salicylates and Hypoxia

Topics: Acidosis; Anti-Bacterial Agents; Bilirubin; Blood Transfusion; Erythroblastosis, Fetal; Female; Gestational Age; Humans; Hyperbilirubinemia; Hypoproteinemia; Hypoxia; Infant, Newborn; Infant, Premature, Diseases; Infections; Infusions, Parenteral; Jaundice, Neonatal; Kernicterus; Liver; Phototherapy; Pre-Eclampsia; Pregnancy; Salicylates; Serum Albumin; Steroids; Sulfisoxazole

Topics: Asthma; Epilepsy; Hypoxia; Muscle Relaxants, Central; Myasthenia Gravis; Salicylates; Tetanus; Toxicology; Wounds and Injuries

Neu2000 (NEU; 2-hydroxy-5-(2,3,5,6-tetrafluoro-4-trifluoromethyl-benzylamino)-benzoic acid), a recently developed derivative of acetylsalicylic acid and sulfasalazine, potently protects against neuronal cell death following ischemic brain injury by antagonizing NMDA receptor-mediated neuronal toxicity and oxidative stress. However, it has yet to be determined whether NEU can attenuate hypoxia-induced impairment of neuronal electrical activity. In this study, we carried out extracellular recordings of hippocampal slices in order to investigate the effects of NEU on the electrical activity of neurons exposed to a hypoxic insult (oxygen and glucose deprivation). NEU prominently suppressed hypoxia-induced impairment of neuronal activity in a concentration-dependent manner. NEU, at a low dose (1 μM), competently depressed the hypoxia-induced convulsive activity in a manner similar to trolox. Furthermore, high concentrations of NEU (50 μM) markedly abolished all hypoxia-mediated impairment of neuronal activity and accelerated the slow recovery of neuronal activity more efficiently than ifenprodil and APV. These results suggest that NEU attenuates hypoxia-induced impairment of neuronal activity more potently than the antioxidant, trolox, and the NMDA receptor antagonists, ifenprodil and APV. We propose that NEU is a striking pharmacological candidate for neuroprotection against hypoxia because of its defensive action on hypoxia-mediated impairment of electrical neurotransmission as well as its neuroprotective action against neuronal cell death induced by exposure to pathological hypoxic conditions.

Topics: Animals; Antioxidants; CA3 Region, Hippocampal; Dose-Response Relationship, Drug; Fluorobenzenes; Glucose; Hypoxia; In Vitro Techniques; meta-Aminobenzoates; Microelectrodes; Neurons; Neuroprotective Agents; Oxygen; Rats; Rats, Sprague-Dawley; Salicylates; Synaptic Transmission

Mitochondrial function is modulated by multiple approaches including physical activity, which can afford cross-tolerance against a variety of insults. We therefore aimed to analyze the effects of endurance-training (ET) and chronic-intermittent hypobaric-hypoxia (IHH) on liver mitochondrial bioenergetics and whether these effects translate into benefits against in vitro salicylate mitochondrial toxicity. Twenty-eight young-adult male rats were divided into normoxic-sedentary (NS), normoxic-exercised (NE), hypoxic-sedentary (HS) and hypoxic-exercised (HE). ET consisted of 1h/days of treadmill running and IHH of simulated atmospheric pressure of 49.3 kPa 5h/days during 5weeks. Liver mitochondrial oxygen consumption, transmembrane-electric potential (ΔΨ) and permeability transition pore induction (MPTP) were evaluated in the presence and absence of salicylate. Aconitase, MnSOD, caspase-3 and 8 activities, SH, MDA, SIRT3, Cyp D, HSP70, and OXPHOS subunit contents were assessed. ET and IHH decreased basal mitochondrial state-3 and state-4 respiration, although no alterations were observed in ΔΨ endpoints evaluated in control mitochondria. In the presence of salicylate, ET and IHH decreased state-4 and lag-phase of ADP-phosphorylation. Moreover, ADP-lag phase in hypoxic was further lower than in normoxic groups. Neither ET nor IHH altered the susceptibility to calcium-induced MPTP. IHH lowered MnSOD and increased aconitase activities. ET and IHH decreased caspase 8 activity whereas no effect was observed on caspase 3. The levels of SIRT3 increased with ET and IHH and Cyp D decreased with IHH. Data suggest that ET and IHH do not alter general basal liver mitochondrial function, but may attenuate some adverse effects of salicylate.

