ascorbic-acid and Hypoxia

Fe(II)/2-oxoglutarate (2OG)-dependent oxygenases are a conserved enzyme class that catalyse diverse oxidative reactions across nature. In humans, these enzymes hydroxylate a broad range of biological substrates including DNA, RNA, proteins and some metabolic intermediates. Correspondingly, members of the 2OG-dependent oxygenase superfamily have been linked to fundamental biological processes, and found dysregulated in numerous human diseases. Such findings have stimulated efforts to understand both the biochemical activities and cellular functions of these enzymes, as many have been poorly studied. In this review, we focus on human 2OG-dependent oxygenases catalysing the hydroxylation of protein and polynucleotide substrates. We discuss their modulation by changes in the cellular microenvironment, particularly with respect to oxygen, iron, 2OG and the effects of oncometabolites. We also describe emerging evidence that these enzymes are responsive to cellular stresses including hypoxia and DNA damage. Moreover, we examine how dysregulation of 2OG-dependent oxygenases is associated with human disease, and the apparent paradoxical role for some of these enzymes during cancer development. Finally, we discuss some of the challenges associated with assigning biochemical activities and cellular functions to 2OG-dependent oxygenases.

Topics: Ascorbic Acid; Biological Phenomena; Catalysis; DNA; DNA Damage; Gene Expression Regulation; Humans; Hydroxylation; Hypoxia; Ketoglutaric Acids; Mixed Function Oxygenases; Models, Molecular; Neoplasms; Oxidation-Reduction; Oxygen; Oxygenases; Protein Processing, Post-Translational; RNA

Ascorbic acid (vitamin C) has been gaining attention as a potential treatment for human malignancies. Various experimental studies have shown the ability of pharmacological doses of vitamin C alone or in combinations with clinically used drugs to exert beneficial effects in various models of human cancers. Cytotoxicity of high doses of vitamin C in cancer cells appears to be related to excessive reactive oxygen species generation and the resulting suppression of the energy production via glycolysis. A hallmark of cancer cells is a strongly upregulated aerobic glycolysis, which elevates its relative importance as a source of ATP (Adenosine 5'-triphosphate). Aerobic glycolysis is maintained by a highly increased uptake of glucose, which is made possible by the upregulated expression of its transporters, such as GLUT-1, GLUT-3, and GLUT-4. These proteins can also transport the oxidized form of vitamin C, dehydroascorbate, permitting its preferential uptake by cancer cells with the subsequent depletion of critical cellular reducers as a result of ascorbate formation. Ascorbate also has a potential to affect other aspects of cancer cell metabolism due to its ability to promote reduction of iron(III) to iron(II) in numerous cellular metalloenzymes. Among iron-dependent dioxygenases, important targets for stimulation by vitamin C in cancer include prolyl hydroxylases targeting the hypoxia-inducible factors HIF-1/HIF-2 and histone and DNA demethylases. Altered metabolism of cancer cells by vitamin C can be beneficial by itself and promote activity of specific drugs.

Topics: Animals; Ascorbic Acid; Combined Modality Therapy; Drug Synergism; Humans; Hypoxia; Neoplasms; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species; Treatment Outcome

Topics: Animals; Ascorbic Acid; Glutathione; Humans; Hypoxia; Infant, Newborn; Oxygen; Oxygen Inhalation Therapy; Positive-Pressure Respiration; Rats; Respiration, Artificial; Respiratory Distress Syndrome; Superoxide Dismutase; Superoxides; Vitamins

Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Copper; Dehydroascorbic Acid; Drug Interactions; Free Radicals; Humans; Hydrogen Peroxide; Hypoxia; Immunity

Topics: Acid-Base Equilibrium; Acidosis; Alkalosis; Ascorbic Acid; Cell Division; Cell Membrane; Cystine; Cytosol; Electron Transport; Galactose; Glucose; Glutathione; Homeostasis; Humans; Hypoxia; Lactates; Lysosomes; Mitochondria; NAD; Neoplasms; Oxidation-Reduction; Oxygen Consumption; Proteins; Pyruvates; Sulfhydryl Compounds

Interleukin (IL)-15 stimulates mitochondrial biogenesis, fat oxidation, glucose uptake and myogenesis in skeletal muscle. However, the mechanisms by which exercise triggers IL-15 expression remain to be elucidated in humans. This study aimed at determining whether high-intensity exercise and exercise-induced RONS stimulate IL-15/IL-15Rα expression and its signaling pathway (STAT3) in human skeletal muscle. Nine volunteers performed a 30-s Wingate test in normoxia and hypoxia (P

Topics: Adult; Antioxidants; Ascorbic Acid; Double-Blind Method; Exercise; Exercise Test; Humans; Hypoxia; Interleukin-15; Male; Muscle, Skeletal; Protein Carbonylation; Receptors, Interleukin-15; Signal Transduction; STAT3 Transcription Factor; Thioctic Acid; Vitamin E; Young Adult

Acute hypoxia increases cerebral blood flow (CBF) and ventilation (V̇e). It is unknown if these responses are impacted with normal aging, or in patients with enhanced oxidative stress, such as (COPD). The purpose of the study was to 1) investigate the effects of aging and COPD on the cerebrovascular and ventilatory responses to acute hypoxia, and 2) to assess the effect of vitamin C on these responses during hypoxia. In 12 Younger, 14 Older, and 12 COPD, we measured peak cerebral blood flow velocity (V̄p; index of CBF), and V̇e during two 5-min periods of acute isocapnic hypoxia, under conditions of 1) saline-sham; and 2) intravenous vitamin C. Antioxidants [vitamin C, superoxide dismutase (SOD), glutathione peroxidase, and catalase], oxidative stress [malondialdehyde (MDA) and advanced protein oxidation product], and nitric oxide metabolism end products (NOx) were measured in plasma. Following the administration of vitamin C, vitamin C, SOD, catalase, and MDA increased, while NOx decreased. V̄p and V̇e sensitivity to hypoxia was reduced in Older by ∼60% (P < 0.02). COPD patients exhibited similar V̄p and V̇e responses to Older (P > 0.05). Vitamin C did not have an effect on the hypoxic V̇e response but selectively decreased the V̄p sensitivity in Younger only. These findings suggest a reduced integrative reflex (i.e., cerebrovascular and ventilatory) during acute hypoxemia in healthy older adults. Vitamin C does not appear to have a large influence on the cerebrovascular or ventilatory responses during acute hypoxia.

Topics: Adaptation, Physiological; Administration, Intravenous; Adult; Age Factors; Aged; Aging; Alberta; Antioxidants; Ascorbic Acid; Biomarkers; Blood Flow Velocity; Cerebrovascular Circulation; Female; Humans; Hypoxia; Lung; Male; Middle Aged; Oxidative Stress; Pulmonary Disease, Chronic Obstructive; Pulmonary Ventilation; Reactive Oxygen Species; Time Factors; Treatment Outcome; Young Adult

Two hundred broiler chicks were randomly assigned to 3 dietary treatments: control [CTL; 3,200 kcal of ME/kg, 23% CP, 1.55% Arg, and 40 IU of vitamin E (VE)/kg of feed], high-Arg (HA; CTL+0.8% Arg), or high-Arg and high antioxidant-vitamin diet (AEC; HA+200 IU of VE/kg of feed and 500 mg of vitamin C/L of water). The chicks were housed in wire cages in hypobaric chambers simulating 3,000 m above sea level. From d 28 to 42, clinically healthy birds were selected for cardiovascular performance (n=7 to 12/treatment). After surgery, pulmonary arterial pressure (PAP) and mean arterial pressure (MAP) readings were taken at 180, 120, and 60 s (basal values) before an epinephrine (EPI) challenge and then at 30, 60, 120, 180, 300, 600, and 1,200 s after the challenge, followed by a second EPI challenge with similar sample readings. There were no differences in the basal PAP values among chicken groups. The PAP increased within 30 s after both EPI challenges in all groups. It took 180 s after the first EPI challenge for the CTL chickens to return to the basal PAP values, whereas HA and AEC chickens returned to basal PAP values in 120 s. After the second EPI challenge, it took 60, 180, and 300 s for the AEC, HA, and CTL groups, respectively, to return to basal PAP values. The MAP response pattern to the EPI challenges mimicked that of PAP, but there were no differences among treatments in MAP at any sampling point. Supplemental Arg, VE, and vitamin C did not reduce ascites incidence in hypoxic broilers. In conclusion, supplemental Arg improved the pulmonary vascular performance of hypoxic broiler chickens and its effects were further improved by the addition of the antioxidant VE and vitamin C. Arginine and antioxidant vitamins may have played synergistic roles to increase NO bioavailability and reduce oxidative stress damage, thus improving cardiopulmonary performance.

Topics: Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Arginine; Ascorbic Acid; Cardiovascular Diseases; Diet; Dietary Supplements; Hypoxia; Poultry Diseases; Pressure; Time Factors; Vitamin E

In subanesthetic concentrations, volatile anesthetics reduce the acute hypoxic response (AHR), presumably by a direct action on the carotid bodies but by an unknown molecular mechanism. To examine a possible involvement of reactive oxygen species or changes in redox state in this inhibiting effect, the authors studied the effect of antioxidants on the isoflurane-induced reduction of the AHR in humans.. In 10 volunteers, the authors studied the effect of antioxidants (intravenous ascorbic acid and oral alpha-tocopherol) on the reduction by isoflurane (0.12% end-tidal concentration) of the AHR on a 3-min isocapnic hypoxic stimulus (hemoglobin oxygen saturation 86 +/- 4%). All subjects participated in three separate sessions in which the effects of the antioxidants (session 1), placebo (session 2), and sham isoflurane plus antioxidants (session 3) were tested on the (sham) isoflurane-induced effect on the AHR.. Isoflurane reduced the acute hypoxic response from 0.82 +/- 0.41 l . min . % to 0.49 +/- 0.23 l . min . % and from 0.89 +/- 0.43 l . min . % to 0.48 +/- 0.28 l . min . % in sessions 1 and 2, respectively (mean +/- SD; P < 0.05 vs. control). This reduction of the AHR was completely reversed by antioxidants (AHR = 0.76 +/- 0.39 l . min . %; not significantly different from control, session 1) but not by placebo in session 2 (AHR = 0.50 +/- 0.30 l . min . %; P < 005 vs. control). Sham isoflurane or antioxidants per se had no effect on the hypoxic response.. The data indicate that isoflurane may depress the AHR by influencing the redox state of oxygen-sensing elements in the carotid bodies. This finding may have clinical implications for patients who are prone to recurrent hypoxic episodes, e.g., due to upper airway obstruction, in the postoperative period when low-dose isoflurane may persist in the body for some time.

Topics: Adolescent; Adult; Algorithms; Anesthetics, Inhalation; Antioxidants; Ascorbic Acid; Female; Hemoglobins; Humans; Hypoxia; Injections, Intravenous; Isoflurane; Male; Oxygen; Reactive Oxygen Species; Respiratory Mechanics; Vitamin E

In healthy humans sustaining static handgrip at 60% of maximal voluntary contraction (MVC) until exhaustion, we measured the venous blood concentration of reduced ascorbic acid (RAA) and thiobarbituric acid reactive substances (TBARS), respectively, used as markers of the post-exercise oxidative stress and lipid peroxidation. Measurements were conducted in normoxemia, then during a 30-min period of hypoxemia (PaO2 = 56 mmHg) produced by inhalation of an hypoxic gas mixture. Compared to normoxemia, hypoxemia did not significantly modify the resting concentrations of TBARS and RAA, and did not affect the consumption of ascorbic acid after 60% MVC but suppressed the post-exercise TBARS increase. We conclude that acute hypoxemia does not modify the production of oxygen free radicals after strenuous static efforts and even seems to attenuate the lipid peroxidation.

Topics: Adult; Ascorbic Acid; Exercise Test; Humans; Hypoxia; Lactic Acid; Male; Muscle Contraction; Oxidative Stress; Rest; Thiobarbituric Acid Reactive Substances

We studied the effect of the antioxidants (AOX) ascorbic acid (2 g, I.V.) and alpha-tocopherol (200 mg, P.O.) on the depressant effect of subanaesthetic doses of halothane (0.11 % end-tidal concentration) on the acute isocapnic hypoxic ventilatory response (AHR), i.e. the ventilatory response upon inhalation of a hypoxic gas mixture for 3 min (leading to a haemoglobin saturation of 82 +/- 1.8 %) in healthy male volunteers. In the first set of protocols, two groups of eight subjects each underwent a control hypoxic study, a halothane hypoxic study and finally a halothane hypoxic study after pretreatment with AOX (study 1) or placebo (study 2). Halothane reduced the AHR by more than 50 %, from 0.79 +/- 0.31 to 0.36 +/- 0.14 l min(-1) %(-1) in study 1 and from 0.79 +/- 0.40 to 0.36 +/- 0.19 l min(-1) %(-1) in study 2, P < 0.01 for both. Pretreatment with AOX prevented this depressant effect of halothane in the subjects of study 1 (AHR returning to 0.77 +/- 0.32 l min(-1) %(-1), n.s. from control), whereas placebo (study 2) had no effect (AHR remaining depressed at 0.36 +/- 0.27 l min(-1) %(-1), P < 0.01 from control). In a second set of protocols, two separate groups of eight subjects each underwent a control hypoxic study, a sham halothane hypoxic study and finally a sham halothane hypoxic study after pretreatment with AOX (study 3) or placebo (study 4). In studies 3 and 4, sham halothane did not modify the control hypoxic response, nor did AOX (study 3) or placebo (study 4). The 95 % confidence intervals for the ratio of hypoxic sensitivities, (AOX + halothane) : halothane in study 1 and (AOX - sham halothane) : sham halothane in study 3, were [1.7, 2.6] and [1.0, 1.2], respectively. Because the antioxidants prevented the reduction of the acute hypoxic response by halothane, we suggest that this depressant effect may be caused by reactive species produced by a reductive metabolism of halothane during hypoxia or that a change in redox state of carotid body cells by the antioxidants prevented or changed the binding of halothane to its effect site. Our findings may also suggest that reactive species have an inhibiting effect on the acute hypoxic ventilatory response.

Topics: Acute Disease; Adult; alpha-Tocopherol; Anesthetics, Inhalation; Antioxidants; Ascorbic Acid; Halothane; Humans; Hypoxia; Male; Respiration; Single-Blind Method

The prognosis of patients with lung cancer accompanied by interstitial pneumonia is poorer than that of patients with lung cancer but without interstitial pneumonia. Moreover, the available therapeutic interventions for lung cancer patients with interstitial pneumonia are limited. Therefore, a new treatment strategy for these patients is required. The aim of the present study was to investigate the pathophysiological relationship between interstitial pneumonia and lung cancer and explore potential therapeutic agents.. A novel hybrid murine model of lung cancer with interstitial pneumonia was established via bleomycin-induced pulmonary fibrosis followed by orthotopic lung cancer cell transplantation into the lungs. Changes in tumor progression, lung fibrosis, RNA expression, cytokine levels, and tumor microenvironment in the lung cancer with interstitial pneumonia model were investigated, and therapeutic agents were examined. Additionally, clinical data and samples from patients with lung cancer accompanied by interstitial pneumonia were analyzed to explore the potential clinical significance of the findings.. In the lung cancer with interstitial pneumonia model, accelerated tumor growth was observed based on an altered tumor microenvironment. RNA sequencing analysis revealed upregulation of the hypoxia-inducible factor 1 signaling pathway. These findings were consistent with those obtained for human samples. Moreover, we explored whether ascorbic acid could be an alternative treatment for lung cancer with interstitial pneumonia to avoid the disadvantages of hypoxia-inducible factor 1 inhibitors. Ascorbic acid successfully downregulated the hypoxia-inducible factor 1 signaling pathway and inhibited tumor progression and lung fibrosis.. The hypoxia-inducible factor 1 pathway is critical in lung cancer with interstitial pneumonia and could be a therapeutic target for mitigating interstitial pneumonia-mediated lung cancer progression.

Topics: Animals; Ascorbic Acid; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Lung; Lung Diseases, Interstitial; Lung Neoplasms; Mice; Pneumonia; Pulmonary Fibrosis; Tumor Microenvironment

High altitude-induced hypoxaemia is often associated with peripheral vascular dysfunction. However, the basic mechanism(s) underlying high-altitude vascular impairments remains unclear. This study tested the hypothesis that oxidative stress contributes to the impairments in endothelial function during early acclimatization to high altitude. Ten young healthy lowlanders were tested at sea level (344 m) and following 4-6 days at high altitude (4300 m). Vascular endothelial function was determined using the isolated perfused forearm technique with forearm blood flow (FBF) measured by strain-gauge venous occlusion plethysmography. FBF was quantified in response to acetylcholine (ACh), sodium nitroprusside (SNP) and a co-infusion of ACh with the antioxidant vitamin C (ACh+VitC). The total FBF response to ACh (area under the curve) was ∼30% lower at high altitude than at sea level (P = 0.048). There was no difference in the response to SNP at high altitude (P = 0.860). At sea level, the co-infusion of ACh+VitC had no influence on the FBF dose response (P = 0.268); however, at high altitude ACh+VitC resulted in an average increase in the FBF dose response by ∼20% (P = 0.019). At high altitude, the decreased FBF response to ACh, and the increase in FBF in response to ACh+VitC, were associated with the magnitude of arterial hypoxaemia (R

Topics: Acetylcholine; Altitude; Antioxidants; Ascorbic Acid; Endothelium, Vascular; Forearm; Humans; Hypoxia; Nitroprusside; Regional Blood Flow; Vasodilation; Vasodilator Agents

Dysregulation of adipose tissue involves increased cellular hypoxia, ER stress, and inflammation and altered adipokine production, contributing to the aetiology of obesity-related diseases including type 2 diabetes and cardiovascular disease. This study aimed to investigate the effects of Vitamin C supplementation on these processes in primary human preadipocytes and adipocytes. Treatment of preadipocytes and adipocytes with the proinflammatory cytokine TNFα and palmitic acid (PA), to mimic the obesogenic milieu, significantly increased markers of hypoxia, ER stress and inflammation and reduced secretion of high molecular weight (HMW) adiponectin. Importantly, Vitamin C abolished TNFα+PA induced hypoxia and significantly reduced the increases in ER stress and inflammation in both cell types. Vitamin C also significantly increased the secretion of HMW adiponectin from adipocytes. These findings indicate that Vitamin C can reduce obesity-associated cellular stress and thus provide a rationale for future investigations.

