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Query: UMLS:C0034063 (pulmonary edema)
 10,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms of hydroperoxide-induced broncho- and vasoconstriction were investigated in the perfused and ventilated rat lung. Hydrogen peroxide (500 microM), tertiary butylhydroperoxide (500 microM) and arachidonic acid (100 microM) induced similar profiles of broncho- and vasoconstriction which could be prevented by the inhibitor of cyclooxygenase, diclofenac (100 microM) but not by nordihydroguaiaretic acid (5 and 25 microM), an inhibitor of lipoxygenase. The hydroperoxides also caused a time-dependent increase in the levels of thromboxane and prostacycline, products of cyclooxygenase. Furthermore, the thromboxane agonist, U44069 (100 pmoles), caused a very rapid broncho- and vasoconstriction that was preventable by the thromboxane antagonist L655.240 (1 microM). L655.240 also inhibited hydrogen peroxide-induced broncho- and vasoconstriction. The phospholipase A2 inhibitors, quinacrine (100 microM) and dibucaine (100 microM), did not prevent hydroperoxide-induced broncho- and vasoconstriction. The Ca2+ chelator, EGTA, prevented hydroperoxide and arachidonic acid-induced lung constriction, although it did not inhibit the release of thromboxane. The infusion of arachidonic acid and hydroperoxides resulted in edema in the lung which was prevented by prior administration of diclofenac, indomethacin or L655.240. These results indicate that hydroperoxide-induced broncho- and vasoconstriction and lung edema are mediated by thromboxane, a product of cyclooxygenase. The mechanism of hydroperoxide-induced release of arachidonic acid is not clear but does not seem to involve Ca2+ nor the activation of phospholipase A2.
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PMID:Mechanisms of hydroperoxide-induced broncho- and vasoconstriction in isolated and perfused rat lung. 190 6

A good model of adult respiratory distress syndrome is lung injury induced by phorbol myristate acetate (PMA). In the present study we examined the effect of mepacrine, an inhibitor of phospholipase A2, on lung injury induced by PMA in isolated blood-perfused rat lungs. In the isolated lung, saline (1 ml) or mepacrine (75 microM) alone in the perfusion system did not discernibly change the pulmonary arterial pressure (PAP) and lung weight (LW). After administration of PMA (0.16 micrograms/ml), severe hypertension and lung edema developed (delta PAP = 40.1 +/- 6.0 mmHg, p less than 0.001; delta LW = 5.5 +/- 0.7 g, p less than 0.001). Whereas, the addition of mepacrine (75 microM) prevented PMA-induced lung edema and pulmonary hypertension (delta PAP = 4.7 +/- 2.2 mmHg, delta LW = 0.2 +/- 0.2 g). To further elucidate the protective mechanism of mepacrine on lung injury, a vasodilator (nitroprusside) was given to decrease PAP levels to +6 mmHg from baseline values in the PMA group, as well as in the mepacrine-pretreated PMA (MPMA) group. During a subsequent venous pressure challenge, severe lung injury developed in the PMA group (delta LW = 9.5 +/- 2.1 g, p less than 0.001). However, with the same venous pressure challenge in the MPMA the lung weight was markedly less than that of the PMA group (delta LW = 1.0 +/- 0.2 g). Histologic findings examined by light microscopy presented intraalveolar hemorrhage and fluid accumulation, disruption of vascular basements and alveolar septa, and aggregation of inflammatory cells within the parenchyma in the lungs of the PMA group. In the MPMA group there was no evidence of intraalveolar hemorrhage and alveolar fluid accumulation, however, the occasional presence of granulocytes in the parenchyma and slight interstitial edema were still observed. In addition, depressed the chemiluminescence release from PMA activated granulocytes which were in a dose-dependent manner in vitro. These observations suggest that mepacrine inhibits PMA-induced lung injury chiefly by protection of vascular permeability. The mechanism of the protection may be due to the inhibition of oxygen radicals released from activated neutrophils and the reduction of neutrophil chemotaxis.
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PMID:The protective effect of mepacrine on acute lung edema induced by phorbol myristate acetate in rats. 209

