Isolated Rat Lung Perfusion Research Articles

Surfactant Attenuates Air Embolism-Induced Lung Injury by Suppressing NKCC1 Expression and NF-\u03baB Activation

Excessive amounts of air can enter the lungs and cause air embolism (AE)-induced acute lung injury (ALI). Pulmonary AE can occur during diving, aviation, and iatrogenic invasive procedures. AE-induced lung injury presents with severe hypoxia, pulmonary hypertension, microvascular hyper-permeability, and severe inflammatory responses. Pulmonary AE-induced ALI is a serious complication resulting in significant morbidity and mortality. Surfactant is abundant in the lungs and its function is to lower surface tension. Earlier studies have explored the beneficial effects of surfactant in ALI; however, none have investigated the role of surfactant in pulmonary AE-induced ALI. Therefore, we conducted this study to determine the effects of surfactant in pulmonary AE-induced ALI. Isolated-perfused rat lungs were used as a model of pulmonary AE. The animals were divided into four groups (n = 6 per group): sham, air embolism (AE), AE + surfactant (0.5 mg/kg), and AE+ surfactant (1 mg/kg). Surfactant pretreatment was administered before the induction of pulmonary AE. Pulmonary AE was induced by the infusion of 0.7 cc air through a pulmonary artery catheter. After induction of air, pulmonary AE was presented with pulmonary edema, pulmonary microvascular hyper-permeability, and lung inflammation with neutrophilic sequestration. Activation of NF-κB was observed, along with increased expression of pro-inflammatory cytokines, and Na-K-Cl cotransporter isoform 1 (NKCC1). Surfactant suppressed the activation of NF-κB and decreased the expression of pro-inflammatory cytokines and NKCC1, thereby attenuating AE-induced lung injury. Therefore, AE-induced ALI presented with pulmonary edema, microvascular hyper-permeability, and lung inflammation. Surfactant suppressed the expressions of NF-κB, pro-inflammatory cytokines, and NKCC1, thereby attenuating AE-induced lung injury.

Phosphodiesterase-4 Inhibitor Roflumilast Attenuates Pulmonary Air Emboli–Induced Lung Injury

BackgroundPulmonary air embolism (PAE)–induced acute lung injury (ALI) can be caused by massive air entry into the lung circulation. PAE can occur during diving, aviation, and some iatrogenic invasive procedures. PAE-induced ALI presents with severe inflammation, hypoxia, and pulmonary hypertension, and it is a serious complication resulting in significant morbidity and mortality. Phosphodiesterase-4 (PDE4) inhibitors can regulate inflammation and are therefore expected to have a therapeutic effect on ALI. However, the effect of the PDE4 inhibitor roflumilast on PAE-induced ALI is unknown. MethodsThe PAE model was undertaken in isolated-perfused rat lungs. Four groups (n = 6 in each group) were defined as follows: control, PAE, PAE + roflumilast 2.5 mg/kg, and PAE + roflumilast 5 mg/kg. Induction of PAE-induced ALI was achieved via the infusion of 0.7 cc air through the pulmonary artery. Roflumilast was administered via perfusate. All groups were assessed for pulmonary microvascular permeability, lung histopathology changes, pulmonary edema (lung weight/body weight, lung wet/dry weight ratio), tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-17, nuclear factor–kappa B (NF-κB), and inhibitor of NF-κB alpha (IκB-α). ResultsAfter the induction of air, PAE-induced ALI presented with pulmonary edema, pulmonary microvascular hyperpermeability, and lung inflammation with neutrophilic sequestration. The PAE-induced ALI also presented with increased expressions of IL-1β, IL-6, IL-8, IL-17, TNF-α, and NF-κB and decreased expression of IκB-α. The administration of roflumilast decreased pulmonary edema, inflammation, cytokines, NF-κB, and restored IκB-α level. ConclusionsPAE-induced ALI presents with lung inflammation with neutrophilic sequestration, pulmonary edema, hyperpermeability, increased cytokine levels, and activation of the NF-κB pathway. Roflumilast attenuates lung edema and inflammation and downregulates the NF-κB pathway and cytokines.

