H₂ Papers

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Molecular Hydrogen Reduces the Degree of Endothelial Alteration under Conditions of Chronic Heart Failure.

慢性心不全モデルラットにおける分子状水素吸入が循環内皮細胞数および心筋構造に及ぼす影響

animal study inhalation positive 2%

Abstract

Using a rat model of chronic heart failure, this study examined how 2% H2 gas inhalation—administered either once (40 min) or repeatedly (40 min/day for 5 consecutive days)—affected the number of circulating endothelial cells and the macrohistological architecture of cardiac tissue. Both inhalation regimens led to a reduction in circulating endothelial cell counts, with the most pronounced decline observed in the repeated-inhalation group at day 14 post-modeling. This reduction was accompanied by partial restoration of myocardial structure and a decrease in heart weight. The findings suggest that H2 inhalation limits endothelial cell damage and supports structural recovery of the myocardium under chronic heart failure conditions.

Mechanism

Inhalation of 2% H2 reduced the number of circulating endothelial cells, indicating attenuation of endothelial injury, and was associated with structural restoration of myocardial tissue and reduced cardiac weight in heart failure rats.

Bibliographic

Authors
Deryugina AV, Danilova DA
Journal
Bull Exp Biol Med
Year
2023
PMID
37773571
DOI
10.1007/s10517-023-05880-5

Tags

Disease:myocardial infarction (28) Delivery:inhalation delivery (196) Mechanism:endothelial function (35) anti-inflammatory (743) oxidative stress (899) reactive oxygen species (774)

Delivery context

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

→ Evidence by delivery route

Safety notes

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

See also:

Other papers on the same disease / condition