| 1. |
- Jansson, Emmelie Å, et al.
(författare)
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A mammalian functional nitrate reductase that regulates nitrite and nitric oxide homeostasis
- 2008
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Ingår i: Nature Chemical Biology. - : Springer Science and Business Media LLC. - 1552-4450 .- 1552-4469. ; 4:7, s. 411-417
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Tidskriftsartikel (refereegranskat)abstract
- Inorganic nitrite (NO(2)(-)) is emerging as a regulator of physiological functions and tissue responses to ischemia, whereas the more stable nitrate anion (NO(3)(-)) is generally considered to be biologically inert. Bacteria express nitrate reductases that produce nitrite, but mammals lack these specific enzymes. Here we report on nitrate reductase activity in rodent and human tissues that results in formation of nitrite and nitric oxide (NO) and is attenuated by the xanthine oxidoreductase inhibitor allopurinol. Nitrate administration to normoxic rats resulted in elevated levels of circulating nitrite that were again attenuated by allopurinol. Similar effects of nitrate were seen in endothelial NO synthase-deficient and germ-free mice, thereby excluding vascular NO synthase activation and bacteria as the source of nitrite. Nitrate pretreatment attenuated the increase in systemic blood pressure caused by NO synthase inhibition and enhanced blood flow during post-ischemic reperfusion. Our findings suggest a role for mammalian nitrate reduction in regulation of nitrite and NO homeostasis.
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| 2. |
- Timby, Niklas, et al.
(författare)
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Effects of age, sex and diet on salivary nitrate and nitrite in infants
- 2020
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Ingår i: Nitric oxide. - : Elsevier. - 1089-8603 .- 1089-8611. ; 94, s. 73-78
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Tidskriftsartikel (refereegranskat)abstract
- The inorganic anions nitrate and nitrite are oxidation products from endogenous nitric oxide (NO) generation and constituents in our diet. A nitrate-nitrite-NO pathway exists in which nitrate can be serially reduced to bioactive NO. The first step of this pathway occurs in the oral cavity where oral bacteria convert salivary nitrate to nitrite, whereafter nitrite is reduced to NO systemically by several enzymatic and non-enzymatic pathways. Data are scarce regarding salivary levels and oral conversion capacity of these anions in infants. We measured salivary nitrate and nitrate in infants at 4 and 12 months of age and related values to age, sex, dietary pattern and oral microbiome. Saliva was collected from a total of 188 infants at 4 and 12 months of age. Salivary nitrate, nitrite and nitrite/nitrate ratio as a measure of oral nitrate-reducing capacity were analyzed by HPLC and related to age, sex, type of diet (breast milk or formula) and oral microbiome. There was no difference in salivary nitrate, nitrite or nitrite/nitrate ratio between boys and girls at any age. At 4 months levels of these parameters were lower than what has been described in adults but they had all increased significantly at 12 months of age. At 4 months of age salivary nitrite/nitrate ratio was lower in breast-fed compared to formula-fed infants, but these differences disappeared at 12 months. Several bacterial species were associated with oral nitrate reducing capacity including Prevotella, Veillonella, Alloprevotella and Leptotrichia. We conclude that in infants there is an increase in salivary nitrate and nitrite as well as in oral nitrate-reductase capacity during the first year of life. Differences observed at 4 months of age between breast-fed and formula-fed infants disappear at one year of age.
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