Protection by Inhaled Hydrogen Therapy in a Rat Model of Acute Lung Injury Can Be Tracked in Vivo Using Molecular Imaging
Audi SH, Jacobs ER, Zhang X, Camara AKS, Zhao M, Medhora M, Rizzo B, Clough AV. · Shock. 2017;48(4):467-476.
Study at a glance
Preclinical
Adult male Sprague-Dawley rats exposed to room air, 98% O₂ plus 2% N₂, or 98% O₂ plus 2% H₂.
Continuous chamber exposure to 98% O₂ plus 2% H₂ for 24, 48 or 60 hours. · The chamber measured >1.8% H₂ and >96% O₂. The article does not report total chamber gas flow, so H₂ and O₂ mL/min cannot be calculated.
Continuous 24-, 48- or 60-hour exposure, with outcome-specific assessments and imaging.
H₂ reduced several imaging, oxidative, inflammatory and pleural-effusion changes and partially protected mitochondrial recovery. It did not improve body-weight change at 24 or 60 hours, did not significantly reduce lung wet-weight/body-weight rise, produced a higher 24-hour wet/dry ratio than hyperoxia alone, and did not change 4-HNE; results differed from some prior rat studies.
Preclinical hyperoxia model with continuous near-pure-oxygen exposure unlike many clinical contexts, outcome-specific subsets, numerous comparisons, no reported total gas flow and some findings inconsistent with earlier studies. NIH, VA and foundation support was reported; no explicit author conflict statement was identified, so absence is not inferred.
What kind of evidence is this?
Preclinical
Controlled time-course hyperoxia experiment with blinded histology and in-vivo molecular imaging subsets
Respiratory health
Inhaled H₂
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
Adult male Sprague-Dawley rats exposed to room air, 98% O₂ plus 2% N₂, or 98% O₂ plus 2% H₂.
181 rats overall: normoxia n=42, hyperoxia n=77 and hyperoxia plus H₂ n=62. Different histology, biochemical and imaging outcomes used prespecified random subsets.
Continuous 24-, 48- or 60-hour exposure, with outcome-specific assessments and imaging.
Continuous chamber exposure to 98% O₂ plus 2% H₂ for 24, 48 or 60 hours.
Inhaled premixed H₂/O₂ gas — not Brown's gas: the source mixture was 2% H₂ and 98% O₂, not the 2:1 H₂:O₂ ratio.
The chamber measured >1.8% H₂ and >96% O₂. The article does not report total chamber gas flow, so H₂ and O₂ mL/min cannot be calculated.
Not reported — no total mixture flow or H₂ mL/min is provided.
Nominal 98% O₂ (measured >96%), but O₂ mL/min is not reportable without total gas flow.
Room-air normoxia and 98% O₂ plus 2% N₂ hyperoxia groups at matching exposure times.
Outcomes and reported result
Body/lung weights, edema and pleural effusion, histology, lavage protein/cells, oxidative markers, mitochondrial membrane recovery, glutathione, and SPECT HMPAO/duramycin uptake.
H₂ reduced several imaging, oxidative, inflammatory and pleural-effusion changes and partially protected mitochondrial recovery. It did not improve body-weight change at 24 or 60 hours, did not significantly reduce lung wet-weight/body-weight rise, produced a higher 24-hour wet/dry ratio than hyperoxia alone, and did not change 4-HNE; results differed from some prior rat studies.
The complete free PMC author manuscript was checked for all exposure groups and totals, gas composition/measurements, time points, imaging and tissue outcomes, positive and null findings, funding and available disclosure section.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
Preclinical hyperoxia model with continuous near-pure-oxygen exposure unlike many clinical contexts, outcome-specific subsets, numerous comparisons, no reported total gas flow and some findings inconsistent with earlier studies. NIH, VA and foundation support was reported; no explicit author conflict statement was identified, so absence is not inferred.
Hyperoxia-induced lung injury in adult male rats; it does not establish inhaled H₂ treatment for human ALI/ARDS.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 28915216 · DOI: 10.1097/SHK.0000000000000872
Free full author manuscript in PubMed Central.
Complete PMC author manuscript and PubMed metadata; full-text extraction checked 9 August 2026.
10 August 2026
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