H₂ Papers

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Daily inhalation of hydrogen gas has a blood pressure-lowering effect in a rat model of hypertension.

水素ガス吸入による高血圧ラットモデルでの血圧低下効果の検討

animal study inhalation positive 1.3%

Abstract

Using a 5/6 nephrectomy rat model, the effects of daily 1-hour inhalation of a 1.3% hydrogen gas mixture on blood pressure were investigated. Hydrogen inhalation significantly suppressed the rise in blood pressure following nephrectomy, and the antihypertensive effect was also confirmed in rats already in a stable hypertensive state three weeks post-surgery. Continuous blood pressure monitoring via an implanted telemetry system revealed that the effect persisted during both daytime rest and nighttime activity periods. Spectral analysis of blood pressure variability indicated that hydrogen inhalation improved autonomic nervous system balance by dampening overactive sympathetic activity and enhancing parasympathetic tone, changes that coincided temporally with the observed blood pressure reduction.

Mechanism

Hydrogen inhalation appears to lower blood pressure by suppressing excessive sympathetic nervous system activity while augmenting parasympathetic activity, thereby restoring autonomic balance as evidenced by spectral analysis of blood pressure variability.

Bibliographic

Authors
Sugai K, Tamura T, Sano M, Uemura S, Fujisawa M, Katsumata Y, et al.
Journal
Sci Rep
Year
2020 (2020-11-26)
PMID
33244027
DOI
10.1038/s41598-020-77349-8
PMC
PMC7692487

Tags

Disease:hypertension (20) kidney disease (45) Delivery:inhalation delivery (196) Mechanism:anti-inflammatory (743) oxidative stress (899)

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