Pulmonary Capillary Filtration Coefficient Research Articles

Effects of Bisphenol A Metabolite 4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene on Lung Function and Type 2 Pulmonary Alveolar Epithelial Cell Growth.

Bisphenol A (BPA) is recognized as a major pollutant worldwide. 4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) is a major active metabolite of BPA. The epidemiological and animal studies have reported that BPA is harmful to lung function. The role of MBP in lung dysfunction after BPA exposure still remains unclear. This study investigated whether MBP would induce lung alveolar cell damage and evaluated the role of MBP in the BPA exposure-induced lung dysfunction. An in vitro type 2 alveolar epithelial cell (L2) model and an ex vivo isolated reperfused rat lung model were used to determine the effects of BPA or MBP on cell growth and lung function. MBP, but not BPA, dose-dependently increased the mean artery pressure (Pa), pulmonary capillary pressure (Pc), pulmonary capillary filtration coefficient (Kfc), and wet/dry weight ratio in isolated reperfused rat lungs. MBP significantly reduced cell viability and induced caspases-3/7 cleavage and apoptosis and increased AMP-activated protein kinas (AMPK) phosphorylation and endoplasmic reticulum (ER) stress-related molecules expression in L2 cells, which could be reversed by AMPK-siRNA transfection. These findings demonstrated for the first time that MBP exposure induced type 2 alveolar cell apoptosis and lung dysfunction through an AMPK-regulated ER stress signaling pathway.

Hepatic Warm Ischemia-Reperfusion–Induced Increase in Pulmonary Capillary Filtration Is Ameliorated by Administration of a Multidrug Resistance–Associated Protein 1 Inhibitor and Leukotriene D4 Antagonist (MK-571) Through Reducing Neutrophil Infiltration and Pulmonary Inflammation and Oxidative Stress in Rats

BackgroundHepatopulmonary syndrome (HPS) is the major complication subsequent to liver ischemia and reperfusion (I/R) injury after resection or transplantation of liver. Hallmarks of HPS include increases in pulmonary leukotrienes and neutrophil recruitment and infiltrating across capillaries. We aimed to investigate the protective efficacy of MK-571, a multidrug resistance-associated protein 1 inhibitor and leukotriene D4 agonist, against hepatic I/R injury–associated change in capillary filtration. MethodsEighteen Sprague-Dawley male rats were evenly divided into a sham-operated group, a hepatic I/R group, and an MK-571–treated I/R group. MK-571 was administered intraperitoneally 15 min before hepatic ischemia and every 12 hours during reperfusion. Ischemia was conducted by occluding the hepatic artery and portal vein for 30 min, followed by removing the clamps and closing the incision. Forty-eight hours after hepatic ischemia, we assessed the pulmonary capillary filtration coefficient (Kfc) through the use of in vitro–isolated, perfused rat lung preparation. We also measured the lung wet-to-dry weight ratio (W/D) and protein concentration in broncho-alveolar lavage fluid (PCBAL). Lung inflammation and oxidative stress were evaluated by use of tissue tumor necrosis factor (TNF)-α and malondialdehyde levels and lavage differential macrophage and neutrophil cell count. ResultsHepatic I/R injury markedly increased Kfc, W/D, PCBAL, tissue TNF-α level, and differential neutrophil cell count (P < .05). MK-571 treatment reduced neutrophil infiltration and lung inflammation and improved pulmonary capillary filtration, collectively suggesting lung protection. ConclusionsTreatment with MK-571 before and during hepatic ischemia and reperfusion protects lung against pulmonary capillary barrier function impairment through decreasing pulmonary lung inflammation and lavage neutrophils.

Oxidative stress increases pulmonary capillary permeability in lean Zucker rats with chronic hyperglycemia (1153.6)