Protective Effect of Inhaled Rho-Kinase Inhibitor on Lung Ischemia-Reperfusion Injury

Rho-kinase, an intracellular serine/threonine kinase, is a key regulator of cytoskeletal dynamics. Recent studies have demonstrated that Rho-kinase is involved in the ischemia-reperfusion injury (IRI) pathogenesis of many organs; however, its involvement with lung IRI remains unclear. This study assessed the association of Rho-kinase with lung IRI and evaluated the protective effect of inhaled Rho-kinase inhibitors in lung IRI. The study included isolated rat lung perfusion models, divided into three groups: sham, Rho-kinase inhibitor, and warm ischemia (n= 6 each). The lungs were exposed to 60 minutes of warm ischemia by perfusion cessation. At the onset of ischemia, nebulized fasudil, a novel Rho-kinase inhibitor, and saline were inhaled in the Rho-kinase inhibitor and warm ischemia groups, respectively. Perfusion was restarted after the ischemic period, and physiologic data were collected for 90 minutes. Lungs in the sham group were continuously perfused without ischemia or drug administrations. Protein expression in tissue specimens related to the Rho-kinase pathway was evaluated by Western blotting. Warm ischemia and subsequent reperfusion enhanced Rho-kinase activity, and this was suppressed by fasudil inhalation. Fasudil inhalation significantly attenuated IRI pathophysiology, including pulmonary vascular contraction, dynamic compliance, lung edema, and oxygenation. Molecular analysis showed that Rho-kinase suppressed myosin phosphatase and endothelial nitric oxide synthase activities, suggesting these are downstream targets of Rho-kinase during lung IRI pathogenesis. The present study suggests that Rho-kinase activation is involved in lung IRI pathogenesis and that inhaled Rho-kinase inhibitors may attenuate this pathogenesis.

(868) - Involvement of Rho-Kinase in Lung Ischemia-Reperfusion Injury Pathogenesis: Molecular Analysis in an Isolated Rat Lung Perfusion Model

(868) - Involvement of Rho-Kinase in Lung Ischemia-Reperfusion Injury Pathogenesis: Molecular Analysis in an Isolated Rat Lung Perfusion Model

(737) - Protective Effect of Nebulized Rho-Kinase Inhibitor on Ischemia Reperfusion Injury in Isolated Rat Lung Perfusion Model

(737) - Protective Effect of Nebulized Rho-Kinase Inhibitor on Ischemia Reperfusion Injury in Isolated Rat Lung Perfusion Model

Platelet Vascular Endothelial Growth Factor is a Potential Mediator of Transfusion-Related Acute Lung Injury.

ObjectiveThe occurrence of non-hemolytic transfusion reactions is highest with platelet and plasma administration. Some of these reactions are characterized by endothelial leak, especially transfusion related acute lung injury (TRALI). Elevated concentrations of inflammatory mediators secreted by contaminating leukocytes during blood product storage may contribute to such reactions, but platelet-secreted mediators may also contribute. We hypothesized that platelet storage leads to accumulation of the endothelial permeability mediator vascular endothelial growth factor (VEGF), and that intravascular administration of exogenous VEGF leads to extensive binding to its lung receptors.MethodsSingle donor, leukocyte-reduced apheresis platelet units were sampled over 5 days of storage. VEGF protein content of the centrifuged supernatant was determined by ELISA, and the potential contribution of VEGF from contaminating leukocytes was quantified. Isolated-perfused rat lungs were used to study the uptake of radiolabeled VEGF administered intravascularly, and the effect of unlabeled VEGF on lung leak.ResultsThere was a time-dependent release of VEGF into the plasma fraction of the platelet concentrates (62 ± 9 pg/ml on day one, 149 ± 23 pg/ml on day 5; mean ± SEM, p<0.01, n=8) and a contribution by contaminating leukocytes was excluded. Exogenous 125I-VEGF bound avidly and specifically to the lung vasculature, and unlabeled VEGF in the lung perfusate caused vascular leak.ConclusionRising concentrations of VEGF occur during storage of single donor platelet concentrates due to platelet secretion or disintegration, but not due to leukocyte contamination. Exogenous VEGF at these concentrations rapidly binds to its receptors in the lung vessels. At higher VEGF concentrations, VEGF causes vascular leak in uninjured lungs. These data provide further evidence that VEGF may contribute to the increased lung permeability seen in TRALI associated with platelet products.

