Effects of nitric oxide synthase inhibitor on acid aspiration-induced lung injury in rats

The possible protective role of pumpkin seed oil in an animal model of acid aspiration pneumonia: Light and electron microscopic study

Aspiration pneumonitis is a common problem occurring in many clinical disorders. Pumpkin seed oil (PO) is a rich source of antioxidants. This work aimed to assess the effect of PO on the lung histopathological changes induced by acid aspiration. Forty male albino rats assigned to four groups were used. Rats of control group were instilled intratracheally with normal saline 2mL/kg. HCL group instilled with 2mL/kg of HCL 0.1N, pH 1.25. PO group received pumpkin seed oil (PO) orally (∼1375mg/kgbw/day) for 7days. HCL+PO group instilled with 2mL/kg of HCL 0.1N, pH 1.25 and received PO at the same dose of PO group. Lung tissue samples were processed for light, electron microscopic and immunohistochemical study using anti inducible NO synthase (iNOS). The lung of HCL group demonstrated thickened interalveolar septa, inflammatory cell infiltration and significant increase in the area percent of collagenous fibers and immune expression of iNOS. Ultra structurally, disrupted alveolocapillay membrane, degenerated type II pneumocytes and plentiful alveolar macrophages were evident. PO administration partially attenuated these histological and ultra structural alterations and reduced iNOS immune-expression in lung tissue. In conclusion, PO has a protective effect against HCL aspiration lung injury most probably through its antioxidant activity.

Akt2 deficiency as a therapeutic strategy protects against acute lung injury

Evaluation of: Vergadi E, Vaporidi K, Theodorakis EE et al. Akt2 deficiency protects from acute lung injury via alternative macrophage activation and miR-146a induction in mice. J. Immunol. 192, 394-406 (2013). Acute respiratory distress syndrome currently has limited effective treatments; however, recent evidence suggests that modulation of alveolar macrophage responses may be an effective method for protection or repair of lung injury. Vergadi et al. are the first to demonstrate that depletion of Akt2 kinase and microRNA-146a induction in mice resulted in polarization of alveolar macrophages towards an M2 activation phenotype and resulted in less severe injury following acid-induced lung injury. However, this M2 polarization also resulted in increased lung bacterial load following infection with Pseudomonas aeruginosa.

The effect of methylene blue treatment on aspiration pneumonia

BACKGROUND

The study aimed to examine whether methylene blue (MB) prevents different pulmonary aspiration materials-induced lung injury in rats.

METHODS

The experiments were designed in 60 Sprague-Dawley rats, ranging in weight from 250-300 g, randomly allotted into one of six groups (n = 10): saline control, Biosorb Energy Plus (BIO), hydrochloric acid (HCl), saline + MB treated, BIO + MB treated, and HCl + MB treated. Saline, BIO, and HCl were injected into the lungs in a volume of 2 mL/kg. After surgical procedure, MB was administered intraperitoneally for 7 days at a daily dose of 2 mg/kg per day. Seven days later, rats were killed, and both lungs in all groups were examined biochemically and histopathologically.

RESULTS

Our findings show that MB inhibits the inflammatory response reducing significantly (P < 0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation in different pulmonary aspiration models. Pulmonary aspiration significantly increased the tissue hydroxyproline content, malondialdehyde levels, and decreased (P < 0.05) the antioxidant enzyme (superoxide dismutase and glutathione peroxidase) activities. MB treatment significantly (P < 0.05) decreased the elevated tissue hydroxyproline content and malondialdehyde levels and prevented the inhibition of superoxide dismutase and glutathione peroxidase (P < 0.05) enzymes in the tissues. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase (iNOS), terminal deoxynucleotidyl transferase dUTP nick end labeling, and arise in the expression of surfactant protein D in lung tissue of different pulmonary aspiration models with MB therapy.

CONCLUSIONS

MB treatment might be beneficial in lung injury and therefore shows potential for clinical use.

