Methylene blue attenuates lung injury after mesenteric artery clamping/unclamping.
BACKGROUND
This controlled, experimental study was designed to assess the effects of intratracheal and intravenous methylene blue on reperfusion lung injury following superior mesenteric artery clamping/unclamping.


METHODS
Superior mesenteric arteries of 144 anaesthetized adult male Wistar rats (n = 12/group) were clamped for 1 h. Ten minutes before unclamping, methylene blue or its vehicle was administered intratracheally or intravenously, followed by a 3 h-respiratory assessment and postexperimental assessment of survival.


RESULTS
Intravenous 3 and 9 mg kg(-1) but not higher methylene blue doses, and intratracheal 6-mg kg(-1) but not lower doses, significantly (P < 0.05) reduced the 100% increase in plateau pressure, 30% reduction in PO(2)/FiO(2), fourfold augmented bronchoalveolar lavage-retrieved volume and the increased polymorphonuclear leukocytes/bronchoalveolar cells' ratio associated with unclamping of the superior mesenteric artery. Lung tissue polymorphonuclear leukocytes count, total xanthine oxidase activity and wet-to-dry-weight ratio were also normal in these dose-treated groups. These effective regimens were also associated with longer animal survival.


CONCLUSIONS
Intratracheal methylene blue mitigates lung reperfusion injury following superior mesenteric artery clamping/unclamping at a similar magnitude as an intravenous regimen. This finding is a novel potential use of methylene blue in vivo.
Weinbroum
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Post-Anaesthesia Care Unit, Animal Research Laboratory, Tel Aviv Sourasky Medical Center and the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. draviw@tasmc.health.gov.il
D000284:Administration, Oral; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D003250:Constriction; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006439:Hemodynamics / Q000187:drug effects; D008168:Lung / Q000098:blood supply*; D008297:Male; D017538:Mesenteric Artery, Superior; D008751:Methylene Blue / Q000627:therapeutic use*; D051381:Rats; D015427:Reperfusion Injury / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D012119:Respiration / Q000187:drug effects
D004791:Enzyme Inhibitors; D008751:Methylene Blue