In experiments on white rats, guinea pigs and cats it was shown that intravenous infusion of phospholipase A2 (FLA2) caused the development of pulmonary edema (PE) in guinea pigs, but did not cause it in rats and cats. Bilateral vagotomy on the neck led to the appearance of the expressed edemogenous effect of FLA2 on the lungs. Pentobarbital anesthesia decreased the effect of vagotomy. This effect is not connected with the turn off of the efferent impulsation in vagus nerves as the infusion of atropine did not repeat the influence of vagotomy. Authors assume that the action of FLA2 is realized across the secretion of humoral factor in vagotomized animals and the increase of the permeability of the aero-hematic barrier.
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PMID:[Effects of phospholipase A2 on the etiology of pulmonary edema hemodynamics of lesser circulation in intact and vagotomized animals]. 226 8

Lung injury induced by phospholipase A2 (PLA2, 0.046 IU/ml perfusate) was studied in a continuous weighing system of isolated perfused guinea pig lungs. The results revealed that lung weight increased progressively during the 30-min perfusion of PLA2. No change of pulmonary arterial pressure was observed in the same period. Albumin permeability-surface area product, lung index, lung water content, exudate from pleura, and angiotensin-converting-enzyme activity increased significantly at the end of 30 min PLA2 perfusion. p-Bromophenacyl bromide, a PLA2 inhibitor, may block the above changes nearly completely. The effects of inhibitors of cyclooxygenase (indomethacin, IM), lipoxygenase (diethylcarbamaxine, DE), and platelet-activating factor (SRI 63-441) on PLA2-induced lung injury were also studied. We found: (1) PLA2 may induce high permeability lung edema. The role of endothelial injury in the permeability change remains to be further investigated. (2) DE ameliorated lung injury significantly within 10 min of PLA2 treatment but showed no effect after 15 min. IM ameliorated lung injury during the whole experimental period. SRI 63-441 had no effect. It is suggested that PLA2 may damage lung by inducing products of cyclooxygenase and lipoxygenase besides its direct effect.
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PMID:Phospholipase A2-induced lung edema and its mechanism in isolated perfused guinea pig lung. 236 33

We examined the effect of phospholipase A2 (PLA2; Naja naja) challenge on pulmonary hemodynamics, airway constriction, and fluid filtration in isolated Ringer-perfused guinea pig lungs. Intratracheal PLA2 (10-100 U) produced dose-dependent increases in pulmonary arterial pressure, intratracheal pressure, and lung weight, although intravenous PLA2 administration had no effect on monitored variables. Morphological features indicative of airway constriction and pulmonary edema were observed by light microscopy. PLA2-induced increases in intratracheal pressure and/or lung weight were attenuated to varying degrees by pretreatment with indomethacin (1 microM, a cyclooxygenase inhibitor), ICI-198,615 (1 microM, a leukotriene D4 receptor antagonist), and WEB 2086 (1 microM, a platelet-activating factor antagonist). PLA2-induced increases in pulmonary arterial pressure and intratracheal pressure were also reduced in lungs removed from animals pretreated with dexamethasone (50 mg/kg ip for 2 days; a steroidal antiinflammatory agent). Pyrilamine (1 microM, a histamine1-receptor antagonist) and Takeda AA861 (1 microM, a delta 5-lipoxygenase inhibitor) did not produce significant inhibitory effects on PLA2-induced pathophysiological changes. Intratracheal instillation of high-dose platelet-activating factor (50 micrograms) or lysophosphatidylcholine (100 micrograms) produced gradual increases in intratracheal pressure and lung weight, but these changes were not as large as those induced by PLA2. Thus these studies suggest that resident cell populations associated with airways may play an important role in PLA2-induced pathophysiological changes in the perfused guinea pig lung. These PLA2-induced effects are most likely partially mediated by generation of eicosanoids and platelet-activating factor.
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PMID:Pulmonary responses to phospholipase A2 in the perfused guinea pig lung. 260 58