Chronic hyperglycemia in obesity and diabetes is associated with increased vascular oxidative stress and endothelial dysfunction, including an increase in endothelial permeability. Increases in pulmonary capillary permeability associated with hyperglycemia and oxidative stress may contribute to lung edema in obesity and diabetes following trauma. We hypothesized that chronic hyperglycemia‐induced oxidative stress increases pulmonary capillary filtration coefficient (Kf). Lean Zucker rats (LZ) (n=12, STZ 50 mg/kg, ip) were hyperglycemia for 4 wks. A subgroup (n=6) was treated with apocynin (NADPH oxidase inhibitor, 2 mM in drinking water for 4 wks). Kf was measured in isolated lungs. Superoxide was measured in aortas using DHE. PMS (superoxide donor, 1 µM) was added to the isolated lung perfusate to determine the effect of an increased superoxide on Kf. Aortas from control LZ (LC) were treated with PMS to verify an increase in superoxide levels. STZ‐treated LZ (LS) exhibited significantly increased vascular superoxide levels and Kf (31 ± 4 ml/mmHg/g/min) compared to LC (7 ± 3 ml/mmHg/g/min). Apocynin treatment significantly reduced the superoxide levels and Kf (18 ± 3 ml/mmHg/g/min) in LS. PMS significantly increased Kf (37 ± 7 ml/mmHg/g/min) in isolated lungs from LC. These results suggest that, during chronic hyperglycemia, elevated vascular superoxide increases pulmonary permeability.Grant Funding Source: Supported by AHA‐12POST12060126, NIH HL‐51971, HL‐89581, and AHA‐12SDG12050525

Niacinamide mitigated the acute lung injury induced by phorbol myristate acetate in isolated rat's lungs.

BackgroundPhorbol myristate acetate (PMA) is a strong neutrophil activator and has been used to induce acute lung injury (ALI). Niacinamide (NAC) is a compound of B complex. It exerts protective effects on the ALI caused by various challenges. The purpose was to evaluate the protective effects of niacinamide (NAC) on the PMA-induced ALI and associated changes.MethodsThe rat's lungs were isolated in situ and perfused with constant flow. A total of 60 isolated lungs were randomized into 6 groups to received Vehicle (DMSO 100 μg/g), PMA 4 μg/g (lung weight), cotreated with NAC 0, 100, 200 and 400 mg/g (lung weight). There were 10 isolated lungs in each group. We measured the lung weight and parameters related to ALI. The pulmonary arterial pressure and capillary filtration coefficient (Kfc) were determined in isolated lungs. ATP (adenotriphosphate) and PARP [poly(adenosine diphophate-ribose) polymerase] contents in lung tissues were detected. Real-time PCR was employed to display the expression of inducible and endothelial NO synthases (iNOS and eNOS). The neutrophil-derived mediators in lung perfusate were determined.ResultsPMA caused increases in lung weight parameters. This agent produced pulmonary hypertension and increased microvascular permeability. It resulted in decrease in ATP and increase in PARP. The expression of iNOS and eNOS was upregulated following PMA. PMA increased the neutrophil-derived mediators. Pathological examination revealed lung edema and hemorrhage with inflammatory cell infiltration. Immunohistochemical stain disclosed the presence of iNOS-positive cells in macrophages and endothelial cells. These pathophysiological and biochemical changes were diminished by NAC treatment. The NAC effects were dose-dependent.ConclusionsOur results suggest that neutrophil activation and release of neutrophil-derived mediators by PMA cause ALI and associated changes. NO production through the iNOS-producing cells plays a detrimental role in the PMA-induced lung injury. ATP is beneficial, while PARP plays a deteriorative effect on the PMA-induced ALI. NAC exerts protective effects on the inflammatory cascade leading to pulmonary injury. This B complex compound may be applied for clinical usage and therapeutic regimen.

Niacinamide mitigated the acute lung injury induced by phorbol myristate acetate in isolated rat's lungs

Phorbol myristate acetate (PMA) is a strong neutrophil activator and has been used to induce acute lung injury (ALI). Niacinamide (NAC) is a compound of B complex. It exerts protective effects on the ALI caused by various challenges. The purpose was to evaluate the protective effects of niacinamide (NAC) on the PMA-induced ALI and associated changes. The rat's lungs were isolated in situ and perfused with constant flow. A total of 60 isolated lungs were randomized into 6 groups to received Vehicle (DMSO 100 μg/g), PMA 4 μg/g (lung weight), cotreated with NAC 0, 100, 200 and 400 mg/g (lung weight). There were 10 isolated lungs in each group. We measured the lung weight and parameters related to ALI. The pulmonary arterial pressure and capillary filtration coefficient (Kfc) were determined in isolated lungs. ATP (adenotriphosphate) and PARP [poly(adenosine diphophate-ribose) polymerase] contents in lung tissues were detected. Real-time PCR was employed to display the expression of inducible and endothelial NO synthases (iNOS and eNOS). The neutrophil-derived mediators in lung perfusate were determined. PMA caused increases in lung weight parameters. This agent produced pulmonary hypertension and increased microvascular permeability. It resulted in decrease in ATP and increase in PARP. The expression of iNOS and eNOS was upregulated following PMA. PMA increased the neutrophil-derived mediators. Pathological examination revealed lung edema and hemorrhage with inflammatory cell infiltration. Immunohistochemical stain disclosed the presence of iNOS-positive cells in macrophages and endothelial cells. These pathophysiological and biochemical changes were diminished by NAC treatment. The NAC effects were dose-dependent. Our results suggest that neutrophil activation and release of neutrophil-derived mediators by PMA cause ALI and associated changes. NO production through the iNOS-producing cells plays a detrimental role in the PMA-induced lung injury. ATP is beneficial, while PARP plays a deteriorative effect on the PMA-induced ALI. NAC exerts protective effects on the inflammatory cascade leading to pulmonary injury. This B complex compound may be applied for clinical usage and therapeutic regimen.