Topics: Adipocytes; Adiponectin; Ascorbic Acid; Diabetes Mellitus, Type 2; Humans; Hypoxia; Inflammation; Obesity; Tumor Necrosis Factor-alpha

We report a case of a man in his 60s who developed pulmonary arterial hypertension (PAH) in association with profound vitamin C deficiency. Decreased availability of endothelial nitric oxide and activation of the hypoxia-inducible family of transcription factors, both consequences of vitamin C deficiency, are believed to be mechanisms contributing to the pathogenesis of the pulmonary hypertension. The PAH resolved following vitamin C supplementation. The current case highlights the importance of testing for vitamin C deficiency in patients with PAH in the proper clinical setting.

Topics: Aged; Anemia; Arthralgia; Ascorbic Acid; Ascorbic Acid Deficiency; Cardiac Catheterization; Echocardiography; Endothelium, Vascular; Exanthema; Humans; Hypoxia; Male; Nitric Oxide; Pulmonary Arterial Hypertension; Transcription Factors; Vitamins

In human blood, oxygen is mainly transported by red blood cells. Accordingly, the dissolved oxygen level in plasma is expected to be limited, although it has not been quantified yet. Here, by developing dedicated methods and tools, we determined that human plasma pO

Topics: Animals; Ascorbic Acid; Cell Line; Cell Lineage; Erythrocytes; Guinea Pigs; HEK293 Cells; Hep G2 Cells; Humans; Hypoxia; Oxidation-Reduction; Oxygen; Plasma; Solubility; Ubiquinone

The coronavirus disease 2019 (COVID-19) pandemic has affected almost 2.5 million people worldwide with almost 170,000 deaths reported to date. So far, there is scarce evidence for the current treatment options available for COVID-19. Vitamin C has previously been used for treatment of severe sepsis and septic shock. We reviewed the feasibility of using vitamin C in the setting of COVID-19 in a series of patients.. We sequentially identified a series of patients who were requiring at least 30% of FiO2 or more who received IV vitamin C as part of the COVID-19 treatment and analyzed their demographic and clinical characteristics. We compared inflammatory markers pre and post treatment including D-dimer and ferritin.. We identified a total of 17 patients who received IV vitamin C for COVID-19. The inpatient mortality rate in this series was 12% with 17.6% rates of intubation and mechanical ventilation. We noted a significant decrease in inflammatory markers, including ferritin and D-dimer, and a trend to decreasing FiO2 requirements, after vitamin C administration.. The use of IV vitamin C in patients with moderate to severe COVID-19 disease may be feasible.

Topics: Administration, Intravenous; Aged; Anti-Inflammatory Agents; Antibodies, Monoclonal, Humanized; Antiviral Agents; Ascorbic Acid; COVID-19; COVID-19 Drug Treatment; Drug Therapy, Combination; Feasibility Studies; Female; Ferritins; Fibrin Fibrinogen Degradation Products; Hospital Mortality; Humans; Hydroxychloroquine; Hypoxia; Intubation, Intratracheal; Male; Methylprednisolone; Middle Aged; Respiration, Artificial; Retrospective Studies; Severity of Illness Index; Vitamins

COVID-19 is a global catastrophic event that causes severe acute respiratory syndrome. The mechanism of the disease remains unclear, and hypoxia is one of the main complications. There is no currently approved protocol for treatment. The microbial threat as induced by COVID-19 causes the activation of macrophages to produce a huge amount of inflammatory molecules and nitric oxide (NO). Activation of macrophages population into a pro-inflammatory phenotype induces a self-reinforcing cycle. Oxidative stress and NO contribute to this cycle, establishing a cascade inflammatory state that can kill the patient. Interrupting this vicious cycle by a simple remedy may save critical patients' lives. Nitrite, nitrate (the metabolites of NO), methemoglobin, and prooxidant-antioxidant-balance levels were measured in 25 ICU COVID-19 patients and 25 healthy individuals. As the last therapeutic option, five patients were administered methylene blue-vitamin C-N-acetyl Cysteine (MCN). Nitrite, nitrate, methemoglobin, and oxidative stress were significantly increased in patients in comparison to healthy individuals. Four of the five patients responded well to treatment. In conclusion, NO, methemoglobin and oxidative stress may play a central role in the pathogenesis of critical COVID-19 disease. MCN treatment seems to increase the survival rate of these patients. Considering the vicious cycle of macrophage activation leading to deadly NO, oxidative stress, and cytokine cascade syndrome; the therapeutic effect of MCN seems to be reasonable. Accordingly, a wider clinical trial has been designed. It should be noted that the protocol is using the low-cost drugs which the FDA approved for other diseases. TRIAL REGISTRATION NUMBER: NCT04370288.

Topics: Acetylcysteine; Ascorbic Acid; Clinical Trials, Phase I as Topic; Compassionate Use Trials; Coronavirus Infections; COVID-19; Critical Illness; Female; Humans; Hypoxia; Male; Methylene Blue; Middle Aged; Pandemics; Pneumonia, Viral

Methemoglobinemia is a rare disorder of the blood in which there is an increase in methemoglobin, which occurs when hemoglobin is present in the oxidized form. Methemoglobin impairs hemoglobin's ability to transport oxygen, produces functional anemia, and leads to tissue hypoxia. We report the successful management of a case of refractory hypoxia due to acutely acquired methemoglobinemia in a patient undergoing treatment for coronavirus disease 2019 (COVID-19) pneumonia. The cause of methemoglobinemia in this patient remains unknown. Hypoxia and methemoglobinemia did not respond to methylene blue and required administration of packed red blood cell transfusions.

Topics: Acute Kidney Injury; Aged; Antibodies, Monoclonal, Humanized; Antioxidants; Ascorbic Acid; Betacoronavirus; Coronavirus Infections; Corynebacterium; Corynebacterium Infections; COVID-19; Cytokine Release Syndrome; Enzyme Inhibitors; Erythrocyte Transfusion; Hematinics; Humans; Hydroxocobalamin; Hydroxychloroquine; Hypoxia; Male; Methemoglobinemia; Methylene Blue; Pandemics; Pneumonia, Bacterial; Pneumonia, Viral; Renal Replacement Therapy; Respiratory Insufficiency; SARS-CoV-2; Shock, Septic

The anticancer mechanism for reduced/oxidized ascorbic acid (AA/DHA) is of great significance for clinical cancer therapies. A pH controlled fluorescent nanocarrier was designed to targetably deliver AA and DHA into tumor cells for investigating their function in inducing intracellular apoptosis pathways. A fluorescent silicon nanoparticle with polymer coating serves as the pH controlled nanocarrier to deliver AA or DHA into HepG2 and B16-F10 cells for studying their biological functions. The intracellular apoptotic pathway was monitored through the Caspase-3 nanoprobe, while the changes of signal molecules H2O2 and NAD(P)H in the redox homeostasis system were monitored through the corresponding fluorescent probes. Under hypoxic conditions, AA can scavenge H2O2 in tumor cells and promote NAD(P)H accumulation, but DHA promotes the production of both H2O2 and NAD(P)H, indicating that the molecular mechanisms for inducing cancer cells' apoptosis are significantly different. AA leads to reductive stress by promoting the accumulation of NAD(P)H in tumor cells, but DHA enhances oxidative stress by increasing the H2O2 concentration in cells.

Topics: Apoptosis; Ascorbic Acid; Humans; Hydrogen Peroxide; Hypoxia; Oxidative Stress

The transcription factor hypoxia-inducible factor 1 (HIF1) is the crucial regulator of genes that are involved in metabolism under hypoxic conditions, but information regarding the transcriptional activity of HIF1 in normoxic metabolism is limited. Different tumor cells were treated under normoxic and hypoxic conditions with various drugs that affect cellular metabolism. HIF1α was silenced by siRNA in normoxic/hypoxic tumor cells, before RNA sequencing and bioinformatics analyses were performed while using the breast cancer cell line MDA-MB-231 as a model. Differentially expressed genes were further analyzed and validated by qPCR, while the activity of the metabolites was determined by enzyme assays. Under normoxic conditions, HIF1 activity was significantly increased by (i) glutamine metabolism, which was associated with the release of ammonium, and it was decreased by (ii) acetylation via acetyl CoA synthetase (ACSS2) or ATP citrate lyase (ACLY), respectively, and (iii) the presence of L-ascorbic acid, citrate, or acetyl-CoA. Interestingly, acetylsalicylic acid, ibuprofen, L-ascorbic acid, and citrate each significantly destabilized HIF1α only under normoxia. The results from the deep sequence analyses indicated that, in HIF1-siRNA silenced MDA-MB-231 cells, 231 genes under normoxia and 1384 genes under hypoxia were transcriptionally significant deregulated in a HIF1-dependent manner. Focusing on glycolysis genes, it was confirmed that HIF1 significantly regulated six normoxic and 16 hypoxic glycolysis-associated gene transcripts. However, the results from the targeted metabolome analyses revealed that HIF1 activity affected neither the consumption of glucose nor the release of ammonium or lactate; however, it significantly inhibited the release of the amino acid alanine. This study comprehensively investigated, for the first time, how normoxic HIF1 is stabilized, and it analyzed the possible function of normoxic HIF1 in the transcriptome and metabolic processes of tumor cells in a breast cancer cell model. Furthermore, these data imply that HIF1 compensates for the metabolic outcomes of glutaminolysis and, subsequently, the Warburg effect might be a direct consequence of the altered amino acid metabolism in tumor cells.

Topics: Acetylation; Ascorbic Acid; Carbonic Anhydrase IX; Cell Line, Tumor; Energy Metabolism; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Glutamine; Glycolysis; High-Throughput Nucleotide Sequencing; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Neoplasms; Protein Stability; RNA, Small Interfering

Maintaining the redox balance of biological systems is a key point to maintain a healthy physiological environment. Excessive iron ions (Fe

Topics: Animals; Ascorbic Acid; Carbon; Cell Hypoxia; Deferoxamine; Fluorescent Dyes; Hep G2 Cells; Humans; Hypoxia; Iron; Ischemia; Limit of Detection; Liver; Mice, Inbred BALB C; Microscopy, Confocal; Microscopy, Fluorescence; Oxidative Stress; Quantum Dots; Zebrafish

Evidence derived from human clinical studies and experimental animal models shows a causal relationship between adverse pregnancy and increased cardiovascular disease in the adult offspring. However, translational studies isolating mechanisms to design intervention are lacking. Sheep and humans share similar precocial developmental milestones in cardiovascular anatomy and physiology. We tested the hypothesis in sheep that maternal treatment with antioxidants protects against fetal growth restriction and programmed hypertension in adulthood in gestation complicated by chronic fetal hypoxia, the most common adverse consequence in human pregnancy. Using bespoke isobaric chambers, chronically catheterized sheep carrying singletons underwent normoxia or hypoxia (10% oxygen [O2]) ± vitamin C treatment (maternal 200 mg.kg-1 IV daily) for the last third of gestation. In one cohort, the maternal arterial blood gas status, the value at which 50% of the maternal hemoglobin is saturated with oxygen (P50), nitric oxide (NO) bioavailability, oxidative stress, and antioxidant capacity were determined. In another, naturally delivered offspring were raised under normoxia until early adulthood (9 months). Lambs were chronically instrumented and cardiovascular function tested in vivo. Following euthanasia, femoral arterial segments were isolated and endothelial function determined by wire myography. Hypoxic pregnancy induced fetal growth restriction and fetal oxidative stress. At adulthood, it programmed hypertension by enhancing vasoconstrictor reactivity and impairing NO-independent endothelial function. Maternal vitamin C in hypoxic pregnancy improved transplacental oxygenation and enhanced fetal antioxidant capacity while increasing NO bioavailability, offsetting constrictor hyper-reactivity and replenishing endothelial function in the adult offspring. These discoveries provide novel insight into mechanisms and interventions against fetal growth restriction and adult-onset programmed hypertension in an animal model of complicated pregnancy in a species of similar temporal developmental milestones to humans.

Topics: Animals; Antioxidants; Ascorbic Acid; Female; Fetal Growth Retardation; Fetal Hypoxia; Hypertension; Hypoxia; Nitric Oxide; Oxidative Stress; Pregnancy; Pregnancy Complications; Prenatal Exposure Delayed Effects; Sheep

Cardiovascular effects were reported to occur in humans and in animal models during transfusion with hemoglobin (Hb)-based oxygen therapeutics. The effects of Hb's iron redox states on cardiac parameters during hypoxia/reoxygenation are however poorly defined. We hypothesize that acute exposures to ferric Hb during hypoxia leads to cardiomyocyte injury and an impaired left ventricular response accompanied by cardiac mitochondrial bioenergetic dysfunction. Recovery of left ventricular functions in an isolated rat heart Langendorff perfusion system was observed following perfusion with ferrous but not with ferric Hb. Ferric Hb induced the development of heart lesions, and impairment of the respiratory chain complex activity. Under normoxia, a sharp decline in cardiac parameters was observed following co-perfusion of low (20 μM) and high (100 μM) ascorbic acid (Asc) with ferrous Hb. This trend continued with ferric Hb co-perfusion, but only at the higher concentration of Asc. These observations suggest that perfusion of the hypoxic heart with ferric Hb increases oxidative stress thereby resulting in cardiac dysfunction. Intervention with Asc to reduce ferric Hb may offer a strategy to control Hb toxicity; however, timing of administration, and dosage of Asc may require individual optimization to target specific redox forms of Hb.

Topics: Animals; Ascorbic Acid; Electron Transport Complex IV; Heart; Heart Ventricles; Hemoglobins; Humans; Hypoxia; Iron; Mitochondria; Myocardium; Organ Culture Techniques; Oxidation-Reduction; Oxidative Stress; Oxygen; Oxyhemoglobins; Rats

Several pharmacological, dietary, and genetic interventions that increase mammalian lifespan are known, but general principles of lifespan extension remain unclear. Here, we performed RNA sequencing (RNA-seq) analyses of mice subjected to 8 longevity interventions. We discovered a feminizing effect associated with growth hormone regulation and diminution of sex-related differences. Expanding this analysis to 17 interventions with public data, we observed that many interventions induced similar gene expression changes. We identified hepatic gene signatures associated with lifespan extension across interventions, including upregulation of oxidative phosphorylation and drug metabolism, and showed that perturbed pathways may be shared across tissues. We further applied the discovered longevity signatures to identify new lifespan-extending candidates, such as chronic hypoxia, KU-0063794, and ascorbyl-palmitate. Finally, we developed GENtervention, an app that visualizes associations between gene expression changes and longevity. Overall, this study describes general and specific transcriptomic programs of lifespan extension in mice and provides tools to discover new interventions.

Topics: Aging; Animals; Ascorbic Acid; Caloric Restriction; Female; Gene Expression Regulation; Gene Knockout Techniques; Hypoxia; Kelch-Like ECH-Associated Protein 1; Life Expectancy; Liver; Longevity; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Inbred C57BL; Morpholines; Pyrimidines; Sirolimus; Transcriptome

Deposition of matrix proteins during development and repair is critical to the transparency of the cornea. While many cells respond to a hypoxic state that can occur in a tumor, the cornea is exposed to hypoxia during development prior to eyelid opening and during the diurnal sleep cycle where oxygen levels can drop from 21% to 8%. In this study, we used 2 three-dimensional (3-D) models to examine how stromal cells respond to periods of acute hypoxic states. The first model, a stromal construct model, is a 3-D stroma-like construct that consists of human corneal fibroblasts (HCFs) stimulated by a stable form of ascorbate for 1, 2, and 4 weeks to self-assemble their own extracellular matrix. The second model, a corneal organ culture model, is a corneal wound-healing model, which consists of wounded adult rat corneas that were removed and placed in culture to heal. Both models were exposed to either normoxic or hypoxic conditions for varying time periods, and the expression and/or localization of matrix proteins was assessed. No significant changes were detected in Type V collagen, which is associated with Type I collagen fibrils; however, significant changes were detected in the expression of both the small leucine-rich repeating proteoglycans and the larger heparan sulfate proteoglycan, perlecan. Also, hypoxia decreased both the number of Cuprolinic blue-positive glycosaminoglycan chains along collagen fibrils and Sulfatase 1, which modulates the effect of heparan sulfate by removing the 6-O-sulfate groups. In the stromal construct model, alterations were seen in fibronectin, similar to those that occur in development and after injury. These changes in fibronectin after injury were accompanied by changes in proteoglycans. Together these findings indicate that acute hypoxic changes alter the physiology of the cornea, and these models will allow us to manipulate the conditions in the extracellular environment in order to study corneal development and trauma.

