The effects of methylene blue on lung injury in septic rats.
OBJECTIVE
We aimed to investigate the effects of methylene blue (MB) on NO production, myeloperoxidase (MPO) activity, antioxidant status and lipid peroxidation in lung injury during different stages of sepsis in rats.


METHODS
Rats were randomly divided into 4 groups (n = 20): group C, sham operated; group CMB, sham operated and receiving MB (25 mg/kg, i.p.); group S, sepsis; group SMB, sepsis and receiving MB (25 mg/kg, i.p.). Sepsis was induced by cecal ligation and puncture (CLP). The MB dose was administered after CLP. Each group was subdivided into two subgroups (n = 10) which were sacrificed at 9 or 18 h after the surgical procedure. The levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX) and MPO activity, total nitrite/nitrate and malondialdehyde (MDA) in the lung tissue were measured. Lung injury was graded from 1 (injury to 25% of the field) to 4 (diffuse injury) by the pathologist.


RESULTS
In group SMB, while SOD and CAT increased in both early and late sepsis periods, GSH-PX increased significantly only in the early sepsis period when compared with group S. Increase in lung MPO activity after CLP-induced sepsis was prevented by MB administration. MB significantly decreased to nitrite/nitrate and MDA levels both in early and late sepsis periods when compared with group S (p < 0.05). Group S showed a marked increase in neutrophil infiltration into the interstitial space and thickening of the alveolar septa, whereas the alveolar damage score was lower in the SMB group (p < 0.05).


CONCLUSIONS
MB reduced the MPO activity and lipid peroxidation by both decreasing oxidative stress and NO overproduction in the lungs, which resulted in the attenuation of lung injury after CLP-induced sepsis in rats.
Department of Anesthesiology and Reanimation, Medical School of Inonu University, Malatya, Turkey. sedemirbilek@inonu.edu.tr
S
S
Demirbilek
E
E
Sizanli
N
N
Karadag
A
A
Karaman
N
N
Bayraktar
E
E
Turkmen
M O
MO
Ersoy
D000818:Animals; D000890:Anti-Infective Agents / Q000627:therapeutic use; D002374:Catalase / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D006207:Half-Life; D015227:Lipid Peroxidation / Q000187:drug effects; D008751:Methylene Blue / Q000493:pharmacokinetics / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012128:Respiratory Distress Syndrome / Q000150:complications* / Q000188:drug therapy / Q000473:pathology; D018805:Sepsis / Q000188:drug therapy* / Q000209:etiology*; D013482:Superoxide Dismutase / Q000378:metabolism
D000890:Anti-Infective Agents; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D008751:Methylene Blue