Topics: Animals; Hypoxia; Liver; Male; Membrane Potentials; Mitochondria; Mitochondrial Membranes; Mitochondrial Proteins; Oxygen Consumption; Physical Conditioning, Animal; Rats; Salicylates

AMP-activated protein kinase (AMPK) is a sensor of cellular energy status found in metazoans that is known to be activated by stimuli that increase the cellular AMP/ATP ratio. Full activation of AMPK requires specific phosphorylation within the activation loop of the catalytic domain of the alpha-subunit by upstream kinases such as the serine/threonine protein kinase LKB1. Here we show that hypoxia activates AMPK through LKB1 without an increase in the AMP/ATP ratio. Hypoxia increased reactive oxygen species (ROS) levels and the antioxidant EUK-134 abolished the hypoxic activation of AMPK. Cells deficient in mitochondrial DNA (rho(0) cells) failed to activate AMPK during hypoxia but are able to in the presence of exogenous H(2)O(2). Furthermore, we provide genetic evidence that ROS generated within the mitochondrial electron transport chain and not oxidative phosphorylation is required for hypoxic activation of AMPK. Collectively, these data indicate that oxidative stress and not an increase in the AMP/ATP ratio is required for hypoxic activation of AMPK.

Topics: Adenosine Triphosphate; AMP-Activated Protein Kinase Kinases; AMP-Activated Protein Kinases; Animals; Antioxidants; Catalytic Domain; Cell Line; Electron Transport Complex III; Fibroblasts; Hydrogen Peroxide; Hypoxia; Mice; Mitochondria; Mutation; Organometallic Compounds; Oxidative Phosphorylation; Protein Serine-Threonine Kinases; Reactive Oxygen Species; Salicylates

Topics: Adipocytes; Adipokines; Cell Line; Gene Expression; Glucose Transport Proteins, Facilitative; Humans; Hypoxia; Salicylates

Hypoxia inhibits Na-K-ATPase activity and leads to its degradation in mammalian cells. Von Hippel Lindau protein (pVHL) and hypoxia inducible factor (HIF) are key mediators in cellular adaptation to hypoxia; thus, we set out to investigate whether pVHL and HIF participate in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase. We found that in the presence of pVHL hypoxia decreased Na-K-ATPase activity and promoted the degradation of plasma membrane Na-K-ATPase. In pVHL-deficient cells, hypoxia did not decrease the Na-K-ATPase activity and the degradation of plasma membrane Na-K-ATPase was prevented. pVHL-mediated degradation of Na-K-ATPase required the functional pVHL E3 ligase and Ubc5 since pVHL mutants and dominant-negative Ubc5 prevented Na-K-ATPase from degradation. The generation of reactive oxygen species was necessary for pVHL-mediated Na-K-ATPase degradation during hypoxia. Desferrioxamine, which stabilizes HIF1/2alpha, did not affect the half-life of plasma membrane Na-K-ATPase. In addition, stabilizing HIF1/2alpha by infecting mammalian cells with adenoviruses containing the oxygen-dependent degradation domain of HIF1alpha did not affect the plasma membrane Na-K-ATPase degradation. In cells with suppression of pVHL by short hairpin RNA, the Na-K-ATPase was not degraded during hypoxia, whereas cells with knockdown of HIF1/2alpha retained the ability to degrade plasma membrane Na-K-ATPase. These findings suggest that pVHL participates in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase in a HIF-independent manner.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Cell Membrane; Cells, Cultured; Chlorocebus aethiops; COS Cells; Deferoxamine; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Organometallic Compounds; Salicylates; Sodium-Potassium-Exchanging ATPase; Von Hippel-Lindau Tumor Suppressor Protein

Exposure of animals to hyperoxia results in respiratory failure and death within 72 h. Histologic evaluation of the lungs of these animals demonstrates epithelial apoptosis and necrosis. Although the generation of reactive oxygen species (ROS) is widely thought to be responsible for the cell death observed following exposure to hyperoxia, it is not clear whether they act upstream of activation of the cell death pathway or whether they are generated as a result of mitochondrial membrane permeabilization and caspase activation. We hypothesized that the generation of ROS was required for hyperoxia-induced cell death upstream of Bax activation. In primary rat alveolar epithelial cells, we found that exposure to hyperoxia resulted in the generation of ROS that was completely prevented by the administration of the combined superoxide dismutase/catalase mimetic EUK-134 (Eukarion, Inc., Bedford, MA). Exposure to hyperoxia resulted in the activation of Bax at the mitochondrial membrane, cytochrome c release, and cell death. The administration of EUK-134 prevented Bax activation, cytochrome c release, and cell death. In a mouse lung epithelial cell line (MLE-12), the overexpression of Bcl-XL protected cells against hyperoxia by preventing the activation of Bax at the mitochondrial membrane. We conclude that exposure to hyperoxia results in Bax activation at the mitochondrial membrane and subsequent cytochrome c release. Bax activation at the mitochondrial membrane requires the generation of ROS and can be prevented by the overexpression of Bcl-XL.