N-Acetylcysteine attenuates acute lung injury induced by fat embolism*

Fat embolism syndrome is a clinical issue in subjects with long-bone fracture. It may lead to acute lung injury. The mechanisms and therapeutic regimen remain unclear. The present study was designed to investigate the pathologic and biochemical changes after fat embolization in isolated rat lungs, and to test the effects of posttreatment with N-acetylcysteine (NAC). Prospective, randomized, controlled animal study. University research laboratory. A total of 36 perfused lungs isolated from Sprague-Dawley rats. The isolated lungs were randomly assigned to receive physiologic saline solution (vehicle group), fat embolism (FE group), or FE with NAC posttreatment (FE + NAC group). There were 12 isolated lungs in each group. FE was produced by introduction of corn oil micelles. NAC at a dose 150 mg/kg was given 10 mins after FE. The extent of acute lung injury was evaluated by lung weight change, protein concentration in bronchoalveolar lavage, and exhaled nitric oxide. We also measured the pulmonary arterial pressure and capillary filtration coefficient and determined the nitrate/nitrite, methylguanidine, tumor necrosis factor-alpha, and interleukin-1beta in lung perfusate. Histopathologic changes of the lung were examined and quantified. The levels of neutrophil elastase and myeloperoxidase were determined. The expression of inducible nitric oxide synthase was detected. FE caused acute lung injury as evidenced by the lung weight changes, increases in exhaled nitric oxide and protein concentration in bronchoalveolar lavage, pulmonary hypertension, increased capillary filtration coefficient, and lung pathology. The insult also increased nitrate/nitrite, methylguanidine, tumor necrosis factor-alpha, and interleukin-1beta in lung perfusate, increased neutrophil elastase and myeloperoxidase levels, and upregulated inducible nitric oxide synthase expression. Posttreatment with NAC abrogated these changes induced by FE. FE caused acute lung injury and associated biochemical changes. Posttreatment with NAC was effective to alleviate the pathologic and biochemical changes caused by FE.

Propofol attenuates oxidant-induced acute lung injury in an isolated perfused rabbit-lung model

Reactive oxygen species have been strongly implicated in the pathogenesis of acute lung injury (ALI). Some animal studies suggest that free radical scavengers inhibit the onset of oxidant-induced ALI. Propofol (2,6-diisopropylphenol) is chemically similar to phenol-based free radical scavengers such as the endogenous antioxidant vitamin E. Both in vivo and in vitro studies have suggested that propofol has antioxidant potential. We hypothesized that propofol may attenuate ALI by acting as a free-radical scavenger. We investigated the effects of propofol on oxidant-induced ALI induced by purine and xanthine oxidase (XO), in isolated perfused rabbit lung, in two series of experiments. In series 1, we examined the relationship between the severity of ALI and the presence of hydrogen peroxide (H2O2). In series 2, we evaluated the effects of propofol on attenuating ALI and the dose dependence of these effects. The lungs were perfused for 90 min, and we evaluated the effects on the severity of ALI by monitoring the pulmonary capillary filtration coefficient (Kfc), pulmonary arterial pressure (Ppa), and the pulmonary capillary hydrostatic pressure (Ppc). In series 1, treatment with catalase (an H2O2 scavenger) prior to the addition of purine and XO resulted in complete prevention of ALI, suggesting that H2O2 may be involved closely in the pathogenesis of ALI. In series 2, pretreatment with propofol at concentrations in excess of 0.5 mM significantly inhibited the increases in the Kfc values, and that in excess of 0.75 mM significantly inhibited the increase in the Ppa values. Propofol attenuates oxidant-induced ALI in an isolated perfused rabbit lung model, probably due to its antioxidant action.