Polyethylene glycol-drug ester conjugates for prolonged retention of small inhaled drugs in the lung

Typically, inhaled drugs are rapidly absorbed into the bloodstream, which results in systemic side effects and a brief residence time in the lungs. PEGylation was evaluated as a novel strategy for prolonging the retention of small inhaled molecules in the pulmonary tissue. Hydrolysable ester conjugates of PEG1000, PEG2000, mPEG2000, PEG3400 and prednisolone, a model drug cleared from the lungs within a few minutes, were synthesised and thoroughly characterised. The conjugates were stable in buffers with hydrolysis half-lives ranging from 1h to 70h, depending on the pH and level of substitution. With the exception of PEG3400-prednisolone, conjugates did not induce a significant lactate dehydrogenase (LDH) release from Calu-3 cells after a 20h exposure. Following nebulisation to isolated perfused rat lungs (IPRL), the PEG2000 and mPEG2000 conjugates reduced the maximum prednisolone concentration in the perfusate (Cmax) by 3.0 and 2.2 fold, respectively. Moreover, while prednisolone was undetectable in the perfusion solution beyond 20min when the free drug was administered, prednisolone concentrations were still quantifiable after 40min following delivery of the conjugates. This study is the first to demonstrate hydrolysable PEG drug ester conjugates are a promising approach for optimising the pharmacokinetic profile of small drugs delivered by inhalation.

Novel Flurometric Tool to Assess Mitochondrial Redox State of Isolated Perfused Rat Lungs after Exposure to Hyperoxia.

Recently, we demonstrated the utility of optical fluorometry to detect a change in the redox status of mitochondrial autofluorescent coenzymes nicotinamide adenine dinucleotide (NADH) and oxidized form of flavin adenine dinucleotide n}{}({rm FADH}_{2}) (FAD), as a measure of mitochondrial function in isolated perfused rat lungs (IPL). The objective of this paper was to utilize optical fluorometry to evaluate the effect of rat exposure to hyperoxia (n}{}{>}{95%}~{rm O}_{2} for 48 h) on lung tissue mitochondrial redox status of NADH and FAD in a nondestructive manner in IPL. Surface NADH and FAD signals were measured before and after lung perfusion with perfusate containing rotenone (ROT, complex I inhibitor), potassium cyanide (KCN, complex IV inhibitor), and/or pentachlorophenol (PCP, uncoupler). ROT- or KCN-induced increase in NADH signal is considered a measure of complex I activity, and KCN-induced decrease in FAD signal is considered a measure of complex II activity. The results show that hyperoxia decreased complex I and II activities by 63% and 55%, respectively, when compared to lungs of rats exposed to room air (normoxic rats). Mitochondrial complex I and II activities in lung homogenates were also lower (77% and 63%, respectively) for hyperoxic than for normoxic lungs. These results suggest that the mitochondrial matrix is more reduced in hyperoxic lungs than in normoxic lungs, and demonstrate the ability of optical fluorometry to detect a change in mitochondrial redox state of hyperoxic lungs prior to histological changes characteristic of hyperoxia.

Therapeutic effect of surfactant inhalation during warm ischemia in an isolated rat lung perfusion model

Warm ischemia-reperfusion injury related to donation after cardiac death donors is a crucial and inevitable issue. As surfactant function is known to deteriorate during warm ischemia, we hypothesized that surfactant inhalation during warm ischemia would mitigate warm ischemia-reperfusion injury. We used an isolated rat lung perfusion model. The rats were divided into three groups: sham, control, and surfactant. In the control and surfactant groups, cardiac arrest was induced by ventricular fibrillation. Ventilation was restarted 110 min later; subsequently, the lungs were flushed, and heart and lung block was recovered. In the surfactant group, a natural bovine surfactant Surfacten(®) was inhaled for 3 min at the end of warm ischemia. Then, the lungs were reperfused for 80 min. Surfactant inhalation significantly improved graft functions, effectively increased lung tissue ATP levels, and significantly decreased mRNA levels of IL-6 and IL-6/IL-10 ratio at the end of reperfusion. Histologically, lungs in the surfactant group showed fewer signs of interstitial edema and hemorrhage, and significantly less neutrophilic infiltration than those in the control group. Our results indicated that surfactant inhalation in the last phase of warm ischemia maintained lung tissue energy levels and prevented cytokine production, resulting in the alleviation of warm ischemia-reperfusion injury.