Topics: Animals; bcl-2-Associated X Protein; bcl-X Protein; Caspases; Cell Death; Cell Line; Cell Nucleus; Cells, Cultured; Cytochromes c; Enzyme Activation; Epithelial Cells; Glutathione; Hypoxia; Immunoblotting; Intracellular Membranes; L-Lactate Dehydrogenase; Lung; Mice; Microscopy, Confocal; Mitochondria; Models, Biological; Organometallic Compounds; Oxygen; Plasmids; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pulmonary Alveoli; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Retroviridae; Salicylates; Superoxide Dismutase; Time Factors

Acetylsalicylic acid (ASA) is the most widely used drug in the prevention of ischemic vascular accidents, mainly because of its antithrombotic effect. Recently, evidence of a neuroprotective effect has appeared. The aim of this study was to evaluate the neuroprotective effect of triflusal, a fluorinated derivative of ASA, in a model of anoxia-reoxygenation in rat brain slices. Rats (n=10 per group) were treated for 7 days with 1, 10 or 50 mg/kg/day p.o. of triflusal or ASA or solvent (control group), then brain slices were obtained and subjected to a period of anoxia followed by 180 min of reoxygenation. We measured oxidative stress parameters (lipid peroxidation, glutathione system), prostaglandins (PGE(2)), nitric oxide pathway activity (NO) (nitrites+nitrates, constitutive and inducible NO synthase activity) and cell death (lactate dehydrogenase (LDH) efflux). Triflusal decreased cell death in rat brain slices subjected to reoxygenation after anoxia by 21%, 42% and 47% with 1, 10 and 50 mg/kg/day, respectively. This effect was proportionately greater than the effect of ASA (0%, 25% and 24%). The antioxidant effects of triflusal on the biochemical mechanisms of cell damage studied here were also greater than the effects of ASA: lipid peroxidation was reduced by 29%, 35% and 36% with triflusal, and 0%, 19% and 29% with ASA. Inducible NO synthase activity was reduced by 25%, 27% and 30% with triflusal, and 0%, 25% and 24% with ASA. Triflusal can be considered an alternative to ASA as a neuroprotective agent, at least in the experimental model of anoxia-reoxygenation used in the present study.

Topics: Analysis of Variance; Animals; Aspirin; Disease Models, Animal; Dose-Response Relationship, Drug; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Glutathione Transferase; Hypoxia; In Vitro Techniques; L-Lactate Dehydrogenase; Lipid Peroxidation; Male; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxidative Stress; Oxygen; Platelet Aggregation Inhibitors; Prostaglandins; Rats; Rats, Wistar; Salicylates

Barbiturates have been shown to be neuroprotective in several animal models, but the underlying mechanisms are unknown. In this study, the authors investigated the effect of barbiturates on free radical scavenging and attempted to correlate this with their neuroprotective effects in a model of hypoxic cell death in human NT2-N neurons.. Hydroxyl radicals were generated by ascorbic acid and iron and were measured by conversion of salicylate to 2,3-dihydroxybenzoic acid. The effect of barbiturates on lipid peroxidation measured as malondialdehyde and 4-hydroxynon-2-enal was also investigated. Hypoxia studies were then performed on human NT2-N neurons. The cells were exposed to 10 h of hypoxia or combined oxygen and glucose deprivation for 3 or 5 h in the presence of thiopental (50-600 microM), methohexital (50-400 microM), phenobarbital (10-400 microM), or pentobarbital (10-400 microM), and cell death was evaluated after 24 h by lactate dehydrogenase release.. Pentobarbital, phenobarbital, methohexital, and thiopental dose-dependently inhibited formation of 2,3-dihydroxybenzoic acid and iron-stimulated lipid peroxidation. There were significant but moderate differences in antioxidant action between the barbiturates. While phenobarbital (10-400 microM) and pentobarbital (10-50 microM) increased lactate dehydrogenase release after combined oxygen and glucose deprivation, thiopental and methohexital protected the neurons at all tested concentrations. At a higher concentration (400 microM), pentobarbital also significantly protected the neurons. At both 50 and 400 microM, thiopental and methohexital protected the NT2-N neurons significantly better than phenobarbital and pentobarbital.. Barbiturates differ markedly in their neuroprotective effects against combined oxygen and glucose deprivation in human NT2-N neurons. The variation in neuroprotective effects could only partly be explained by differences in antioxidant action.

