The combination of hydrogen gas and hydrogen-rich solution does not protect against ischemic spinal cord injury in rabbits.

Purpose: This study aimed to determine whether the combination of H₂ gas inhalation and administration of hydrogen-rich acetated Ringer's solution (HS) could protect against ischemic spinal cord injury in rabbits.

Methods: In Experiment 1, rabbits were randomly assigned to a 1.2% H₂ gas group, HS group, 1.2% H₂ gas + HS group (combination group), or control group (n = 6 per group). The H₂ concentration of HS was 0.65 mM. H₂ was inhaled for 60 min, starting 5 min before reperfusion. HS (20 mL/kg) was divided into six bolus injections at 10-min intervals, starting 5 min before reperfusion. Spinal cord ischemia was produced by occluding the abdominal aorta for 15 min. Neurologic and histopathologic evaluations were performed 7 days after reperfusion. In Experiment 2, H₂ concentrations in spinal cord tissue according to the administration of 1.2% H₂ gas or HS were compared by measuring the electric current through a platinum needle electrode (n = 2). In Experiment 3, rabbits were assigned to a 2% H₂ gas group or control group (n = 6 per group). Spinal cord ischemia was produced and neurologic and histopathologic evaluations were performed as in Experiment 1.

Results: There were no significant differences among the groups in the neurologic and histopathologic outcomes in Experiments 1 and 3. Bolus administration of HS (10 mL) transiently increased the current to only 1/30th and 1/27th of the plateau current with 1.2% H₂ gas inhalation in two animals.

Conclusion: These results suggest that the combination of 1.2% H₂ gas inhalation and administration of a hydrogen-rich solution does not protect against ischemic spinal cord injury and that the increase in H₂ concentration in spinal cord tissue after administration of HS is very low compared to 1.2% H₂ gas inhalation.