Oxidative Stress-Induced Glomerular Mineralocorticoid Receptor Activation Limits the Benefit of Salt Reduction in Dahl Salt-Sensitive RatsReportar como inadecuado




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Background

Mineralocorticoid receptor MR antagonists attenuate renal injury in salt-sensitive hypertensive rats with low plasma aldosterone levels. We hypothesized that oxidative stress causes MR activation in high-salt-fed Dahl salt-sensitive rats. Furthermore, we determined if MR activation persisted and induced renal injury, even after switching from a high- to a normal-salt diet.

Methods and Findings

High-salt feeding for 4 weeks increased dihydroethidium fluorescence DHE, an oxidant production marker, p22phox a NADPH oxidase subunit and serum and glucocorticoid-regulated kinase-1 SGK1, an MR transcript in glomeruli, compared with normal-salt feeding, and these changes persisted 4 weeks after salt withdrawal. Tempol treatment 0.5 mmol-L during high-salt feeding abolished the changes in DHE fluorescence, p22phox and SGK1. Dietary salt reduction after a 4-week high-salt diet decreased both blood pressure and proteinuria, but was associated with significantly higher proteinuria than in normal control rats at 4 weeks after salt reduction. Administration of tempol during high-salt feeding, or eplerenone, an MR antagonist 100 mg-kg-day, started after salt reduction, recovered proteinuria to normal levels at 4 weeks after salt reduction. Paraquat, a reactive oxygen species generator, enhanced MR transcriptional activity in cultured rat mesangial cells and mouse podocytes.

Conclusions

These results suggest that oxidative stress plays an important role in glomerular MR activation in Dahl salt-sensitive rats. Persistent MR activation even after reducing salt intake could limit the beneficial effects of salt restriction.



Autor: Kento Kitada , Daisuke Nakano , Ya Liu, Yoshihide Fujisawa, Hirofumi Hitomi, Yuki Shibayama, Hirotaka Shibata, Yukiko Nagai, Hiro

Fuente: http://plos.srce.hr/



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