Topics: Barbiturates; Blood Glucose; Cell Death; Cell Line; Humans; Hydroxybenzoates; Hydroxyl Radical; Hydroxylation; Hypoxanthines; Hypoxia; L-Lactate Dehydrogenase; Lipid Peroxidation; Malondialdehyde; Neurons; Oxygen Consumption; Salicylates

The changes in nitric oxide (NO) formation during hypoxia and reoxygenation were measured in slices of rat cerebral cortex, and the possible involvement of NO and its decomposition products, including peroxynitrite and hydroxyradical, in the hypoxia/reoxygenation injury was subsequently investigated. NO formation estimated from cGMP accumulation in the extracellular fluids was enhanced during hypoxia and to a lesser extent in the reoxygenation period. The mRNA for inducible NO synthase (NOS) was detected 3-5 h after reoxygenation, although neuronal NOS mRNA decreased after reoxygenation. Several NOS inhibitors such as N(G)-monomethyl-L-arginine and N(G)-nitro-L-arginine blocked not only the NO formation but also the hypoxia/reoxygenation injury as determined by lactate dehydrogenase (LDH) leakage. The hypoxia/reoxygenation injury was prevented by peroxynitrite scavengers including deferoxamine and uric acid, or several hydroxyradical scavengers such as dimethylthiourea, 2-mercaptopropionylglycine and D(-) mannitol. In addition, the hypoxia/reoxygenation injury was attenuated by poly(ADP-ribose)synthetase inhibitors such as banzamide, 3-aminobenzamide and 1,5-isoquinolinediol. On the other hand, both N-morpholinosidnonimine, a peroxynitrite generator, and hydroxyradical-liberating solution containing FeCl(3)-ADP and dihydroxyfumarate caused a marked LDH leakage in normoxic slices. These findings suggest that the enhanced formation of NO causes hypoxia/reoxygenation injury after degradation to peroxynitrite and hydroxyradical and the resultant activation of poly(ADP-ribose)synthetase.

Topics: Adenosine Triphosphate; Animals; Cell-Free System; Cerebral Cortex; Cyclic AMP; Enzyme Inhibitors; Hydroxyl Radical; Hypoxia; Male; Neurons; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxidants; Poly(ADP-ribose) Polymerase Inhibitors; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Salicylates; Tyrosine

Cardiac surgery with cardiopulmonary bypass induces ischemia to the heart, hypoxemia to various tissues and release of endotoxins. The endothelial cell may suffer from hypoxia and trigger cascades of adverse reactions by activation of neutrophils through adhesion molecules. The authors measured expression of intercellular adhesion molecule-1 (ICAM-1), during hypoxia and normoxia and hypothesized that salicylate, which inhibits the nuclear factor-kappaB (NFkappaB), an hypoxia-dependent transmission factor, could reduce this expression.. Human umbilical vein endothelial cells were cultured and exposed to normoxia and hypoxia in the presence of lipopolysaccharide (LPS). The endothelial cells were thereafter treated with salicylate or indomethacin under the same conditions. The surface expression of ICAM-1 was measured by whole cell enzyme-linked immunosorbent assay (ELISA) and the NFkappaB expression by Western blotting.. In the presence of LPS and under hypoxic conditions, the endothelial cells produced a 300 +/- 41% increased expression of ICAM-1 compared with normoxia. The addition of salicylate (0.02-20 mM) completely inhibited the enhanced expression of ICAM-1, the addition of indomethacin at equivalent concentrations did not reduce ICAM-1 expression under either condition.. ICAM-1 expression is greatly enhanced by the hypoxic endothelial cell in the presence of circulating endotoxin. Pre-treatment with salicylate completely abolishes the enhanced expression. The study suggests that salicylate administered before cardiopulmonary bypass might protect the heart against ischemic/reperfusion injuries and reduce the load of the overall inflammatory reaction.

Topics: Blotting, Western; Cardiopulmonary Bypass; Cardiovascular Surgical Procedures; Cells, Cultured; Endothelium, Vascular; Enzyme-Linked Immunosorbent Assay; Humans; Hypoxia; Indomethacin; Intercellular Adhesion Molecule-1; Myocardial Reperfusion Injury; NF-kappa B; Salicylates; Umbilical Veins