Short-term glutamine supplementation decreases lung inflammation and the receptor for advanced glycation end-products expression in direct acute lung injury in mice

Background

Glutamine (GLN) has been reported to improve clinical and experimental sepsis outcomes. However, the mechanisms underlying the actions of GLN remain unclear, and may depend upon the route of GLN administration and the model of acute lung injury (ALI) used. The aim of this study was to investigate whether short-term GLN supplementation had an ameliorative effect on the inflammation induced by direct acid and lipopolysaccharide (LPS) challenge in mice.

Methods

Female BALB/c mice were divided into two groups, a control group and a GLN group (4.17% GLN supplementation). After a 10-day feeding period, ALI was induced by intratracheal administration of hydrochloric acid (pH 1.0; 2 mL/kg of body weight [BW]) and LPS (5 mg/kg BW). Mice were sacrificed 3 h after ALI challenge. In this early phase of ALI, serum, lungs, and bronchoalveolar lavage fluid (BALF) from the mice were collected for further analysis.

Results

The results of this study showed that ALI-challenged mice had a significant increase in myeloperoxidase activity and expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α in the lung compared with unchallenged mice. Compared with the control group, GLN pretreatment in ALI-challenged mice reduced the levels of receptor for advanced glycation end-products (RAGE) and IL-1β production in BALF, with a corresponding decrease in their mRNA expression. The GLN group also had markedly lower in mRNA expression of cyclooxygenase-2 and NADPH oxidase-1.

Conclusions

These results suggest that the benefit of dietary GLN may be partly contributed to an inhibitory effect on RAGE expression and pro-inflammatory cytokines production at an early stage in direct acid and LPS-induced ALI in mice.

Akt2 deficiency protects from acute lung injury via alternative macrophage activation and miR-146a induction in mice

Acute respiratory distress syndrome (ARDS) is a major cause of respiratory failure, with limited effective treatments available. Alveolar macrophages participate in the pathogenesis of ARDS. To investigate the role of macrophage activation in aseptic lung injury and identify molecular mediators with therapeutic potential, lung injury was induced in wild-type (WT) and Akt2(-/-) mice by hydrochloric acid aspiration. Acid-induced lung injury in WT mice was characterized by decreased lung compliance and increased protein and cytokine concentration in bronchoalveolar lavage fluid. Alveolar macrophages acquired a classical activation (M1) phenotype. Acid-induced lung injury was less severe in Akt2(-/-) mice compared with WT mice. Alveolar macrophages from acid-injured Akt2(-/-) mice demonstrated the alternative activation phenotype (M2). Although M2 polarization suppressed aseptic lung injury, it resulted in increased lung bacterial load when Akt2(-/-) mice were infected with Pseudomonas aeruginosa. miR-146a, an anti-inflammatory microRNA targeting TLR4 signaling, was induced during the late phase of lung injury in WT mice, whereas it was increased early in Akt2(-/-) mice. Indeed, miR-146a overexpression in WT macrophages suppressed LPS-induced inducible NO synthase (iNOS) and promoted M2 polarization, whereas miR-146a inhibition in Akt2(-/-) macrophages restored iNOS expression. Furthermore, miR-146a delivery or Akt2 silencing in WT mice exposed to acid resulted in suppression of iNOS in alveolar macrophages. In conclusion, Akt2 suppression and miR-146a induction promote the M2 macrophage phenotype, resulting in amelioration of acid-induced lung injury. In vivo modulation of macrophage phenotype through Akt2 or miR-146a could provide a potential therapeutic approach for aseptic ARDS; however, it may be deleterious in septic ARDS because of impaired bacterial clearance.