Topics: Animals; Ascorbic Acid; Collagen; Corneal Keratocytes; Corneal Stroma; Extracellular Matrix; Extracellular Matrix Proteins; Fluorescent Antibody Technique, Indirect; Glycosaminoglycans; Humans; Hypoxia; Microscopy, Confocal; Models, Biological; Organ Culture Techniques; Proteoglycans; Rats; Real-Time Polymerase Chain Reaction; Wound Healing

Onion Allium cepa and ginger Zingiber officinale have health-promoting properties that qualify them as functional foods. The effect of repeated acute stressors was examined in juvenile Brown-marbled Grouper Epinephelus fuscoguttatus that were fed four diets supplemented with onion at 1.8%, ginger at 1.8%, vitamin C at 0.86%, and β-glucan at 0.8% of the diet. The non-supplemented diet served as the control. After 12 weeks of feeding, fish were exposed to stressors and were experimentally infected with a fish pathogen, the bacterium Vibrio harveyi JML1. After repeated exposure to hypoxia, cortisol levels rose significantly in the non-supplemented fish compared to those fed onion, ginger, β-glucan, or vitamin C. Within groups, postexposure cortisol levels in the onion-, ginger-, and vitamin C-fed fish did not change relative to pre-stress levels, whereas significant increases in poststress values were observed in the control and β-glucan groups. The net cortisol increase was also significantly greater in the non-supplemented group compared to the supplemented groups. The net cortisol increase did not vary among the supplemented groups except that the β-glucan-fed group exhibited a higher net increase than the onion-fed group. Similarly, repeated acute exposure to osmotic stress significantly increased the plasma cortisol level in the non-supplemented group compared to groups that received supplements; no differences were found in the supplemented groups except the β-glucan group. Within groups, significant increases in poststress values relative to pre-stress levels were found only in the control and β-glucan groups. Repeated acute exposure to hypoxia significantly increased cumulative mortality in the control group compared to the supplemented groups (except the β-glucan group), whereas repeated exposure to acute osmotic stress significantly increased cumulative mortality only in the control group 10 d after infection with V. harveyi JML1. Based on our collective results, most of the supplemented groups performed better than the control, but the best supplements were onion and ginger in terms of enhancing stress tolerance and increasing survival of Brown-marbled Grouper upon infection with V. harveyi JML1.

Topics: Animals; Ascorbic Acid; Bass; beta-Glucans; Dietary Supplements; Fish Diseases; Hydrocortisone; Hypoxia; Onions; Osmotic Pressure; Vibrio; Vibrio Infections; Zingiber officinale

A hypoxic tumor microenvironment is linked to poor prognosis. It promotes tumor cell dedifferentiation and metastasis and desensitizes tumor cells to type-I IFN, chemotherapy, and irradiation. The cytoplasmic immunoreceptor retinoic acid-inducible gene-I (RIG-I) is ubiquitously expressed in tumor cells and upon activation by 5'-triphosphate RNA (3pRNA) drives the induction of type I IFN and immunogenic cell death. Here, we analyzed the impact of hypoxia on the expression of RIG-I in various human and murine tumor and nonmalignant cell types and further investigated its function in hypoxic murine melanoma. 3pRNA-inducible RIG-I-expression was reduced in hypoxic melanoma cells compared with normoxic controls, a phenomenon that depended on the hypoxia-associated transcription factor HIF1α. Still, RIG-I functionality was conserved in hypoxic melanoma cells, whereas responsiveness to recombinant type-I IFN was abolished, due to hypoxia-induced loss of type I IFN receptor expression. Likewise, RIG-I activation in hypoxic melanoma cells, but not exposure to recombinant IFNα, provoked melanocyte antigen-specific CD8

Topics: Animals; Antioxidants; Ascorbic Acid; Cell Line; Cell Line, Tumor; Female; Gene Knockout Techniques; Humans; Hypoxia; Immune Tolerance; Melanoma; Mice, Inbred C57BL; Reactive Oxygen Species; Receptors, Retinoic Acid; RNA; Spleen

Since induced regulatory T cells (iTregs) can be produced in a large quantity in vitro, these cells are expected to be clinically useful to induce immunological tolerance in various immunological diseases. Foxp3 (Forkhead box P3) expression in iTregs is, however, unstable due to the lack of demethylation of the CpG island in the conserved non-coding sequence 2 (CNS2) of the Foxp3 locus. To facilitate the demethylation of CNS2, we over-expressed the catalytic domain (CD) of the ten-eleven translocation (TET) protein, which catalyzes the steps of the iterative demethylation of 5-methylcytosine. TET-CD over-expression in iTregs resulted in partial demethylation of CNS2 and stable Foxp3 expression. We also discovered that TET expression was enhanced under low oxygen (5%) culture conditions, which facilitated CNS2 DNA demethylation and stabilization of Foxp3 expression in a TET2- and TET3-dependent manner. In combination with vitamin C treatment, which has been reported to enhance TET catalytic activity, iTregs generated under low oxygen conditions retained more stable Foxp3 expression in vitro and in vivo and exhibited stronger suppression activity in a colitis model compared with untreated iTregs. Our data indicate that the induction and activation of TET enzymes in iTregs would be an effective method for Treg-mediated adoptive immunotherapy.

Topics: Animals; Ascorbic Acid; Colitis; Conserved Sequence; CpG Islands; Demethylation; Dioxygenases; DNA-Binding Proteins; Enzyme Induction; Forkhead Transcription Factors; Gene Expression Regulation; Humans; Hypoxia; Immunotherapy, Adoptive; Mice; Proto-Oncogene Proteins; T-Lymphocyte Subsets; T-Lymphocytes, Regulatory

Topics: Abdominal Pain; Anemia; Antioxidants; Ascorbic Acid; Child, Preschool; Cough; Cytochrome-B(5) Reductase; Diagnosis, Differential; Emergency Service, Hospital; Glucosephosphate Dehydrogenase Deficiency; Headache; Humans; Hypoxia; Intensive Care Units; Jaundice; Male; Methemoglobinemia; Methylene Blue; Morocco; Oxygen Inhalation Therapy; United States; Vicia faba

Three novel cobalt(iii)-triazole complexes with structural and redox properties suitable for hypoxia-activated drug delivery were obtained. A major influence of the ancillary ligands (TPA, py2en, py2enMe2) on the electronic properties and reactivity of their complexes was observed. An [O2]-dependent reduction to cobalt(ii) by ascorbic acid provided evidence of hypoxic selectivity.

Topics: Ascorbic Acid; Cobalt; Coordination Complexes; Drug Delivery Systems; Hypoxia; Ligands; Models, Biological; Molecular Structure; Oxidation-Reduction; Oxygen; Prodrugs; Triazoles

We first reported the role of 5-hydroxymethyl-2-furfural (5-HMF) against hypoxia. Here, we studied the mechanism by using oxygen-dependent degradation domain (ODD)-Luc mice, which are a useful model to probe the stabilization of hypoxia-inducible factor 1α (HIF-1α). Compared with three other compounds that have been reported to have a role in stabilizing HIF-1α, 5-HMF caused stronger bioluminescence, which is indicative of HIF-1α stability in the brain and kidney of ODD-Luc mice. We further demonstrated that the HIF-1α protein accumulated in response to 5-HMF in the brains and kidneys of these mice, as well as in PC12 cells. Additionally, 5-HMF promoted the nuclear translocation of HIF-1α and the transcriptional activity of HIF-1, which was evaluated by detecting vascular endothelial growth factor (VEGF ) mRNA expression. These results suggest that 5-HMF stabilized HIF-1α and increased its activity. Considering the role of proline hydroxylases (PHDs) in negatively regulating HIF-1α stability, we explored whether 5-HMF interacts with the substrates and cofactors of PHDs, such as 2-oxoglutarate (2-OG), Fe(2+) and vitamin C (VC), which affects the activity of PHDs. The result revealed that 5-HMF did not interact with Fe(2+) or 2-OG but interacted with VC. This interaction was confirmed by subsequent experiments, in which 5-HMF entered into cells and reduced the VC content. The enhanced stability of HIF-1α by 5-HMF was reversed by VC supplementation, and the improved survival of mice caused by 5-HMF under hypoxia was abrogated by VC supplementation. Thus, we demonstrated for the first time that 5-HMF increases HIF-1α stability by reducing the VC content, which mediates the protection against hypoxia.

Topics: Animals; Ascorbic Acid; Brain; Furaldehyde; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Ketoglutaric Acids; Kidney; Luciferases, Firefly; Mice, Inbred C57BL; Mice, Transgenic; PC12 Cells; Protective Agents; Protein Structure, Tertiary; Rats

Ascorbic acid bound to KMUP-1 and sildenafil were examined for their antioxidant effects on vascular endothelium growth factor (VEGF) and endothelium nitric oxide synthase (eNOS) in hypoxic pulmonary artery (PA). Inhaled KMUP-1 and oral sildenafil released NO from eNOS. The effect of buffered l-ascorbic acid, alone and bound to KMUP-1 or sildenafil, for treating pulmonary arterial hypertension (PAH) is unclear. In this study, the antioxidant capacity of ascorbic acid increased the beneficial effects of KMUP-1 on PAH. KMUP-1A and sildenafil-A (5 mg/kg/d) were administered to hypoxic PAH rats. Pulmonary artery blood pressure, and VEGF, Rho kinase II (ROCK II), eNOS, soluble guanylate cyclase (sGC-α), and protein kinase G expression in lung tissues were measured to link PAH and right ventricular hypertrophy. Hypoxic rats had higher pulmonary artery blood pressure, greater PA medial wall thickness and cardiac weight, and a higher right ventricle/left ventricle + septum [RV/(LV+S)] ratio than normoxic rats. Oral KMUP-1A or sildenafil-A for 21 days in hypoxia prevented the rarefaction of eNOS in immunohistochemistry (IHC), reduced the IHC of VEGF in PAs, restored eNOS/protein kinase G/phosphodiesterase 5A; unaffected sGC-α and inactivated ROCK II expression were also found in lung tissues. In normoxic PA, KMUP-1A/Y27632 (10μM) increased eNOS and reduced ROCK II. ROCK II/reactive oxidative species was increased and eNOS was reduced after long-term hypoxia for 21 days. KMUP-1A or Y27632 blunted ROCK II in short-term hypoxic PA at 24 hours. l-Ascorbic acid + l-sodium ascorbate (40, 80μM) buffer alone directly inhibited the IHC of VEGF in hypoxic PA. Finally, KMUP-1A or sildenafil-A reduced PAH and associated right ventricular hypertrophy.

Topics: Amides; Animals; Ascorbic Acid; Endothelium, Vascular; Hypertension, Pulmonary; Hypoxia; Male; Nitric Oxide Synthase Type III; Piperidines; Pulmonary Artery; Pyridines; Rats; Sildenafil Citrate; Vascular Endothelial Growth Factors; Xanthines

This study demonstrated the protective efficiency of extracts of the Indian variety of Ophiocordyceps sinensis (=Cordyceps sinensis) (CSEs) in HT22 (murine hippocampal) cells under hypoxic conditions. Various parameters such as cell viability, reactive oxygen species, levels of endogenous antioxidants, inflammatory cytokines, transcription factors, and oxidation of macromolecules were analyzed. In addition, the radical scavenging abilities of hydroxyl radicals, nitric oxide, and superoxide radicals were also studied. Antioxidant compounds, ascorbic acid, hesperidin, and rutin were quantified by high-performance thin-layer chromatography. The information acquired from high-performance thin-layer chromatography profiling was subjected to principal component analysis for data clustering. Findings of this research revealed that ascorbic acid and rutin were highest in aqueous CSE, whereas the maximum amount of hesperidin was found in 25% alcoholic CSE. In vitro studies showed that all the CSEs protected HT22 cells well by upregulating the level of endogenous antioxidants and preventing the oxidation of lipids and proteins. These extracts also reduced the amount of hypoxia-induced inflammatory cytokines and transcription factors on par with the normoxic control with more or less equal protection in the cells under hypoxia, and indicated significant radical scavenging potential.

Topics: Agaricales; Animals; Antioxidants; Ascorbic Acid; Biological Products; Cell Survival; Cordyceps; Cytokines; Hesperidin; Hippocampus; Hydroxyl Radical; Hypoxia; India; Lipid Peroxidation; Mice; Neuroprotective Agents; Nitric Oxide; Oxidation-Reduction; Oxidative Stress; Protein Carbonylation; Reactive Oxygen Species; Rutin

This study explores the link between the antiproliferative activity of emodin through the generation of reactive oxygen species (ROS) in various cancer cell lines and the expression of the androgen receptor (AR) in the prostate cancer cell lines LNCaP (androgen-sensitive) and PC-3 (androgen-refractory), as well as the pro-metastatic low-density lipoprotein receptor-related protein 1 (LRP1) in the above prostate cancer cells and the nonprostate cell lines A549 (lung), HCT-15 (colon) and MG-63 (bone) under normoxic and hypoxia-like conditions. Among all cell lines, emodin showed most growth inhibition in LNCaP, followed by A549. The mechanism of cytotoxicity of emodin was postulated to be the widely reported ROS generation, based on the observations of poor in vitro radical-scavenging activity and increased growth inhibition of emodin by ascorbic acid (AA) pre-treatment owing to the additive effects of ROS generation by emodin and pro-oxidant effects of AA. Emodin downregulated AR in LNCaP under normoxic and hypoxia-like conditions (simulated by CoCl(2)) and LRP1 under normoxia. Emodin upregulated LRP1 in other cell lines, except HCT-15, under normoxic, and even more markedly under hypoxia-like conditions. The downregulation of AR in LNCaP and upregulation of LRP1 in all cell lines, except HCT-15, under hypoxia-like conditions along with growth inhibition by emodin, suggests that emodin may be a useful therapeutic option against androgen-sensitive prostate cancer and other such LRP1-expressing cancers to attempt the targeting of the elevated LRP1 levels to allow the uptake of emodin and/or any other accompanying therapeutic agents by LRP1.

Topics: Ascorbic Acid; Cell Line, Tumor; Down-Regulation; Emodin; Gene Expression Regulation, Neoplastic; Humans; Hypoxia; Low Density Lipoprotein Receptor-Related Protein-1; Male; Prostatic Neoplasms; Reactive Oxygen Species; Receptors, Androgen; Up-Regulation

At high altitudes, hypoxia, oxidative stress or both compromise sheep fertility. In the present work, we tested the relative effect of short- or long-term exposure to high altitude hypobaric hypoxia and oxidative stress on corpora luteal structure and function.. The growth dynamics of the corpora lutea during the estrous cycle were studied daily by ultrasonography in cycling sheep that were either native or naïve to high-altitude conditions and that were supplemented or not supplemented with antioxidant vitamins. Arterial and venous blood samples were simultaneously drawn for determination of gases and oxidative stress biomarkers and progesterone measurement. On day five after ovulation in the next cycle, the ovaries were removed for immunodetection of luteal HIF-1alpha and VEGF and IGF-I and to detect IGF-II gene expression.. The results showed that both short- and long-term exposure to high-altitude conditions decreased luteal growth and IGF-I and IGF-II gene expression but increased HIF-1 alpha and VEGF immunoexpression. The level of plasma progesterone was also increased at a high altitude, although an association with increased corpus luteum vascularization was only found in sheep native to a high-altitude location. Administration of antioxidant vitamins resulted in a limited effect, which was restricted to decreased expression of oxidative stress biomarkers and luteal HIF-1alpha and VEGF immunoexpression.. Exposure of the sheep to high-altitude hypobaric hypoxia for short or long time periods affects the development and function of the corpus luteum. Moreover, the observed association of oxidative stress with hypoxia and the absence of any significant effect of antioxidant vitamins on most anatomical and functional corpus luteum traits suggests that the effects of high altitude on this ovarian structure are mainly mediated by hypoxia. Thus, these findings may help explain the decrease in sheep fertility at a high altitude.

Topics: Altitude; Animals; Antioxidants; Ascorbic Acid; Corpus Luteum; Estrous Cycle; Female; Fertility; Gene Expression; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Ovary; Oxidative Stress; Progesterone; Reverse Transcriptase Polymerase Chain Reaction; Sheep; Time Factors; Ultrasonography; Vascular Endothelial Growth Factor A; Vitamin E

To evaluate and compare the potential role of vitamins E and C in protecting against acute swimming induced reproductive function damage at different altitudes.. The study was carried between October and November 2010. A total of 36 adult male Wistar rats weighing 250+/-5 g, and aged 8 weeks were used in this study, which was carried at the Physiology laboratory of King Khalid University in Abha City (high altitude area [HA]), and at the College of Science, King Saud University in Riyadh city (low altitude area [LA]), Kingdom of Saudi Arabia. The rats of each area were divided into 3 groups (n=6 each): control, acute exercise stress, and vitamins E and C pretreated stress. At the end of the study, oxidative stress, reproductive function, histopathology, and expression of stem cell factor (CSF) were examined in all rats.. Living under HA conditions decreased expression of SCF, sperm count, and serum levels of reproductive hormones, and significantly increased testicle tissue oxidative stress and lipid peroxidation. Exhaustive exercise-induced stress at both altitudes resulted in similar results with more deteriorating effects in rats of HA compared with LA. Supplementation of vitamins E and C prior to stress induction at both altitudes prevented all these structural and functional aberrations from happening.. High altitude or strenuous exercise, or both, may impair male reproductive function, while vitamins E and C in combination potentially mitigate these adverse effects.