Experimental Model of Isolated Lung Perfusion in Rats: First Brazilian Experience Using the IL-2 Isolated Perfused Rat or Guinea Pig Lung System

Introduction Lung transplantation has become the mainstay therapy for patients with end-stage lung disease refractory to medical management. However, the number of patients listed for lung transplantation largely exceeds available donors. The study of lung preservation requires accurate, cost-effective small animal models. We have described a model of ex vivo rat lung perfusion using a commercially available system. Methods Male Wistar rats weighing 250 g–300 g were anesthetized with intraperitoneal sodium thiopental (50 mg/kg body weight). The surgical technique included heart-lung block extraction, assembly, and preparation for perfusion and data collection. We used an IL-2 Isolated Perfused Rat or Guinea Pig Lung System (Harvard Apparatus, Holliston, Mass, United States; Hugo Sachs Elektronik, Alemanha). Results Preliminary results included hemodynamic and pulmonary mechanics data gathered in the experiments. Conclusion The isolated rat lung perfusion system is a reliable method to assess lung preservation.

Post-ischemic Infusion of Atrial Natriuretic Peptide Attenuates Warm Ischemia–Reperfusion Injury in Rat Lung

The serious shortage of organs for transplantation, especially lungs, has drawn increasing attention to donation after cardiac death and protection of organs against warm ischemic injury. Atrial natriuretic peptide (ANP) activates guanylate cyclase receptors and increases cyclic guanosine monophosphate (cGMP) levels, which decrease in the lung during ischemia. In this study we investigated the effect on lung ischemia-reperfusion injury of administering synthetic ANP (carperitide) at the onset of reperfusion after warm ischemia. An isolated rat lung perfusion model was used. The rats were allocated into three groups: the control group; the ANP group; and the sham group. In the control and ANP groups, the heart-lung block was exposed to 60 minutes of ischemia at 37 degrees C, and subsequently reperfused for 60 minutes. At the onset of reperfusion, either saline or ANP was added to the perfusate. In the sham group, lungs were continuously perfused without ischemia and only saline was added to the perfusate. ANP significantly reduced pulmonary vascular resistance and pulmonary edema, and improved oxygenation. It also significantly increased cGMP levels in reperfused lungs. Histologically, lungs in the ANP group showed significantly fewer signs of injury and fewer cells demonstrated apoptotic changes or single-stranded DNA than lungs in the control group. Our results indicate that ANP administered at the onset of reperfusion increases cGMP in lung tissue and attenuates warm ischemia-reperfusion injury in isolated perfused rat lung.

Nebulized Phosphodiesterase III Inhibitor During Warm Ischemia Attenuates Pulmonary Ischemia–Reperfusion Injury

The control of warm ischemia-reperfusion injury is crucial in managing donors after cardiac death for lung transplantation. We focused on transalveolar administration as a drug-delivery route for such donors. Milrinone is a phosphodiesterase 3 inhibitor that inhibits the breakdown of cyclic adenosine monophosphate and selectively relaxes smooth muscle. We hypothesized that nebulized milrinone would mitigate warm ischemia-reperfusion injury of lung. This study was conducted with an isolated rat lung perfusion model. Lungs were excised, exposed to 55-minute ischemia at 37 degrees C, and reperfused for 60 minutes. During ischemia, nebulized milrinone (n = 6) or saline (n = 6) was inhaled. Lungs were continuously perfused without ischemia as a sham group (n = 6). Airway resistance, pulmonary vascular resistance, pulmonary compliance, weight gain and blood gas were measured. Adenine nucleotide levels and apoptosis were investigated in the reperfused lungs. Milrinone nebulization decreased post-ischemic pulmonary vascular resistance (0.98 +/- 0.05 and 1.74 +/- 0.17 cm H(2)O/ml.min at 60 minutes of reperfusion in the milrinone and control groups, respectively [p < 0.01]). It did not alter cyclic adenosine monophosphate levels, but it did elevate adenosine triphosphate levels (9.87 +/- 0.38 and 6.91 +/- 0.45 in the milrinone and control groups, respectively [p < 0.01]) and suppressed apoptosis (3.83 +/- 0.91 and 46.17 +/- 3.39 of mean apoptotic cell numbers in the milrinone and control groups, respectively [p < 0.01]). Milrinone nebulization decreased post-ischemic pulmonary vascular resistance, elevated adenosine triphosphate levels, and suppressed apoptosis. Nebulized milrinone has some protective effects against warm ischemia.

