Rat Lung Ischemia-reperfusion Research Articles

Circulating mtNFPs Are Associated with ARDS after CPB and Regulate Endothelial Barrier through FPR2.

Cardiopulmonary bypass (CPB) increases the risk of acute respiratory distress syndrome (ARDS) due to endothelial cell (EC) barrier dysfunction. However, the specific role of mitochondrial N-formyl peptides (mtNFPs) in ARDS following CPB remains unexplored. Here, we investigated the differential expression of circulating mtNFPs in patients after CPB, focusing on the novel role of FPR2 in ECs. Levels of circulating mtNFPs were assessed using enzyme-linked immunosorbent assay (ELISA). Several mtNFPs (ND4, ND5, ND6, and Cox1) were significantly upregulated in patients with ARDS at day 1 post-CPB compared to patients without ARDS. Higher levels of ND6 were correlated with worst PaO2/FiO2 (r=-0.2219 and P<0.0001) and cardiac Troponin T (r=2.107 and P<0.0001). Utilizing patient-derived serum and a rat lung ischemia reperfusion injury (LIRI) model, we observed a positive correlation between serum ND6 concentration and ARDS, which is also associated with EC barrier dysfunction. In vitro experiments, using trans-endothelial electric resistance (TEER) measurements and fluorescence microscopy with FITC-labeled VE-cadherin, demonstrated that ND6 disrupts the EC barrier through FPR2. Furthermore, FPR2 controls the release of ND6 out of mitochondria and cytoplasm under hypoxia reoxygenation (HR). Activated FPR2 leads to upregulation of nuclear transcription factor-kappa B (NF-κB) by inducing IκBα phosphorylation, promoting ICAM1 and VCAM1 expression, thereby compromising EC barrier integrity. Circulating pro-inflammatory and barrier-disruptive mtNFPs, particularly ND6, are associated with ARDS in patients undergoing CPB. The novel ND6-FPR2 axis regulates inflammation and EC permeability through the NF-κB pathway.

MMP2 and MMP9 contribute to lung ischemia–reperfusion injury via promoting pyroptosis in mice

BackgroundLung ischemia–reperfusion injury (LIRI) is a cause of poor prognosis in several lung diseases and after lung transplantation. In LIRI, matrix metalloproteinases and pyroptosis indicators change in parallel, both of them involvement of inflammatory modulation, but it is unclear whether they are related to each other.MethodsWe analyzed the matrix metalloproteinases (MMPs) changes from RNA sequencing (RNA-Seq) data of human transplantation and rat ischemia–reperfusion lung tissues in the Group on Earth Observations (GEO) database. Then established the mouse LIRI model to validate the changes. Further, the severity of lung injury was measured after intervening the matrix metalloproteinases changes with their selective inhibitor during Lung ischemia–reperfusion. Meanwhile, lung, pyroptosis was assessed by assaying the activity of Caspase-1 and interleukin 1β (IL-1β) before and after intervening the matrix metalloproteinases changes.ResultsThe RNA-Seq data revealed that matrix metallopeptidase 2 (MMP2), matrix metallopeptidase 9 (MMP9) mRNA expression was elevated both in human lung transplantation and rat lung ischemia–reperfusion tissues, consistent with the change in our mouse model. At the same time, the activity of Caspase-1 and IL-1β were increased after LIRI. While, the lung injury was attenuated for the use of MMP2 and MMP9 selective inhibitor SB-3CT. Likewise, lung pyroptosis alleviated when treatment the mice with SB-3CT in LIRI.ConclusionWe conclude that MMP2 and MMP9 are involved in the process of LIRI, the mechanism of which is related to the promotion of lung pyroptosis.

Propofol Regulates the Expression of BecliN-1 through miR-30b and Protects against Lung Ischemia-Reperfusion Injury.

Pulmonary ischemia-reperfusion can cause severe dysfunction of alveolar epithelium and alveolar cells. Drugs such as propofol have a protective effect on lung ischemia-reperfusion, but this protective mechanism is not stable and requires other factors such as nucleosides. The purpose of this article is to study the protective mechanism of propofol on lung ischemia-reperfusion injury by regulating the expression of BecliN-1 by miR-30b. With 72 male rats as the research object, a rat lung ischemia-reperfusion model was established. Phenol agents were perfused as the perfusion solution to detect the expression levels of miR-30b and BecliN-1, statistical experimental data and analyze the regulatory mechanism of miR-30b on the expression of BecliN-1 and the effect of propofol on the protection of lung ischemia-reperfusion. Research results show that propofol can reduce inflammation, reduce oxidative stress, inhibit lung tissue apoptosis, improve lung function and pathological changes of lung tissue by inhibiting the activation of the JAK-STAT signaling pathway, and propofol can pass. The protection of miR-30b's regulation of BecliN-1 expression against lung ischemia-reperfusion injury is 30% higher than that of other protective mechanisms. At the same time, the apoptosis rate of inflammatory lung tissue cells is reduced by 13%.