Topics: Animals; Ascorbic Acid; Base Sequence; DNA Primers; Hematocrit; Hydrocortisone; Hypoxia; Lipid Peroxidation; Male; Physical Conditioning, Animal; Rats; Rats, Wistar; Reproduction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Stem Cell Factor; Vitamin E

Fetal hypoxia is common and in vitro evidence supports its role in the programming of adult cardiovascular dysfunction through the generation of oxidative stress. Whether fetal chronic hypoxia programmes alterations in cardiovascular control in vivo, and if these alterations can be prevented by antioxidant treatment, is unknown. This study investigated the effects of prenatal fetal hypoxia, with and without maternal supplementation with vitamin C, on basal and stimulated cardiovascular function in vivo in the adult offspring at 4 months of age in the rat.. From days 6 to 20 of pregnancy, Wistar rats were subjected to Normoxia, Hypoxia (13% O2), Hypoxia+Vitamin C (5mg/ml in drinking water) or Normoxia+Vitamin C. At 4 months, male offspring were instrumented under urethane anaesthesia. Basal mean arterial blood pressure, heart rate and heart rate variability (HRV) were assessed, and stimulated baroreflex curves were generated with phenylephrine and sodium nitroprusside. Chronic fetal hypoxia increased the LF/HF HRV ratio and baroreflex gain, effects prevented by vitamin C administration during pregnancy.. Chronic intrauterine hypoxia programmes cardiovascular dysfunction in vivo in adult rat offspring; effects ameliorated by maternal treatment with vitamin C. The data support a role for fetal chronic hypoxia programming cardiovascular dysfunction in the adult rat offspring in vivo through the generation of oxidative stress in utero. 

Topics: Animals; Antioxidants; Ascorbic Acid; Cardiovascular Diseases; Female; Fetal Hypoxia; Hypoxia; Male; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Time Factors

Sheep pregnancy in high-altitude environments frequently involves hypoxia and oxidative stress and causes intrauterine growth retardation. The adverse effects of altitude on fetal growth can be prevented by the administration of antioxidant vitamins, but the mechanisms responsible are not well known. The maintenance of a viable pregnancy depends largely on adequate placental steroidogenesis, especially in the last two-thirds of pregnancy. Thus, in the present study we evaluated the effect of antioxidant vitamins (C and E) on plasma concentrations of progesterone and 17β-oestradiol during the last two-thirds of high-altitude pregnancies in ewes both native and naïve to the high-altitude environment. In addition, pregnancy outcomes were evaluated by determining the bodyweight of newborn lambs. Sex steroid patterns differed between ewes with and without vitamin supplementation. Concentrations of plasma progesterone and 17β-oestradiol were significantly higher in the supplemented groups from approximately 40 days before parturition until near term. Newborn weights were significantly lower in animals not adapted to the higher altitude, and vitamin supplementation prevented this decrease. In conclusion, the administration of antioxidant vitamins in the present study enhanced placental steroidogenesis, thus favouring fetal development in pregnancies developing at high altitudes.

Topics: Altitude; Animals; Ascorbic Acid; Body Weight; Estradiol; Female; Fetal Growth Retardation; Hypoxia; Linear Models; Pregnancy; Progesterone; Sheep; Sheep Diseases; Steroids; Vitamin E

This study isolated the effects of maternal hypoxia independent of changes in maternal nutrition on maternal circulatory and placental molecular indices of oxidative stress and determined whether maternal antioxidant treatment conferred protection. Pregnant rats were subjected to normoxic pregnancy or 13% O2 chronic hypoxia for most of gestation with and without maternal treatment with vitamin C in the drinking water. Maternal hypoxia with and without vitamin C did not affect maternal food or water intake and led to a significant increase in maternal and fetal haematocrit. At gestational day 20, maternal plasma urate and L-cysteine concentrations, and placental levels of 4-hydroxynonenal and heat shock protein 70 were increased while placental heat shock protein 90 levels were decreased in hypoxic pregnancy. The induction of maternal circulatory and placental molecular indices of oxidative stress in hypoxic pregnancies was prevented by maternal treatment with vitamin C. Maternal hypoxia during pregnancy with or without vitamin C increased placental weight, but not total or compartmental volumes. Maternal treatment with vitamin C increased birth weight in both hypoxic and normoxic pregnancies. The data show that maternal hypoxia independent of maternal undernutrition promotes maternal and placental indices of oxidative stress, effects that can be prevented by maternal treatment with vitamin C in hypoxic pregnancy. While vitamin C may not be the ideal candidate of choice for therapy in pregnant women, and taking into consideration differences in ascorbic acid metabolism between rats and humans, the data do underlie that antioxidant treatment may provide a useful intervention to improve placental function and protect fetal growth in pregnancy complicated by fetal hypoxia.

Topics: Animals; Animals, Newborn; Antioxidants; Ascorbic Acid; Birth Weight; Catalase; Cysteine; Disease Models, Animal; Female; Hematocrit; Hypoxia; Oxidative Stress; Placenta; Pregnancy; Pregnancy Complications; Rats; Rats, Wistar; Superoxide Dismutase; Uric Acid

Fetal hypoxia is a common complication of pregnancy. It has been shown to programme cardiac and endothelial dysfunction in the offspring in adult life. However, the mechanisms via which this occurs remain elusive, precluding the identification of potential therapy. Using an integrative approach at the isolated organ, cellular and molecular levels, we tested the hypothesis that oxidative stress in the fetal heart and vasculature underlies the molecular basis via which prenatal hypoxia programmes cardiovascular dysfunction in later life. In a longitudinal study, the effects of maternal treatment of hypoxic (13% O(2)) pregnancy with an antioxidant on the cardiovascular system of the offspring at the end of gestation and at adulthood were studied. On day 6 of pregnancy, rats (n = 20 per group) were exposed to normoxia or hypoxia ± vitamin C. At gestational day 20, tissues were collected from 1 male fetus per litter per group (n = 10). The remaining 10 litters per group were allowed to deliver. At 4 months, tissues from 1 male adult offspring per litter per group were either perfusion fixed, frozen, or dissected for isolated organ preparations. In the fetus, hypoxic pregnancy promoted aortic thickening with enhanced nitrotyrosine staining and an increase in cardiac HSP70 expression. By adulthood, offspring of hypoxic pregnancy had markedly impaired NO-dependent relaxation in femoral resistance arteries, and increased myocardial contractility with sympathetic dominance. Maternal vitamin C prevented these effects in fetal and adult offspring of hypoxic pregnancy. The data offer insight to mechanism and thereby possible targets for intervention against developmental origins of cardiac and peripheral vascular dysfunction in offspring of risky pregnancy.

Topics: Animals; Arteries; Ascorbic Acid; Female; Heart Diseases; Hypoxia; Longitudinal Studies; Male; Myocardial Contraction; Oxidative Stress; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Vascular Diseases

Thiosemicarbazones are a group of compounds that have received comprehensive investigation as anticancer agents. The antitumor activity of the thiosemicarbazone, 3-amino-2-pyridinecarboxaldehyde thiosemicarbazone (3-AP; triapine), has been extensively assessed in more than 20 phase I and II clinical trials. These studies have demonstrated that 3-AP induces methemoglobin (metHb) formation and hypoxia in patients, limiting its usefulness. Considering this problem, we assessed the mechanism of metHb formation by 3-AP compared with that of more recently developed thiosemicarbazones, including di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT). This was investigated using intact red blood cells (RBCs), RBC lysates, purified oxyhemoglobin, and a mouse model. The chelation of cellular labile iron with the formation of a redox-active thiosemicarbazone-iron complex was found to be crucial for oxyhemoglobin oxidation. This observation was substantiated using a thiosemicarbazone that cannot ligate iron and also by using the chelator, desferrioxamine, that forms a redox-inactive iron complex. Of significance, cellular copper chelation was not important for metHb generation in contrast to its role in preventing tumor cell proliferation. Administration of Dp44mT to mice catalyzed metHb and cardiac metmyoglobin formation. However, ascorbic acid administered together with the drug in vivo significantly decreased metHb levels, providing a potential therapeutic intervention. Moreover, we demonstrated that the structure of the thiosemicarbazone is of importance in terms of metHb generation, because the DpT analog, di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), does not induce metHb generation in vivo. Hence, DpC represents a next-generation thiosemicarbazone that possesses markedly superior properties. This investigation is important for developing more effective thiosemicarbazone treatment regimens.

Topics: Animals; Antineoplastic Agents; Ascorbic Acid; Cell Proliferation; Deferoxamine; Drug Interactions; Erythrocytes; Humans; Hypoxia; Iron; Iron Chelating Agents; Kinetics; Methemoglobin; Mice; Oxidation-Reduction; Oxyhemoglobins; Pyridines; Thiosemicarbazones

We described recently that systemic hypoxia provokes vasoconstriction in heart failure (HF) patients. We hypothesized that either the exaggerated muscle sympathetic nerve activity and/or endothelial dysfunction mediate the blunted vasodilatation during hypoxia in HF patients. Twenty-seven HF patients and 23 age-matched controls were studied. Muscle sympathetic nerve activity was assessed by microneurography and forearm blood flow (FBF) by venous occlusion plethysmography. Peripheral chemoreflex control was evaluated through the inhaling of a hypoxic gas mixture (10% O(2) and 90% N(2)). Basal muscle sympathetic nerve activity was greater and basal FBF was lower in HF patients versus controls. During hypoxia, muscle sympathetic nerve activity responses were greater in HF patients, and forearm vasodilatation in HF was blunted versus controls. Phentolamine increased FBF responses in both groups, but the increase was lower in HF patients. Phentolamine and N(G)-monomethyl-l-arginine infusion did not change FBF responses in HF but markedly blunted the vasodilatation in controls. FBF responses to hypoxia in the presence of vitamin C were unchanged and remained lower in HF patients versus controls. In conclusion, muscle vasoconstriction in response to hypoxia in HF patients is attributed to exaggerated reflex sympathetic nerve activation and blunted endothelial function (NO activity). We were unable to identify a role for oxidative stress in these studies.

Topics: Adult; Ascorbic Acid; Case-Control Studies; Chemoreceptor Cells; Forearm; Heart Failure; Hemodynamics; Humans; Hypoxia; Middle Aged; Muscle, Smooth, Vascular; omega-N-Methylarginine; Oxidative Stress; Phentolamine; Regional Blood Flow; Sympathetic Nervous System; Vasoconstriction; Vasodilation

Hypoxia induces reactive oxygen species production. Supplements with antioxidant mixtures can compensate for the decline in red cell membrane stability following intermittent hypobaric hypoxia by decreasing protein and lipid oxidation. We aimed to determine whether supplementation with vitamin C is implicated in the regulation of erythropoiesis and in the oxygen-carrying capacity of the blood, and also whether antioxidant supplementation prevents the oxidative stress associated to intermittent hypoxia. Twenty-four male Wistar rats were randomly divided into four experimental groups: normoxia control (n=6), normoxia + vitamin C (n=6), hypoxia control (12 h pO(2) 12%/12 h pO(2) 21%) (n=6), and hypoxia + vitamin C (n=6). Animals were supplemented with vitamin C at a dose of 250 mg·kg(-1)·day(-1) for 21 days. Red blood cell count, hemoglobin, hematocrit, reticulocytes, erythropoietin, and oxidative stress parameters such as malondialdehyde and protein oxidation in plasma were analyzed at two different time points: basal sample (day zero) and final sample (day 21). Similar RBC, Hb, Hct, and Epo increments were observed in both hypoxic groups regardless of the vitamin C supplementation. There was no change on MDA levels after intermittent hypoxic exposure in any experimental group. However, we found an increase in plasma protein oxidation in both hypoxic groups. Vitamin C does not affect erythropoiesis and protein oxidation in rats submitted to intermittent hypoxic exposure.

Topics: Animals; Antioxidants; Ascorbic Acid; Biomarkers; Blood Proteins; Dietary Supplements; Drug Administration Schedule; Erythropoiesis; Hematologic Tests; Hypoxia; Male; Malondialdehyde; Oxidation-Reduction; Oxidative Stress; Random Allocation; Rats; Rats, Wistar

Inhaled nitric oxide (NO) has the capacity to selectively dilate pulmonary blood vessels, and thus enhance the matching of ventilation and perfusion, improve oxygenation and decrease pulmonary hypertension. However, existing approaches for the administration of inhaled NO are associated with the co-delivery of potentially toxic concentrations of nitrogen dioxide (NO2) due to the oxidation of NO in oxygen rich environments. We tested the ability of a novel methodology for generating highly purified NO through the reduction of NO2 by ascorbic acid to reverse pulmonary hypertension. In vitro testing demonstrated that the NO output of the novel device is ultrapure and free of NO2. An in vivo hypoxemic swine model of pulmonary hypertension was used to examine the dose response to NO in terms of pulmonary pressures and pulmonary vascular resistance. Pulmonary hypertension was induced by lowering inspired oxygen to 15% prior to treatment with inhaled ultra purified NO (1, 5, 20, and 80PPM). Hypoxemia increased mean pulmonary artery pressures and pulmonary vascular resistance. Inhaled ultra purified NO doses (down to 1PPM) show a marked reduction of hypoxemia-induced pulmonary vascular resistance. These experiments demonstrate a simple and robust method to generate purified inhaled NO that is devoid of NO2 and capable of reversing hypoxemia induced pulmonary hypertension.

Topics: Administration, Inhalation; Animals; Ascorbic Acid; Disease Models, Animal; Hypertension, Pulmonary; Hypoxia; Nitric Oxide; Nitrogen; Nitrogen Dioxide; Oxygen; Pulmonary Artery; Swine; Vascular Resistance

Chronic intermittent hypoxia (CIH), a characteristic of sleep obstructive apnea, enhances carotid body (CB) chemosensory responses to hypoxia, but its consequences on CB vascular area and VEGF expression are unknown. Accordingly, we studied the effect of CIH on CB volume, glomus cell numbers, blood vessel diameter and number, and VEGF immunoreactivity (VEGF-ir) in male Sprague-Dawley rats exposed to 5% O(2), 12 times/h for 8 h or sham condition for 21 days. We found that CIH did not modify the CB volume or the number of glomus cells but increased VEGF-ir and enlarged the vascular area by increasing the size of the blood vessels, whereas the number of the vessels was unchanged. Because oxidative stress plays an essential role in the CIH-induced carotid chemosensory potentiation, we tested whether antioxidant treatment with ascorbic acid may impede the vascular enlargement and the VEGF upregulation. Ascorbic acid, which prevents the CB chemosensory potentiation, failed to impede the vascular enlargement and the increased VEGF-ir. Thus present results suggest that the CB vascular enlargement induced by CIH is a direct effect of intermittent hypoxia and not secondary to the oxidative stress. Accordingly, the subsequent capillary changes may be secondary to the mechanisms involved in the neural chemosensory plasticity induced by intermittent hypoxia.

Topics: Animals; Antioxidants; Ascorbic Acid; Carotid Body; Cell Count; Chemoreceptor Cells; Hypoxia; Immunohistochemistry; Male; Oxidative Stress; Rats; Rats, Sprague-Dawley; Sleep Apnea, Obstructive; Up-Regulation; Vascular Endothelial Growth Factor A

Topics: Ascorbic Acid; Azathioprine; Blood Gas Analysis; Dapsone; Female; Follow-Up Studies; Humans; Hypercapnia; Hypoxia; Methemoglobinemia; Methylene Blue; Middle Aged; Myositis; Oximetry; Polysomnography; Prednisone; Respiratory Function Tests; Respiratory Insufficiency; Risk Assessment; Severity of Illness Index; Treatment Outcome

Intermittent hypoxia, a feature of obstructive sleep apnoea, potentiates ventilatory hypoxic responses, alters heart rate variability and produces hypertension, partially owing to an enhanced carotid body responsiveness to hypoxia. Since oxidative stress is a potential mediator of both chemosensory and cardiorespiratory alterations, we hypothesised that an antioxidant treatment may prevent these alterations. Accordingly, we studied the effects of ascorbic acid (1.25 g.L(-1) drinking water) on plasma lipid peroxidation, nitrotyrosine and inducible nitric oxide synthase (iNOS) immunoreactivity in the carotid body, ventilatory and carotid chemosensory responses to acute hypoxia, heart rate variability and arterial blood pressure in male Sprague-Dawley rats exposed to 5% O(2); 12 episodes.h(-1); 8 h.day(-1) or sham condition for 21 days. Intermittent hypoxia increased plasma lipid peroxidation, nitrotyrosine and iNOS expression in the carotid body, enhanced carotid chemosensory and ventilatory hypoxic responses, modified heart rate variability and produced hypertension. Ascorbic acid prevented the increased plasma lipid peroxidation and nitrotyrosine formation within the carotid body, and the enhanced carotid chemosensory and ventilatory responses to hypoxia, as well as heart rate variability alterations and hypertension. The present results support an essential role for oxidative stress in the generation of carotid body chemosensory potentiation and systemic cardiorespiratory alterations induced by intermittent hypoxia.

Topics: Animals; Antioxidants; Ascorbic Acid; Carotid Body; Chemoreceptor Cells; Heart Rate; Hypertension; Hypoxia; Lipid Peroxidation; Lipids; Male; Malondialdehyde; Nitric Oxide Synthase Type II; Nitrosamines; Oxidative Stress; Pulmonary Ventilation; Rats; Sleep Apnea, Obstructive; Tyrosine

The HIF (hypoxia-inducible factor) hydroxylases [PHDs or EGLNs (prolyl hydroxylases), which in humans are PHD isoforms 1-3, and FIH (factor inhibiting HIF)] regulate HIF levels and activity. These enzymes are Fe(II)/2-oxoglutarate-dependent oxygenases, many of which are stimulated by ascorbate. We have investigated the ascorbate dependence of PHD2-catalysed hydroxylation of two prolyl hydroxylation sites in human HIF-1alpha, and of FIH-catalysed hydroxylation of asparaginyl hydroxylation sites in HIF-1alpha and in a consensus ankyrin repeat domain peptide. The initial rate and extent of hydroxylation was increased in the presence of ascorbate for each of these reactions. When ascorbate was replaced with structural analogues, the results revealed that the ascorbate side chain was not important in its contribution to HIF hydroxylase catalysis, whereas modifications to the ene-diol portion of the molecule negated the ability to promote hydroxylation. We investigated whether alternative reducing agents (glutathione and dithiothreitol) could be used to promote HIF hydroxylase activity, and found partial stimulation of hydroxylation in an apparently enzyme- and substrate-specific manner. The results raise the possibility of developing reducing agents targeted to specific HIF hydroxylase-catalysed reactions.