446: Successful Subzero Non-Freezing Preservation of Rat Lungs with Supercooling Technology

Purpose: Supercooling is defined as a non-freezing state of liquid below freezing temperature. Stable supercooling at the temperature between 0°C to –10°C is achieved in a newly developed refrigerator with a power voltage of 3,000 V. We hypothesized that supercooling would reduce metabolism of organ grafts and lungs preserved in supercooling would have better physiological function than in the clinically standard storage at 4°C. Methods and Materials: We investigated in a previously published isolated rat lung perfusion model, in which physiological parameters such as tidal volume, arterial oxygen tension, and lung weight were measured. The heart-lung block was preserved for 17 hr and subsequently reperfused for 60 minutes. All animals were divided into three groups. In the supercoolng group (n 7), non-freezing preservation at -2°C was kept in a supercooling refrigerator. In the control group (n 7), the ordinary hypothermic preservation was maintained at 4°C. In the sham group (n 7), after harvesting lungs were continuously perfused without hypothermic preservation. Results: Two animals in the control group were excluded from the following analysis because of severe lung edema within 12 minutes of reperfusion. Oxygen tensions at 60 minutes of reperfusion were 101.8 2.6 in the supercooling, 58.6 10.8 in the control, and 104.4 1.9 in the fresh (mmHg). At 60 minutes, tidal volumes were 2.0 0.1 in the supercooing, 1.0 0.3 in the control, and 2.2 0.1 in the fresh (mL). The lung weight gains during the 60 minutes were 1248 56, 2983 543, and 693 69, in supercooling, in control and in fresh, respectively (mg). Throughout the experiment, oxygen tensions and tidal volumes in the supercooling and the fresh were significantly higher than the control group(p 0.001, p 0.05, respectively), and the lung weight gains in the supercooling and the fresh were significantly lower than the control (p 0.001). Conclusions: Supercooling demonstrated the superiority in hypothermic preservation of rat lungs to the standard storage of 4°C in an isolated rat lung perfusion model.

Hydroxyurea attenuates activated neutrophil-mediated sickle erythrocyte membrane phosphatidylserine exposure and adhesion to pulmonary vascular endothelium

Activated neutrophils increase erythrocyte phosphatidylserine (PS) exposure. PS-exposed sickle red blood cells (SSRBCs) are more adhesive to vascular endothelium than non-PS-exposed cells. An increase in SSRBC fetal hemoglobin (HbF) concentration has been associated with improved rheology and decreased numbers of vasoocclusive episodes. This study examined the effects of HbF, PS-exposed SSRBCs, and chronic hydroxyurea (HU) treatment on activated neutrophil-mediated SSRBC retention/adherence in isolated-perfused rat lungs. Lungs were perfused with erythrocyte suspensions from 1) individuals homozygous for hemoglobin S with 0-7% HbF (SS), 2) with > or =8% HbF (SS + F), and 3) individuals homozygous for hemoglobin S treated with HU therapy for > or =1 yr (SS + HU). Retention of SSRBCs from the SS + HU group was significantly less than that seen in both the SS and SS + F groups. No difference was observed between the SS and SS + F groups. The percentage of HbF and F-cells did not differ between the SS + F and SS + HU groups. At baseline, the proportion of PS-exposed SSRBCs was not different between the SS and SS + HU groups. However, SSRBC treatment with activated neutrophil supernatant caused a twofold increase in PS-exposed SSRBCs in the SS control and no change in the SS + HU group. We conclude that 1) HU attenuates SSRBC retention/adherence in the pulmonary circulation seen in response neutrophil activation, 2) HU stabilizes SSRBC membrane PS, and 3) HU attenuation SSRBC retention/adherence in the pulmonary circulation occurs through a mechanism(s) independent of HbF.

