Objective: To investigate the effect of hydrogen inhalation on acute lung injury after hemorrhagic shock in rats.
Methods: Twenty-four adult male Sprague-Dawley (SD) rats were equally randomized into three groups: sham operation group, model group and hydrogen-treatment group. Pressure-controlled hemorrhagic shock and resuscitation model was reproduced by blood-letting for 1 hour followed by fluid replacement for 2 hours. The rats in model group received a mixture of 50% oxygen-50% nitrogen during the process. The rats in hydrogen-treatment group received inhalation of a mixture of 2% hydrogen-48% nitrogen-50% oxygen 10 minutes before fluid replacement till the end of resuscitation. The arterial blood samples were collected for the measurement of arterial partial pressure of oxygen (PaO₂) before exsanguination, 1 hour after shock, 1 hour and 2 hours after fluid replacement. Blood and lung tissues were collected at the end of experiment, and tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels in plasma, lung wet/dry weight ratio (W/D), malondialdehyde (MDA) content, superoxide dismutase (SOD) and myeloperoxidase (MPO) activity in the lung tissue were determined. The lung tissue was subjected to pathological examination.
Results: At the end of fluid replacement, compared with model group, hydrogen could significantly reduce pulmonary edema (lung W/D ratio: 4.72 ± 0.12 vs. 4.94 ± 0.14, P<0.05), inhibit oxidative stress (MDA: 0.55 ± 0.09 nmol/mg vs. 0.72 ± 0.08 nmol/mg, P<0.05), enhance antioxidant activity (SOD activity: 79.53 ± 14.33 U/mg vs. 59.55 ± 9.07 U/mg, P<0.05), reduce the release of pro-inflammatory cytokines (TNF-α: 55.58 ± 10.06 ng/L vs. 66.58 ± 5.17 ng/L; IL-6: 23.00 ± 2.77 ng/L vs. 27.09 ± 2.46 ng/L, both P<0.05) and inhibit neutrophil infiltration (MPO: 1.05 ± 0.18 U/g vs. 1.40 ± 0.14 U/g, P<0.05). It alleviated the damage to lung tissue, and then improved the lung function (PaO₂: 146.3 ± 22.1 mm Hg vs. 123.6 ± 16.0 mm Hg, P<0.05).
Conclusions: Hydrogen treatment can alleviate acute lung injury as a result of hemorrhagic shock and resuscitation.