Topics: Ankyrin Repeat; Ascorbic Acid; Asparagine; Humans; Hydroxylation; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia-Inducible Factor-Proline Dioxygenases; Ketoglutaric Acids; Peptide Fragments; Procollagen-Proline Dioxygenase; Reducing Agents; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

The aim of our study was to compare and assess the effectiveness of antioxidant mixtures on the erythrocytes (RBC) of adult male albino rats (Wister) subjected to simulated intermittent high altitudes--5,100 m (AL(1)) and 6,700 m (AL(2))--to induce oxidative stress (OS). To achieve our objective, we pre-supplemented four sets of animals with different antioxidant mixtures [vitamin E (vit.E; 50 IU/kg BW), vitamin C (vit.C; 400 mg/kg) and L: -carnitine (400 mg/kg)] in different combinations [M1 (vit.E+vit.C), M2 (vit.C+carnitine), M3 (vit.E+carnitine) and M4 (vit.C+vit.E+carnitine)] for 30 days prior to as well during exposure to intermittent hypobaric hypoxia (IHH). Membrane instability, in terms of osmotic fragility and hemolysis, decreased in RBCs of supplemented animals. There was a significant increase in the activity of glutathione peroxidase in the RBCs of supplemented animals. We confirmed OS imposed by IHH with assays relating to lipid [thiobarbituric acid reactive substances (TBARS) and lipofuscin (LF)] and protein (carbonyl, PrC) oxidation, and found a positive correlation between PrC and hemolysis, with a decrease in both upon supplementation with M3 and M4 mixtures. Fluorescence microscopic observation showed a maximum decrease in the LF content in rats administered M4 and M1 compared to those on M2 and M3 mixtures at both altitudes. We suggest that multiple antioxidant fortifications are effective in overcoming increased OS experienced by RBCs at high altitudes.

Topics: Altitude; Animals; Antioxidants; Ascorbic Acid; Carnitine; Erythrocytes; Glutathione Peroxidase; Hemolysis; Hypoxia; Lipid Peroxidation; Male; Microscopy, Fluorescence; Oxidative Stress; Rats; Rats, Wistar; Time Factors; Vitamin E

Episodes of hypoxia in utero present a potentially serious challenge to the fetus, but are counteracted by defence responses including marked redistribution of blood flow from peripheral circulations to the brain. Here, we report the novel observation that the oxidant tone is an important modulator of this cardiovascular defence. Using pregnant Welsh Mountain sheep surgically prepared for long-term recording, we investigated in vivo the effects on the fetal cardiovascular defence to acute hypoxaemia of fetal treatment with the antioxidant vitamin C. The mechanisms via which vitamin C may affect the vascular oxidant tone were investigated by monitoring fetal plasma concentrations of nitrates and nitrites, by determining changes in the activity of superoxide dismutase (SOD) in fetal plasma, and by investigating the effect of vitamin C treatment on the fetal cardiovascular defence to hypoxaemia following nitric oxide (NO) synthase blockade. Fetal treatment with vitamin C markedly depressed the normal femoral constrictor response to acute hypoxaemia in the fetus (5.2 ± 1.0 vs. 1.1 ± 0.3 mmHg (ml min(-1))(-1), mean ± s.e.m.; P < 0.05) an effect which was completely restored following NO synthase blockade (6.2 ± 1.3 mmHg (ml min(-1))(-1)). Compared to saline infusion, fetal treatment with vitamin C during acute hypoxaemia also significantly increased fetal plasma SOD activity from normoxic baseline (-8.9 ± 6.5 vs. 15.0 ± 6.6% inhibition, P < 0.05) and decreased the plasma concentration ratio of nitrate:nitrite from normoxic baseline (ΔNO3(-):NO2(-); 0.15 ± 0.30 vs. -0.29 ± 0.11, P < 0.05). The data provide in vivo evidence of redox modulation of redistribution of blood flow in the fetus, part of the fetal brain sparing during acute hypoxaemic stress.

Topics: Animals; Antioxidants; Ascorbic Acid; Blood Gas Analysis; Cardiovascular System; Female; Fetus; Hypoxia; Models, Animal; Nitrates; Nitric Oxide; Nitrites; Oxidation-Reduction; Pregnancy; Sheep; Superoxide Dismutase

In healthy subjects, hypoxemia and exercise represent independent stressors promoting the exercise-induced cytokine response and oxidative stress. We hypothesized that hypoxemia in patients with chronic obstructive pulmonary disease (COPD) may affect the cytokine production and/or the changes in oxidant-antioxidant status in response to maximal exercise. Exercise-induced changes in PaO2 allowed to transiently increase or decrease baseline hypoxemia and to point out its specific action on muscle metabolism. COPD patients with severe to moderate hypoxemia (56 < PaO2 < 72 mmHg) performed an incremental cycling exercise until volitional exhaustion. Two cytokines [interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha] and three blood indices of oxidative stress [plasma thiobarbituric acid reactive substances (TBARS) and two antioxidants, reduced erythrocyte glutathione (GSH), and reduced plasma ascorbic acid, RAA] were measured at rest, then during and after exercise. The changes in the cytokine levels and oxidant-antioxidant status were analysed in relation with the baseline PaO2 and its exercise-induced variations. Data were compared with those obtained in an age- and body mass index-matched group of healthy subjects. Compared with healthy subjects, COPD patients presented a marked accentuation of exercise-induced increase in IL-6 level and earlier changes in their oxidant-antioxidant status. Resting levels of IL-6 and TNF-alpha and exercise-induced peak variations of TBARS, IL-6 and TNF-alpha were negatively correlated with the baseline PaO2. In COPD patients, the peak increases in IL-6 and TBARS were attenuated when exercise hyperventilation reduced the baseline hypoxemia. Our study indicates that the PaO2 level affects both the exercise-induced oxidative stress and cytokine response in hypoxemic COPD patients.

Topics: Adult; Ascorbic Acid; Biomarkers; Case-Control Studies; Exercise; Female; Glutathione; Humans; Hypoxia; Interleukin-6; Male; Middle Aged; Oxidative Stress; Oxygen; Pulmonary Disease, Chronic Obstructive; Thiobarbituric Acid Reactive Substances; Time Factors; Tumor Necrosis Factor-alpha

Control of the transcription factor hypoxia inducible factor (HIF)-1 is mediated by hydroxylation by proline and asparagine hydroxylases. These enzymes require ascorbate for optimal activity, but little attention has been given to the effect of ascorbate on HIF-1 activation. Furthermore, cells in culture are ascorbate deficient. We investigated the effect of intracellular ascorbate on HIF-1alpha protein levels and on HIF-1-mediated gene expression in two human primary cell lines (umbilical vein endothelial cells and skin fibroblasts) and one human cancer cell line (A431 epithelial cells). Under normal culture conditions the cells contained no ascorbate and adding ascorbate to the medium increased intracellular concentrations in a dose-dependent manner. A basal level of HIF-1alpha detected in nonsupplemented cells under normoxic conditions disappeared when 10 microM ascorbate was added to the medium. Induction of HIF-1alpha by hypoxia (1% O(2)) or by CoCl(2) was markedly inhibited by ascorbate and loading with physiological levels resulted in almost complete reversal of HIF-1alpha stabilisation. Gene expression was similarly affected, with VEGF mRNA and GLUT-1 up-regulation being inhibited by ascorbate. Hence intracellular ascorbate is a major regulator of the hypoxic response in normal cells and optimal levels of this vitamin will have a profound effect on HIF-1-regulated processes.

Topics: Ascorbic Acid; Blotting, Western; Cell Line, Tumor; Cells, Cultured; Dose-Response Relationship, Drug; Endothelium, Vascular; Fibroblasts; Gene Expression Regulation; Glucose Transporter Type 1; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; RNA, Messenger; Vascular Endothelial Growth Factor A

Some anticancer compounds are pro-drugs which give rise to toxic species through enzymatic reduction. The quinoxaline-di-N-oxide derivative Q-85 HCl (7-chloro-3-[[(N,N-dimethylamino)propyl]amino]-2-quinoxalinecarbonitrile 1,4-di-N-oxide hydrochloride) is a bioreductive compound selectively toxic in hypoxia. Due to the possibility of secondary tumors the study of the genotoxic capability of antitumoral drugs is very important. The aim of this study was to assess the ability of Q-85 HCl to produce reactive oxygen species (ROS) and oxidative DNA damage in Caco-2 cells, both in hypoxia and in well-oxygenated conditions. Secondly, we attempted to evaluate the effect of vitamins C and E under hypoxic and normoxic conditions, in order to determine if these antioxidant substances modify Q-85 HCl effect in hypoxic cells or possibly exert a protective action in normal cells. Caco-2 cells were treated with Q-85 HCl for 2h, at high concentrations in normoxia (0.1-5 microM) and at low concentrations in hypoxia (0.002-0.1 microM). In normoxia, a dose-related significant increase in intracellular ROS level was evident; in hypoxia all the concentrations produced very high level of ROS. Just after the treatment and 24h later, oxidative DNA damage was evaluated by the modified comet assay after post-digestion of the cells with formamidopyrimidine-DNA glycosylase (FPG) and endonuclease III (Endo III). Q-85 HCl treatment evoked a significant dose-dependent increase in the total comet score of the cells both in hypoxia and normoxia, indicating that this compound or some metabolite is able to oxidize purine and pyrimidine bases. After 24h DNA damage caused by the compound was completely repaired with only one exception: cells treated with the highest concentration of Q-85 HCl in hypoxia and post-digested with FPG. Vitamin C (5-100 microM) and vitamin E (500-400 microM) did not have a pro-oxidant effect in Caco-2 cells. Treatment of cells with vitamin C (10 microM) or vitamin E (100 microM) did not significantly reduce oxidative DNA damage in hypoxia and normoxia. In conclusion, the use of these vitamins would not hinder toxicity against hypoxic cells, but a protective effect in normoxic cells was not evident.

Topics: Ascorbic Acid; Caco-2 Cells; DNA Damage; DNA Glycosylases; DNA-Formamidopyrimidine Glycosylase; Humans; Hypoxia; Prodrugs; Quinoxalines; Reactive Oxygen Species; Vitamin E

Animal and tissue studies have indicated that the carotid bodies are sensitive to glucose concentrations within the physiological range. This glucose sensitivity may modulate the ventilatory response to hypoxia, with hyperglycaemia suppressing the hypoxic response and hypoglycaemia stimulating it. This study was designed to determine whether hypo- and hyperglycaemia modulate the hypoxic ventilatory response in humans. In 11 normal research participants, glucose levels were clamped at 2.8 and 11.2 mmol l(-1) for 30 min. At the start and end of each clamp, blood was drawn for hormone measurement and the isocapnic hypoxic ventilatory response was measured. Because generation of reactive oxygen species may be a common pathway for the interaction between glucose and oxygen levels, the experiments were repeated with and without pretreatment for 1 week with vitamins C and E. Hypoglycaemia caused an increase in the counter-regulatory hormones, a 54% increase in isocapnic ventilation, and a 108% increase in the hypoxic ventilatory response. By contrast, hyperglycaemia resulted in small but significant increases in both ventilation and the hypoxic ventilatory response. Antioxidant vitamin pretreatment altered neither response. In conclusion, the stimulant effect of hypoglycaemia on the hypoxic ventilatory response is consistent with a direct effect on the carotid body, but an indirect effect through the activation of the counter-regulatory response cannot be excluded. The mechanisms behind the mild stimulating effect of hyperglycaemia remain to be elucidated.

Topics: Adult; Antioxidants; Ascorbic Acid; Female; Glucose Clamp Technique; Hormones; Humans; Hyperglycemia; Hypoglycemia; Hypoxia; Male; Respiration; Vitamin E

The purpose of the study was to determine the oxidative and antioxidative status of plasma in patients with fibromyalgia. Total antioxidant capacity (TAC) of plasma was significantly lower in patients with fibromyalgia (n = 20) than in healthy controls (n = 20) [1.5 (SD 0.3) and 1.9 (SD 0.3) mmol Trolox equiv./l, P = 0.001]. In contrast, the total peroxide level of plasma was significantly higher in patients than in healthy controls [37.4 (SD 6.7) and 33.0 (SD 2.7) micromol H2O2/l; P = 0.01]. The oxidative stress index (OSI) level was significantly higher in patients with fibromyalgia than in healthy controls [2.5 (SD 1.0) and 1.8 (SD 0.4); P = 0.007]. A significant negative correlation between visual analogue scale (VAS) and TAC level was determined (r = -0.79, P < 0.001). The present results indicate that patients with fibromyalgia are exposed to oxidative stress and this increased oxidative stress may play a role in the etiopathogenesis of the disease. Supplementation of antioxidant vitamins such as vitamins C and E to the therapy may be indicated.

Topics: Adult; Antioxidants; Ascorbic Acid; Case-Control Studies; Female; Fibromyalgia; Free Radicals; Humans; Hypoxia; Male; Oxidative Stress; Pain; Vitamin E

The pharmacological action of vitamin E on the mechanical activity of isolated guinea pig colonic smooth muscle was examined in normoxic and hypoxic conditions. In hypoxia, but not normoxia, alpha-tocopherol (1-160 microM) evoked rapid concentration-dependent contractions from the colon. This was also seen with other members of the vitamin E family, and potency measurements gave EC(50) values (microM) of 10.6 +/- 0.9 for D-alpha-tocopherol, 6.0 +/- 1.2 for D-beta-tocopherol, 7.5 +/- 0.7 for D-gamma-tocopherol, and 6.1 +/- 1.5 for D-delta-tocopherol. This order of potency for the components of the vitamin differs from previously studied bioassay systems and from their antioxidant activity. A range of potent natural and synthetic antioxidants was not active in this system. Compounds with structural similarities to the side chain of vitamin E produced similar stimulatory responses and some, like phytol, were more potent than the vitamin (EC(50): 1.0 +/- 0.2 microM), whereas ring structures related to the vitamin, like Trolox C, antagonized the stimulant responses in a concentration-dependent manner. Therefore, this model system measures, directly, vitamin E-induced responses through a mechanism that does not appear to be related to the known antioxidant capacity of these agents.

Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; Chromans; Colon, Transverse; Dose-Response Relationship, Drug; Female; Guinea Pigs; Hypoxia; In Vitro Techniques; Isometric Contraction; Male; Methacrylates; Muscle Contraction; Muscle, Smooth; Phytol; Pyrogallol; Quantitative Structure-Activity Relationship; Stereoisomerism; Temperature; Terpenes

The combined effect of traumatic brain injury (TBI) and secondary insult on biochemical changes of cerebral tissue is not well known. For this purpose, we studied the time-course changes of parameters reflecting ROS-mediated oxidative stress and modifications of cell energy metabolism determined in rats subjected to cerebral insult of increasing severity.. Rats were divided into four groups: 1) sham-operated, 2) subjected to 10 minutes of hypoxia and hypotension (HH), 3) subjected to severe diffuse TBI, and 4) subjected to severe diffuse TBI + HH. Rats were killed at different times after injury, and analyses of malondialdehyde, ascorbate, high-energy phosphates, nicotinic coenzymes, oxypurines, nucleosides, and N-acetylaspartate (NAA) were made by high-performance liquid chromatography on whole-brain tissue extracts.. Data indicated a close relationship between degree of oxidative stress and severity of brain insult, as evidenced by the highest malondialdehyde values and lowest ascorbate levels in rats subjected to TBI + HH. Similarly, modifications of parameters related to cell energy metabolism were modulated by increasing severity of brain injury, as demonstrated by the lowest values of energy charge potential, nicotinic coenzymes, and NAA and the highest levels of oxypurines and nucleosides recorded in TBI + HH rats. Both the intensity of oxidative stress-mediated cerebral damage and perturbation of energy metabolism were minimally affected in rats subjected to HH only.. These results showed that the severity of brain insult can be graded by measuring biochemical modifications, specifically, reactive oxygen species-mediated damage, energy metabolism depression, and NAA, thereby validating the rodent model of closed-head diffuse TBI coupled with HH and proposing NAA as a marker with diagnostic relevance to monitor the metabolic state of postinjured brain.

