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[Effects of limb ischemia preconditioning on pulmonary free radicals and cytokine levels in a rabbit model of lung ischemia-reperfusion injury].

OBJECTIVE
To study the effects of limb ischemia preconditioning on pulmonary free radicals and cytokine levels during lung ischemia-reperfusion injury in rabbits.


METHODS
Eighteen healthy rabbits were randomly divided into three groups: control group (group C, n = 6), ischemia/reperfusion group (group I/R, n = 6), limb ischemia preconditioning group (group L, n = 6). At the end of experiments, the wet to dry-weight ratio (W/D), activities of superoxide dismutase (SOD) and myeloperoxidase (MPO), levels of malondialdehyde (MDA) and the contents of cytokines (TNF-α, IL-6, IL-8 and IL-10) were determined in lung tissues. Protein levels of bronchoalveolar lavage fluid and serum were measured to calculate the lung permeability index. Pathologic changes of lung tissues were also observed.


RESULTS
Compared to the group I/R, the lung tissue W/D ratio, MPO activity, lung permeability index, MDA and the cytokines (TNF-α, IL-6 and IL-8) levels were significantly decreased in group L (P < 0.05), while the SOD activity (P < 0.05) and IL-10 contents were significantly increased (P < 0.01). There was no statistical difference in the changes of the above parameters between group L and group C (P > 0.05). The morphologic damages were significantly reduced in group L than that in group I/R.


CONCLUSION
Limb ischemia preconditioning has protective effect against lung ischemia-reperfusion injury, which may at least in part through inhibiting the release of oxygen-derived free radicals and pro-inflammatory cytokines (TNF-α, IL-6, IL-8) and increasing the production of anti-inflammatory cytokine IL-10.