Acute lung injury and acute respiratory distress syndrome: experimental and clinical investigations

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can be associated with various disorders. Recent investigation has involved clinical studies in collaboration with clinical investigators and pathologists on the pathogenetic mechanisms of ALI or ARDS caused by various disorders. This literature review includes a brief historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the long-term experimental studies and clinical investigations from our laboratory, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Acute respiratory distress syndrome and lung injury: Pathogenetic mechanism and therapeutic implication

To review possible mechanisms and therapeutics for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). ALI/ARDS causes high mortality. The risk factors include head injury, intracranial disorders, sepsis, infections and others. Investigations have indicated the detrimental role of nitric oxide (NO) through the inducible NO synthase (iNOS). The possible therapeutic regimen includes extracorporeal membrane oxygenation, prone position, fluid and hemodynamic management and permissive hypercapnic acidosis etc. Other pharmacological treatments are anti-inflammatory and/or antimicrobial agents, inhalation of NO, glucocorticoids, surfactant therapy and agents facilitating lung water resolution and ion transports. β-adrenergic agonists are able to accelerate lung fluid and ion removal and to stimulate surfactant secretion. In conscious rats, regular exercise training alleviates the endotoxin-induced ALI. Propofol and N-acetylcysteine exert protective effect on the ALI induced by endotoxin. Insulin possesses anti-inflammatory effect. Pentobarbital is capable of reducing the endotoxin-induced ALI. In addition, nicotinamide or niacinamide abrogates the ALI caused by ischemia/reperfusion or endotoxemia. This review includes historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Effects of a selective iNOS inhibitor versus norepinephrine in the treatment of septic shock

Inhibition of NOS is not beneficial in septic shock; selective inhibition of the inducible form (iNOS) may represent a better option. We compared the effects of the selective iNOS inhibitor BYK191023 with those of norepinephrine (NE) in a sheep model of septic shock. Twenty-four anesthetized, mechanically ventilated ewes received 1.5 g/kg body weight of feces into the abdominal cavity to induce sepsis. Animals were randomized into three groups (each n = 8): NE-only, BYK-only, and NE + BYK. The sublingual microcirculation was evaluated with sidestream dark-field videomicroscopy. MAP was higher in the NE + BYK group than in the other groups, but there were no significant differences in cardiac index or systemic vascular resistance. Mean pulmonary arterial pressure was lower in BYK-treated animals than in the NE-only group. PaO2/FiO2 was higher and lactate concentration lower in the BYK groups than in the NE-only group. Mesenteric blood flow was higher in BYK groups than in the NE-only group. Renal blood flow was higher in the NE + BYK group than in the other groups. Functional capillary density and proportion of perfused vessels were higher in the BYK groups than in the NE-only group 18 h after induction of peritonitis. Survival times were similar in the three groups. In this model of peritonitis, selective iNOS inhibition had more beneficial effects than NE on pulmonary artery pressures, gas exchange, mesenteric blood flow, microcirculation, and lactate concentration. Combination of this selective iNOS inhibitor with NE allowed a higher arterial pressure and renal blood flow to be maintained.

Effects of Nigella sativa seed extract on ameliorating lung tissue damage in rats after experimental pulmonary aspirations

Aspiration of gastric contents can cause serious lung injury, although the mechanisms of pulmonary damage are still not clear and means of amelioration of the pulmonary damage have been little investigated. The black cumin seed, Nigella sativa L. (NS) has been shown to have specific health benefits and the aim of the current study was to investigate the possible beneficial effects of NS on experimental lung injury in male Wistar rats after pulmonary aspiration of different materials. The rats were randomly allotted into one of six experimental groups (n=7 per group): (1) saline control, (2) saline+NS treated, (3) Pulmocare (a specialized nutritional supplement given to pulmonary patients), (4) Pulmocare+NS treated, (5) hydrochloric acid, (6) hydrochloric acid+NS treated. The saline, Pulmocare and hydrochloric acid were injected into the lungs in a volume of 2 ml/kg. The rats received daily oral doses of NS volatile oil (400mg/kg body weight) by means of intragastric intubation for 7 days starting immediately after the pulmonary aspiration of the materials. After 7 days, the rats were sacrificed and tissue samples from both lungs were taken for histopathological investigation. To date, no similar study investigating the potential for NS treatment to protect against lung injury after pulmonary aspiration of materials has been reported. Our study showed that NS treatment inhibits the inflammatory pulmonary responses, reducing significantly (p<0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar macrophages, interstitial fibrosis, granuloma and necrosis formation in different pulmonary aspiration models. Our data indicate a significant reduction in the activity of inducible nitric oxide synthase (iNOS) and a rise in surfactant protein D in lung tissue of different pulmonary aspiration models after NS therapy. Based on our results, we conclude that NS treatment might be beneficial in lung injury and have potential clinical use.