Topics: Animals; Ascorbic Acid; Aspartic Acid; Biomarkers; Brain; Brain Chemistry; Brain Injuries; Chromatography, High Pressure Liquid; Energy Metabolism; Head Injuries, Closed; Hypotension; Hypoxia; Male; Malondialdehyde; NAD; NADP; Nucleosides; Oxidative Stress; Phosphates; Purines; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species

The incidence of Alzheimer disease is increased following ischemic episodes, and we previously demonstrated that following chronic hypoxia (CH), amyloid beta (Abeta) peptide-mediated increases in voltage-gated L-type Ca(2+) channel activity contribute to the Ca(2+) dyshomeostasis seen in Alzheimer disease. Because in certain cell types mitochondria are responsible for detecting altered O(2) levels we examined the role of mitochondrial oxidant production in the regulation of recombinant Ca(2+) channel alpha(1C) subunits during CH and exposure to Abeta-(1-40). In wild-type (rho(+)) HEK 293 cells expressing recombinant L-type alpha(1C) subunits, Ca(2+) currents were enhanced by prolonged (24 h) exposure to either CH (6% O(2)) or Abeta-(1-40) (50 nm). By contrast the response to CH was absent in rho(0) cells in which the mitochondrial electron transport chain (ETC) was depleted following long term treatment with ethidium bromide or in rho(+) cells cultured in the presence of 1 microm rotenone. CH was mimicked in rho(0) cells by the exogenous production of O2(-.). by xanthine/xanthine oxidase. Furthermore Abeta-(1-40) enhanced currents in rho(0) cells to a degree similar to that seen in cells with an intact ETC. The antioxidants ascorbate (200 microm) and Trolox (500 microm) ablated the effect of CH in rho(+) cells but were without effect on Abeta-(1-40)-mediated augmentation of Ca(2+) current in rho(0) cells. Thus oxidant production in the mitochondrial ETC is a critical factor, acting upstream of amyloid beta peptide production in the up-regulation of Ca(2+) channels in response to CH.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Antioxidants; Ascorbic Acid; Biological Transport; Brain Ischemia; Calcium; Calcium Channels; Cell Line; Chromans; Electron Transport; Electrons; Electrophysiology; Ethidium; Humans; Hypoxia; Immunohistochemistry; Mitochondria; Neurodegenerative Diseases; Oxidants; Oxygen; Peptides; Reactive Oxygen Species; Rotenone; Superoxides; Transfection; Up-Regulation; Xanthine Oxidase

Ascorbate has long been thought to play an important role in intestinal iron absorption. The recent identification of a possible ascorbate-dependent duodenal ferric reductase suggests a role for intracellular ascorbate in the control of iron absorption. We set out to determine whether duodenal ascorbate concentrations are altered by treatments known to alter the rate of iron absorption and whether ascorbate levels affect duodenal reductase activity. Duodenal ascorbate was extracted and assayed by HPLC and/or a chemical assay. Ferric reductase was assayed in vitro with ferric nitrilotriacetate or nitroblue tetrazolium as substrates. Duodenal ascorbate concentrations were increased by iron deficiency, genetic hypotransferrinemia, and hypoxia. Parenteral iron overload increased iron stores but did not affect duodenal ascorbate concentrations. Hemolytic anemia induced in mice by phenylhydrazine injection also did not affect duodenal ascorbate concentrations. In vitro studies with incubated duodenum showed that decreased tissue ascorbate was associated with decreased mucosal ferric reductase activity, whereas incubation with dehydroascorbate prevented both the decrease in ascorbate concentration and reductase activity. Mouse duodenum ascorbate concentrations changed in response to treatments that altered iron absorption rates; in particular, ascorbate levels generally increased when iron absorption was increased by iron deficiency, hypoxia, or genetic hypotransferrinemia. We conclude that changes in ascorbate levels are associated with changes in ferric reductase activity. These findings are consistent with the proposal that duodenal ascorbate plays a role in intestinal iron absorption.

Topics: Animals; Ascorbic Acid; Dehydroascorbic Acid; Duodenum; Hypoxia; Intestinal Absorption; Intestinal Mucosa; Iron; Iron Deficiencies; Male; Mice; Phenylhydrazines; Transferrin

Exposure of cells to carcinogenic compounds of nickel(II) and cobalt(II) causes activation of the HIF-1 transcription factor and up-regulates a battery of hypoxia-inducible genes. However, the mechanism of HIF-1 activation by these metals is not known. It was shown recently that hydroxylation of prolines in the HIFalpha subunit of HIF-1 is required for its binding with the von Hippel-Lindau tumor suppressor protein and the subsequent proteasomal destruction. Here we show that responsible prolyl hydroxylases are targets for both nickel(II) and cobalt(II) because degradation of a reporter protein containing the oxygen-dependent degradation domain (Pro-402/564) of HIFalpha was abolished in a von Hippel-Lindau-dependent manner in cells exposed to nickel(II) or cobalt(II). The enzymatic activity of prolyl hydroxylases depends on iron as the activating metal, 2-oxoglutarate as a co-substrate, and ascorbic acid as a cofactor. Hydroxylase activity can be impaired by the depletion of any of these factors. We found that exposure of cells to nickel(II) or cobalt(II) did not affect the level of intracellular iron. Instead, nickel(II) or cobalt(II) exposure greatly depleted intracellular ascorbate. Co-exposure of cells to metals and ascorbate resulted in the increase of intracellular ascorbate and reversed both metal-induced stabilization of HIF-1alpha and HIF-1-dependent gene transcription. Because ascorbate is essential for maintaining iron in prolyl hydroxylases in the active iron(II) state, we suggest that the observed depletion of ascorbate by nickel(II) or cobalt(II) favors iron oxidation and thus inactivation of the enzyme.

Topics: Ascorbic Acid; Blotting, Western; Carcinogens; Cell Line; Chromatography, High Pressure Liquid; Cobalt; Cysteine Endopeptidases; DNA-Binding Proteins; Dose-Response Relationship, Drug; Genes, Reporter; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Iron; Ketoglutaric Acids; Models, Biological; Multienzyme Complexes; Mutation; Nickel; Nuclear Proteins; Oxygen; Plasmids; Procollagen-Proline Dioxygenase; Proline; Proteasome Endopeptidase Complex; Protein Structure, Tertiary; Time Factors; Transcription Factors; Transcription, Genetic; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Up-Regulation; Von Hippel-Lindau Tumor Suppressor Protein

The depression of excitatory synaptic transmission by hypoxia in area CA1 of the hippocampus is largely dependent upon the activation of adenosine A(1) receptors on presynaptic glutamatergic terminals. As well as adenosine, norepinephrine levels increase in the hypoxic/ischemic hippocampus. We sought to determine the influence of alpha- and beta-adrenoceptor (AR) activation on the hypoxic depression of synaptic transmission utilizing electrophysiological, pharmacological and adenosine sensor techniques. Norepinephrine depressed synaptic transmission and significantly accelerated the hypoxic depression of synaptic transmission. The alpha-AR agonist 6-fluoronorepinephrine mimicked both of these effects whilst the alpha(2)-AR antagonist yohimbine, but not the alpha(1)-AR antagonist urapidil, prevented the actions of 6-fluoronorepinephrine. In contrast, the beta-AR agonist isoproterenol enhanced synaptic transmission and only accelerated the hypoxic depression of transmission in hypoxia-conditioned slices in which the hypoxic release of adenosine is reduced. The effects of isoproterenol were blocked by the non-selective beta-AR antagonist propranolol and the selective beta(1)-AR antagonist betaxolol. Using an enzyme-based adenosine sensor we observed that the application of the beta-AR agonist resulted in increased extracellular adenosine during repeated hypoxia. Our results suggest that alpha(2)-AR activation facilitates the hypoxic depression of synaptic transmission probably via the known alpha(2)-AR-mediated inhibition of presynaptic calcium channels whereas beta(1)-AR activation does so via increased extracellular adenosine and greater activation of inhibitory adenosine A(1) receptors.

Topics: Adenosine; Adrenergic alpha-Agonists; Adrenergic alpha-Antagonists; Adrenergic beta-Agonists; Animals; Animals, Newborn; Antioxidants; Ascorbic Acid; Drug Interactions; Excitatory Postsynaptic Potentials; Female; Hippocampus; Hypoxia; In Vitro Techniques; Isoproterenol; Male; Neural Inhibition; Neurons; Norepinephrine; Piperazines; Rats; Rats, Sprague-Dawley; Receptor, Adenosine A1; Synaptic Transmission; Time Factors; Yohimbine

Reactive oxygen species play a central role in myocardial ischemic injury and are a target for therapeutic intervention. Vitamin C is an essential antioxidant yet difficult to deliver in pharmacologic concentration to the myocardium. We found that adult rat cardiomyocytes accumulate vitamin C by transporting dehydroascorbic acid (DHA), the oxidized form of vitamin C, but do not transport ascorbic acid. Loading cells with vitamin C by DHA treatment resulted in resistance to hypoxia- and hypoxia/reoxygenation-induced cell death associated with the quenching of reactive oxygen species. When rats were injected with DHA before coronary occlusion, the ascorbic acid content in the heart was six to eight times higher than in untreated controls and myocardial infarction was reduced by 62%. DHA also provided significant protection when administered intravenously 2 h after coronary occlusion. In cardiomyocytes subjected to hypoxia/reoxygenation, DHA treatment resulted in decreased apoptosis associated with inhibition of Bax expression, caspase-3 activation, and cytochrome c translocation into the cytoplasm. DHA treatment also inhibited Jak2, STAT1, and STAT5 phosphorylation, and increased STAT3 phosphorylation, in hypoxic cardiomyocytes and ischemic myocardial tissue. Our findings suggest that DHA may be useful as a cardioprotectant in ischemic heart disease.

Topics: Animals; Apoptosis; Ascorbic Acid; Cell Hypoxia; Dehydroascorbic Acid; Disease Models, Animal; Heart; Hypoxia; Muscle Cells; Myocardial Ischemia; Myocardium; Rats; Rats, Sprague-Dawley; Signal Transduction

The major damaging factor during and after the ischemic/hypoxic insult is the generation of free radicals, which leads to apoptosis, necrosis, and ultimately cell death. Rubia cordifolia (RC), Fagonia cretica linn (FC), and Tinospora cordifolia (TC) have been reported to contain a wide variety of antioxidants and have been in use in the eastern system of medicine for various disorders. Hippocampal slices were subjected to oxygen-glucose deprivation (OGD) and divided into three groups, control, OGD, and OGD+drug treated. Cytosolic reduced glutathione (GSH), nitric oxide [NO, measured as nitrite (NO2)]. EPR was used to establish the antioxidant effect of RC, FC, and TC with respect to superoxide anion (O*2-), hydroxyl radicals (*OH), nitric oxide (NO) radical, and peroxynitrite anion (ONOO-) generated from pyrogallol, menadione, DETA-NO, and Sin-1, respectively. RT-PCR was performed for the three herbs to assess their effect on the expression of gamma-glutamylcysteine ligase (GCLC), iNOS, and GAPDH gene expression. All the three herbs were effective in elevating the GSH levels and expression of the GCLC. The herbs also exhibited strong free radical scavenging properties against reactive oxygen and nitrogen species as revealed by electron paramagnetic resonance spectroscopy, diminishing the expression of iNOS gene. RC, FC, and TC therefore attenuate oxidative stress mediated cell injury during OGD and exert the above effects at both the cytosolic as well as at gene expression levels and may be effective therapeutic tool against ischemic brain damage.

Topics: Animals; Ascorbic Acid; Electrodes; Electron Spin Resonance Spectroscopy; Electrons; Free Radical Scavengers; Free Radicals; Glucose; Glutamate-Cysteine Ligase; Glutathione; Hippocampus; Hypoxia; Ions; Ischemia; Lipid Peroxidation; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxygen; Plant Extracts; Rats; Rats, Wistar; Reactive Nitrogen Species; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Rubia; Time Factors; Tinospora; Zygophyllaceae

Little is known about the role of pleiotropic drug resistance (PDR)-type ATP-binding (ABC) proteins in plant responses to environmental stresses. We characterised ospdr9, which encodes a rice ABC protein with a reverse (ABC-TMS(6))(2) configuration. Polyethylene glycol and the heavy metals Cd (20 microM) and Zn (30 microM) rapidly and markedly induced ospdr9 in roots of rice seedlings. Hypoxic stress also induced ospdr9 in rice roots, salt stress induced ospdr9 at low levels but cold and heat shock had no effect. The plant growth regulator jasmonic acid, the auxin alpha-naphthalene acetic acid and the cytokinin 6-benzylaminopurine triggered ospdr9 expression. The antioxidants dithiothreitol and ascorbic acid rapidly and markedly induced ospdr9 in rice roots; the strong oxidant hydrogen peroxide also induced ospdr9 but at three times lower levels. The results suggested that redox changes may be involved in the abiotic stress response regulation of ospdr9 in rice roots.

Topics: Ascorbic Acid; ATP-Binding Cassette Transporters; Cadmium; Dithiothreitol; Drug Resistance, Multiple; Gene Expression Regulation, Plant; Hydrogen Peroxide; Hypoxia; Oryza; Oxidation-Reduction; Plant Growth Regulators; Plant Roots; Polyethylene Glycols; rac1 GTP-Binding Protein; RNA, Plant; Seedlings; Sodium Chloride; Temperature; Zinc

Glutathione S-transferases (GSTs) have poorly understood roles in plant responses to environmental stresses. A polyethylene glycol (PEG)-induced tau class GST was identified in rice roots by protein microsequencing. PEG and the heavy metals Cd (20 microM), Zn (30 microM), Co and Ni rapidly and markedly induced osgstu4 and osgstu3 in rice seedling roots. Osgstu4 and osgstu3 were also induced in roots by hypoxic stress but not by cold nor heat shock. Salt stress and abscisic acid (ABA) rapidly induced osgstu3 in rice roots, whereas osgstu4 exhibited a late salt stress and no ABA response. Salicylic acid, jasmonic acid and the auxin alpha-naphthalene acetic acid triggered osgstu4 and osgstu3 expression. Osgstu4 and osgstu3 were rapidly and markedly induced by the antioxidant dithiothreitol and the strong oxidant hydrogen peroxide, which suggested that redox perturbations and reactive oxygen species are involved in their stress response regulations.

Topics: Amino Acid Sequence; Ascorbic Acid; Dithiothreitol; Enzyme Induction; Gene Expression Regulation, Plant; Genes, Plant; Glutathione Transferase; Hydrogen Peroxide; Hypoxia; Metals, Heavy; Molecular Sequence Data; Oryza; Plant Growth Regulators; Plant Roots; Polyethylene Glycols; rac1 GTP-Binding Protein; RNA; Sequence Analysis, Protein; Sodium Chloride

Topics: Animals; Ascorbic Acid; Carotid Body; Cats; Chemoreceptor Cells; Chromatography, High Pressure Liquid; Female; Hypoxia; In Vitro Techniques; Male; Signal Transduction

Tyrosine nitration is a common modification to proteins in vivo, but the reactive nitrogen species responsible for nitration are often studied in vitro using just the amino acid tyrosine in simple phosphate solutions. To investigate which reactive nitrogen species could nitrate proteins in a complex biological system, we exposed rat heart and brain homogenates to peroxynitrite, nitric oxide under aerobic conditions, and other putative nitrating agents. Peroxynitrite was by far the most efficient nitrating agent when alternative targets were available to compete with tyrosine. Curiously, proteins in heart homogenates were substantially more resistant to nitration than brain homogenates. Ultrafiltration to remove low molecular weight compounds made the heart proteins equally susceptible as the brain proteins to nitration. Endogenous ascorbate and free thiols had little effect on nitration by peroxynitrite in either heart or brain. However, accumulation of urate formed by the oxidation of hypoxanthine by xanthine dehydrogenase and oxidase in heart appeared to be the major inhibitor of nitration. Heart homogenates treated with uricase, which converts urate to allantoin, showed equivalent nitration as in brain homogenates. Urate, as assayed by HPLC, was 58 +/- 8 microM in heart but only 4 +/- 2 microM in brain homogenates. Although xanthine dehydrogenase conversion to a free radical-producing oxidase can serve as an important source of superoxide and hydrogen peroxide during ischemia/reperfusion, our results suggest that urate formation by xanthine dehydrogenase may provide a significant antioxidant defense against peroxynitrite and related nitric oxide-derived oxidants.

Topics: Animals; Ascorbic Acid; Brain; Heart; Hypoxanthine; Hypoxia; In Vitro Techniques; Myocardium; Nitric Oxide; Nitrosation; Peroxynitrous Acid; Rats; Rats, Sprague-Dawley; Tyrosine; Urate Oxidase; Uric Acid; Xanthine Dehydrogenase; Xanthine Oxidase

Antioxidant plasma activities of ascorbate, alpha-tocopherol and glutathione peroxidase were analysed in adult male sea bass, Dicentrarchus labrax, in normal conditions and after hypoxia-recovery. In addition, tank measurements of temperature, pH, salinity and chlorine changes were carried out. Ascorbate and alpha-tocopherol were measured using a high-pressure liquid chromatography method and glutathione peroxidase activity enzymatically. Ascorbate and alpha-tocopherol showed a relationship with the velocity of body growing in normal and hypoxia-recovery conditions. In sea bass exposed to hypoxia, only ascorbate and alpha-tocopherol levels were significantly lower compared with the control group. Slope study and expression percent of antioxidants reduction after stress conditions revealed a predominant role of plasma alpha-tocopherol. Sea bass subjected to variations of salinity and chlorine showed a significant decrease in plasma alpha-tocopherol. A relationship could be suggested between antioxidant defence and fish response in aquaculture.

Topics: alpha-Tocopherol; Animals; Antioxidants; Aquaculture; Ascorbic Acid; Bass; Body Weight; Chlorine; Chromatography, High Pressure Liquid; Glutathione Peroxidase; Hydrogen-Ion Concentration; Hypoxia; Male; Osmolar Concentration; Seawater; Stress, Physiological; Temperature

Exposure of PC12 cells to chronic hypoxia (CH; 10 % O(2), 24 h) augments catecholamine secretion via formation of a Cd2+-resistant Ca2+ influx pathway, and up-regulates native L-type Ca2+ channels. These effects are mimicked by exposure of cells to Alzheimer's disease-associated amyloid beta peptides (AbetaPs). Since pathological effects of AbetaPs have been associated with increased levels of reactive oxygen species (ROS), the involvement of ROS in hypoxia-mediated up-regulation of exocytosis and Ca2+ channel activity was examined. Both melatonin and ascorbic acid (two structurally unrelated antioxidants) fully blocked the enhancement of catecholamine secretion caused by CH (as determined amperometrically). Enhanced immunofluorescence, observed in chronically hypoxic cells using a primary monoclonal antibody raised against the N-terminus of AbetaP, was also suppressed by melatonin. Ascorbic acid, melatonin and ebselen (an additional antioxidant) also fully prevented augmentation of whole-cell Ca2+ currents caused by CH (as monitored using whole-cell patch-clamp recordings). Exposure of normoxic cells to H(2)O(2) (40 microM, 24 h), like hypoxia, caused Ca2+ channel up-regulation. Importantly, AbetaP formation appeared to be an absolute requirement for the effects of hypoxia, since the ability of CH to augment exocytosis and Ca2+ channel activity was blocked by two novel inhibitors of gamma secretase, an enzyme complex required for AbetaP formation. Our results indicate that the effects of hypoxia require ROS generation from AbetaPs, and suggest that elevated levels of ROS mediate hypoxic and AbetaP-mediated pathological remodelling of Ca2+ homeostasis.