Carbon monoxide poisoning produces both immediate and delayed neuronal injury in selective regions of the brain that is not readily explained on the basis of tissue hypoxia. One possibility is that cellular injury during and after CO poisoning is related to the production of reactive oxygen species (ROS) by the brain. In this study, we hypothesized that the extent of ROS generation in the brain would be greater after CO than after hypoxic hypoxia due to intracellular uptake of CO. We assessed hydroxyl radical (OH.) production by comparing the nonenzymatic hydroxylation of salicylic acid to 2,3-dihydroxybenzoic acid (2,3-DHBA) in the hippocampus of the rat by microdialysis during either CO hypoxia or an exposure to hypoxic hypoxia that produced similar PO2 and cerebral blood flow (CBF) values in the region of microdialysis. We found neither control animals nor animals exposed to 30 min of hypoxic hypoxia at a mean tissue PO2 of 15 mmHg demonstrated significant increases in 2,3-DHBA production in the hippocampus over the 2-h the exposure. In contrast, CO exposed rats which also developed brain PO2 values in the range of 15 mmHg showed highly significant increases in 2,3-DHBA production. We conclude that cerebral oxidative stress in the hippocampus of the rat during CO hypoxia in vivo is not a direct effect of decreased tissue oxygen concentration.

Topics: Animals; Carbon Monoxide Poisoning; Cerebrovascular Circulation; Hemoglobins; Hippocampus; Hydroxybenzoates; Hydroxyl Radical; Hydroxylation; Hypoxia; Male; Oxidative Stress; Oxygen Consumption; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Salicylates; Salicylic Acid

The difficulty in direct detection of oxygen-derived free radicals (OFR) in the intact kidney has left uncertain the role of OFR in renal hypoperfusion injury. Salicylate hydroxylation was used as a sensitive method of estimating the extent of production of highly reactive hydroxyl radicals in renal ischaemia-reperfusion injury in the intact rat kidney perfused with recirculating cell-free medium. The reaction products were detected and quantified by HPLC with electrochemical detection. Hydroxyl radicals were detected as 2,5-dihydroxybenzoic acid (2,5-DHBA). Ischaemia for 15 min followed by reperfusion for 15 min caused more than a twofold increase in 2,5-DHBA concentration (to 2279 +/- 225 pg/g tissue weight) compared to controls (933 +/- 103, P < 0.001). Addition of 15 mM dimethylthiourea (DMTU) before induction of ischaemia prevented this increase. Induction of hypoxia for 15 min with continued perfusion (as a model of low-flow ischaemia) had no significant effect on hydroxyl radical formation. We conclude that significant quantities of hydroxyl radicals form in the absence of circulating leucocytes during reperfusion following ischaemia, but not during hypoxia in the perfused rat kidney.

Topics: Animals; Chromatography, High Pressure Liquid; Gentisates; Hydroxybenzoates; Hydroxyl Radical; Hypoxia; Ischemia; Kidney; Male; Rats; Rats, Wistar; Reperfusion; Salicylates

Isolated adult rat cardiac myocytes were subjected to anoxia and substrate deprivation for 15, 30, 60, 90, and 120 minutes and reoxygenation for 120 seconds. The supernatant and cell extract were analyzed for hydroxyl radicals (.OH) with high-performance liquid chromatography using salicylate as a trapping agent. The production of intracellular H2O2 as a possible precursor of .OH was also documented using the fluorescent probe dichlorofluorescein diacetate. The release of the cytosolic enzyme lactate dehydrogenase (LDH) and malondialdehyde (MDA) formation were used as cell injury markers. Trypan blue and horseradish peroxidase stains were used as markers for altered membrane permeability. Maximum formation of .OH was observed in myocytes subjected to 15 minutes of anoxia/reoxygenation (2.83 +/- 0.27 nmol/mg protein), at which time no injury was observed at light and ultramicroscopic levels. On the other hand, there was no correlation between the amount of .OH production and different parameters of cell injury in myocytes subjected to anoxia/reoxygenation longer than 15 minutes. Myocytes developed extensive blebbing, loss of cell membrane permeability, and ultrastructural damage. The enzyme leakage was minimal at 15 minutes (0.094 +/- 0.021 units/mg protein) and increased fivefold after 120 minutes (0.428 +/- 0.069 units/mg protein). Similarly, MDA increased from 0.78 +/- 0.14 nmol/mg protein at 15 minutes to 1.65 +/- 0.35 nmol/mg protein at 120 minutes. Incubation with 1 mM deferoxamine reduced the .OH production at all anoxic intervals, most significantly at 15 minutes, but did not decrease LDH and MDA release or provide ultrastructural preservation. However, preincubation with 2.5 microM diphenylphenylenediamine markedly reduced both LDH and MDA release and offered prominent ultrastructural protection. These results suggest that 1) myocytes were able to generate .OH endogenously; 2) maximum .OH was produced at 15 minutes after anoxic reoxygenation without compromising cell viability; 3) prolongation of the anoxic period exacerbated cell damage without parallel increase in .OH generation; 4) there was no significant production of .OH after 15 minutes of anoxia/reoxygenation with or without treatment of deferoxamine, suggesting that prolonged anoxia/reoxygenation does not induce additional .OH formation and thus mediate cell injury; and 5) it is likely that the damage to myocytes in this system was still mediated by free radicals other than .OH, as indica