Protective effects of low respiratory frequency in experimental ventilator-associated lung injury*

To determine whether ventilator-associated lung hyperinflation injury can be attenuated by a reduction in respiratory frequency. Prospective comparative laboratory investigation. University medical center research laboratory. Male Sprague-Dawley rats. Eight groups of isolated, perfused rat lungs were exposed to cyclic ventilation at different respiratory frequencies and tidal volumes. Each group of six to eight lung preparations was assigned to one of four respiratory frequencies (10, 20, 40, or 80 breaths/min) and one of two tidal volumes (5 or 20 mL.kg). Measurement of capillary filtration coefficient (Kf,c), a sensitive index of lung microvascular permeability and injury, was made at baseline and at 30, 60, and 90 mins of the experimental conditions. Lungs exposed to 5 mL.kg tidal volume had no elevation in Kf,c at any time point regardless of respiratory frequency. Lungs exposed to 20 mL. kg tidal volume and a respiratory frequency of 80 had significant elevations in Kf,c at all times after baseline compared with lungs exposed to respiratory frequencies of 10, 20, or 40 (0.14 +/- 0.03, 0.16 +/- 0.02, 0.31 +/- 0.05 vs. 0.76 +/- 0.16). Furthermore, the Kf,c at 90 mins was significantly higher than permeability at baseline in this group (1.53 +/- 0.45 vs. 0.12 +/- 0.02 mL.min.cm H2O.100 g of lung tissue). Reduction in respiratory frequency to values much lower than normal ameliorated experimental ventilator-induced hyperinflation lung injury as determined by pulmonary capillary filtration coefficient.

Fullerene derivative attenuates ischemia-reperfusion-induced lung injury

Reactive oxygen species are the major contributing factors to lung ischemia-reperfusion (IR) injury. In this study, we tested whether a water soluble antioxidant fullerene derivative [C 60(ONO 2) 7 ± 2] attenuates IR lung injury. Young Wistar rats were divided into two groups: control and C 60(ONO 2) 7 ± 2. Under ventilation with 95% air-5% CO 2 gas mixture and a 2.5 cm H 2O end-expiratory pressure, the isolated lungs were perfused with a physiological solution. The experimental protocol included three periods: baseline (10 min), ischemia (45 min) and reperfusion (60 min, ventilated with 95% O 2-5% CO 2 gas mixture). Before and after ischemia, we measured pulmonary arterial pressure (Ppa), pulmonary venous pressure and lung weight (W). Then, pulmonary capillary pressure and filtration coefficient (K fc) were calculated. Ischemia caused increases in Ppa, W and K fc in the control group. For most cases, the above ischemia-induced increases were attenuated by the C 60(ONO 2) 7 ± 2 pretreatment. Our results suggest that the antioxidant C 60(ONO 2) 7 ± 2 attenuates IR-induced lung injury.

Pentoxifylline Rescue Preserves Lung Function in Isolated Canine Lungs Injured With Phorbol Myristate Acetate

We hypothesized that pentoxifylline, administered after phorbol myristate acetate (PMA), would diminish the severity of lung injury. Animal research laboratory. Comparative study. Mongrel dogs (n = 33). Baseline measurements were obtained from the isolated blood-perfused dog lung lobes after 1 h of stable perfusion and ventilation. Four different measures of lung compliance were obtained along with WBC and neutrophil counts. Pulmonary vascular resistance (PVR) and capillary filtration coefficient (Kf) were calculated, and the ratio of a normalized maximal enzymatic conversion rate to the Michaelis-Menten constant (Amax/Km) was used to assess perfused capillary surface area. The control lobes (n = 8) were ventilated and perfused for an additional 40 min while the injured lobes (n = 17) received PMA (0.1 microg/mL of perfusate). The pentoxifylline-protected lobes (n = 8) were treated with pentoxifylline (1 mg/mL of perfusate) 10 min after injury with PMA. All measurements were then repeated. The three groups did not differ significantly at baseline. The control lobes remained relatively stable over time. The injured lobes demonstrated marked deterioration in compliance: 8.79 +/- 0.7 to 5.97 +/- 0.59 mL/cm H(2)O (p < 0.05) vs 10.1 +/- 1.0 to 8.07 +/- 0.72 mL/cm H(2)O and 9.6 +/- 1.1 to 9.9 +/- 0.85 mL/cm H(2)O in the control and protected lobes, respectively. Both groups receiving PMA had similar drops in WBC and neutrophil counts, but the pentoxifylline-protected lobes had preservation of all four compliance measures. PVR increased from 37.8 +/- 1.8 to 118.6 +/- 12.7 cm H(2)O/L/min (p < 0.05) in the injured lobes vs 35.4 +/- 0.5 to 36.3 +/- 2.8 cm H(2)O/L/min and 40.4 +/- 0.04 to 46.7 +/- 2.8 cm H(2)O/L/min (p < 0.05) in the control and protected lobes, respectively. Kf increased < 25% in the protected group but more than tripled in the injured group. Amax/Km dropped from 559 +/- 36 to 441 +/- 33 mL/min (p < 0.05) in the injured lobes vs 507 +/- 14 to 490 +/- 17 mL/min and 609 +/- 34 to 616 +/- 37 mL/min in the control and pentoxifylline-protected lobes, respectively. The use of pentoxifylline as a rescue agent prevented the PMA-induced deterioration of lung compliance, vascular integrity, and endothelial metabolic function in this acute lung injury model, despite significant pulmonary neutrophil sequestration.

