Related Experiment Video
Updated: Aug 5, 2026
11:28
Analytical Techniques for Assaying Nitric Oxide Bioactivity
Published on: June 18, 2012
A new physiological biomarker for nitrate exposure in humans
E H Jansen1, R H van den Berg, A B Boink
1Laboratory of Toxicology, National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands.
Toxicology Letters
|May 1, 1995
Summary
N-methylnicotinamide (NMN) may serve as a biomarker for nitrite exposure. Studies in rats and humans showed increased NMN levels after exposure, though individual human responses varied.
Area of Science:
- Toxicology
- Biomarker Discovery
- Human Health
Background:
- Nitrate and nitrite exposure can have toxicological implications.
- N-methylnicotinamide (NMN), a tryptophan metabolite, was observed to increase following toxicological studies.
- The potential of NMN as a biomarker for nitrate/nitrite exposure requires further investigation.
Purpose of the Study:
- To investigate N-methylnicotinamide (NMN) as a potential biomarker for nitrate and nitrite exposure.
- To assess the induction of urinary NMN in response to controlled nitrate/nitrite administration in both animal models and human subjects.
Main Methods:
- Rats were exposed to potassium nitrite (KNO2) or potassium nitrate (KNO3) for 13 weeks.
- Nuclear magnetic resonance was used to measure N-methylnicotinamide (NMN) levels.
- Human volunteers received oral doses of sodium nitrate, and urinary NMN concentrations were monitored.
Main Results:
- Rats exposed to KNO2 showed a significant 2-fold increase in NMN compared to controls.
- Urinary NMN levels in rats decreased after prolonged exposure.
- Human volunteers exhibited varied responses, with some showing up to a 6-fold increase in urinary NMN after nitrate intake.
Conclusions:
- N-methylnicotinamide (NMN) shows potential as a biomarker for internal nitrite exposure in humans.
- Individual variability in human response to nitrate warrants further investigation.
- Additional research is necessary to fully establish the utility of NMN as a reliable biomarker.
Related Concept Videos
01:202° Amines to N-Nitrosamines: Reaction with NaNO2
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
01:28Nitric Oxide Signaling Pathway
Nitric oxide (NO), an inorganic gas, acts as a potent second messenger in most animal and plant tissues. NO diffuses out of the cells that produce it and enters the neighboring cells to generate a downstream response. NO synthase (NOS) catalyzes NO production by the deamination of the amino acid arginine. There are three isoforms of NOS. Endothelial cells have endothelial NOS (eNOS), nerve and muscle cells have neuronal NOS (nNOS), and macrophages produce inducible NOS (iNOS) upon exposure to...
01:19Blood Studies for Cardiovascular System II: CRP, Hcy, and Cardiac Natriuretic Peptide Markers
Cardiac biomarkers are critical in diagnosing, prognosing, and managing cardiovascular diseases. Routine measurement of specific biomarkers such as B-type natriuretic peptide (BNP), C-reactive protein (CRP), and homocysteine (Hcy) is common practice in clinical settings to evaluate heart function and predict cardiovascular events.
These markers indicate stress or strain on the heart muscle:
Natriuretic Peptides (BNP)
Cardiac myocytes produce these hormones in response to ventricular stretching...
These markers indicate stress or strain on the heart muscle:
Natriuretic Peptides (BNP)
Cardiac myocytes produce these hormones in response to ventricular stretching...
01:22Inorganic Nitrogen Assimilation
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme nitrate reductase...