Methylene Blue Attenuates Ischemia-reperfusion-induced Mitochondrial Injury In Heart And Lung

Methylene blue (MB) is a kind of phenothiazine salts, which is used to treat methemoglobinemia and cyanide poisoning. It has been reported that MB could act as electron carrier so that enhanced the function of respiratory chain in mitochondria. Our studies used hydrogen peroxide (H2O2) to stimulate mouse peritoneal macrophages RAW264.7 and caused oxidative stress, and we also established rat isolated heart and lung ischemia-reperfusion (IR) injury models to study the protective effects and mechanisms of MB in oxidative stress injury and IR injury.In the study of oxidative stress injury induced by H2O2 stimulating RAW264.7,RAW264.7 treated with 0.1 ?M and 1 ?M MB increased the viability of cells and decreased the release of LDH in cells, which indicated that MB could alleviate cell damage. Treated with MB also reduced the production of reactive oxygen species (ROS) and increased the activity of superoxyde dismutase (SOD) in RAW264.7 stimulated by H2O2, which showed that MB could improved oxidative stress effectively. Moreover, treated with MB increased the mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) output,while decreased the activation level of Caspase 3 and reduced apoptosis. All of these indexes indicated that MB could enhance the function of mitochondria and inhabit apoptosis.The results of rat heart and lung IR experiments showed that rats intraperitoneal injected with 2 mg/kg MB 2 hours before operation improved isolated heart and lung function,alleviated pathologic lesion, reduced the release of LDH, which indicated that MB improved organs function after IR. Compared with IR group, treated with MB decreased the production of ROS and malondialdehyde (MDA), meanwhile enhanced SOD activity, which improved oxidative stress effectively. MB also increased MMP level and ATP concentration, while attenuating mitochondrial swelling, reflecting that MB protected mitochondria injury. In lung IR experiments, treated with MB inhabited cytochrome C release from mitochondria to cytosol so that reduced apoptosis.In conclusion, the results of studies indicate that MB attenuates oxidative stress injury in RAW264.7 induced by H2O2 and IR injury in rat isolated heart and lung. The potential mechanism behind this protection might related with maintaining mitochondrial function and alleviating mitochondrial damage.