In vivo microelectrode monitoring of real-time hydrogen concentration in different tissues of rats after inhaling hydrogen gas
Liu BY, Xue JL, Gu QQ, Zhao M, Zhang MY, Wang MY, Wang Y, Qin SC. · Medical Gas Research. 2022;12(3):107–112.
Study at a glance
Preclinical
Fifty anesthetized eight-week-old male Sprague–Dawley rats with microelectrodes placed approximately 1 mm into one of seven exposed tissues.
Continuous hood administration of 4%, 42% or 67% H₂ until tissue equilibrium, followed by air until return to baseline. · Total hood flow was 3 L/min. Target H₂ concentrations were detector-confirmed and O₂ was held at approximately 21%.
Continuous exposure until equilibrium and then air washout; time varied by tissue and concentration rather than following a fixed treatment duration.
Tissue H₂ increased dose-dependently. Mean equilibrium concentration was highest in brain and lowest in thigh muscle; liver/spleen/kidney generally equilibrated faster than muscle/adipose tissues, and higher concentrations took longer to approach 90% saturation and to wash out. This was a distribution study and measured no therapeutic efficacy endpoint.
Anesthetized rats, surgically exposed tissue, shallow single-location microelectrode readings, only one tissue per rat and no efficacy or safety endpoint. Anesthesia can alter tissue blood flow. Chinese public/institutional grants funded the work; authors declared no conflict.
What kind of evidence is this?
Preclinical
In-vivo rat tissue pharmacokinetic experiment across three inhaled H₂ concentrations
Other molecular hydrogen research
Other forms
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Fifty anesthetized eight-week-old male Sprague–Dawley rats with microelectrodes placed approximately 1 mm into one of seven exposed tissues.
Fifty rats overall; equilibrium/dynamic measurements used three to six rats per tissue.
Continuous exposure until equilibrium and then air washout; time varied by tissue and concentration rather than following a fixed treatment duration.
Continuous hood administration of 4%, 42% or 67% H₂ until tissue equilibrium, followed by air until return to baseline.
Cylinder H₂ deliberately mixed with air and separately adjusted O₂ to keep O₂ near 21% — not Brown's gas. Even the 67% H₂ condition was approximately 67% H₂/21% O₂/remainder carrier gas, not the 2:1 electrolytic H₂/O₂ mixture.
Total hood flow was 3 L/min. Target H₂ concentrations were detector-confirmed and O₂ was held at approximately 21%.
Within-experiment comparisons across H₂ concentrations and tissues, with air baseline/washout; there was no disease or therapeutic-outcome control.
Outcomes and reported result
Real-time equilibrium H₂ concentration plus 50%/90% saturation and desaturation times in brain, liver, spleen, kidney, thigh muscle and visceral/subcutaneous white adipose tissue.
Tissue H₂ increased dose-dependently. Mean equilibrium concentration was highest in brain and lowest in thigh muscle; liver/spleen/kidney generally equilibrated faster than muscle/adipose tissues, and higher concentrations took longer to approach 90% saturation and to wash out. This was a distribution study and measured no therapeutic efficacy endpoint.
The complete free PMC article, device/methods, figures and disclosures were checked for exact mixture construction, total and calculated component flows, tissue samples, pharmacokinetic findings, limitations, funding and conflicts.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Anesthetized rats, surgically exposed tissue, shallow single-location microelectrode readings, only one tissue per rat and no efficacy or safety endpoint. Anesthesia can alter tissue blood flow. Chinese public/institutional grants funded the work; authors declared no conflict.
Rat tissue distribution under anesthesia; it informs exposure design but does not establish a therapeutic dose or effect in humans.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 34854421 · DOI: 10.4103/2045-9912.330694
Free full article in PubMed Central.
Complete PMC article and PubMed metadata; full-text extraction checked 9 August 2026.
10 August 2026
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