Topics: Animals; Cell Membrane Permeability; Cell Survival; Cells, Cultured; Free Radicals; Horseradish Peroxidase; Hydroxides; Hydroxyl Radical; Hypoxia; L-Lactate Dehydrogenase; Lipid Peroxides; Male; Myocardium; Oxygen; Rats; Rats, Sprague-Dawley; Salicylates; Salicylic Acid

Intracellular iron reportedly mediates many forms of tissue injury, including ischemic and myohemoglobinuric acute renal failure. This action may be explained by the ability of iron to catalyze the formation of the highly toxic hydroxyl radical (.OH) from H2O2 via the Fenton/Haber-Weiss reactions. To assess whether renal tubular myoglobin/iron loading, induced by a physiological mechanism (endocytosis), alters its susceptibility to O2 deprivation/reoxygenation- and H2O2-mediated injury, rats were infused with myoglobin or its vehicle (5% dextrose, control rats), and after 2 hours, proximal tubular segments (PTSs) were isolated for study. This infusion caused substantial myoglobin endocytic uptake (approximately 25 micrograms/mg PTS protein), and it doubled PTS catalytic iron content (assessed by bleomycin assay). Nevertheless, PTS viability (percent lactate dehydrogenase release) was minimally affected (4% to 6% increase), and an increased .OH burden (assessed by the salicylate trap method) did not appear to result. Deferoxamine addition, reported to protect against in vivo acute renal failure, paradoxically increased .OH levels (approximately 25%) in myoglobin-loaded, but not control, PTSs. Conversely, dimethylthiourea (an .OH scavenger) depressed .OH (by approximately 80%) in all PTSs. Myoglobin/iron loading modestly increased PTS vulnerability to exogenous H2O2 addition (P < .001). However, tubular susceptibility to hypoxia (15 and 30 minutes)/reoxygenation injury was not affected. .OH levels appeared to fall in response to both forms of injury, suggesting decreased .OH production and/or .OH scavenging. To assess whether myoglobin decreases .OH levels in the presence of Fenton reactants, myoglobin and six other test proteins were incubated with Fe2+/H2O2. Myoglobin decreased .OH levels by approximately 70%, a significantly greater decrement than was observed with the other proteins tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acute Kidney Injury; Animals; Hydrogen Peroxide; Hydroxybenzoates; Hydroxyl Radical; Hypoxia; In Vitro Techniques; Iron; Kidney Tubules, Proximal; L-Lactate Dehydrogenase; Male; Myoglobin; Rats; Rats, Sprague-Dawley; Salicylates

Hydroxyl radicals (.OH) in isolated cultured cardiomyocytes upon reoxygenation (reoxy) were measured after graded anoxia (A) using high performance liquid chromatography (HPLC). Isolated myocytes were subjected to A for 15, 30, 60, 90 and 120 minutes and reoxy for 120 seconds. Supernatant was collected after reoxy, extracted with ether and injected into HPLC for measuring hydroxylation products of salicylic acid (2,5-DHBA) as an indicator of .OH formation. 2,5-DHBA was detected maximally after 15 minutes of A and 120 seconds of reoxygenation (34.2 +/- 3 pmol/mg protein), at which time 80% of cells had maintained their rod shape and 99% of cells excluded both trypan blue (TB) and horseradish peroxidase (HP). There was significantly less (P < 0.05) 2,5-DHBA in the group subjected to 15 minutes of A only without reoxy (7.95 +/- 1.2 pmol/mg protein). 2,5-DHBA decreased to 13.1 +/- 2 pmol/mg protein at 120 minutes of A/120 seconds reoxy. With increasing anoxic time, the number of rod-shaped cells decreased from 80% at 15 minutes to 30% at 120 minutes, while the number of TB/HP positive cells increased from 0% at 15 minutes to 100% at 120 minutes. The cell membrane blebs were nonexistent at 15 minutes, but at 120 minutes A intense bleb formation was observed. These data suggest that .OH is produced upon reoxygenation of anoxic cultured cardiomyocytes and their production is maximum when majority of myocytes are viable.

