PURPOSE

This study aimed to determine whether the combination of H 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% H gas group, HS group, 1.2% H gas + HS group (combination group), or control group (n = 6 per group). The H concentration of HS was 0.65 mM. H 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, H concentrations in spinal cord tissue according to the administration of 1.2% H 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% H 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% H gas inhalation in two animals.

CONCLUSION

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