# [A comparison of the measurements of local cerebral blood flow by hydrogen clearance with hydrogen inhalation and by its electrochemical generation in brain tissue].
> 水素クリアランス法における吸入投与と脳組織内電気化学的発生による局所脳血流測定値の比較


## Abstract

In acute experiments using urethane-anesthetized Wistar rats (n=39), local cerebral blood flow (LCBF) was assessed simultaneously from the same platinum electrodes using two modifications of the hydrogen clearance technique: inhalation (H2-Inh) and electrochemical generation within brain tissue (H2-Gen). Sharpened platinum electrodes (tip diameter 20–40 µm) were implanted into the sensorimotor cortex, with one electrode generating H2 via DC current (3–5 µA) and the remaining electrodes recording partial H2 pressure polarographically. Mean resting LCBF was 1.67 ± 0.54 ml/g/min by H2-Inh (N=149) and 3.17 ± 0.91 ml/g/min by H2-Gen (N=147). The ratio of clearance values between the two methods ranged from 1.0 to 4.0 across experiments. A diffusional component estimated at 1.2–2.5 equivalent units was identified in dead cortex. LCBF responses to 7.5% CO2 inhalation and middle cerebral artery branch occlusion were also evaluated, and morphological verification was performed using India ink perfusion and frozen sections.

### Mechanism

Electrochemically generated H2 within tissue introduces a diffusional component absent in the inhalation method, leading to systematically higher LCBF estimates with H2-Gen compared to H2-Inh.

## Bibliographic

- **Authors**: Moskalenko IuE, Rovainen CM, Woolsey TA, Wei L, Lui D, Spence ME, et al.
- **Journal**: Fiziol Zh Im I M Sechenova
- **Year**: 1994
- **PMID**: [7550427](https://pubmed.ncbi.nlm.nih.gov/7550427/)
- **Study type**: animal study
- **Delivery route**: mixed routes
- **Effect reported**: not assessed

## 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)

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> **Cite as**: H2 Papers — PMID 7550427. https://h2-papers.org/en/papers/7550427
> **Source**: PubMed PMID [7550427](https://pubmed.ncbi.nlm.nih.gov/7550427/)