RESUMO
<p><b>OBJECTIVE</b>To study the effects of limb ischemia preconditioning on pulmonary free radicals and cytokine levels during lung ischemia-reperfusion injury in rabbits.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>