Preventive effects of curcumin on different aspiration material-induced lung injury in rats

PURPOSE

We have studied whether curcumin protects different pulmonary aspiration material-induced lung injury in rats.

MATERIALS AND METHODS

The experiments were designed in 60 Sprague-Dawley rats, randomly allotted into one of six groups (n=10): normal saline (NS, control), enteral formula (Biosorb Energy Plus, BIO), hydrochloric acid (HCl), NS+curcumin-treated, BIO+curcumin-treated, and HCl+curcumin-treated. NS, BIO, HCl were injected in to the lungs. The rats received curcumin twice daily only for 7 days. Seven days later, both lungs in all groups were examined histopathologically, immunohistochemically, and biochemically. Histopathologic examination was performed according to the presence of peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation. Immunohistochemical assessments were examined for the activity of inducible nitric oxide synthase (iNOS) and the expression of surfactant protein D (SP-D). Malondialdehyde (MDA), hydroxyproline (HP), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity were measured in the lung tissue.

RESULTS

Our findings show that curcumin inhibits the inflammatory response reducing significantly (P<0.05) all histopathological parameters in different pulmonary aspiration models. Pulmonary aspiration significantly increased the tissue HP content, MDA levels and decreased the antioxidant enzyme (SOD, GSH-Px) activities. Curcumin treatment significantly decreased the elevated tissue HP content, and MDA levels and prevented inhibition of SOD, and GSH-Px enzymes in the tissues. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and a rise in the expression of SP-D in lung tissue of different pulmonary aspiration models with curcumin therapy.

CONCLUSION

Our findings support the use of curcumin as a potential therapeutic agent in acute lung injury.

Time course for expression of VEGF and its receptor and regulator levels of contraction and relaxation in increased vascular permeability of lung induced by phosgene

Acute lung injury (ALI) induced by phosgene increases risk of serious edema and mortality. Increased permeability of the microvascular endothelium is implicated in the progression of ALI, but the processing interaction and time course activity of the vascular regulators in exudation are still not understood. The main aim of this study was to investigate the time course and potential role for vascular endothelial growth factor (VEGF), its receptors, and some vascular function regulators related to increased vascular permeability of lung induced by phosgene. Sprague Dawley rats were randomly divided into seven groups according to time post phosgene exposure (control, and 1, 3, 6, 12, 24, and 48 h groups). Lung tissue was removed to evaluate VEGF isoforms, fms-like tyrosine kinase receptor 1 (Flt-1), and kinase insert domain containing region (KDR/Flk-1) by reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Blood samples were collected for measurement of plasma endothelin-1 (ET-1) and nitric oxide (NO) level. The results showed that the mRNA and protein expression profile of the VEGF system after phosgene exposure was time dependent. The VEGF system expression in lung tissue was related closely to the level of ET-1 and NO. In conclusion, increased permeability of the lung microvascular endothelium induced by phosgene was primarily a result of differential expression of VEGF and its receptors, and was related to the level of ET-1 and NO. The results suggest that the cooperation of VEGF system, ET-1, and NO plays a critical role, and all those parameters emerge as time dependent in the early phase of the permeability process induced by phosgene exposure.