Phospholipase A2, injected as a bolus into the jugular vein of adult male Wistar rats was investigated with respect to its action upon lung morphology and blood- plasma- histamine. In comparison with the injection of saline, phospholipase A2 causes hyperemia of the lungs, sequestration of granulocytes and intraalveolar pulmonary edema; the histamine level is increased to the sixfold. Pretreatment of the animals with indomethacin diminishes the toxic effect of phospholipase A2 upon the lungs and the histamine level.
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PMID:Phospholipase A2 induced diffuse alveolar damage--effect of indomethacin and dexamethasone upon morphology and plasma-histamine level. 292 54

Serious pulmonary complications are often associated with acute pancreatitis. The destruction of pulmonary surfactant by the action of pancreatic phospholipase A2 (PLA2), together with pulmonary edema, is considered an important etiopathogenic factor of acute respiratory insufficiency. This experimental study was undertaken to elucidate the destruction of pulmonary surfactant in acute pancreatitis using the lung pressure volume curve (P-V curve). Acute hemorrhagic pancreatitis was induced in mongrel dogs by a retrograde injection of Na-taurocholate into the main pancreatic duct. Pulmonary surface tension was measured by P-V curve and the effect of PLA2 on pulmonary surfactant was assessed by the ratio of lysolecithin and lecithin, which are essential components of pulmonary surfactant (Ly/Le) in lung wash. Extravascular lung water volume (Ww/Dw) and blood gases were also measured. The value of Ly/Le and serum PLA2 rose significantly from the 3rd hour. On the contrary, no significant differences were seen on P-V curve until the 12th hour but after 20 hours surface tension increased significantly. Ww/Dw and A-aDO2 increased after 3 and 12 hours, respectively. These findings, the degradation of lecithin and the elevation of surface tension accompanied with an increase of serum PLA2, suggest that pulmonary surfactant is destroyed in severe acute pancreatitis, and that the increased capillary permeability of the lung precedes the deterioration of surface tension as the cause of pulmonary insufficiency.
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PMID:[Experimental study on the pathogenesis of pulmonary insufficiency in acute pancreatitis and changes in the pulmonary surfactant]. 322 26

The Gaboon viper has acquired an impressive reputation which is at least partly unfounded. This handsome animal with such striking features is undoubtedly docile which accounts for the very low incidence of bite amongst humans. There are only six detailed clinical reports on the effect of bite and these are summarized in the review. The viper does indeed produce prodigious amounts of venom, but the toxicity, weight for weight, is rather low compared to other poisonous snakes. Venom extractions have been carried out on four snakes over a 13-year-period and the effects of this venom have been studied in a variety of experimental animals. Systemic envenomation is characterized by immediate abrupt hypotension, subsequent cardiac damage and dyspnoea. The individual venom components responsible for these effects have not been isolated but it seems likely that the two enzymes which have been studied extensively (phospholipase A2 and the thrombin-like enzyme, gabonase) do not contribute significantly to lethality. We propose three principal activities which give rise to the major signs of systemic envenomation. Haemorrhagin; causing widespread damage to microvasculature which leads to the pulmonary oedema and hence dyspnoea, and locally causes blistering. Cardiotoxin; a long-acting material causing cardiac muscle damage, arrhythmia and ultimately cardiac failure. Peripheral vasodilator; a short acting effect, operating either locally via bradykinin formation and/or unknown peptides or centrally on the vasomotor centre.
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PMID:The Gaboon viper (Bitis gabonica): its biology, venom components and toxinology. 639 43

