The protective effect of methylene blue in lungs, small bowel and kidney after intestinal ischemia and reperfusion.

Purpose: To study the role of methylene blue as an inhibitor of superoxide production by xanthine oxidase.

Methods: Thirty-two Wistar rats were divided into 2 groups of 16 animals: the control group and the experimental group. All were submitted to a laparotomy for the occlusion of the cranial mesenteric artery during 60 minutes. The reperfusion was confirmed by the pulsation of the artery after the release of the temporary ligature and color change of the intestines. In the animals of the control group, 2 ml of saline were injected in the peritoneal cavity and in the animals of the experimental group, 2 ml of methylene blue were injected in the peritoneal cavity. After reperfusion for 4 hours, the animals were then sacrificed. The lungs were excised from all 32 rats. Simultaneously, the small intestine and kidneys were ressected in 20 animals (10 from the control group and 10 from the experimental group). Samples of the organs were taken to evaluate the action of xanthine-oxidase, for histopathology studies and for characterization of the edema.

Results: In the animals of the experimental group, the inflammatory lesion as well as the edema in the lung was greater than in the control group. The intestinal and renal lesions were similar in both groups, but the lung damage was superior to that observed in the intestines and kidneys. .

Conclusion: Despite similar action of the xanthine oxidase in the control and the experimental group, after intestinal ischemia and reperfusion, the protective effect of methylene blue was observed only in the lungs of the experimental group.