Protective Effect of a Nebulized β 2-Adrenoreceptor Agonist in Warm Ischemic–Reperfused Rat Lungs

It seems inevitable that non-beating-heart donors will be utilized to resolve the shortage of donors for clinical lung transplantation. The control of warm ischemia-reperfusion injury is crucial in manipulating non-beating-heart donors. We hypothesized that nebulization of a beta2-adrenoreceptor agonist, salmeterol xinafoate (SLM), during warm ischemia would increase lung tissue cyclic adenosine monophosphate (cAMP) levels, resulting in lung protection. Two studies were conducted. The first investigated the effect of SLM nebulization during ischemia on pulmonary ischemia-reperfusion injury, using an isolated rat lung-perfusion model. The heart-lung block was excised with cannulation of the pulmonary artery and vein, exposed to 55 minutes of ischemia at 37 degrees C, and subsequently reperfused for 60 minutes. Several parameters were measured during reperfusion. In the second study, to measure changes in lung tissue cAMP levels during warm ischemia with or without SLM nebulization, rat lungs were harvested and exposed to 60 minutes of warm ischemia with ventilation. Salmeterol xinafoate nebulization significantly decreased the pulmonary shunt fraction, airway resistance, and pulmonary vascular resistance. It also inhibited pulmonary edema throughout the reperfusion period. Lung tissue cAMP was effectively maintained by SLM nebulization at the end of reperfusion. Myeloperoxidase activity in the lungs was decreased significantly by SLM nebulization. Lung tissue cAMP levels decreased during the 60 minutes of warm ischemia, but increased with SLM nebulization (p < 0.01). Our results confirmed that SLM nebulization during warm ischemia maintained lung tissue cAMP levels, resulting in the alleviation of pulmonary warm ischemia-reperfusion injury.

392 C0-Administration of captopril or niacin with paraquat in isolated rat lung perfusion

392 C0-Administration of captopril or niacin with paraquat in isolated rat lung perfusion

Stretch activates nitric oxide production in pulmonary vascular endothelial cells in situ.

Whereas endothelial responses to shear stress have been studied extensively, the responses to circumferential vascular stretch are yet poorly defined. Circumferential stretch in pulmonary microvessels is largely determined by the transmural pressure gradient, hence by both vascular perfusion and alveolar ventilation pressures. Here, we have studied the production of nitric oxide (NO) by the endothelial nitric oxide synthase (eNOS) in two different models of vascular stretch in the intact lung: In isolated-perfused rat lungs, vascular stretch was induced by elevation of vascular pressure. In situ digital fluorescence microscopy revealed stretch-dependent NO production, which was localized to capillary endothelial cells and inhibited by NOS blockers. In isolated-perfused mouse lungs, vascular stretch was generated by ventilation with elevated negative pressure. Stretch-induced phosphorylation of Akt and eNOS in lung endothelial cells was demonstrated by immunohistochemistry and increased NO production by in situ fluorescence microscopy. Stretch-induced endothelial responses in both models were abrogated by pretreatment with phosphatidylinositol-3-OH kinase inhibitors. These findings demonstrate that circumferential stretch activates NO production in pulmonary endothelial cells by a signaling cascade involving phosphatidylinositol-3-OH kinase, Akt, and eNOS and that this response is independent from the mechanical factors causing vascular distension.