Effect of dexmedetomidine on pyroptosis during lung ischemia-reperfusion in rats: an in vitro experiment

Objective To evaluate the effect of dexmedetomidine on pyroptosis during lung ischemia-reperfusion (I/R) in rats. Methods Adult male Sprague-Dawley rats, weighing 250-320 g, were used in this study.The model of isolated lung perfusion was established using an IL-2 Isolated Perfused Rat or Guinea Pig Lung System after the rats were anesthetized.Thirty lungs in which an ex vivo lung perfusion model was successfully established were divided into 3 groups (n=10 each) by a random number table method: control group (C group), I/R group and dexmedetomidine group (DEX group). The lungs were continuously perfused with K-H solution for 150 min in C group.After 15 min of perfusion, lungs were subjected to 60-min suspension of ventilation and perfusion, followed by 75 min of reperfusion and ventilation to establish the model of lung I/R injury in I/R and DEX groups.In DEX group, dexmedetomidine 10 nmol/L was added to K-H solution at the beginning of reperfusion.Lung tissues were obtained for determination of wet/dry weight ratio (W/D ratio) and for examination of pathological changes (with a light microscope) and ultrastructure (using an electron microscope), and the alveolar damage rate (IAR) was calculated.The expression of pyroptosis-related factors including NOD-like receptor family protein 3 (NLRP3), caspase-1, interleukin-1β (IL-1β), IL-18 and gasdermin D (GSDMD) protein and mRNA was detected by Western blot or by real-time polymerase chain reaction. Results Compared with C group, the W/D ratio and IAR in lung tissues were significantly increased, and the expression of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD protein and mRNA was up-regulated in I/R and DEX groups (P<0.05). Compared with I/R group, the W/D ratio and IAR in lung tissues were significantly decreased, the expression of NLRP3, caspase-1, IL-1β, IL-18 and GSDMD protein and mRNA was down-regulated (P<0.05), and the pathological changes were significantly attenuated in DEX group. Conclusion The mechanism by which dexmedetomidine reduces isolated rat lung I/R injury may be related to inhibiting pyroptosis. Key words: Dexmedetomidine; Reperfusion injury; Lung; Pyroptosis

Effect of dexmedetomidine on expression of Semaphorin 7A during lung ischemia-reperfusion in rats

Objective To evaluate the effect of dexmedetomidine on the expression of Semaphorin 7A during lung ischemia-reperfusion(I/R)in rats. Methods Thirty healthy clean-grade adult male Sprague-Dawley rats, aged 8-12 weeks, weighing 200-240 g, were divided into 3 groups (n=10 each) using a random number table method: sham operation group (S group), I/R group and dexmedetomidine group (D group). Only sternotomy was performed, and the left hilum of lung was not clamped in S group.The model of lung I/R injury was established by clamping the left hilum of lung for 45 min followed by 120 min of reperfusion in I/R group.Dexmedetomidine 50 μg/kg was intraperitoneally injected at 30 min before ischemia, and then the model was established in D group.The rats were sacrificed at the end of reperfusion, and the lungs were removed for examination of the pathological changes(using haematoxylin and eosin staining)which were scored and for determination of the wet to dry weight ratio (W/D ratio), expression of Semaphorin 7A protein and mRNA (by Western blot or real-time polymerase chain reaction), and contents of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in lung tissues (by enzyme-linked immunosorbent assay). Results Compared with S group, W/D ratio and pathological scores were significantly increased, the expression of Semaphorin 7A protein and mRNA was up-regulated, and the contents of TNF-α and IL-1β were increased in I/R and D groups (P<0.05). Compared with I/R group, W/D ratio and pathological scores were significantly decreased, the expression of Semaphorin 7A protein and mRNA was down-regulated, and the contents of TNF-α and IL-1β were decreased in D group (P<0.05). Conclusion The mechanism by which dexmedetomidine reduces lung I/R injury may be related to down-regulating Semaphorin 7A expression, thus inhibiting inflammatory responses of rats. Key words: Semaphorins; Dexmedetomidine; Reperfusion injury; Lung

Effects of dexmedetomidine on inflammatory response and lipid peroxidation during lung ischemia-reperfusion in rats: an in vitro experiment