Polynitroxyl-albumin (PNA) plus tempol attenuate lung capillary leak elicited by prolonged intestinal ischemia and reperfusion

Stable nitroxyl radicals (nitroxides) are potential antioxidant drugs, and we have previously reported that linking nitroxide to biological macromolecules can improve therapeutic activity in at least two ways. First, polynitroxylated compounds such as polynitroxyl human serum albumin (PNA) are a novel class of high molecular weight, extracellular antioxidants. Second, compounds such as PNA can prolong the half-life of free (unbound, low molecular weight) nitroxides such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (Tempol) in vivo. Unlike PNA, Tempol can readily access the intracellular compartment. Thus PNA can act alone in the extracellular compartment, or in concert with Tempol, to provide additional antioxidant protection within cells. In this study, we compared the abilities of PNA, Tempol, and the combination of PNA + Tempol to prevent lung microvascular injury secondary to prolonged gut ischemia (I, 120 min) and reperfusion (R, 20 min) in the rat. Pulmonary capillary filtration coefficient (K f,c) and lung neutrophil retention (tissue myeloperoxidase activity, MPO) were measured in normal, isolated rat lungs perfused with blood harvested from I/R rats. Blood donor rats were treated with drug during ischemia. Gut I/R resulted in a marked increase in pulmonary capillary coefficient and lung MPO. PNA + Tempol, but not PNA alone or Tempol alone, at the doses used, prevented the development of lung leak. None of the treatments had an effect on lung neutrophil retention. Anti-inflammatory therapeutic activity appeared to correlate with blood Tempol level: in the presence of PNA, blood Tempol levels were maintained in the 50–100 μM range vs. essentially undetectable levels shortly after Tempol was administered alone. In this model of lung injury secondary to prolonged gut I/R, lung capillary leak was prevented when the membrane-permeable compound Tempol was maintained in its active, free radical state by PNA.

Effect of hypothermic pulmonary artery flushing on capillary filtration coefficient.

We previously demonstrated that surfactant dilution and inhibition occur immediately after pulmonary artery flushing with hypothermic modified Euro-Collins solution. Consequently, we speculated that increased capillary permeability contributed to these surfactant changes. To test this hypothesis, we evaluated the effects of hypothermic pulmonary artery flushing on the pulmonary capillary filtration coefficient (Kfc), and additionally performed a biochemical analysis of surfactant. We used a murine isolated, perfused lung model to measure the pulmonary capillary filtration coefficient and hemodynamic parameters, to determine the wet to dry weight ratio, and to evaluate surfactant by biochemical analysis of lung lavage fluid. We defined three study groups. In group I (controls), we harvested lungs without hypothermic pulmonary artery flushing, and measured Kfc immediately. In group II (in situ flush), we harvested lungs after hypothermic pulmonary artery flushing with modified Euro-Collins solution, and then measured Kfc. Experiments in groups I and II were designed to evaluate persistent changes in Kfc after pulmonary artery flushing. In group III (ex vivo flush), we flushed lungs ex vivo to evaluate transient changes in Kfc during hypothermic pulmonary artery flushing. Groups I and II did not differ significantly in capillary filtration coefficient and hemodynamics. Group II showed significant alterations on biochemical surfactant analysis and a significant increase in wet-to-dry weight ratio, when compared with group I. In group III, we observed a significant transient increase in capillary filtration coefficient during pulmonary artery flushing. Hypothermic pulmonary artery flushing transiently increases the capillary filtration coefficient, leads to an increase in the wet to dry weight ratio, and induces biochemical surfactant changes. These findings could be explained by the effects of hypothermic modified Euro-Collins solution on pulmonary capillary permeability.

