Magnesium sulfate mitigates lung injury induced by bilateral lower limb ischemia-reperfusion in rats

Background: Lower limb ischemia-reperfusion (I/R) elicits oxidative stress and causes inflammation in lung tissues that may lead to lung injury. Magnesium sulfate (MgSO ₄) possesses potent anti-oxidation and anti-inflammation capacity. We sought to elucidate whether MgSO ₄ could mitigate I/R-induced lung injury. As MgSO ₄ is an L-type calcium channel inhibitor, the role of the L-type calcium channels was elucidated. Materials and Methods: Adult male rats were allocated to receive I/R, I/R plus MgSO ₄ (10, 50, or 100 mg/kg), or I/R plus MgSO ₄ (100 mg/kg) plus the L-type calcium channels activator BAY-K8644 (20 μg/kg) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquets high around each thigh for 3 h followed by reperfusion for 3 h. After euthanization, degrees of lung injury, oxidative stress, and inflammation were determined. Results: Arterial blood gas and histologic assays, including histopathology, leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity), and lung water content, confirmed that I/R caused significant lung injury. Significant increases in inflammatory molecules (chemokine, cytokine, and prostaglandin E ₂ concentrations) and lipid peroxidation (malondialdehyde concentration) confirmed that I/R caused significant inflammation and oxidative stress in rat lungs. MgSO ₄, at the dosages of 50 and 100 mg/kg but not 10 mg/kg, attenuated the oxidative stress, inflammation, and lung injury induced by I/R. Moreover, BAY-K8644 reversed the protective effects of MgSO ₄. Conclusions: MgSO ₄ mitigates lung injury induced by bilateral lower limb I/R in rats. The mechanisms may involve inhibiting the L-type calcium channels.