Objective To investigate the effects of dexmedetomidine on inflammatory response and lipid peroxidation during lung ischemia-reperfusion(I/R)in rats. Methods Thirty lungs, which were isolated from SPF adult male Sprageue-Dawley rats, in which the model of isolated lung perfusion was successfully established, were divided into 3 groups(n=10 each)using a random number table: sham operation group(S group), I/R group and dexmedetomidine group(D group). The lungs were subjected to 60 min of ischemia and apnea after 15-min ischemia followed by 75 min of reperfusion and ventilation to establish the model of isolated lung I/R injury.In group D, the lungs were perfused with K-H solution containing 10 nmol/L dexmedetomidine for 15 min and then subjected to 60 min of ischemia and apnea followed by ventilation and reperfusion with K-H sloution containing 10 nmol/L dexmedetomidine for 75 min.Airway resistance, lung compliance, perfusion flow and partial pressure of arterial oxygen(PaO2)were recorded at 10 min of perfusion(T0)and 15, 45 and 75 min after restoration of perfusion(T1-3). Lung tissues were obtained at 75 min after restoration of perfusion for determination of wet/dry weight ratio(W/D ratio)and for examination of pathological changes and ultrastructure of lungs.The activity of superoxide dismutase(SOD)and content of malondialdehyde(MDA)in lung tissues were measured by improved pyrogallol autoxidation method and thiobarbituric acid method, respectively.The expression of β-endorphin and interleukin-8(IL-8)in lung tissues was detected by Western blot. Results Compared with group S, the airway resistance was significantly increased, and the lung compliance, perfusion flow and PaO2 were decreased during the perfusion restoration period, the W/D ratio and content of MDA were increased, the activity of SOD was decreased, and the expression of β-endorphin and IL-8 was up-regulated in I/R and D groups(P<0.05). Compared with group I/R, the airway resistance was significantly decreased, and the lung compliance, perfusion flow and PaO2 were increased during the perfusion restoration period, the W/D ratio and content of MDA were decreased, the activity of SOD was increased, the expression of β-endorphin and IL-8 was down-regulated(P<0.05), and the pathological changes of lungs were significantly attenuated in group D. Conclusion The mechanism by which dexmedetomidine reduces lung I/R injury may be related to inhibiting lipid peroxidation and inflammatory response of lung tissues in rats. Key words: Dexmedetomidine; Inflammation; Lipid peroxidation; Reperfusion injury; Lung

Effect of emulsified isoflurane post-conditioning on mitochondrial function during lung ischemia-reperfusion in rats: an in vitro experiment

Objective To evaluate the effect of emulsified isoflurane post-conditioning on the mitochondrial function during lung ischemia-reperfusion (I/R) in rats in an in vitro experiment. Methods Twenty-four SPF healthy male Sprague-Dawley rats, weighing 250-300 g, were used in the study.After the animals were anesthetized, the lungs were removed, connected to the perfusion system and then divided into 4 groups (n=6 each) using a random number table: control group (group C), group I/R, emulsified isoflurane post-conditioning group (group EI) and intralipid post-conditioning group (group IL). After 20 min of equilibration, the lungs were continuously perfused for 105 min in group C, and the lungs were subjected to 45 min ischemia followed by 60 min reperfusion to establish the model of lung I/R injury in the other three groups.During the reperfusion period, the common perfusate was used in group I/R, the perfusate containing 1.68 mmol/L emulsified isoflurane was used in group EI, and the equal volume of perfusate containing 30% intralipid was used in group IL.At the end of the equilibration (T0), immediately after beginning of reperfusion (T1) and at 30 and 60 min of reperfusion (T2, 3), the arterial oxygen partial pressure (PaO2), airway resistance, pulmonary compliance and tidal volume (VT) were recorded.The right upper lobe of the lung was removed at T3 for determination of wet to dry weight ratio (W/D ratio). The right middle lobe of the lung was removed at T3 for pathologic examination with light microscope.The contents of reactive oxygen species (ROS), NAD+ and ATP in lung tissues were detected. Results Compared with group C, the PaO2, pulmonary compliance and VT were significantly decreased, and the airway resistance was increased at T1-3, and the W/D ratio and ROS content were increased, and NAD+ and ATP contents were decreased at T3 in I/R, EI and IL groups (P<0.05). Compared with I/R and IL groups, the PaO2, pulmonary compliance and VT were significantly increased, and the airway resistance was decreased at T2, 3, and the W/D ratio and ROS content were decreased, and NAD+ and ATP contents were increased at T3 in group EI (P<0.05). The pathologic changes of lungs were significantly attenuated in group EI as compared with group I/R. Conclusion The mechanism by which emulsified isoflurane post-conditioning attenuates lung I/R injury is related to decrease in mitochondrial dysfunction in rats in an in vitro experiment. Key words: Isoflurane; Fat emulsions, intravenous; Reperfusion injury; Lung; Mitochondrial; Ischemia post-conditioning

Protective effect of Shenfu injection preconditioning on lung ischemia-reperfusion injury.

