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Antioxidant and antihypertensive responses to oral nitrite involves activation of the Nrf2 pathway. Free Radic Biol Med 2019 09;141:261-268

Date

06/30/2019

Pubmed ID

31251976

DOI

10.1016/j.freeradbiomed.2019.06.028

Scopus ID

2-s2.0-85067870043   20 Citations

Abstract

Impaired redox balance contributes to the cardiovascular alterations of hypertension and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway may counteract these alterations. While nitrite recycles back to NO and exerts antioxidant and antihypertensive effects, the mechanisms involved in these responses are not fully understood. We hypothesized that nitrite treatment of two-kidney, one-clip (2K1C) hypertensive rats activates the Nrf2 pathway, promotes the transcription of antioxidant genes, and improves the vascular redox imbalance and dysfunction in this model. Two doses of oral nitrite were studied: 15 mg/kg and the sub-antihypertensive dose of 1 mg/kg. Nitrite 15 mg/kg (but not 1 mg/kg) decreased blood pressure and increased circulating plasma nitrite and nitrate. Both doses blunted hypertension-induced increases in mesenteric artery reactive oxygen species concentrations assessed by DHE technique and restored the impaired mesenteric artery responses to acetylcholine. While 2K1C hypertension decreased nuclear Nrf2 accumulation, both doses of nitrite increased nuclear Nrf2 accumulation and mRNA expression of Nrf2-regulated genes including superoxide dismutase-1 (SOD1), catalase (CAT), glutathione peroxidase (GPX), thioredoxin-1(TRDX-1) and -2 (TRDX-2). To further confirm nitrite-mediated antioxidant effects, we measured vascular SOD and GPX activity and we found that nitrite at 1 or 15 mg/kg increased the activity of both enzymes (P < 0.05). These results suggest that activation of the Nrf2 pathway promotes antioxidant effects of nitrite, which may improve the vascular dysfunction in hypertension, even when nitrite is given at a sub-antihypertensive dose. These findings may have many clinical implications, particularly in the therapy of hypertension and other cardiovascular diseases.

Author List

Amaral JH, Rizzi ES, Alves-Lopes R, Pinheiro LC, Tostes RC, Tanus-Santos JE

Author

Joseph L. Amaral PhD Assistant Professor in the Neurology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Antihypertensive Agents
Antioxidants
Blood Pressure
Catalase
Disease Models, Animal
Glutathione Peroxidase
Humans
Hypertension, Renovascular
Male
NF-E2-Related Factor 2
Nitrites
Oxidation-Reduction
Rats
Reactive Oxygen Species
Signal Transduction
Superoxide Dismutase-1
Thioredoxins