Protective effects of S-methylisothiourea sulfate on different aspiration materials-induced lung injury in rats

OBJECTIVES

The aim of this study was to evaluate the efficiency of inducible nitric oxide synthase (iNOS) specific inhibitor, S-methylisothiourea sulfate (SMT) in preventing lung injury after different pulmonary aspiration materials in rats.

MATERIAL AND METHODS

The experiments were performed in 80 Sprague-Dawley rats, ranging in weight from 220 to 250 g, randomly allotted into one of the eight groups (n=10): normal saline (NS, control), Biosorb Energy Plus (BIO), sucralfate (SUC), hydrochloric acid (HCl), NS+SMT treated, BIO+SMT treated, SUC+SMT treated, and HCl+SMT treated. NS, BIO, SUC, HCl were injected in to the lungs in a volume of 2 ml/kg. The rats received twice daily intraperitoneal injections of 20 mg(kg day) SMT (Sigma Chemical Co.) for 7 days. Seven days later, rats were killed, and both lungs in all groups were examined immunohistochemically and histopathologically.

RESULTS

Our data show that SMT inhibits the inflammatory response significantly reducing (p<0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation in different pulmonary aspiration models. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and arise in the expression of surfactant protein D in lung tissue of different pulmonary aspiration models with SMT therapy.

CONCLUSION

It was concluded that SMT treatment might be beneficial in lung injury, therefore shows potential for clinical use.

Nitric oxide mediates acute lung injury caused by fat embolism in isolated rat's lungs

BACKGROUND

The involvement of nitric oxide (NO) in acute lung injury (ALI) induced by fat embolism (FE) has not been investigated. The present study elucidated the role of NO in ALI because of FE.

METHODS

FE was produced by introduction of fatty acid (corn oil micelles) into the isolated rat's lungs. Nonselective NO synthase (NOS) and selective inducible NOS (iNOS) inhibitors, N-nitro-l-arginine methyl ester (l-NAME) and l-N(1-iminoethyl)-lysine (l-Nil) as well as NO donors, sodium nitroprusside (SNP), and S-nitroso-N-acetylpenicillamine (SNAP) at a dose of 10 mol/L were given 60 minutes before FE. There were six groups of isolated lungs randomly assigned to receive vehicle (physiologic saline solution), FE, FE with pretreatment of l-NAME, l-Nil, SNP, or SNAP. Each group was observed for 4 hours.

RESULTS

FE significantly increased the lung weight changes, pulmonary arterial pressure, and microvascular permeability. The concentration of nitrate or nitrite, methyl guanidine, tumor necrosis factor-alpha, and interleukin-1beta was significantly elevated after FE. Hisotopathologic examination revealed lung edema with multiple fatty droplets in lung tissue. Pretreatment with l-NAME or l-Nil attenuated, whereas SNP or SNAP exacerbated most of the FE-induced changes. Addition of NO donors (SNP or SNAP) into the isolated lungs did not produce significant changes in the lungs, suggesting that NO donation alone without FE does not exerts harmful effect.

CONCLUSIONS

Our results suggest that NO production through the iNOS isoform plays a detrimental role in the FE-induced ALI. Free radical and proinflammatory cytokines may also be involved in the pathogenesis of ALI because of FE.

Clinical and pathological features of fat embolism with acute respiratory distress syndrome