Lung ischemia-reperfusion injury remains a problem in thoracic surgery, as minimal progress has been made concerning its prevention and control. In the present study, the protective effects and the underlying mechanism of Shenfu injection preconditioning on a rat lung ischemia-reperfusion model was investigated. Shenfu injection is a well-known Chinese traditional medicine, which is composed of Red Radix Ginseng and Radix Aconitum carmichaelii, with ginseng saponin and aconitum alkaloids as the active ingredients. A total of 72 specific pathogen-free, healthy male Wistar rats were randomly divided into control, model and Shenfu injection (10 ml/kg injection prior to injury) groups and were assessed at the following points: Ischemia 45 min; reperfusion 60 min; and reperfusion 120 min. Blood collected from the aorta abdominalis was cryopreserved at −70°C for the analysis of malondialdehyde (MDA) and superoxide dismutase (SOD) activity. Lung tissues were divided into three equal sections in order to assess the wet-to-dry (W/D) lung ratio, tumor necrosis factor (TNF)-α expression levels, myeloperoxidase (MPO) activity, alveolar damage, total protein and hematoxylin and eosin staining. The results demonstrated that the lung W/D weight ratio, TNF-α expression levels and SOD activity in the Shenfu group were significantly lower at 120 min reperfusion (P<0.05), as compared with the model group. MPO and MDA activity significantly decreased following reperfusion at 60 and 120 min (P<0.05), as compared with the model group. In addition, the degree of alveolar damage in the Shenfu group was significantly decreased (P<0.05), as compared with the model group. In addition, compared with the model group, the degree of alveolar damage in the Shenfu group was significantly lower (P<0.05); however, no significant changes in total protein were observed. The extent of alveolar structural damage and the proportion of interstitial neutrophils and alveolar and interstitial red blood cells were lower in the Shenfu group, as compared with the model and control groups. Therefore, the results of the present study suggested that Shenfu injection may have protective effects on lung ischemia-reperfusion injury.

Effect of creatine phosphate on myocardial injury induced by lung ischemia-reperfusion in rats

Objective To evaluate the effect of creatine phosphate on the myocardial injury induced by lung ischemia-reperfusion (I/R) in rats. Methods Twenty-four male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-350 g, were randomly divided into 3 groups (n=8 each) using a random number table: sham operation group (group S), I/R group, and I/R+ creatine phosphate group (group CP). Lung I/R was induced by clamping the left hilum of lung for 0.5 h with a non-invasive microvascular clip followed by mechanical ventilation and 2.0 h of reperfusion.Creatine phosphate 6.6 mg·kg-1·min-1 were infused intravenously at 30 min before ischemia in group CP, while the equal volume of normal saline was administered in group I/R.At 2.0 h of reperfusion, blood samples were obtained from the right ventricle for determination of the serum concentration of cardiac troponin I (cTnI). Myocardial specimens were obtained from the apex for microscopic examination and for determination of the levels of myocardial superoxide dismutase (SOD), malondialdehyde (MDA), and myeloperoxidase (MPO). Results Compared with group S, the serum cTnI concentrations, MDA content, and MPO activity were significantly increased, and the SOD activity was significantly decreased in I/R and CP groups (P<0.05). Compared with group I/R, the serum cTnI concentrations, MDA content, and MPO activity were significantly decreased, and the SOD activity was significantly increased in group CP (P<0.05). Myocardial injury was significantly attenuated in group CP as compared with group I/R. Conclusion Creatine phosphate can attenuate the myocardial injury induced by lung I/R in rats, and the mechanism is related to decrease in damage caused by lipid peroxidation. Key words: Phosphocreatine; Lung; Reperfusion injury

Modulatory effect of silymarin on pulmonary vascular dysfunction through HIF-1α-iNOS following rat lung ischemia-reperfusion injury.