Topics: Amyloid beta-Peptides; Animals; Antioxidants; Ascorbic Acid; Cadmium; Calcium Channels; Electrophysiology; Exocytosis; Hypoxia; Immunohistochemistry; Melatonin; Membrane Potentials; Microelectrodes; Oxidative Stress; Patch-Clamp Techniques; PC12 Cells; Rats; Reactive Oxygen Species

Eight subjects were placed in a decompression chamber for 31 days at pressures from sea level (SL) to 8848 m altitude equivalent. Whole blood lipid peroxidation (LP) was increased at 6000 m by a mean of 23% (P<0.05), at 8000 m by 79% (P<0.01) and at 8848 m by 94% (P<0.01). (All figures are means.) Two days after return to sea level (RSL), it remained high, by 81% (P<0.01), while corresponding erythrocyte GSH/GSSG ratios decreased by 31, 46, 49, 48%, respectively (each P<0.01). Erythrocyte SOD and plasma ascorbate did not change significantly. At sea level, maximal exercise induced a 49% increase in LP (P<0.01), and a 27% decrease in erythrocyte GSH/GSSG ratio relative to resting values (P<0.05). At 6000 m, the LP was enhanced further from 23 (P<0.05) to 66% (P<0.01), and after RSL from 81 (P<0.01) to 232% (P<0.01), while pre-exercise GSH/GSSG ratios did not change significantly. Exercise did not change plasma ascorbate relative to sea level or to 6000 m, but decreased after RSL by 32% (P<0.01). These findings suggest that oxidative stress is induced by prolonged hypobaric hypoxia, and is maintained by rapid return to sea level, similar to the post-hypoxic re-oxygenation process. It is increased by physical exercise.

Topics: Acclimatization; Adult; Altitude; Antioxidants; Ascorbic Acid; Circadian Rhythm; Erythrocytes; Exercise; France; Glutathione; Hematocrit; Humans; Hyperbaric Oxygenation; Hypoxia; Lipid Peroxidation; Male; Oxidative Stress; Oxygen Consumption; Reference Values; Rest; Severity of Illness Index; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances

To explore the therapeutic methods for hypoxia and cold induced blood vessel damage by observing the changes of NO synthase (NOS) activity in hypoxia and development of coldm induced blood vessels damage, and studying the effects of SOD and vitamin C on the changes of NOS activity.. The main artery was isolated from Wistar rats and exposed to hypoxia and/or cold environment in vitro. LDH activity was measured using an automatic biochemical analyzer and NOS and SOD activities in blood vessels were analyzed respectively by Griess assay and adrenaline autoxidantion method.. NOS activity in hypoxia, cold and hypoxia-cold damaged vessels decreased by 18.2%, 19.1% and 25.9% respectively after exposure as compared with the control vessels. The changes of NOS activity were time dependent. The NOS activity in damaged vessels was negatively correlated with LDH activity in the culture medium of the respective vessels. The SOD activity in hypoxia and/or cold damaged vessels also decreased significantly. Giving SOD (200 u/ml) or vitamin C (50 mg/ml) immediately after hypoxia and/or cold exposure increased the NOS activity and SOD activity in the damaged vessels significantly, as compared with the non-treatment controls.. The decrease of NOS activity is closely related to the development of damage induced by hypoxia and/or cold injury. SOD and vitamin C could protect the blood vessels exposed to hypoxia and/or cold from damage, possibly by increasing NOS activity.

Topics: Animals; Ascorbic Acid; Blood Vessels; Cold Temperature; Female; Hypoxia; L-Lactate Dehydrogenase; Male; Nitric Oxide Synthase; Rats; Rats, Wistar; Superoxide Dismutase

Post-hypoxic-ischemic (HI) reperfusion induces excess production of non-protein-bound iron (NPBI), leading to formation of the highly reactive hydroxyl radical. We investigated whether the iron-chelator deferoxamine (DFO) could reduce reperfusion injury and improve left ventricular (LV) function. We produced severe HI in 14 newborn lambs and measured pre-HI, upon reperfusion, 60 and 120 min after HI the following parameters: mean aortic blood pressure, total peripheral resistance, stroke volume (SV), ejection fraction (EF) and LV contractility (pre-HI, 60 and 120 min post-HI). These parameters were assessed by measuring LV pressure (tip manometer) and volume (conductance catheter), using inflow occlusion to obtain slope (Ees) and volume intercept of the end-systolic P-V relationship (V10). We determined the antioxidative capacity, i.e. the ratio of ascorbic acid and dehydroascorbic acid (AA/DHAA) and malondialdehyde from coronary sinus blood at pre-HI and at 15, 60 and 120 min post-HI. Seven lambs received DFO (10 mg/kg i.v.) immediately after HI, 6 control lambs received a placebo. While neither Ees nor EF changed significantly in either group, the volume intercept V10 in the DFO-treated group was significantly smaller (0.25 +/- 0.03 vs. 0.70 +/- 0.09, p < 0.05), whereas SV was larger (3.6 +/- 0.6 vs. 2.2 +/- 0.2 ml, p < 0.05) and the AA/DHAA ratio was significantly lower at 15 min post-HI (p < 0.05) providing evidence for HI damage and for the protective effect of DFO.. post-HI treatment of the newborn lamb with DFO has a modifying effect on free radical-induced damage to the myocardium and protects myocardial performance.

Topics: Animals; Animals, Newborn; Ascorbic Acid; Chelating Agents; Deferoxamine; Dehydroascorbic Acid; Female; Heart; Hypoxia; Male; Malondialdehyde; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Oxidation-Reduction; Sheep

Antioxidants are known to play an important role in mitigating oxidative stress injury. Regional concentrations of non-enzymatic antioxidants, redox ratio and lipid peroxides were studied in normal, ischemic and ischemic-reperfused rat hearts. Isolated perfused rat hearts were made globally ischemic for 45 min and reperfused for 15 min. Right ventricular wall (RVW), septum (S) and left ventricular wall (LVW) from control, ischemic (I) and reperfused (I-R) hearts were analysed. Tocopherol, retinol and ascorbic acid concentrations in different regions of perfused control hearts were not different. Reduced glutathione (GSH) was significantly lower in the RVW, while S and LVW had about three-fold higher levels. Oxidized glutathione (GSSG) was lower in the RVW and most concentrated in the LVW. The GSH:GSSG ratio was highest in the septum while RVW and LVW had similar values. Lipid hydroperoxide (LPx) concentrations in the three regions of control hearts were not different from each other. In I and I-R hearts, vitamin E declined in all three regions but the loss was significant only in the septum in the I group and in the septum and LVW of the I-R group. Vitamin A showed significant loss in all three regions of the I-R group. Vitamin C declined significantly only in the RVW of the I-R group. GSH increased in the RVW of the I and I-R groups compared to controls. GSSG was increased in the RVW and septum of the I group and in all regions of the I-R group. The redox ratio, GSH:GSSG, decreased in all regions of both I and I-R groups. LPx were increased in the septum of the I group and in all regions of the I-R group. Despite unique regional differences in non-enzymatic antioxidants, a comparable increase in LPx in the I-R group and similar extent of reduction in the redox ratio in different regions of the I and I-R groups, suggest that each myocardial region may use different antioxidant mechanisms to withstand oxidative stress.

Topics: Animals; Antioxidants; Ascorbic Acid; Glutathione; Glutathione Disulfide; Heart; Hypoxia; Ischemia; Lipid Peroxides; Male; Oxidative Stress; Perfusion; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Tissue Distribution; Vitamin A; Vitamin E

Recently, marked oxygen dependence of respiration by isolated mitochondria after exposure to prolonged hypoxia has been described. Because mitochondrial oxygen-dependent respiration could significantly influence oxygen consumption during critical illness, we sought to confirm the oxygen-dependent behavior of mitochondria. We hypothesized that mitochondria isolated during sepsis would exhibit increased oxygen dependence. We isolated rat liver mitochondria 16 h after cecal ligation and puncture and found a 30-40% greater oxygen uptake compared with control rats under state 3 conditions. Mitochondria incubated in deoxygenated buffer were studied for oxygen dependence at 10-min intervals for 90 min. Mitochondrial respiration after reoxygenation was stable over a 60-min period of hypoxia for control rats and decreased slightly for septic rats (10-15%). State 3 respiration was 10% lower when mitochondria were reoxygenated at low (15-25 Torr) versus high (90-100 Torr) and low (10-15 Torr) versus intermediate (40-45 Torr) oxygen tension. Oxygen consumption with ascorbate+N, N, N', N'-tetramethyl-p-phenylenediamine was 20% lower at low versus high oxygen tension. No increase in oxygen dependence was observed during 1 h of hypoxic incubation. Our data indicate only a modest oxygen dependence of respiration between 10 and 100 Torr, which is similar for septic and control mitochondria. Additionally, oxygen dependence did not increase significantly during a 1-h hypoxic exposure for well-coupled mitochondrial preparations.

Topics: Animals; Ascorbic Acid; Cecum; Hypoxia; Kinetics; Male; Mitochondria, Liver; Oxygen Consumption; Rats; Rats, Sprague-Dawley; Reference Values; Sepsis; Tetramethylphenylenediamine; Time Factors

Defenses against free radicals were evaluated in the dog under different conditions of ventilation. Changes in the levels of reduced glutathione (GSH), alpha-tocopherol (vitamin E), ascorbic acid (vitamin C) and the lipid peroxidation end-products, estimated as malondialdehyde (MDA) and the activity of superoxide dismutase (SOD), were studied in serial liver biopsies from dogs ventilated with either oxygen, halothane and oxygen, hypoxic gas mixture of 8% oxygen and 92% nitrogen or halothane under hypoxic conditions. Simultaneous determination of GSH, vitamin E and MDA were carried out in the plasma. The results showed time-dependent depletion of GSH and vitamin E in liver and plasma and vitamin C in the liver. This was accompanied by a simultaneous increase in the levels of MDA. The magnitude of the change was in the following order: halothane and hypoxia > hypoxia > halothane and oxygen > oxygen. The greatest depletion was observed for vitamin E and the least for vitamin C. The rise in the level of MDA in plasma was much higher than in the liver tissue. Hypoxia resulted in inhibition of liver SOD activity. It seems that increased production of free radicals under hypoxic conditions may have overwhelmed the anti-oxidant defenses in the liver. In addition, the much higher level of MDA in plasma, as compared to liver tissue, may indicate that MDA could have originated in tissues or organs other than the liver and leaked into the blood, indicating possible damage in other locations in the body.

Topics: Anesthesia; Anesthetics, Inhalation; Animals; Ascorbic Acid; Dogs; Free Radical Scavengers; Free Radicals; Glutathione; Halothane; Hypoxia; Liver; Malondialdehyde; Oxidative Stress; Oxygen Consumption; Superoxide Dismutase; Vitamin E

In the present study, we examined the effect of blockade of the brain stem renin-angiotensin system on renal sympathetic baroreflexes and chemoreflexes in conscious rabbits and examined the role of central catecholaminergic pathways in these responses. Eleven rabbits underwent preliminary surgical instrumentation and pretreatment with central 6-hydroxydopamine (6-OHDA, 500 micrograms/kg) or ascorbic acid 6 wk before the commencement of the experiments. Baroreflex curves were determined under conditions of normoxia and hypoxia (10% O2 + 3% CO2) before and after central administration of either Ringer solution, the ANG II receptor antagonist losartan (10 micrograms), or the angiotensin-converting enzyme inhibitor enalaprilat (500 ng) on separate days. Losartan increased the upper plateau and the range of the mean arterial pressure (MAP)-renal sympathetic nerve activity (RSNA) curve (79 and 78%, respectively) in intact rabbits, whereas this effect was not observed in 6-OHDA-pretreated rabbits. Hypoxia elicited an increase in resting RSNA (111% in intact rabbits and 74% in 6-OHDA-injected rabbits) and elevated the upper plateau of the RSNA-MAP curve in both groups (89% in intact rabbits and 114% in 6-OHDA-injected rabbits). During hypoxia, losartan and enalaprilat increased the RSNA upper plateau in intact rabbits but had no effect in 6-OHDA-pretreated rabbits. No effects on the MAP-heart rate baroreflex curves were observed. Thus the effect of losartan to increase RSNA, particularly during hypoxia and baroreceptor unloading, being abolished by central noradrenergic depletion suggests that the endogenous ANG II which normally causes an inhibition of renal sympathetic motoneurons is dependent on the integrity of central catecholaminergic pathways.

Topics: Angiotensin II; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Ascorbic Acid; Baroreflex; Blood Pressure; Brain; Enalaprilat; Female; Heart Rate; Hypoxia; Kidney; Losartan; Male; Oxidopamine; Rabbits; Reference Values; Renin-Angiotensin System; Sympathetic Nervous System

To observe the effects of large dose of vitamin C (Vc) on myocardial mitochondrial function, ATP content, and myocardial structure in acute and chronic hypoxic rats.. Rats were exposed to a simulated altitude 4000 m (barometric pressure = 43 kPa) for 3 and 30 d. Vc (0.75 g.kg-1.d-1) was injected i.p. The heart mitochondrial respiratory function were determined by Clark-type O2 electrode; mitochondrial membrane fluidity (MMF) were assayed through fluorescence polarizative method; the contents of ATP, ADP, and AMP in myocardial tissue were measured with HPLC.. After administration of Vc, the ATP content was increased from 35 +/- 3 mg.g-1 to 53 +/- 3 mg.g-1 in acute hypoxic rats (P < 0.01), from 42 +/- 4 mg.g-1 to 48 +/- 3 mg.g-1 in chronic hypoxic rats (P < 0.01); Pa, O2 was increased from 7.2 +/- 1.4 kPa to 9.5 +/- 1.2 kPa in acute hypoxic rats (P < 0.01); mitochondrial respiratory control rate (RCR) was increased from 2.1 +/- 0.6 to 4.7 +/- 0.5 in acute hypoxic rats (P < 0.01), and from 3.3 +/- 0.7 to 4.5 +/- 0.6 in chronic hypoxic rats (P < 0.01); MMF was increased in acute and chronic hypoxic rats (P < 0.05); the degree of myocardial necrosis in vitamin C preventive rats was attenuated as compared with those of acute hypoxic rats.. Vc is effective on improving myocardial energy metabolism and protecting against myocardial structural injury in hypoxic rats.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Ascorbic Acid; Cell Respiration; Female; Hemodynamics; Hypoxia; Male; Membrane Fluidity; Mitochondria, Heart; Rats; Rats, Wistar

An important role in O2 sensing has been assigned to microsomal and membrane-bound b-type cytochromes which generate regulatory reactive O2 species (ROS). Recently, ROS have been shown to suppress the in vitro synthesis of erythropoietin (Epo). We investigated the potential of the antioxidant vitamins A, E and C to enhance renal and hepatic Epo production. Renal effects were studied in isolated serum-free perfused rat kidneys. In control experiments without antioxidant vitamins, Epo secretion amounted to 441 +/- 23 mU/g kidney (mean +/- SEM, N = 5) during the three hour period of hypoxic perfusion (arterial pO2 35 mm Hg). Epo secretion significantly increased to 674 +/- 92 mU/g kidney (N = 7) when vitamins A (0.5 microgram/ml), E (0.5 microgram/ml) and C (10 micrograms/ml) in combination were added to the perfusion medium. The effects of the single vitamins were studied in Epo-producing hepatoma cell cultures (lines HepG2 and Hep3B). Vitamin A induced a dose-dependent increase (half-maximal stimulation at 0.2 microgram/ml) in the production of immunoreactive Epo during 24 hours of incubation (such as 680 +/- 51 U Epo/g cell protein in HepG2 cultures with 3 micrograms/ml retinol acetate compared to 261 +/- 15 U/g in untreated controls; N = 4). In contrast, vitamin E (tested from 0.05 to 500 micrograms/ml) and vitamin C (tested from 2 to 200 micrograms/ml) did not increase Epo production in hepatoma cell cultures. Thus, while vitamins E and C may have the potential to protect cells from oxidative damage, vitamin A exerts a specific stimulation of Epo production. Preliminary evidence suggests that this effect of vitamin A involves increased mRNA levels of hypoxia-inducible factor 1 alpha (HIF-1 alpha).

Topics: Animals; Antioxidants; Ascorbic Acid; Cell Line; DNA-Binding Proteins; Erythropoietin; Gene Expression; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; In Vitro Techniques; Kidney; Liver; Male; Nuclear Proteins; Perfusion; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transcription Factors; Vitamin A; Vitamin E; Vitamins

Vitamin C or L-ascorbate is an effective endogenous reducing agent influencing the functions that are involved with the redox mechanism. Detection of oxygen tension changes by the carotid body chemoreceptors is one such function. In this study we investigated the hypothesis that the level of ascorbate, if present, could change in the carotid body as a result of ascorbate's interaction in the chemosensing process, which would be reflected in the production of the ascorbyl radical. We addressed this issue by examining changes of the ascorbyl radical, using the in vitro electron spin resonance spectroscopy (ESR), in the carotid bodies dissected from pentobarbitone anesthetized cats exposed in vivo to three eucapnic, breathing gas mixtures of different O2 concentration: normoxic, 21% O2; hypoxic, 7% O2; and hypoxic-reoxygenated, 7% O2 followed by 100% O2. Each group consisted of five cats, yielding five pairs of carotid bodies for the ESR signal recording. We found that the intensity of ESR signals, measured as peak-to-peak amplitude, was diminished by 39 and 43% in the hypoxic and hypoxic-reoxygenated groups, respectively, compared with that in normoxia. The study shows that ascorbate was present in the normoxic carotid body and was depleted by hypoxia. We conclude that ascorbate is part of free radical mechanisms operative in the carotid body in hypoxia.