FES (fat embolism syndrome) is a clinical problem, and, although ARDS (acute respiratory distress syndrome) has been considered as a serious complication of FES, the pathogenesis of ARDS associated with FES remains unclear. In the present study, we investigated the clinical manifestations, and biochemical and pathophysiological changes, in subjects associated with FES and ARDS, to elucidate the possible mechanisms involved in this disorder. A total of eight patients with FES were studied, and arterial blood pH, PaO(2) (arterial partial pressure of O(2)), PaCO(2) (arterial partial pressure of CO(2)), biochemical and pathophysiological data were obtained. These subjects suffered from crash injuries and developed FES associated with ARDS, and each died within 2 h after admission. In the subjects, chest radiography revealed that the lungs were clear on admission, and pulmonary infiltration was observed within 2 h of admission. Arterial blood pH and PaO(2) declined, whereas PaCO(2) increased. Plasma PLA(2) (phospholipase A(2)), nitrate/nitrite, methylguanidine, TNF-alpha (tumour necrosis factor-alpha), IL-1beta (interleukin-1beta) and IL-10 (interleukin-10) were significantly elevated. Pathological examinations revealed alveolar oedema and haemorrhage with multiple fat droplet depositions and fibrin thrombi. Fat droplets were also found in the arterioles and/or capillaries in the lung, kidney and brain. Immunohistochemical staining identified iNOS (inducible nitric oxide synthase) in alveolar macrophages. In conclusion, our clinical analysis suggests that PLA(2), NO, free radicals and pro-inflammatory cytokines are involved in the pathogenesis of ARDS associated with FES. The major source of NO is the alveolar macrophages.

A novel inhibitor of inducible nitric oxide synthase, ONO-1714, does not ameliorate hypoxia-induced pulmonary hypertension in rats

A recent study showed that long-term administration of the inducible nitric oxide synthase (iNOS) inhibitor L-NIL reduced the development of pulmonary hypertension. The purpose of the present study was to identify the effect of an another iNOS inhibitor, ONO-1714, on the development of pulmonary hypertensive vascular changes in chronic hypoxic pulmonary hypertension in rats. ONO-1714 was administered to rats exposed to hypobaric hypoxia (air at 380 mmHg) for 10 days. Muscularization of normally nonmuscular peripheral arteries and medial hypertrophy of normally muscular arteries were assessed by light microscopy. iNOS mRNA and protein levels of the lung were assessed in normal and hypoxic rats. Chronic hypoxia induced pulmonary hypertension, right ventricular hypertrophy, and hypertensive pulmonary vascular changes. Although an acute single injection of ONO-1714 induced a significant increase in mean pulmonary artery pressure in chronic hypoxic pulmonary hypertensive rats, the increase was slight and transient. There were no significant differences among rats with and without long-term administration of ONO-1714 in pulmonary artery pressure, right ventricular hypertrophy, medial wall thickness of muscular arteries, and the percentage of muscularized arteries at the alveolar wall and duct levels. Although there was a significantly increased expression of iNOS as assessed with the reverse-transcription polymerase chain reaction in rats that were exposed to 10 days of hypobaric hypoxia, we could not detect a significant level of iNOS protein by Western blotting. ONO-1714 does not have a therapeutic role in preventing the development of chronic hypoxic pulmonary hypertension.

A novel potent inhibitor of inducible nitric oxide synthase, ONO-1714, reduces hyperoxic lung injury in mice

STUDY OBJECTIVES

High-concentration oxygen therapy is used to treat tissue hypoxia, but hyperoxia causes lung injury. Overproduction of nitric oxide by nitric oxide synthase (NOS) is thought to promote hyperoxic lung injury. The present study was conducted to examine the role of inducible nitric oxide synthase (iNOS) in hyperoxic lung injury in mice.

MEASUREMENTS AND RESULTS

Mice were exposed to >98% oxygen for 72 h, and ONO-1714 (0.05 mg/kg) (ONO) was subcutaneously administered to block iNOS. Hyperoxia significantly increased total cell count, protein concentration, and nitrites/nitrates in the bronchoalveolar lavage fluid and proinflammatory cytokines in the lung tissue. ONO significantly prevented the increases in all of these variables. ONO suppressed histologic evidence of lung injury. ONO markedly inhibited iNOS protein expression and nitrotyrosine production in lung homogenates. After exposure to hyperoxia, alveolar epithelial cells stained positively for 8-hydroxy-2'-deoxyguanosine, a proper marker of oxidative DNA damage by reactive oxygen species. ONO attenuated this finding.

