# Changes in the negative logarithm of end-tidal hydrogen partial pressure indicate the variation of electrode potential in healthy Japanese subjects.
> 呼気終末水素分圧の負の対数（pH₂）変化が健康な日本人被験者における電極電位の変動を反映する


## Abstract

Molecular hydrogen produced by colonic microbiota is exhaled and can be sampled non-invasively as end-tidal H₂. Applying the Nernst equation, the H⁺/H₂ ratio logarithm reflects electrode potential in solution; by analogy with pH, the authors defined pH₂ as the negative logarithm of H₂ effective pressure. In phosphate-buffered solution (pH 7.1), electrode potential changes were proportional to pH₂ differences. A handheld H₂ sensor was used to measure end-tidal H₂ in 149 healthy Japanese participants at two time points: morning baseline and noon after routine daily activities. The median baseline pH₂ was 4.89, rising by 0.15 units at noon. Multiplying this difference by the relevant Nernst coefficient indicated an oxidation shift of approximately +4.6 mV following daily activities. The findings suggest that end-tidal pH₂ monitoring can serve as a practical, portable means of tracking redox electrode potential fluctuations in healthy individuals.

### Mechanism

Based on the Nernst equation, the logarithm of the H⁺/H₂ ratio is proportional to electrode potential in solution; therefore, pH₂ (negative logarithm of end-tidal H₂ partial pressure) serves as a proxy for in vivo redox potential shifts.

## Bibliographic

- **Authors**: Kiyama T, Tokunaga A, Naji A, Barbul A
- **Journal**: Sci Rep
- **Year**: 2023 (2023-09-19)
- **PMID**: [37726384](https://pubmed.ncbi.nlm.nih.gov/37726384/)
- **DOI**: [10.1038/s41598-023-42651-8](https://doi.org/10.1038/s41598-023-42651-8)
- **PMC**: [PMC10509160](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10509160/)
- **Study type**: human observational study
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 37726384. https://h2-papers.org/en/papers/37726384
> **Source**: PubMed PMID [37726384](https://pubmed.ncbi.nlm.nih.gov/37726384/)