Silymarin is a traditional therapeutic used to protect the liver, acting to oppose lipid peroxidation, to enhance liver regeneration and functioning as an antioxidant. However, the effects of silymarin on pulmonary vascular dysfunction have not been investigated. In the present study, the modulatory effects of silymarin on pulmonary vascular dysfunction and the underlying mechanisms behind this were investigated in a lung ischemia-reperfusion (I/R) injury rat model. Male Sprague Dawley rats were randomly divided into 3 groups, including: i) A control group (n=10); ii) an I/R group (n=10); and iii) a silymarin-treated group (n=10). All experimental rats received 250 mg/kg/day of silymarin for 8 days. Silymarin was demonstrated to markedly improve lung I/R-induced pulmonary vascular dysfunction and lung moisture. Following silymarin treatment, inflammation and oxidative stress in the lung I/R-injury rats were demonstrably suppressed. Treatment with silymarin also inhibited the activation of caspase-3 and -9, and hypoxia inducible factor-1α (HIF-1α) and inducible nitric oxide synthase (iNOS) protein expression in the lung I/R-injury rats. Silymarin was concluded to impact upon pulmonary vascular dysfunction through the HIF-1α-iNOS pathway in the lung I/R injury rat model.

Effects of sevoflurane preconditioning and postconditioning on activity of NF-κB during lung ischemia-reperfusion in rats

Objective To evaluate the effects of sevoflurane preconditioning and postconditioning on the activity of NF-κB during lung ischemia-reperfusion (I/R) in rats.Methods Fifty-four adult male Sprague-Dawley rats,weighing 300-350 g,were randomly divided into 3 groups (n =18 each) using a random number table:sham operation group (S group),I/R group and sevoflurane preconditioning and postconditioning group (SPP group).Lung I/R was induced by clamping the left pulmonary hilum for 45 min followed by 120 min reperfusion in I/R and SP groups.The left pulmonary hilum was only isolated but not ligated in group S.In group SP,2.1％ sevoflurane was inhaled for 30 min followed by 10 min washout,the left pulmonary hilum was then ligated for 45 min,and 2.1％ sevoflurane was inhaled for 30 min again starting from onset of reperfusion.Six rats were chosen at 30,60 and 120 min of reperfusion and sacrificed in each group,lungs were removed for determination of wet/dry lung weight (W/D) ratio and content of tumor necrosis factor-α (TNF-α) (by ELISA) and expression of nuclear transcription factor κB (NF-κB) p65 of nuclear protein (by Western blot) and for microscopic examination of the pathologic changes of lungs (with light microscope).Results Compared with S group,W/D ratio,TNF-α content and nuclear protein NF-κB p65 expression in lung tissues were significantly increased at each time point of reperfusion in I/R and SPP groups.Compared with I/R group,W/D ratio,TNF-α content and nuclear protein NF-κB p65 expression in lung tissues were significantly increased at each time point of reperfusion,and the pathological changes of lungs were attenuated in SPP group.Conclusion Sevoflurane preconditioning combined with postconditioning can reduce the lung I/R injury in rats through inhibiting NF-κB activity in lung tissues. Key words: Anesthetics, inhalation; Ischemic preconditioning; Reperfusion injury; Lung; NF-kappa B; Ischemic postconditioning

Effect of sevoflurane on tissue permeability of lung ischemia-reperfusion injury in rats

ObjectiveTo investigate the effect of sevoflurane on tissue permeability of lung ischemia-reperfusion injury (LIRI) in rats. MethodsA total of 45 wistar rats were randomly divided into 3 groups I, II, III. Modified Eppinger method was adopted to establish the rat lung ischemia-reperfusion injury model. Group I served as the control group, group III as ischemia reperfusion group, group III as sevoflurane ischemia-reperfusion group. Blood gas index, lung permeability index (LPI) change, lung tissue pathology change and lung water content were observed and compared between groups of rats at different time points. ResultsDuring ischemia reperfusion, all rats kept balance of the MAP during different time points, SPO2 of group II and III decreased significantly than I group (P<0.05); after reperfusion lung permeability index in Group II and III was higher than the control group significantly (P<0.05), 120 min after reperfusion LPI change and injury of group III was significantly lower than II group (P<0.05); interstitial and alveolar cavity effusion in of group III were lower than that of group II. ConclusionsSevoflurane pretreatment can reduce the lung tissue permeability, and LIRI plays a protective role in LIRI.