Differential time scale of fluid and solute permeability following hypothermic lung preservation

Background Assessment of the quality of lung graft preservation by simple functional measures in some laboratory models may fail to detect endothelial injury. The effects of hypothermic preservation in isolation were investigated by measuring the pulmonary capillary filtration coefficient (Kf) and the albumin surface area product (PS) at various cold ischemic intervals. Methods Rat lungs were flushed with University of Wisconsin solution at 4° C. Following storage at 4° C, lungs for Kf measurement were subjected to a change in pulmonary arterial pressure. Kf was calculated from the change in rate of weight gain as a function of hydrostatic stress. PS lungs were exposed to Tris buffered Ringer’s solution containing I 125 albumin (20 μM) in an isogravimetric state. Following a vascular flush the lungs were homogenized and underwent scintillation counting. Using the Kedem-Katchalsky equation PS was calculated. Results The Kf for the control, 4-hour, and 7-hour groups were 0.778, 1.816, 4.853 g/cm H 2O/min/100 g wet lung tissue, respectively. There was a significant increase in Kf with each time increment ( P,0.01). The Kf for the 24-hour group was 5.587 g/cm H 2O/min/100 g wet lung tissue; not an additional significant increase. PS for the control and 4-hour groups (0.0115 and 0.0101 cm 3/g wet lung tissue/minute, respectively) were not significantly different. After 7 hours there was a significant increase to 0.171 cm 3/g wet lung tissue/min. PS could not be measured after 24 hours. Conclusions Significant endothelial injury occurs after 4 hours of cold ischemic preservation. There is progressive injury with time. Increase in water permeability is not secondary to increase in albumin permeability.

PENTOXIFYLLINE RESCUE PRESERVES LUNG FUNCTION IN ISOLATED CANINE LUNGS INJURED WITH PHORBOL MYRISTATE ACETATE

Objective: We hypothesized that pentoxifylline, administered after phorbol myristate acetate (PMA), would diminish the severity of lung injury. Setting: Animal research laboratory. Design: Comparative study. Subjects: Mongrel dogs (n 5 33). Interventions: Baseline measurements were obtained from the isolated blood-perfused dog lung lobes afte r1ho fstable perfusion and ventilation. Four different measures of lung compliance were obtained along with WBC and neutrophil counts. Pulmonary vascular resistance (PVR) and capillary filtration coefficient (Kf) were calculated, and the ratio of a normalized maximal enzymatic conversion rate to the Michaelis-Menten constant (Amax/Km) was used to assess perfused capillary surface area. The control lobes (n 5 8) were ventilated and perfused for an additional 40 min while the injured lobes (n 5 17) received PMA (0.1 mg/mL of perfusate). The pentoxifylline-protected lobes (n 5 8) were treated with pentoxifylline (1 mg/mL of perfusate) 10 min after injury with PMA. All measurements were then repeated. Measurement and main results: The three groups did not differ significantly at baseline. The control lobes remained relatively stable over time. The injured lobes demonstrated marked deterioration in compliance: 8.79 6 0.7 to 5.97 6 0.59 mL/cm H2 O( p< 0.05) vs 10.1 6 1.0 to 8.07 6 0.72 mL/cm H2O and 9.6 6 1.1 to 9.9 6 0.85 mL/cm H2O in the control and protected lobes, respectively. Both groups receiving PMA had similar drops in WBC and neutrophil counts, but the pentoxifylline-protected lobes had preservation of all four compliance measures. PVR increased from 37.8 6 1.8 to 118.6 6 12.7 cm H2O/L/min (p < 0.05) in the injured lobes vs 35.4 6 0.5 to 36.3 6 2.8 cm H2O/L/min and 40.4 6 0.04 to 46.7 6 2.8 cm H2O/L/min (p < 0.05) in the control and protected lobes, respectively. Kf increased < 25% in the protected group but more than tripled in the injured group. Amax/Km dropped from 559 6 36 to 441 6 33 mL/min (p < 0.05) in the injured lobes vs 507 6 14 to 490 6 17 mL/min and 609 6 34 to 616 6 37 mL/min in the control and pentoxifylline-protected lobes, respectively. Conclusions: The use of pentoxifylline as a rescue agent prevented the PMA-induced deterioration of lung compliance, vascular integrity, and endothelial metabolic function in this acute lung injury model, despite significant pulmonary neutrophil sequestration. (CHEST 2001; 119:1893‐1900)