Paraquat poisoning and hyperbaric oxygen exposure are well established models of oxidative stress in lung. The aim of this study was focused on the contribution of oxygen free radicals and other cytotoxic species, such as lipid hydroperoxides, to the overall toxicity. Adult Wistar rats were injected with paraquat (30 or 60 mg/kg b.w.) or exposed to hyperbaric oxygen (0.2 MPa), and several parameters of lung damage were measured. Both treatments resulted in increased spontaneous lung chemiluminescence, number of lung PMN, malondialdehyde content, lung edema, and pleural liquid. Of note, spontaneous lung chemiluminescence, used to monitor the steady-state concentration of oxygen free radicals in vivo, did not increase significantly after either treatment. The increase in spontaneous lung chemiluminescence started after PMN migration, being both maxima separated by a delay time of 4-6 h. After PMN migrated and became activated in the lung, the survival of the animals started to decline. Thus, PMN can be considered as additional sources of oxygen free radicals supported by the subsequent increase in chemiluminescence. Their role in lung damage was evidenced by the increase in lung edema, augmented pleural liquid, and decreased survival after PMN migration. Lipid hydroperoxide concentration in lung membranes was also increased after either treatment. This increased concentration may be a consequence of an increased rate of lipid peroxidation, initiated by oxidative stress on lipid membranes, or by an inhibition of their catabolism. Ester lipid hydroperoxides normally produced in membranes cannot be catabolized directly by the glutathione peroxidase-reductase system unless phospholipase A2 catalyses the release of free lipid hydroperoxides. In both experimental models, phospholipase A2 activity was decreased to almost negligible values. Betamethasone (1 mg/ml; IV) administered to the rats 3 h before paraquat injection accelerated the decrease in survival and phospholipase A2 inactivation. Inactivation of phospholipase A2, detected in paraquat or oxygen exposed rats, could be attributed to a O2(.-)-driven Fenton reaction. However, phospholipase A2 inactivation by betamethasone pretreatment may be attributed to the presence of lipocortin, a corticosteroid-inducible factor and inhibitor of phospholipase A2. Besides the mechanism underlying the inactivation of phospholipase A2, the increase in lipid hydroperoxides may indicate their role as long-lived cytotoxic species that contribute to the damage already initiated by oxidative stress. Indeed, lipid hydroperoxides are very well known modifiers of membrane physical properties.
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PMID:Lung damage in paraquat poisoning and hyperbaric oxygen exposure: superoxide-mediated inhibition of phospholipase A2. 774 3

A novel active-site directed specific inhibitor of phospholipase A2 (PLA2), 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol (MJ33), administered endotracheally co-dispersed in liposomes, significantly reduced the formation of thiobarbituric acid reactive substances (TBARS) in isolated rat lungs subjected to ischemia-reperfusion. Elevated conjugated dienes were unaffected. This contrasts with the effects of the cyclo-/lipoxygenase inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA), which decreased formation of both TBARS and conjugated dienes (CD). The effects of MJ33 plus ETYA were additive for TBARS but results for CD were similar to ETYA alone. A similar dissociation of inhibition of TBARS and CD formation by MJ33 was observed with t-butyl hydroperoxide induced lipid peroxidation of isolated lung microsomes. Assay of lung homogenate with phosphatidylcholine as substrate showed that MJ33 selectively inhibited the Ca(2+)-independent acidic PLA2. MJ33 had no effect on thromboxane B2 release by the isolated lung, indicating the effects of acidic PLA2 inhibition do not involve the arachidonate cascade. MJ33 also partially prevented lung edema and lactate dehydrogenase release associated with ischemia-reperfusion. The observations show that this PLA2 inhibitor can be delivered to oxidant-sensitive lung sites by its co-dispersal in liposomes, and that oxidant-induced lipid peroxidation in this model of lung injury occurs in a complex lipid prior to PLA2 activity.
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PMID:A phospholipase A2 inhibitor decreases generation of thiobarbituric acid reactive substance during lung ischemia-reperfusion. 846 33


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