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Updated: Jul 26, 2026

Analytical Techniques for Assaying Nitric Oxide Bioactivity
Published on: June 18, 2012
Salivary contribution to exhaled nitric oxide
W Zetterquist1, C Pedroletti, J O Lundberg
1Dept of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden.
Dietary nitrate intake significantly increases exhaled nitric oxide (NO) by boosting salivary nitrite levels. This finding suggests oral bacteria influence NO measurements, potentially mimicking airway inflammation.
Area of Science:
- Physiology
- Biochemistry
- Respiratory Medicine
Background:
- Dietary nitrate is converted to nitrite in saliva by oral bacteria.
- Nitrite can nonenzymatically form nitric oxide (NO).
- Exhaled NO is a marker for airway inflammation.
Purpose of the Study:
- To investigate the influence of salivary nitrite on exhaled NO measurements.
- To determine if dietary nitrate loading affects exhaled NO levels.
- To assess the impact of oral bacteria on NO production.
Main Methods:
- Ten healthy subjects ingested potassium nitrate.
- Exhaled and nasal NO levels were measured using chemiluminescence.
- Salivary nitrite concentrations were monitored.
- Oral bacteria activity was manipulated using mouthwashes (chlorhexidine acetate, sodium bicarbonate).
Main Results:
- Ingesting nitrate significantly increased exhaled NO levels peaking at 120 minutes.
- Salivary nitrite concentrations rose in parallel with exhaled NO.
- Antibacterial mouthwash (chlorhexidine acetate) reduced exhaled NO by approximately 50%.
- Sodium bicarbonate also decreased exhaled NO, but less effectively.
Conclusions:
- Salivary nitric oxide formation significantly contributes to exhaled NO.
- High nitrate intake can elevate exhaled NO, potentially leading to misinterpretation as airway inflammation.
- Standardized methods for exhaled NO measurement should account for oral nitrate-to-nitrite conversion.
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