Effects of sevoflurane preconditioning on expression of angiotensin converting enzyme mRNA in lung tissues during lung ischemia-reperfusion in rats

Objective To investigate the effects of sevoflurane preconditioning on the expression of pulmonary angiotensin converting enzyme (ACE) mRNA in lung tissues during lung ischemia-reperfusion (I/R) in rats.Methods Fifty-four male Sprague-Dawley rats,weighing 250-320 g,were randomly divided into 3 groups (n =18 each):sham operation group (group S),I/R group and sevoflurane preconditioning group (group SP).The animals were anesthetized,tracheostomized and mechanically ventilated.Lung I/R was induced by clamping the left pulmonary hilum for 45 min followed by 120 min reperfusion in groups I/R and SP.While the left pulmonary hilum was only isolated but not ligated in group S.2.1％ sevoflurane was inhaled for 30 min,and lung I/R was induced 10 min after the end of inhalation in group SP.Six rats in each group were chosen at 30,60 and 120 min of reperfusion and sacrificed,lungs were removed for determination of wet/dry lung weight (W/D) ratio,MPO activity (by colorimetric method) and the expression of ACE mRNA (by RT-PCR) and for microscopic examination in lung tissues.Results Compared with group S,the W/D ratio,MPO activity and expression of ACE mRNA were significantly increased in groups I/R and SP (P ＜ 0.05).Compared with group I/R,the W/D ratio,MPO activity and expression of ACE mRNA were significantly decreased in group SP (P ＜ 0.05).Microscopic examination showed that the pathologic changes were significantly attenuated in group SP compared with group I/R.Conclusion Sevoflurane preconditioning can reduce lung I/R injury through downing-regulating the expression of ACE mRNA in rats. Key words: Anesthetics, inhalation; Reperfusion injury ; Lung ; Peptidyl-dipeptidase A ; Ischemic preconditioning

Restoration of alveolar type II cell function contributes to simvastatin-induced attenuation of lung ischemia-reperfusion injury

Alveolar type (AT) II cells transdifferentiate into ATI cells and as such represent a promising source for regenerating lung epithelium following lung injury. ATII cells are characterized by the presence of lamellar bodies (LBs), which store and secrete the surfactant protein-C (SP-C). Lung ischemia-reperfusion injury (LIRI) causes a distinct impairment of the ATII cell function, subsequently hindering lung repair by loss of ATI transdifferentiation. In this study, we provide new evidence that the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor simvastatin may restore the function of impaired ATII cells in vitro and in vivo. ATII cell lines, A549 (human) and MLE-12 (mouse), were subjected to hypoxia-reoxygenation (H/R) injury. Simvastatin pretreatment at low (5-20 µM), but not high (50-100 µM) doses markedly reduced apoptosis and increased proliferation and SP-C expression. In a rat lung ischemia-reperfusion (I/R) model, simvastatin treatment also increased ATII cell proliferation in vivo, as demonstrated by proliferating cell nuclear antigen/SP-C double staining. Transmission electron microscopy revealed that the number and volume density of LBs were significantly increased in the simvastatin-treated rat lungs. The protective effects of simvastatin were reversed in vitro by PI3-kinase (PI3K) inhibitors wortmannin and L-mevalonate, indicating that the PI3K/Akt and mevalonate pathways may be involved in simvastatin-induced ATII cell function restoration. These data demonstrate that an appropriate dose of simvastatin has a protective effect on LIRI in vitro and in vivo, due at least partially to restored ATII cell function via the HMG-CoA reductase pathway-dependent activation of PI3K/Akt signaling in a mevalonate pathway-dependent manner.

Effect of GSK-3.BETA. inhibitor TDZD-8 on activation of NF-kB during lung ischemia-reperfusion in rats

Objective To investigate the effect of GSK-3β inhibitor TDZD-8 on activation of NF-kB during lung ischemia-repeffusion （I/R） in rats. Methods Thirty-two healthy male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-280 g, were randomly divided into 4 groups （n = 8 each）： sham operation group （sham group） ; I/R group, I/R ＋ dimethyl sulfoxide （DMSO） group and I/R ＋ TDZD-8 group. Lung I/R was induced by clamping the left hilum of lung for 1 h followed by 2 h reperfusion. 10% DMSO and TDZD-8 1 mg/kg were inject- ed intravenously at 5 min before reperfusion in groups I/R ＋ DMSO and I/R ＋ TDZD-8, respectively. Blood sam- ples were taken at 2 h of repeffusion for determination of arterial partial pressure of oxygen （PaO2） and concentra- tions of plasma interleukin-6 （IL-6） and tumor necrosis factor-a （TNF-a） . The animals were then sacrificed and the left lung was removed for determination of W/D lung weight ratio, myeloperpxidase （MPO） activity, expression of phosphorylated glycogen synthase kinase-3 beta （p-GSK-313） and phosphorylated nuclear factor-kappa B p65 （p- NF-kB p65） and for microscopic examination. Results Compared with sham group, PaO2 and the expression of p- GSK-3β were significantly decreased, and the concentrations of plasma IL-6 and TNF-a, W/D lung weight ratio, MPO activity and expression of p-NF-kB p65 were significantly increased in the other groups （P 〈 0.05）, and PaO2 and the expression of p-GSK-3β were significantly increased and the other Parameters were significantly de- creased in I/R ＋ TDZD-8 group （P 〈 0.05）. There were no significant differences in the parameters mentioned above among groups I/Rand I/R ＋ DMSO （ P 〉 0.05）. Microscopic examination showed that I/R-induced lung in- jury was ameliorated by TDZD-8.Conclusion GSK-3β inhibitor TDZD-8 can attenuate lung I/R injury by down- regulating phosphorylation of NF-kB p65 and inhibiting inflammatory response. Key words: Protein-serine-threonine kinases; Reperfusion injury; Lung; NF-kappa B

