Effect of low-level laser therapy on lung injury induced by hindlimb ischemia/reperfusion in rats

To investigate the effect of low-level laser therapy (LLLT 650 nm) on the lung remote organ injury induced by hindlimb ischemia/reperfusion (I/R). The experiments were performed on 50 healthy mature male Wistar rats weighing mean 230 ± 20 g. The rats were randomly allocated into five equal groups as follows: normal group (animals nonmanipulated), sham group (operated with no ischemia), laser group (animals nonmanipulated and irradiated with laser), I/R group, and I/R + LLLT group. Rats were prepared for sterile surgery, and then, right hindlimbs were subjected to I/R induced by the femoral artery occlusion for duration of 120 min, followed by a 60-min reperfusion. The LLLT (K30 handheld probe, AZOR, Technica, Russia, 650 nm, 30 mW, surface area = 1 cm², 60 S/cm², energy density = 1.8 J/cm²) was carried out by irradiating the rats over a unique point on the skin over the right upper bronchus for 5 and 15 min after initiating reperfusion for 3 min. At the end of the trial, rats were euthanized under deep anesthesia and the right lung tissues were removed. Myeloperoxidase (MPO) and superoxide dismutase (SOD) activities and nitric oxide (NO), malondialdehyde (MDA), and glutathione (GSH) levels were measured in the lung tissues. The tissue samples were further examined histopathologically under light microscopy. It was found that I/R elevated MPO activity, MDA, and NO levels accompanied by a reduction in SOD activities and GSH levels (P < 0.05). LLLT restored MDA and NO levels, MPO and SOD activity, GSH levels, and lung injury scores (P < 0.05). In light of these findings, the LLLT has alleviated the lung tissue injuries after skeletal muscle I/R in this experimental model.