Addition of ATP and MgCl2 to the Preservation Solution Attenuates Lung Reperfusion Injury following Cold Ischemia

Background: In lung transplantation, reperfusion injury following cold ischemia is one of the crucial problems for recipients. Objective: We evaluated the protective effect of adding a combination of ATP and MgCl₂ to the preservation solution against lung reperfusion injury following cold ischemia. Methods: Using an isolated rat lung perfusion model with fresh rat blood as the perfusate, the rats were divided into five groups (n = 6). In the fresh group, the study lungs were flushed with phosphate-buffered saline (PBS), then immediately reperfused for 120 min. In the control group, the study lungs were flushed with PBS, then cold ischemia was induced for 9 h (4°C), after which reperfusion was performed. In the other three groups, the protocols were the same as for the control group except that ATP and/or MgCl₂ were added to the PBS: ATP group (100 µM ATP), MgCl₂ group (100 µM MgCl₂) and ATP + MgCl₂ group (100 µM ATP + 100 µM MgCl₂). Results: In the ATP + MgCl₂ group, the intrapulmonary shunt fraction, peak airway pressure and wet to dry lung weight ratio were significantly lower than those in the control group. No improvement was observed in the ATP or MgCl₂ groups. Histological examination supported these physiological results. In all groups, flush time and lipid peroxide levels in the lungs after cold ischemia did not show any significant differences. Conclusion: The addition of ATP and MgCl₂ to the preservation solution attenuated reperfusion injury following cold ischemia in rat lungs.

"Chemical preconditioning" by 3-nitropropionate reduces ischemia-reperfusion injury in cardiac-arrested rat lungs.

Chemical preconditioning was defined as the induction of resistance to massive disruption of energy metabolism through prior chemical suppression of oxidative phosphorylation, by which phenomena similar to those resulting from increased ischemic tolerance as a result of ischemic preconditioning can be induced. It could be induced by the inhibitor of either mitochondrial complex I or II. We investigated whether or not chemical preconditioning by 3-nitropropionate (an inhibitor of the mitochondrial complex II) can suppress ischemia-reperfusion injury in cardiac-arrested lungs, which will be the major problem in lung transplants donated from non-heart-beating cadavers. In an isolated rat lung perfusion model with fresh rat blood as perfusate, administration of 3-nitropropionate (20 mg/kg) immediately before the induction of cardiac arrest attenuated pulmonary dysfunction during reperfusion after 1 hr postmortem warm ischemia and 1 hr cold preservation. 3-Nitropropionate administration reduced the mitochondrial respiratory functions (state 3 and state 4 respiration, and the respiratory control ratio) before cardiac arrest and kept them at a lower level of activity than when decreased by ischemia alone. 3-Nitropropionate administration also reduced the ATP levels immediately after drug administration. However, 3-nitropropionate did not significantly reduce lipid peroxidation in the lung tissue and mitochondria. These results demonstrated that chemical preconditioning by 3-nitropropionate administration immediately before cardiac arrest suppressed succinate-related oxidation during postmortem warm ischemia and reduced ischemia-reperfusion injury in cardiac arrested rat lungs.

Reperfusion lung injury after cold preservation correlates with decreased levels of intrapulmonary high-energy phosphates.

To evaluate the role of energy state in primary graft dysfunction, which is crucial in lung transplantation, we investigated the relationship between intrapulmonary high-energy phosphate compounds and reperfusion lung injury after cold preservation. Using an isolated rat lung perfusion model with fresh rat blood as perfusate, rat lungs were exposed to various cold preservation periods (0, 6, 9, and 12 hr) and reperfused. We found that extending the preservation period exacerbated the pulmonary hemodynamics after reperfusion. The levels of intrapulmonary high-energy phosphate compounds did not change during cold preservation, but these levels after reperfusion decreased as the preservation period was prolonged. The pulmonary hemodynamics after reperfusion were inversely correlated with the intrapulmonary high-energy phosphate compound levels after reperfusion. Total adenine nucleotide and ATP were sensitive indicators of reperfusion lung injury after cold preservation. Energy charge was not a sensitive indicator. The decreased levels of intrapulmonary high-energy phosphate compounds after reperfusion following cold preservation period were partially caused by their decreased production. These results demonstrated that reperfusion lung injury after cold preservation was closely correlated with decreased levels of intrapulmonary high-energy phosphate compounds after reperfusion, although the levels of the intrapulmonary high-energy phosphate compounds did not change during cold preservation of up to 12 hr.