Phosphodiesterase-5 inhibitor and rat lung ischemia-reperfusion injury

To explore the protective effect of the phosphodiesterase-5 inhibitor, sildenafil, on lung ischemia-reperfusion injury, 30 rats were randomly divided into 3 groups of 10: a sham-operated group A, a lung ischemia-reperfusion injury group B, and a sildenafil preconditioned group C. A 0.1% sildenafil solution was administrated orally 2 h before establishing an in-vivo lung ischemia-reperfusion model in group C; 0.9% normal saline solution was used in the controls. The lung wet-to-dry ratio, malondialdehyde content, myeloperoxidase and nitric oxide synthase activity in groups B and C were significant higher than those in group A, while the partial pressure of oxygen in arterial blood and cyclic guanosine-3',5'-monophosphate content in groups B and C were significant lower than those in group A. Compared to group B, lung wet/dry ratio, malondialdehyde content, myeloperoxidase and nitric oxide synthase activity in group C were significantly lower, while arterial O(2) and cyclic guanosine-3',5'-monophosphate content in group C were significantly higher. The expected histological and cytological changes were significantly alleviated in group C. Oral preconditioning with sildenafil prevented rat lung ischemia-reperfusion injury and improved pulmonary function. The mechanisms of this effect might be prevention of cyclic guanosine monophosphate degradation and inhibition of nitric oxide synthase activity.

Protective effect of simvastatin on alveolar type II cells in a rat lung ischemia-reperfusion injury model

Objective To evaluate the protective effects on alveolar type Ⅱ cells induced by simvastatin in a rat lung ischemia-reperfusion injury (LIRI) long-term survival model. Methods 108 healthy SD rats were randomly divided into 3 groups: group Ⅰ, the sham group (n =36, no hilar blocking); group Ⅱ, LIRI group ( n = 36, left hilar blocking); group Ⅲ, simvastatin group ( n = 36, animals were orally lung tissue and blood samples were collected at basehne before hilar occlusion and 1 h after ischemia, 4 h,1 day, 3 days and 7 days after reperfusion respectively. The indices were determined as follows: the myeloperoxidase (MPO) activity of lung tissue, the arterial partial pressure of oxygen ( PaO2 ), pulmonary surfactant-C (SP-C) expression and proliferation of AT Ⅱ cells determined by SP-C/proliferating cell nuclear antigen (PCNA) immunofluorensence double staining. Results The rat LIRI long-term survival model was successfully established. As compared with group Ⅱ , the MPO activity, PaO2 and the SP-C mRNA level were significantly reduced in group Ⅲ at the time-points of 4 h and 1 day after reperfusion (P ＜0. 01 respectively). The number of SP-C/PCNA double positive AT Ⅱ cells displayed that as compared with Group Ⅱ , the proliferation of AT Ⅱ cells in group Ⅲ was significantly increased at day 1 after repeffusion.Conclusion AT Ⅱ cells might be a novel target of simvastatin-induced-attenuation of LIRI, in which enhancing the proliferation ability of AT Ⅱ is involved as one of the important mechanisms. Key words: Lung ischemia; Repeffusion injury; Alveolar type Ⅱ cell; Proliferation; Simvastatin

Effects of sevoflurane or ischemic preconditioning on the expression of ERK and CaM during lung ischemia-reperfusion in rats

