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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leukotriene B4 (LTB4) is a metabolite of arachidonic acid that has potent chemotactic activity for polymorphonuclear leukocytes (PMN). Pulmonary oxygen toxicity is considered to be a good model of an acute inflammatory lung injury, and an increase in the number of PMN is found in the lungs acutely injured by hyperoxia. In order to estimate the role of LTB4 responsible for this influx of PMN, we measured the LTB4 by radioimmunoassay in lung lavages of rats exposed to hyperoxia for 60 h. We found that the level of LTB4 in lung lavages in rats exposed to hyperoxia for 60 h increased significantly compared with that in normoxic control rats. At the same time, the marked increase in the number of PMN in lung lavages and the decrease in the activity of NADPH-cytochrome c reductase in lung microsomes were also observed. The administration of AA861, a 5-lipoxygenase inhibitor, reduced not only the increase in LTB4 but also the increase in the number of PMN in lung lavages of rats exposed to hyperoxia for 60 h. Furthermore, treatment with AA861 also protected the decrease in the activity of NADPH-cytochrome c reductase. The effects of AA861 on these parameters were observed in a dose-dependent fashion. In addition, there is a good correlation between the level of LTB4 and the number of PMN in the lavage of rats exposed to hyperoxia for 60 h with or without AA861 administration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of leukotriene B4 in the genesis of oxygen toxicity in the lung. 301 Jul 81

We examined whether lipid mediators have a causal role in neonatal hyperoxia-induced lung damage, specifically, airway remodeling and hyperresponsiveness. Newborn rat pups were exposed to hyperoxia (> 95% O2 from Days 4 to 14 and 65% from Days 14 to 32) or normoxia. The 5-lipoxygenase inhibitor, LTD4 receptor antagonist, and inhibitor of platelet-activating factor synthesis, Wy-50,295 (30 mg/kg), or vehicle was administered daily from Days 3 to 32. Oxygen exposure significantly increased (p < 0.05) the production of one potential lipid mediator group, peptido-LTs, from explanted lung slices and large airways from 2-wk-old rat pups. At 4 wk, only the large airway tissue output showed significant elevation because of oxygen exposure. At both ages, Wy-50,295 significantly decreased (p < 0.05) the production of peptido-LTs in the lung and large airways of oxygen-exposed pups. Pulmonary function and airway wall morphometry were studied in 5-wk-old rat pups 2 to 3 d after oxygen exposure and drug administration ceased. The resistance change in response to methacholine (0 to 20 microg/kg body weight given intravenously) was greater (p < 0.02) in oxygen-exposed animals. Oxygen exposure caused significant (60% increase) smooth muscle thickening (p < 0.05). Wy-50,295 prevented the oxygen-induced airway hyperresponsiveness and smooth muscle thickening. We conclude that chronic hyperoxic exposure causes an increase in pulmonary production of at least one lipid mediator, peptido-LTs, from newborn rats and that this is associated with airway smooth muscle layer thickening and, consequently, airway hyperresponsiveness.
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PMID:Lipid mediators in oxygen-induced airway remodeling and hyperresponsiveness in newborn rats. 888 72

We investigated the role of leukotrienes (LT) in hyperoxia-induced changes in lung parenchyma in neonatal rat pups. Rat pups were exposed to 21% O(2) (air) or >95% O(2) from days 4 to 14 after birth and were administered the 5-lipoxygenase (5-LO) inhibitor and LTD4 receptor antagonist Wy-50295, 5-LO-activating protein inhibitor MK-0591, or vehicle from days 3 to 14. All measurements were done on days 12-14. There was a significant (P < 0.05) increase in peptido-LT output from lung slices of animals exposed to O(2) compared with air-exposed animals. Both Wy-50295 and MK-0591 significantly lowered (P < 0.05) peptido-LT output in O(2)-exposed animals. The 6-ketoprostaglandin F(1alpha) output was increased similarly in both vehicle- and drug-treated O(2)-exposed animals. O(2) exposure also caused a significant increase in bronchoalveolar lavage fluid protein and extravascular lung water that could not be ameliorated by Wy-50295 or MK-0591. Hyperoxia-induced inhibition of alveolarization, indicated by a significantly (P < 0.05) lower parenchymal tissue density, specific internal surface area, and airspace perimeter-to-area ratio, and a significantly (P < 0.05) higher mean linear intercept and airspace unit volume than air-exposed animals, was prevented by both Wy-50295 and MK-0591. Although hyperoxia had no effect on septal thickness, Wy-50295 caused significant thickening in both air- and O(2)-exposed pups. Our studies provide evidence that hyperoxia-induced peptido-LT may mediate O(2)-induced inhibition of alveolarization and that this is not caused by an arachidonic acid shunt to cyclooxygenase.
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PMID:Leukotrienes are indicated as mediators of hyperoxia-inhibited alveolarization in newborn rats. 912

