham, Alabama, United States

Paul W. Sanders,

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