Objectlve To investigate the effects of sevoflurane or ischemic preconditioning on the expression of extracellular signal-regulated kinase （ERK） and calmodulin （CaM） during lung ischemia-reperfusion （I/R）in rats. Methods Twenty-four male SD rats weighing 270-320 g were randomly divided into 4 groups （ n = 6each）： sham operation group （group S）, group I/R, ischemic preconditioning group （group IP）, and sevoflurane preconditioning group （group SP）. In group S, the hilum of the left lung was dissociated after thoracotomy but not occluded. In group I/R, lung I/R was produced by occlusion of the hilum of the left lung for 45 min followed by 120 min of reperfusion. In group IP, the hilum of the left lung was occluded for 5 min and unclamped for 5 min for 2 times before the model was established. In group SP, sevoflurane was inhaled for 30 min at the end-tidal concentration of 2.1% before lung ischemia. All rats were sacrificed at 120 min of reperfusion and the lung tissues were taken for determination of the contents of TNF-α and IL-6 by ELISA and the expression of ERK mRNA and CaM mRNA by RT-PCR. Results Compared with group S, the contents of TNF-α and IL-6 and the expression of ERK mRNA and CaM mRNA were significantly increased in group I/R, IP and SP （ P 〈 0.05）. Compared with group I/R, the contents of TNF-α and IL-6 and the CaM mRNA expression were significantly decreased, while the expression of ERK mRNA was significantly increased in group IP and SP （ P 〈 0.05）. There was no significant difference in the each index metioned above between group IP and SP （ P 〉 0.05 ）. Conclusion Sevoflurane preconditioning and ischemic preconditioning can protect the lung from I/R injury through down-regulating the expression of CaM and up-regulating the expression of ERK. Key words: Anesthetics, inhalation; Ischemic preconditioning; Extracellular signal-regulated MAP kinases; Calcium-calmodulin-dependent protein kinases; Reperfusion injury; Lung

Dynamic investigation of alveolar type II cell function in a long-term survival model of rat lung ischemia-reperfusion injury

Background. Alveolar type II (ATII) cells are capable of repairing the alveolar epithelium injury induced by lung ischemia-reperfusion injury (LIRI). In the present study, we aim to dynamically investigate the morphological and functional alternations of ATII cells using a long-term survival model of rat LIRI. Materials and methods. Male Sprague-Dawley rats were randomized into sham and ischemia-reperfusion (IR) groups. Animals of IR group underwent warm ischemia for 60 minutes by left pulmonary hilum occlusion. Injury was assessed by histological examination and myeloperoxidase activity assay. The proliferation profile of ATII cells was evaluated by immunofluorescence double staining. Surfactant protein-C (SP-C) and caspase-3 expression were determined by reverse transcription polymerase chain reaction. Ultrastructure and stereological analysis were used to quantify the alterations of nuclei and lamellar bodies (LBs) of ATII cells. Results. As compared with the sham group, SP-C expression in the IR group significantly decreased at the early phase of LIRI and returned to normal in 7 days after reperfusion. SP-C/PCNA double positive cell number significantly increased at 1d, peaked at 3d and decreased to normal until 7 days after reperfusion. Ultrastructure and stereological analysis of ATII cells also showed that LBs were remarkably impaired at the early phase of LIRI and recovered up to 7 days after reperfusion. Conclusions. This model is simple, stable and reproducible. ATII cells demonstrated a self-repair capacity in a slow manner following the early phase of LIRI. Enhancing self-repair capacity of ATII cells may be a potential way of alleviating or curing LIRI.

Establishment of a rat lung ischemia-reperfusion injury long-term survival model

Objective To establish a simple and stable rat lung ischemia-reperfusion (LIRI) long-term survival model. Methods Eighty-four healthy SD rats were randomly divided into two groups:Group Ⅰ,the sham-operated group (n=42, no hilar blocking);Group Ⅱ, lung ischemia reperfusion group (n=42,left hilar blocking). The lung tissues and blood samples were collected at baseline before hilar oc-clusion,and 0 h,2 h,4 h,1 day,3 days and 7 days after repeffusion. The indices were determined as fol-lows:the myeloperoxidase (MPO) activity, wet/dry ratio (W/D ratio), lung permeability index (LPI) and the ultrastructure of AT Ⅱ. Results All the SD rats survived during the observation period. Compared with group Ⅰ,the MPO activity, W/D ratio, and the LPI were significantly increased in group Ⅱ at the time points of 2 h,4 h, 1 day after reperfusion (all P<0.01). The ultrastructure of AT Ⅱ displayed that the most serious injury occurred at the fine point of 4 h after reperfusion. The repair process emerged at 1st day after reperfusion. At 7th day after reperfusion, the lung tissue structure almost recovered to normal. Conclu-sion It is a simple and reliable animal model. The related indices of lung injury were in accordance with the changes of ultrastruture of ATⅡ. Key words: Lung ischemia; Reperfusion injury; Alveolar; Model,animal