Intact Alveolar Epithelial Permeability and Transalveolar Fluid Absorption after Thoracic Irradiation in Rats

We have addressed the question of how the alveolar space stays relatively free of fluid when thoracic irradiation injures the pulmonary capillary endothelium and plasma fluid leaks into the interstitium. A single dose of 15 Gy to the thorax of rats significantly increased the pulmonary capillary filtration coefficient and the lung wet/dry weight ratio 2 h after irradiation. However, there was no significant increase in the release of lactose dehydrogenase or leaking of Evans blue dye into the alveolar space, indicating that alveolar epithelial permeability remained intact. We found no significant difference in the basal alveolar fluid clearance between control and irradiated animals. There was also no significant difference in blockage of alveolar fluid clearance by amiloride. This indicates that the function of the alveolar epithelial Na(+) channels is not impaired and that alveolar epithelium absorbs fluid normally. Examination of lung tissue by light microscopy demonstrated accumulation of fluid in the perivascular region but not in the alveolar space. Our data appear to indicate that the alveolar epithelial barrier function is more resistant to radiation than that of the pulmonary capillary endothelium. We conclude that intact alveolar epithelial permeability and normal transalveolar epithelial fluid absorption ability are of critical importance in keeping the alveolar space relatively free of fluid during acute radiation lung injury.

Effect of femoral fracture and intramedullary fixation on lung capillary leak.

Pulmonary injury is an important complication in the trauma patient with long-bone fractures. The purpose of this study was to determine the effect of femoral fracture or fracture and intramedullary fixation on lung capillary leak. The contribution of leukocytes to lung injury in this model was also determined. The pulmonary capillary filtration coefficient was determined in lungs of rats after femur fracture or fracture and reamed or unreamed intramedullary fixation. Pulmonary arterial vascular resistance and lung neutrophil content were also determined. Fracture alone did not cause lung injury, whereas fracture and intramedullary fixation elicited lung capillary leak. Fracture alone and intramedullary fixation increased pulmonary vascular resistance, whereas unreamed intramedullary fixation caused lung leukosequestration. Femoral fracture alone does not cause an increase in pulmonary microvascular permeability. Femoral fracture and intramedullary fixation causes lung capillary leak, which is not increased by reaming the femoral canal.

Pulmonary edema induced by phorbol myristate acetate is attenuated by compounds that increase intracellular cAMP.

We have investigated the effect of terbutaline, aminophylline and dibutyryl cyclic AMP (DBcAMP) on phorbol myristate acetate (PMA)-induced acute lung injury in isolated, blood-perfused rabbit lungs. Pulmonary arterial pressure and lung weight were measured for 30 min after a bolus injection of PMA (10 mu g/kg). In the group exposed to PMA alone, the mean pulmonary arterial pressure (PAP) increased from 16.33 + or - 1.28 to 77.30 + or - 6.40 mmHg (P <0.001), and lung weight increased by 70.69 + or - 10.94 g during the 30 min after PMA challenge (P<0.001). Pretreatment with terbutaline, aminophylline or DBcAMP prevented the increases in both PAP and lung weight (P <0.001). Each of the three drugs also prevented the increase in pulmonary vascular permeability induced by PMA: terbutaline, aminophylline, and DBcAMP all significantly reduced the pulmonary capillary filtration coefficient (KfC) as well as the albumin concentration in the lung lavage fluid after PMA exposure. Post-treatment with terbutaline 5 min after PMA administration also had a protective effect. The mechanisms responsible for these protectivp3 effects may all involve an increase in intracellular cAMP, since all three drugs increase cAMP in the lung (though by different mechanisms). Our data further indicate that the inhibition of tumor necrosis factor production may likewise play an important role in the protective effect exerted by these drugs.

Protective effects of BQ-123, an ETA receptor antagonist, against leukotoxin-induced injury in rat lungs.

