How Inhaled Hydrogen Gas Moves Through the Body in Pigs
- Authors
- Motoaki Sano, Genki Ichihara, Yoshinori Katsumata, Takahiro Hiraide, Akeo Hirai, Mizuki Momoi, Tomoyoshi Tamura, Shigeo Ohata, Eiji Kobayashi
- Journal
- PLoS One
- Year
- 2020
- DOI
- 10.1371/journal.pone.0234626
- Study Type
- Pig
- Outcome
- Neutral
- Peer Reviewed
- Yes
- Country
- Japan
- Health Condition
- Whole Body
- Body System
- Respiratory
TL;DR
Scientists have discovered how hydrogen gas moves and breaks down in the body after being inhaled by using a new method in pigs.
Key Finding
Inhaled hydrogen gas is rapidly absorbed through the lungs into arterial blood within seconds, with peak concentrations dropping to very low levels within 3 minutes, but then redistributing to venous blood and tissues where it persists for at least 60 minutes.
Summary
Researchers used pigs to study what happens when hydrogen gas is inhaled into the lungs. They filled the lungs with pure hydrogen gas and then tracked where it went in the body by measuring hydrogen levels in blood samples taken from different blood vessels over 60 minutes. The hydrogen was quickly absorbed into the bloodstream, peaked immediately after inhalation, and then spread throughout the body, with some hydrogen still detectable in certain blood vessels an hour later.
Practical Takeaway
This is an animal study (in pigs) that maps out the basic path hydrogen gas takes through the body after inhalation—useful foundational information for researchers. However, pig physiology differs from human physiology, and this study does not measure any health effects or benefits. Much more research, including human studies, would be needed to understand whether inhaled hydrogen has practical health applications.
Abstract
The benefits of inhaling hydrogen gas (H2) have been widely reported but its pharmacokinetics have not yet been sufficiently analyzed. We developed a new experimental system in pigs to closely evaluate the process by which H2 is absorbed in the lungs, enters the bloodstream, and is distributed, metabolized, and excreted. We inserted and secured catheters into the carotid artery (CA), portal vein (PV), and supra-hepatic inferior vena cava (IVC) to allow repeated blood sampling and performed bilateral thoracotomy to collapse the lungs. Then, using a hydrogen-absorbing alloy canister, we filled the lungs to the maximum inspiratory level with 100% H2. The pig was maintained for 30 seconds without resuming breathing, as if they were holding their breath. We collected blood from the three intravascular catheters after 0, 3, 10, 30, and 60 minutes and measured H2 concentration by gas chromatography. H2 concentration in the CA peaked immediately after breath holding; 3 min later, it dropped to 1/40 of the peak value. Peak H2 concentrations in the PV and IVC were 40% and 14% of that in the CA, respectively. However, H2 concentration decay in the PV and IVC (half-life: 310 s and 350 s, respectively) was slower than in the CA (half-life: 92 s). At 10 min, H2 concentration was significantly higher in venous blood than in arterial blood. At 60 min, H2 was detected in the portal blood at a concentration of 6.9-53 nL/mL higher than at steady state, and in the SVC 14-29 nL/mL higher than at steady state. In contrast, H2 concentration in the CA decreased to steady state levels. This is the first report showing that inhaled H2 is transported to the whole body by advection diffusion and metabolized dynamically.