CONCLUSIONS

NOS play important roles in the pathogenesis of hyperoxic lung injury. Selective iNOS inhibitors may be useful for the treatment of hyperoxic lung injury.

Propofol exerts protective effects on the acute lung injury induced by endotoxin in rats

Acute lung injury (ALI) is a major culprit of mortality in endotoxemia. Propofol has been commonly used in critical ill patients for sedation. This experiment attempted to elucidate the effects and possible mechanisms of propofol on the ALI induced by endotoxin. Experimentations were carried out using anesthetized, ventilated rats and isolated perfused rat lungs. Endotoxemia was induced by intravenous lipopolysaccharide (LPS, 10 mg kg(-1)). Various groups of rats received infusion of physiological saline solution (PSS) and LPS. Five min after LPS, propofol at low dose (5 mg kg(-1)h(-1)) or high dose (10 mg kg(-1)h(-1)) was infused for 6h. In isolated perfused rat lungs, PSS, LPS, and propofol (30 or 60 mg kg(-1)) were added into the perfusion circuit. During or after 6h observation, we determined the lung weight (LW)/body weight ratio, LW gain, exhaled nitric oxide (NO) and protein concentration in broncheoalveolar lavage. Lung pathology was evaluated to quantify the lung injury score. Plasma nitrate/nitrite, methyl guanidine (MG), tumor necrosis factor(alpha), and interleukin-1(beta) were examined. Blood leukocytes were counted. Capillary filtration coefficient (K(fc)) was obtained in isolated perfused lungs. Posttreatment of propofol at low or high dose attenuated or prevented the extent of ALI. It also reduced the plasma nitrate/nitrite, MG, and pro-inflammatory cytokines including tumor necrosis factor(alpha) (TNF(alpha)) and interleukin-1(beta) (IL-1(beta)). In the isolated perfused rat lungs, propofol significantly reduced the LPS-induced increase in K(fc). This agent did not affect the leukocytopenia caused by LPS. Accordingly, the effects of propofol on the ALI were not related to leukocyte activation or sequestration. Our results suggest that propofol exerts protective effect on the endotoxin-induced ALI. The mechanisms of actions may be mediated through inhibition on the release of pro-inflammatory cytokines, free radicals and NO. In addition, propofol abrogates the microvascular leakage of water and protein in the lungs. The results imply that the use of propofol in critically ill is not only for sedation, but also useful for the prevention of inflammatory progression and lung damage.

Activated protein C attenuates acid-aspiration lung injury in rats

Acid aspiration causes direct lung damage and secondary inflammatory response involving several cytokines and accumulation of neutrophils. Activated protein C (APC) exhibits antithrombotic and anti-inflammatory properties. We examined the effect and mechanism of pre-treatment APC on acid-aspirated lung injury in rats. Anesthetized rats were instilled intratracheally with normal saline (NS, 2 ml kg(-1)) or hydrochloric acid (HCl, 0.1 N, 2 ml kg(-1)). Thirty minutes before HCl instillation, APC (200 U kg(-1) h(-1)) was infused continuously into the right jugular vein. Animals were ventilated during the experiments. Five hours after HCl or NS instillation, bronchoalveolar lavage fluid (BALF) and lung tissue samples were obtained. Total and differential cell count, absorbance, albumin concentration, concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and cytokine-induced neutrophil chemoattractant (CINC) in BALF, wet and dry weight (W/D) ratio were measured. Platelet count and fibrin degradation product (FDP) in peripheral blood were also measured. HCl instillation markedly increased these values in BALF as well as W/D ratio. APC attenuated the parameters increased by HCl-induced lung injury in rats. However, HCl instillation and APC treatment did not cause significant changes in platelet count and FDP compared with the control. We conclude that APC treatment protected the rats against HCl-induced lung injury and that this action seemed to be due to the anti-inflammatory properties of this protein rather than its anti-coagulant effects.