Methylene blue prevents lung injury after intestinal ischemia reperfusion in rabbit

Objective To investigate the protective effect and its mechanisms of methylene blue (MB) on pulmonary injury after ischemia reperfusion (I/R),and the mechanism of MB. Methods Twenty four rabbits were randomly divided into three groups:sham operated group (group S) underwent an identical laparotomy except for the superior mesenteric artery (SMA) occlusion. The I/R group and MB treated group was produced by occluding the SMA for 1 hr,reperfusing for 2hrs respectively. MB group was received 1% MB by 10mg/kg before immediately removed the clip,I/R group was administered with saline. The model of intestinal I/R was developed by occluding the SMA. The serum IL-8,TNF-α concentration,the level of MDA,the activities of SOD,XOD,CAT and O2-in lung tissue were determined at the end of the experiment. Results The mean artary pressure (MAP) was significantly lower in I/R group than that in MB group after intestinal I-R (P0.01),but MAP did not significantly change in MB group. The level of O-2 and MDA in the lung tissue were markedly increased in I-R group than that of in the S group (P0.01),but no significant change in MB group. The activities of SOD and XOD in lung tissue did not significantly change in all groups. The serum concentration of IL-8 and TNF-α were significantly higher in group I/R than that in group S (P0.01),but no significant change in MB group compared to group S. The serum concentration of IL-8 and TNF-α were significantly lower in MB group than that in I-R group (P0.01). Conclusion MB can reduce lung injury after intestinal I-R. The mechanisms may be associated with inhibiting the generation of OFR and decreasing inflammatory response.