Topics: Animals; Cell Membrane Permeability; Cell Survival; Cells, Cultured; Free Radicals; Horseradish Peroxidase; Hydroxides; Hydroxyl Radical; Hypoxia; Myocardium; Oxygen; Salicylates; Salicylic Acid; Time Factors

To assess the possibility that salicylate stimulates VE by direct excitation of phrenic motoneurons, we compared two groups of anesthetized vagotomized dogs with respect to increases in phrenic nerve activity elicited by a large dose of sodium salicylate (225 mg/kg). The sole difference between the two groups of animals was the condition of the spinal cord (SC); SC remained intact in one group of animals (i.e., intact animals) whereas the other group of animals (i.e., T1 spinal-transected animals) underwent complete transection of the SC at the first thoracic level. Both groups of animals were ventilated by a respirator and arterial PCO2 was maintained constant throughout all experiments. Following salicylate infusion, intact animals exhibited two- to threefold increases in the frequency of phrenic nerve bursts and three- to fivefold increases in moving average minute phrenic activity (i.e., the summation of peak integrated burst activity per minute). In contrast, salicylate infusion into T1 spinal-transected animals elicited no statistically significant increase in the frequency of phrenic nerve bursts while increases in minute phrenic activity were limited to 32 +/- 8%. Since T1 spinal transection markedly diminishes increases in phrenic nerve activity elicited by salicylate, we conclude that salicylate stimulates VE by a reflex mechanism whose afferent pathways originate in metameres below T1.

Topics: Action Potentials; Animals; Denervation; Dogs; Hypoxia; Phrenic Nerve; Respiration; Salicylates; Stimulation, Chemical; Vagus Nerve

1. These studies examined the theory that ATP served to regulate muscle sugar transport by a feedback mechanism. Xylose uptake by isolated rat soleus muscle was determined over a 5-min period following preincubation at 37 degrees C for various times in the presence of insulin (0.1 unit/ml), 2,4-dinitrophenol (0.5 or 0.05 mM) or salicylate (5 mM) or under anaerobic conditions. 2. Xylose uptake, measured in freshly isolated soleus muscles, was approximately 3.5--4.0 mumol/g per h. When the muscles were preincubated at 37 degrees C, this rate fell by 50% during the first 30 min and then slowly increased. 3. The stimulatory effect of insulin was evident within 2 min in freshly isolated soleus muscle and increased on preincubation, reaching a maximum value (approx. 14 mumol/g per h) after 20 min. 4. There was a 10-min lag period before xylose uptake was stimulated by anoxia. This lag period was approximately doubled when the incubation temperature was lowered from 37 degrees C. The stimulatory effect of anoxia was promptly reversed when muscles were transferred from anaerobic to aerobic conditions. 5. There was a 5-min lag period before xylose uptake was stimulated by 2,4-dinitrophenol (0.05 mM) or by sodium salicylate (mM). At a concentration of 0.5 mM, 2,4-dinitrophenol stimulated xylose uptake in freshly isolated muscle. Whereas the stimulatory effects of insulin, anoxia and salicylate all tended to plateau with time, the effect of 2,4-dinitrophenol tended to peak and then decline. 6. There was no obvious relationship between total muscle ATP levels and xylose uptake. The stimulatory effect of anoxia, 2,4-dinitrophenol or salicylate on xylose uptake was not preceded by the fall in muscle ATP. Similarly, ATP levels did not change when xylose uptake was stimulated by anoxia at 27 degrees C, or when xylose uptake was restored to basal values by transferring muscles from anaerobic to aerobic conditions. 7. It was argued that the presence of the myofibrils could act as a permeability barrier, which would limit the access of ATP produced within the interior of the cell to a regulatory site on, or close to, the sarcolemma. On the other hand, it is conceivable that the ATP produced on the periphery of the fibre by the subsarcolemmal mitochondria could play a more specific role in the feedback regulation of sugar transport. 8. Insulin stimulated xylose uptake in the presence of 2,4-dinitrophenol (0.5 mM) when this was measured in freshly isolated muscle, but not aft

Topics: Adenosine Triphosphate; Aerobiosis; Anaerobiosis; Animals; Biological Transport, Active; Dinitrophenols; Glycolysis; Hypoxia; Insulin; Kinetics; Mitochondria, Muscle; Muscles; Rats; Salicylates; Time Factors; Xylose

The ultimate cause of the clinical abnormalities associated with changes in oxygen supply and oxygen utilization is the development of abnormal tissue oxygen metabolism. Until now, there has been no satisfactory term to describe abnormal tissue oxygen metabolism. We propose the term "dysoxia" to fill this gap. There are a number of causes of dysoxia. One of the most interesting is that form of dysoxia related to abnormal mitochondrial structure and function. In this group of disorders, there is abnormal tissue oxygen metabolism, although oxygen supply is normal. Another interesting cause of dysoxia is exposure to high oxygen concentrations. High oxygen concentrations are involved in producing abnormal tissue oxygen metabolism under a number of different circumstances. The concept underlying dysoxia provides a unified approach to a large and important group of disorders involving most branches of clinical medicine.