We tested the hypothesis that BQ-123, a novel endothelin type A (ETA) receptor antagonist, protects the lung against leukotoxin 9,10-epoxy-12-octadecenoate (Lx), which causes acute lung injury in animals. In isolated rat lungs perfused with Earle's balanced salt solution, BQ-123 suppressed the Lx-induced increase in wet lung weight, wet lung weight/dry lung weight, the effluent perfusate lactic dehydrogenase activity, and effluent perfusate and lung tissue ET-1 levels. BQ-123 also significantly attenuated the Lx-induced increase of the pulmonary capillary filtration coefficient. Thus our experimental results indicate that the ETA receptor antagonist, BQ-123, protects against Lx-induced experimental lung vascular injury.

Effects of inflation volume during lung preservation on pulmonary capillary permeability

The degree of lung allograft inflation during harvest and storage may affect posttransplantation function. High volume ventilation causes pulmonary vascular injury and increased pulmonary capillary permeability. However, the effect of lung inflation on pulmonary capillary permeability after hypothermic flush and storage is unknown. The current study was designed to examine the effects of hyperinflation and hypoinflation during preservation on pulmonary vascular permeability. Methods: An isolated, ex vivo rabbit lung gravimetric model without the confounding effects of reperfusion was used to determine post pulmonary capillary filtration coefficient (K f). New Zealand White rabbits (2.75 to 3.15 kg) were intubated and the lungs ventilated with room air (tidal volume 25 ml). After sternotomy and heparinization, the pulmonary artery was flushed with low potassium dextran–1% glucose solution (200 ml). The heart-lung block was then excised. Two studies were conducted. For measurement of changes in airway pressure and lung volume during preservation, lungs were inflated to one of four storage volumes (12, 25, 40, 55 ml) with room air, 100% O 2, or 100% N 2 and stored at 10° C in a sealed container filled with saline solution. During preservation, lung volume and airway pressure were measured at 3, 6, 12, and 24 hours. In the K f study, lungs were inflated with 100% O 2, 50% O 2 (with 50% N 2), or room air and preserved. After 24 hours of preservation at 10° C, the heart-lung block was suspended from a strain-gauge force transducer and the lungs were ventilated with room air. The pulmonary artery was connected to a reservoir of hetastarch solution (6% hetastarch with 0.9% saline solution). Lung weight gain, airway pressure, pulmonary artery pressure, and left atrial pressure were measured continuously. After a brief flush with hetastarch solution, the reservoir was then elevated to achieve 1.0 to 1.5 mm Hg increments in pulmonary artery pressure. Results: The slope of subsequent steady-state lung weight gain was used to determine the K f. The current study demonstrated the following: (1) changes in lung volume and airway pressure during storage increased with intraalveolar O 2 concentration, (2) irrespective of inflation, fraction of inspired oxygen, hyperinflation during lung preservation increased the K f in a volume-dependent fashion; (3) K f was increased in lungs stored hypoinflated with room air; and (4) at any inflation volume, the K f was significantly increased with 100% O 2 inflation after 24 hours of preservation. Conclusion: These results suggest that storage at high lung volume or high inspired oxygen fraction increases pulmonary capillary permeability. (J T horac C ardiovasc S urg 1996;112:85-93)

Influence of hypoxia and pulmonary air embolism on lung injury in perfused rat lungs.

We investigated the influence of low oxygen ventilation, air-bubble infusion into the pulmonary artery and their synergistic effect on pulmonary hemodynamics and microvascular permeability in isolated perfused rat lungs. Pulmonary arterial pressure was significantly increased by 70 min of ventilation with 3% O2 (hypoxia, group H); by 0.2-ml air-bubble infusion (pulmonary air embolism, group AE), and by 0.2-ml air-bubble infusion and 70 min of 3% O2 ventilation (hypoxia and pulmonary air embolism, group H & AE) compared with that of a control group (0.2 ml saline infusion, group C). Neither total (TPR) nor arterial (Ra) pulmonary vascular resistance in group H showed any difference compared to control values. TPR and Ra in groups AE and H & AE were significantly higher than those in group C. However, there was no significant difference in TPR or Ra between groups AE and H & AE. The pulmonary capillary fluid filtration coefficient, dry lung to wet lung weight ratio and white blood cell count in the perfusate of group H were not changed, while those of the groups AE and H & AE were significantly increased compared to those of controls. However, there was no significant difference in these values between groups AE and H & AE. Since hypoxia did not damage isolated perfused rat lungs, as determined by hemodynamics and permeability, nor enhance lung injury caused by air embolism, it was suggested that air embolism contributed more to high-altitude lung injury than low oxygen.