Methylene Blue Attenuates Lung Injury Induced by Hindlimb Ischemia Reperfusion in Rats.

Lida Jin,Xiangqing Xiong,Liangrong Wang,Baihui Chen,Caiying Bao,Yuzhu Ye,Bi Lin,Xiyue Zhao

doi:10.1155/2018/2508620

Abstract

Objective This study was aimed to investigate the protective effect of methylene blue against lung injury induced by reperfusion of ischemic hindlimb in a rat model. Methods Twenty-four healthy adult male Sprague-Dawley rats were equally randomized into three groups: sham (SM) group, ischemia reperfusion (IR) group, and methylene blue (MB) group. Rats in both IR and MB groups were subjected to 4 h of ischemia by clamping the left femoral artery and then followed by 4 h of reperfusion. Treatment with 1% methylene blue (50 mg/kg) was administrated intraperitoneally at 10 min prior to reperfusion in the MB group. After 4 h of reperfusion, malondialdehyde (MDA) level, myeloperoxidase (MPO), and superoxide dismutase (SOD) activities in lung tissue were detected; inflammatory cytokines, including IL-1β and IL-6, were measured in bronchoalveolar lavage fluid (BALF); correspondingly, the morphological changes and water content in both gastrocnemius muscle and lung samples were evaluated. Results Hindlimb IR caused remarkable morphological abnormalities and edema in both muscle and lung tissues. SOD activity was decreased, both the MPO activity and MDA level in lung tissue, as well as IL-1β and IL-6 levels in BALF, were increased in the IR group (p < 0.05). Compared with the IR group, SOD activity was increased, whereas MPO activity and MDA level in lung tissue and IL-1β and IL-6 levels in BALF were decreased in the MB group (p < 0.05). Also, the histological damage and edema in both lung and muscle tissues were significantly attenuated by the treatment of methylene blue. Conclusion Methylene blue attenuates lung injury induced by hindlimb IR in rats, at least in part, by inhibiting oxidative stress.

Highlights

Prolonged cessation of the blood flow in lower extremity would cause ischemic damage, while subsequent restoration of blood flow paradoxically provokes ischemia reperfusion (IR) injury
It is reported that methylene blue transfers electrons from flavoenzymes, primarily xanthine oxidase (XO), where molecular oxygen is normally converted into superoxide radicals; methylene blue could be used as an antioxidative agent [9]
Light microscope examination revealed muscular fiber degeneration, sarcoplasm dissolution, neutrophil infiltration, and erythrocyte diapedesis in muscle tissue from the IR group (Figure 1(b)), and skeletal muscle damage was attenuated by methylene blue treatment (Figure 1(c))

Summary

Introduction

Prolonged cessation of the blood flow in lower extremity would cause ischemic damage, while subsequent restoration of blood flow paradoxically provokes IR injury. It has been well documented that lower limb IR could lead to remote lung injury, which is primarily characterized by increased pulmonary capillary permeability, edema, and neutrophil infiltration [1, 2]. The exact mechanisms underlying these processes are not fully understood, oxygen radical formation and oxidative stress are believed to play key roles [3, 4]. It is reported that methylene blue transfers electrons from flavoenzymes, primarily xanthine oxidase (XO), where molecular oxygen is normally converted into superoxide radicals; methylene blue could be used as an antioxidative agent [9]. The aim of this study was to determine whether methylene blue would attenuate lung injury induced by hindlimb IR in a rat model

Methods

Results

Conclusion