Ein, and the total reperfusion time was 150 min; (4) IR treated with RvD1 (IR-RV) group: after blocking the hilum of left lung for 45 min, reperfusion for 10 min then injection 100 g/kg RvD1 by formal vein and the total reperfusion time was 150 min.Blood and tissue harvestThe animal procedures were approved by Wenzhou Medical University Animal Care and Use Committee, which were certified by the Chinese Association of Accreditation of Laboratory Animal Care and were consistent with the Guide for the Care and Use of Laboratory Animals [updated (2011) version of the NIH guidelines]. Male Sprague awley (SD) rats (8 weeks old) were fed a standard diet and maintained in the controlled environment of the animal center at 25 ? 1 under a 12 h light ark cycle. The LIRI rat model was induced by the following procedures. Briefly, rats were anesthetized by an intraperitoneal injection of 10 chloral hydrate (300 mg/kg body weight) and placed in a supine position. The animals were then intubated for artificial ventilation with oxygen using a small animal breathing machine (tidal volume 5 ml, frequency 70 per min) and electrocardiograph monitor. Thoracotomy was performed at the anterior lateral side of the left fourth intercostal. The muscular layer and pleura were gentle dissected to PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28893839 expose the heart and lung. After that, the hilum of left lung was dissociated and the artery clamp was used to pass through the hilum of lung from the upper right to lower left. The wholeBlood samples were collected in each group immediately before thoracotomy (T1) and after the experiments (T2). In Sham group, T2 was achieved after 195 min of the artery clip across the left hilus pulmonis. For all the other groups, T2 blood samples were obtained after 150 min of reperfusion. Rats were killed after blood collection. The bronchoalveolar lavage fluid (BALF) was then collected by washing the airways of the left lungs three times with a total of 5 mL of phosphate buffer solution (PBS) through a tracheal cannula (recovery rate >80 ), which was pooled and centrifuged at 3000 rpm/min for 15 min for further use. At time point of T2, the left lung tissue of rats was dissected to measure the W/D value (wet to dry weight ratio, W/D). Other lung tissue were fixed in 4 paraformaldehyde or frozen in -70 refrigerator for further analysis.Lung tissue hematoxylin osin (HE) GW 4064 site staining and transmission electron microscopy (TEM)The obtained lung tissue samples at T2 were fixed in 10 neutral-buffered formalin and subsequently embedded in paraffin. Tissue sections (5 m thick) were stainedZhao et al. J Transl Med (2016) 14:Page 3 ofwith HE using a standard protocol and analyzed by light microscopy. For TEM examination, lung tissue containing a 2 mm portion from the edge of the incision were immediately fixed in 0.1 M phosphate buffer containing 2.5 glutaraldehyde and 2 paraformaldehyde for at least 4 h. Samples were made of resin-embedded blocks, which were cut into 60 80 nm ultrathin sections with an ultramicrotome (PT-XL, RMC, USA). The ultrathin sections were placed on carbon coated nickel grids and examined with an H-7500 transmission electron microscope (H-7500, Tokyo, Japan) operating at 80 kV.Measurement of injured alveoli rate (IAR)according to the kit protocol (Jiancheng Bioengineering Institute, Nanjing, China). The amount of Pi was measured with the malachite green dye method.Measurement of glycogen and lactic acid content in the lung tissueThe lung tis.