Topics: Child; Child, Preschool; Cyanides; Dinitrophenols; Edema; Electron Transport; Humans; Hyperthyroidism; Hypothyroidism; Hypoxia; Infant, Newborn; Iron; Menkes Kinky Hair Syndrome; Mitochondria; Muscles; Oxygen; Oxygen Consumption; Reye Syndrome; Salicylates

It is usually assumed that the concentration of glucose in the brain reflects that in the blood, so that measuring the latter provides an accurate index of the former. However, in two experimental situations analogous to anoxia and salicylate poisoning, brain glucose was found to be dangerously low in the presence of normal or even elevated blood glucose levels, and in these experiments administering glucose prolonged survival.

Topics: Animals; Blood Glucose; Brain; Brain Chemistry; Glucose; Hydrocortisone; Hypoxia; Mice; Salicylates

Topics: Acetazolamide; Chemoreceptor Cells; Cyanosis; Dexamethasone; Diabetes Insipidus; Feeding and Eating Disorders; Heart Failure; Humans; Hypercapnia; Hypoventilation; Hypoxia; Infant, Newborn; Male; Respiration, Artificial; Salicylates; Syndrome

Topics: Cardiovascular Diseases; Cobalt; Ethanol; Heart; Humans; Hypoxia; Myocardium; Salicylates

Topics: Antidepressive Agents; Barbiturates; Blood Circulation; Carbamates; Carbon Monoxide Poisoning; France; Humans; Hypoxia; Lung Diseases; Morphinans; Phenothiazines; Poisoning; Respiration; Salicylates; Seizures; Trichloroethylene; Vascular Diseases

Topics: Aminopterin; Animals; Antimetabolites; Chloromercuribenzoates; Colchicine; DNA; Enzyme Inhibitors; Estriol; Female; Galactose; Glyceraldehyde; Growth Hormone; Hexosephosphates; Hormones; Hypoxia; In Vitro Techniques; Mitosis; Ovum; Pentoses; Rabbits; Salicylates

Topics: Acetylcholine; Animals; Bradykinin; Guinea Pigs; Hypoxia; Muscle Contraction; Muscle, Smooth; Phenylbutazone; Propranolol; Salicylates; Trachea

Topics: Acetoacetates; Adenine Nucleotides; Adenosine Triphosphate; Adrenalectomy; Animals; Diabetes Mellitus, Experimental; Dinitrophenols; Enzymes; Fatty Acids; Glucose; Heart; Hexosephosphates; Hydroxybutyrates; Hypophysectomy; Hypoxia; In Vitro Techniques; Perfusion; Phosphates; Phosphofructokinase-1; Pyruvates; Rats; Salicylates; Starvation

Topics: Animals; Arabinose; Carbon Dioxide; Diabetes Mellitus, Experimental; Diaphragm; Fatty Acids; Glucose; Glycogen; Glycolysis; Heart; Hydroxybutyrates; Hypoxia; In Vitro Techniques; Muscles; Myocardium; Perfusion; Phosphofructokinase-1; Pyruvates; Rats; Salicylates; Starvation

Topics: Acetoacetates; Animals; Butyrates; Carbon Dioxide; Diabetes Mellitus, Experimental; Diaphragm; Fatty Acids; Glucose; Glycerophosphates; Heart; Hydroxybutyrates; Hypoxia; In Vitro Techniques; Ketone Bodies; Lactates; Muscles; Myocardium; NAD; Palmitic Acids; Perfusion; Phosphates; Pyruvates; Rats; Salicylates; Starvation

Topics: Acetylcholine; Aniline Compounds; Animals; Dinitrophenols; Fumarates; Glucose; Glutamates; Hormones; Hypoxia; In Vitro Techniques; Insulin; Islets of Langerhans; Malonates; Mannose; Phenazines; Rabbits; Salicylates; Secretory Rate; Tolbutamide

Topics: Humans; Hypoxia; Salicylates; Salicylic Acid

Topics: Animals; Biological Transport; Dinitrophenols; Glucose; Hypoxia; Insulin; Muscles; Myocardium; Nitrophenols; Phosphorylation; Rats; Salicylates

Topics: Acid-Base Equilibrium; Blood; Carbon Dioxide; Chronic Disease; Emphysema; Humans; Hypoxia; Pulmonary Emphysema; Salicylates