Methylene Blue Protects the Isolated Rat Lungs from Ischemia-Reperfusion Injury by Attenuating Mitochondrial Oxidative Damage

Abstract

Introduction: Impaired mitochondrial function is a key factor attributing to the lung ischemia reperfusion injury (LIRI). Methylene blue (MB) has been reported to attenuate brain and renal ischemia-reperfusion injury. We hypothesized that MB also could have a protective effect against LIRI by preventing mitochondrial oxidative damage.

Methods: Isolated rat lungs were assigned to the following four groups (n = 6): a sham group: perfusion for 105 min without ischemia; I/R group: shutoff of perfusion and ventilation for 45 min followed by reperfusion for 60 min; and I/R + MB group and I/R + glutathione (GSH) group: 2 mg/kg MB or 4 μM glutathione were intraperitoneally administered for 2 h, and followed by 45 min of ischemia and 60 min of reperfusion.

Results: MB lessened pulmonary dysfunction and severe histological injury induced by ischemia-reperfusion injury. MB reduced the production of reactive oxygen species and malondialdehyde and enhanced the activity of superoxide dismutase. MB also suppressed the opening of the mitochondrial permeability transition pore and partly preserved mitochondrial membrane potential. Moreover, MB inhibited the release of cytochrome c from the mitochondria into the cytosol and decreased apoptosis. Additionally, MB downregulated the mRNA expression levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18).

Conclusion: MB protects the isolated rat lungs against ischemia-reperfusion injury by attenuating mitochondrial damage.

Keywords: Isolated lung reperfusion; Lung ischemia–reperfusion injury; Methylene blue; Mitochondrial damage.