In this study, the authors examined in newborn rat lung tissues the release of leukotriene B(4) (LTB(4)) from tissue explants in vitro, the protein expression of the LT-synthesizing enzyme, 5-lipoxygenase (5-LO), and its activating protein (FLAP), and the effects of in vivo hyperoxic exposure (>95% O(2)) on these parameters. Basal LTB(4) output increased from 0.98 ng/mgDNA/30 min at day 1 to 3.3 ng/mgDNA/30 min at day 28 (P <.05). Exposure of rat pups to >95% O(2) from days 1 to 7 and 60% O(2) from days 7 to 28 stimulated a 1.6-fold (P <.05) increase in LTB(4) output, compared to normoxic pups (to 1.6 ng/mgDNA/30 min) by day 1 and on day 7. The calcium ionophore, A23187, caused an increase in LTB(4) output from both exposure groups, but LTB(4) output was consistently greater (P <.05) from hyperoxia-exposed pups. Western immunoblotting of lung tissue showed that 5-LO and FLAP protein mass increased (P <.05) from days 4 to 14. Hyperoxia exposure increased the mass of both proteins (P <.05). Immunohistochemistry localized 5-LO and FLAP mainly to alveolar macrophages on day 14, but some staining was evident in parenchymal tissue. These data show that hyperoxia increases LTB(4) output, as well as protein levels of 5-LO and FLAP, in newborn rat lungs during early postnatal life. Elevated LTB(4) may contribute to the etiology of newborn lung disease.
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PMID:Hyperoxia increases protein mass of 5-lipoxygenase and its activating protein, flap, and leukotriene B(4) output in newborn rat lungs. 1249 39

Premature infants often develop serious clinical complications associated with respiratory failure and hyperoxic lung injury that includes lung inflammation and alterations in lung development. The goal of these studies is to test the hypothesis that there are differences in the course of lung injury in newborn mice exposed to 85% or >95% oxygen that provide models to address the differential effects of oxidation and inflammation. Our results indicate differences between the 85% and >95% O2 exposure groups by day 14 in weight gain and lung alveolarization. Inflammation, assessed by neutrophil counts, was observed in both hyperoxia groups by day 3 but was dramatically greater in the >95% O2-exposed groups by day 14 and associated with greater developmental deficits. Cytoplasmic phospholipase A2, cyclooxygenase-2, and 5-lipoxygenase levels were elevated but no patterns of differences were observed between exposure groups. Prostaglandins D2, E2, and F2alpha were increased in the tissues from mouse pups exposed to >95% O2 at 7 d indicating a differential expression of cyclooxygenase-2 products. Our data indicate that there are differences in the models of 85% or >95% O2 exposure and these differences may provide mechanistic insights into hyperoxic lung injury in an immature system.
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PMID:Differential responses in the lungs of newborn mouse pups exposed to 85% or >95% oxygen. 1870 92

Prematurely born infants are often treated with supraphysiologic amounts of oxygen, which is associated with lung injury and the development of diseases such as bronchopulmonary dysplasia. Complimentary responses between the lung and liver during the course of hyperoxic lung injury have been studied in adult animals, but little is known about this relationship in neonates. These studies tested the hypothesis that oxidant stress occurs in the livers of newborn mice in response to continuous hyperoxia exposure. Greater levels of glutathione disulfide and nitrotyrosine were detected in lung tissues but not liver tissues from newborn mice exposed to hyperoxia than in room air-exposed controls. However, early increases in 5-lipoxygenase and cyclooxygenases-2 protein levels and increases in total hydroxyeicosatetraenoic acid and prostaglandin levels were observed in the liver tissues of hyperoxia-exposed pups. These studies indicate that free radical oxidation occurs in the lungs of newborn pups exposed to hyperoxia, and alterations in lipid metabolism could be a primary response in the liver tissues. The findings of this study identify possible new mechanisms associated with hyperoxic lung injury in a newborn model of bronchopulmonary dysplasia and thus open opportunities for research.
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PMID:Hyperoxia exposure alters hepatic eicosanoid metabolism in newborn mice. 1980 77

Exposure to hypoxia and hyperoxia in a rodent model of perinatal ischemia results in delayed cell death and inflammation. Hyperoxia increases oxidative stress that can trigger inflammatory cascades, neutrophil activation, and brain microvascular injury. Here we show that 100% oxygen resuscitation in our rodent model of perinatal ischemia increases cortical COX-2 protein levels, S-nitrosylated COX-2cys526, PGE2, iNOS and 5-LOX, all components of the prostaglandin and leukotriene inflammatory pathway.
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PMID:Oxygen resuscitation after hypoxia ischemia stimulates prostaglandin pathway in rat cortex. 2151 73