# Comparison of hydrogen administration methods in the treatment of radiation-induced heart disease in rats.
> 放射線誘発性心疾患ラットモデルにおける水素投与経路（水素水摂取vs吸入）の比較検討


## Abstract

Male Wistar rats subjected to 10 Gy X-ray thoracic irradiation showed marked elevations in lactate dehydrogenase (LDH), catalase, glutathione peroxidase activity, malondialdehyde, superoxide, and tumor necrosis factor-alpha in blood plasma or cardiac tissue at 2 and 9 days post-exposure. Both oral intake of hydrogen-rich water (minimum 4 mg/L) and inhalation of 4% H2 gas restored these oxidative stress and inflammatory markers toward baseline values. The Nrf2/Keap1 antioxidative signaling pathway, which was activated by irradiation, was also normalized by both delivery routes. Cardiac damage was attenuated under both conditions, with H2 gas inhalation showing a more pronounced trend; however, the authors note that larger studies are required to achieve statistical significance and clarify underlying mechanisms.

### Mechanism

H2 normalizes the irradiation-activated Nrf2/Keap1 antioxidative pathway, reducing lipid peroxidation products, superoxide levels, and TNF-alpha, thereby limiting oxidative and inflammatory damage to cardiac tissue.

## Bibliographic

- **Authors**: Kura B, Pavelkova P, Kalocayova B, Sykora M, Vlkovicova J, Kluknavsky M, et al.
- **Journal**: Can J Physiol Pharmacol
- **Year**: 2026 (2026-01-01)
- **PMID**: [41806364](https://pubmed.ncbi.nlm.nih.gov/41806364/)
- **DOI**: [10.1139/cjpp-2025-0085](https://doi.org/10.1139/cjpp-2025-0085)
- **Study type**: animal study
- **Delivery route**: mixed routes
- **Effect reported**: positive
- **H2 concentration**: 4%

## Delivery context

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and 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)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

---

> **Cite as**: H2 Papers — PMID 41806364. https://h2-papers.org/en/papers/41806364
> **Source**: PubMed PMID [41806364](https://pubmed.ncbi.nlm.nih.gov/41806364/)