Topics: Animals; Ascorbic Acid; Carotid Body; Cats; Electron Spin Resonance Spectroscopy; Female; Free Radicals; Hypoxia; Male; Tidal Volume

Cerebral injury may occur not only during brain ischemia but also during reperfusion afterward. A characteristic event during reperfusion after cerebral ischemia, or reoxygenation after anoxia in hippocampal slices, is hyperoxidation of the electron carriers of the mitochondrial respiratory chain. Earlier studies suggested that mitochondrial hyperoxidation was produced by an oxyradical mechanism and was linked to neuronal damage. Present studies sought to test this hypothesis by determining whether antioxidants could suppress mitochondrial hyperoxidation and improve electrical recovery after anoxia in hippocampal slices. Both 500 microM ascorbate and 50 microM glutathione decreased post-anoxic hyperoxidation of NADH and improved electrical recovery in hippocampal slices. These data support a role of oxygen free radicals in promoting post-anoxic mitochondrial hyperoxidation and electrical failure, and suggest that these effects of anoxia or ischemia may be linked.

Topics: Animals; Antioxidants; Ascorbic Acid; Glutathione; Hippocampus; Hypoxia; In Vitro Techniques; Male; Membrane Potentials; Mitochondria; NAD; Oxidation-Reduction; Rats; Rats, Wistar; Time Factors

Ascorbic acid and glutathione (GSH) are antioxidants and free radical scavengers that provide the first line of defense against oxidative damage in the CNS. Using HPLC with electrochemical detection, we determined tissue contents of these antioxidants in brain and spinal cord in species with varying abilities to tolerate anoxia, including anoxia-tolerant pond and box turtles, moderately tolerant garter snakes, anoxia-intolerant clawed frogs (Xenopus laevis), and intolerant Long-Evans hooded rats. These data were compared with ascorbate and GSH levels in selected regions of guinea pig CNS, human cortex, and values from the literature. Ascorbate levels in turtles were typically 100% higher than those in rat. Cortex, olfactory bulb, and dorsal ventricular ridge had the highest content in turtle, 5-6 mumol g-1 of tissue wet weight, which was twice that in rat cortex (2.82 +/- 0.05 mumol g-1) and threefold greater than in guinea pig cortex (1.71 +/- 0.03 mumol g-1). Regionally distinct levels (2-4 mumol g-1) were found in turtle cerebellum, optic lobe, brainstem, and spinal cord, with a decreasing anterior-to-posterior gradient. Ascorbate was lowest in white matter (optic nerve) in each species. Snake cortex and brainstem had significantly higher ascorbate levels than in rat or guinea pig, although other regions had comparable or lower levels. Frog ascorbate was generally in an intermediate range between that in rat and guinea pig. In contrast to ascorbate, GSH levels in anoxia-tolerant turtles, 2-3 mumol g-1 of tissue wet weight, were similar to those in mammalian or amphibian brain, with no consistent pattern associated with anoxia tolerance. GSH levels in pond turtle CNS were significantly higher (by 10-20%) than in rat for several regions but were generally lower than in guinea pig or frog. GSH in box turtle and snake CNS were the same or lower than in rat or guinea pig. The distribution GSH in the CNS also had a decreasing anterior-to-posterior gradient but with less variability than ascorbate: levels were similar in optic nerve, brainstem, and spinal cord. The paradoxically high levels of ascorbate in turtle brain, which has a lower rate of oxidative metabolism than mammalian, suggest that ascorbate is an essential cerebral antioxidant. High levels may have evolved to protect cells from oxidative damage when aerobic metabolism resumes after a hypoxic dive.

Topics: Adaptation, Physiological; Animals; Ascorbic Acid; Central Nervous System; Colubridae; Female; Glutathione; Humans; Hypoxia; Male; Mammals; Periaqueductal Gray; Reptiles; Species Specificity; Tissue Distribution; Turtles; Xenopus laevis

Topics: Animals; Ascorbic Acid; Hypoxia; Rats; Rats, Wistar; Vitamin E

We determined the ascorbic acid (ascorbate) and glutathione (GSH) contents of eight regions of the CNS from anoxia-tolerant turtles collected in summer and in winter. Ascorbate was of special interest because it is found in exceptionally high levels in the turtle CNS. The temperature-dependence of CNS ascorbate content was established by comparing levels in animals collected from two geographic zones with different average winter temperatures and in animals re-acclimated to different temperatures in the laboratory. The analytical method was liquid chromatography with electrochemical detection. Turtle ascorbate levels were 30-40% lower in animals acclimatized to winter (2 degrees C) than to summer (23 degrees C) in all regions of the CNS. Similarly, GSH levels were 20-30% lower in winter than in summer. Winter ascorbate levels were higher in turtles from Louisiana (19 degrees C) than in turtles acclimatized to winter in Wisconsin (2 degrees C). Summer and winter levels of ascorbate could be reversed by re-acclimating animals to cold (1 degree C) or warm (23 degrees C) temperatures for at least one week. CNS water content did not differ between cold- and warm-acclimated turtles. Taken together, the data indicated that ascorbate and GSH undergo significant seasonal variation and that the catalyst for change is environmental temperature. Steady-state ascorbate content showed a linear dependence on temperature, with a slope of 1.5% per degree C that was independent of CNS region. Lower levels of cerebral antioxidants in turtles exposed to colder temperatures were consistent with the decreased rate of cerebral metabolism that accompanies winter hibernation. Cerebral ascorbate and GSH levels in the turtle remained similar to or higher than those in mammals, even during winter, however. These findings support the notion that unique mechanisms of antioxidant regulation in the turtle contribute to their tolerance of the hypoxia-reoxygenation that characterizes diving behavior.

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Central Nervous System; Cold Temperature; Cricetinae; Free Radicals; Glutathione; Hibernation; Hot Temperature; Hypoxia; Olfactory Bulb; Oxygen; Seasons; Turtles

In the first part of our experiments we investigated the ascorbic acid content in five areas of the brain in 11 age groups of rats aged 1 to 90 postnatal days. In the area of the olfactory lobe the values vary within the range of 2.9-4.5 mmol/kg fresh weight, with a significant drop on the 21st, 35th and 90th day. In the cerebral cortex the scatter of values was similar with a significant drop on the 21st and 90th day. From the hippocampal area varying values were obtained, the drop on the 5th, 12th, 15th, 21st, 35th and 90th day being significant. The curve of the ascorbic acid content in the area of the vermis cerebelli has the typical shape of a wave. The initial drop is followed by a rise with the maximum on the 18th day. A significant drop was observed on the 5th, 7th and 90th day, a significant rise on the 12th, 15th, 18th and 21st day. In the area of the medulla oblongata the lowest ascorbic acid values in our experiment were recorded. A significant drop was observed on the 5th, 21 st, 35th and 90th day, a significant rise on the 18th day. All significances are referred to one-day old rats. In the second part of our experiments we studied the influence of acute and chronic hypoxia on the ascorbic acid content in liver, adrenal, plasma, cerebrospinal fluid and brain in 18-day-old rats. Due to acute hypoxia a significant decrease in ascorbic acid concentration in the adrenal occurred. Its levels in plasma and cerebrospinal fluid increased significantly compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aging; Animals; Antioxidants; Ascorbic Acid; Brain; Female; Hypoxia; Male; Rats; Rats, Wistar; Vitamin E

Topics: Altitude Sickness; Animals; Ascorbic Acid; Brain; Hypoxia; Male; Rats; Rats, Wistar; Superoxide Dismutase

Topics: Altitude; Animals; Ascorbic Acid; Brain; Hypoxia; Male; Rats; Rats, Wistar; Superoxide Dismutase

In vivo electrochemistry has been a valuable tool in detecting real time neurochemical changes in extracellular fluid. Absolute selectivity has been difficult to achieve previously, but we report here a carbon fiber electrode and measurement technique which is specific for one oxidizable species: ascorbic acid. Ascorbic acid is highly concentrated in extra- as well as intracellular brain spaces, and appears to undergo dynamic changes in response to a variety of physiological and pathophysiological circumstances. Recent studies have implicated glutamatergic mechanisms which give rise to extracellular changes in brain ascorbate, and we confirm and extend these observations. Preliminary studies, directed towards examining ascorbic acid as an index and/or result of hypoxia, spreading depression, and seizure activity, have been undertaken and the results are reported herein.

Topics: Animals; Ascorbate Oxidase; Ascorbic Acid; Brain; Cortical Spreading Depression; Electric Stimulation; Electrochemistry; Glutamates; Glutamic Acid; Hypoxia; Male; Potassium; Rats; Rats, Inbred Strains; Seizures

Two horses with red maple (Acer rubrum) toxicity responded to treatment with high doses of vitamin C (ascorbic acid), in addition to blood transfusions, and intravenous fluid therapy. The clinical course included Heinz body anemia, marked methemoglobinemia, depression, and evidence of severe tissue anoxia. Clinical recovery was dramatic with stabilization achieved 36 hours following the initiation of ascorbic acid therapy.

Topics: Anemia; Animals; Ascorbic Acid; Heinz Bodies; Horse Diseases; Horses; Hypoxia; Male; Methemoglobinemia; Plant Poisoning; Trees

The isolated turtle brain maintains intra- and extracellular concentrations of ascorbate when incubated in ascorbate-free physiological saline for as long as 24 h. After incubation for 1 h, total tissue content of ascorbate in the turtle cerebellum was the same as in unincubated controls. After 20-24 h, tissue ascorbate content remained at 65% of control levels, while extracellular ascorbate concentration, measured with carbon fiber voltammetric microelectrodes, was 56% of the initial value. For an intermediate incubation period of 6 h, reduced ascorbate content was maintained at about 80% of control levels, regardless of whether incubation was under normal conditions or in the absence of glucose or oxygen. By contrast, only 4% of the ascorbate content of guinea pig brain slices remained after a 6 h incubation. Maintenance of high levels of ascorbate by the anoxia-resistant turtle brain could be an important factor in the amelioration of oxidative injury in this tissue. Inclusion of ascorbate in media used for in vitro studies of mammalian brain tissue is recommended.

Topics: Animals; Ascorbic Acid; Brain; Cerebellum; Dehydroascorbic Acid; Disease Susceptibility; Extracellular Space; Female; Hypoxia; In Vitro Techniques; Male; Osmolar Concentration; Reference Values; Turtles

A single dose of ascorbic acid, 1 mg/g of body weight by the i.p. route, caused a marked increase of its content in five areas of the brain in 18-day-old laboratory rats, as compared with intact animals. Acute hypoxia at 9000 m mitigated this increase. Conversely a combination of chronic intermittent hypoxia and ascorbic acid administration led in all investigated areas of the brain to a mild but insignificant rise of values except for the vermis cerebelli, where a significant rise at the 5% level of significance occurred.

Topics: Animals; Ascorbic Acid; Brain; Hypoxia; Rats; Rats, Inbred Strains

Two groups of male rats were exposed to simulated altitudes of 6060 m and 7576 m for 6 h/day for 7 days (intermittent exposure). In two additional groups of animals exposed to the same altitude, 100 mg of ascorbic acid (AA) was fed daily for 5 days prior to the exposure period and also during the exposure period. Rats that did not receive AA showed loss of body weight and weight of reproductive organs after exposure. Sex organs showed atrophy on histological examination and there was a deterioration in spermatozoal quality. There was an increase in alkaline and acid phosphatase, and decrease in protein, sialic acid and glyceryl phosphorylcholine content in various reproductive tissues after exposure. All the above changes in histology and biochemical composition could be partially prevented by AA supplementation. AA supplementation can therefore protect the male reproductive system from deleterious effects of hypoxia. The probable mechanism of action of AA is discussed.

Topics: Altitude; Animals; Ascorbic Acid; Genitalia, Male; Hypoxia; Male; Rats; Rats, Inbred Strains

Topics: Animals; Ascorbic Acid; Biological Transport; Cations, Divalent; Duodenum; Ferric Compounds; Ferrous Compounds; Hypoxia; Intestinal Absorption; Intestinal Mucosa; Male; Mice; Microvilli; Nitrilotriacetic Acid; Oxidation-Reduction

The influence of acute and chronic hypoxia on the ascorbic acid content in liver, adrenal, plasma, cerebrospinal fluid and brain in 18-day-old rats was studied. Due to acute hypoxia a significant decrease in ascorbic acid concentration in the adrenal occurred. Its levels in plasma and cerebrospinal fluid increased significantly compared with controls. Chronic hypoxia caused a significant ascorbic acid concentration increase in all samples studied with the exception of olfactory lobe and vermis cerebelli.

Topics: Acute Disease; Adrenal Glands; Age Factors; Animals; Ascorbic Acid; Brain; Chronic Disease; Hypoxia; Liver; Rats; Rats, Inbred Strains

The transepithelial transport of ascorbate across the isolated rabbit ciliary epithelium (CE) was investigated. Unidirectional 14C-ascorbate fluxes were measured in the presence of equal concentrations of ascorbate on both sides of the tissue within the range of 0.025 to 1 mM. The blood to aqueous (Bl----Aq) flux increased from 6 to 95 nmoles/hr and showed nonlinearity and saturation. The aqueous to blood (Aq----Bl) flux increased, for the same range, from 0.5 to 23 nmoles/hr in a linear fashion. The permeability calculated from the Aq----Bl flux was similar to the CE permeability for mannitol suggesting that the Aq----Bl flux is mainly paracellular. The flux ratio Bl----Aq/Aq----Bl was between 4 to 12. Anoxia, ouabain and low Na+ in the media inhibited the Bl----Aq flux indicating that the transport system requires energy and a Na+ gradient. 3-O-methyl-D-glucose, D-isoascorbic acid and phlorizin also inhibited the Bl----Aq flux, suggesting that ascorbate and glucose may share a common carrier mechanism. Although the isolated CE preparation was clearly capable of flux separation and active transport, the rate of ascorbate transport measured in vitro is insufficient to maintain the aqueous ascorbate concentration observed in vivo.

Topics: 3-O-Methylglucose; Amphotericin B; Animals; Aqueous Humor; Ascorbic Acid; Biological Transport, Active; Blood; Cell Membrane Permeability; Ciliary Body; Epithelium; Female; Hypoxia; In Vitro Techniques; Methylglucosides; Osmolar Concentration; Phlorhizin; Rabbits

The ability of ascorbic acid, alpha-tocopherol, and hypoxia to modify iron uptake, chelation, and toxicity as manifested by the generation of malonyldialdehyde (MDA) was studied in myocardial cell cultures obtained from newborn rats. Exposure to 20 micrograms/ml iron provided as 59Fe-ferric ammonium citrate in serum-free Ham F-10 culture medium resulted in the accumulation of 39% of the iron within 24 hours and a 10- to 12-fold increase in cellular MDA. Hypoxia (1% oxygen) resulted in a more than twofold increase in iron uptake but only minor changes in cellular MDA concentrations. Ascorbic acid and alpha-tocopherol (1 mg/ml) had opposing effects on iron uptake and MDA production. Ascorbic acid reduced 24-hour iron uptake by 73% (P less than 0.001) whereas alpha-tocopherol increased iron uptake by 19% (P less than 0.025). In contrast, cellular MDA after iron loading increased by 86% with the addition of ascorbate, and was reduced by 75% with alpha-tocopherol (P less than 0.001). The ratio of increase in cellular MDA relative to percent iron uptake (lipid peroxidation ratio) was 7.29 with iron loading plus ascorbate vs. 0.13 with iron loading plus alpha-tocopherol, a 56-fold difference between the two extremes. In vitro deferoxamine treatment for 3 hours resulted in a 53% reduction in the radioactive iron content of iron-loaded heart cells and a 40% reduction in MDA. Simultaneous deferoxamine and ascorbate or alpha-tocopherol treatment did not affect iron mobilization, but had a profound effect on MDA concentrations. Ascorbic acid prevented entirely the beneficial effect of deferoxamine on MDA concentrations in iron-loaded cells, whereas alpha-tocopherol potentiated the effect of deferoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Ascorbic Acid; Cells, Cultured; Hypoxia; Iron; Lipid Metabolism; Lipid Peroxides; Malonates; Malondialdehyde; Myocardium; Rats; Vitamin E

The incisive detection of bioenergetic insufficiency in an organ of known workload by P MRS is noninvasive and nondestructive, and in some cases the portion of the organ involved can be determined, particularly if both PCr and ATP are depleted. The fractional loss of ATP and hence the relative volumes of viable and "metabolically dead" tissue are thereby evaluated. In addition, the value of P MRS in following a therapy complements its value in diagnosis as this has been demonstrated in cases followed over 6 months to three years. The fact that deficiencies of the enzymes and substrates of oxidative metabolism can be detected by P MRS affords a global overview of energy metabolism that can be a key to rapid diagnosis. The distinction of the enzyme and/or substrate deficiency, while not directly indicated by steady state P MRS, can be identified by use of the "Crossover Theorem" and its impact upon blood and tissue levels of substrates (including oxygen). In the case of neonatal systemic hypoxia, there is no doubt about which of the equations applies, and similarly in metabolic disease, a glutaric acid urea is a direct consequence of the crossover response of metabolism and signifies that an enzyme deficiency may be involved. Furthermore, the clinical danger of a high Pi/PCr value is clarified by our observations, both from the animal models and from the theory, the high clues; i.e. 2 and over, suggest work stresses near the capability of oxidative metabolism and imminent failure of the negative feedback afforded by metabolic regulation, particularly ADP control of oxidative metabolism. This control is lost because of the fall of phosphocreatine to the point where creatine kinase is no longer in equilibrium, leading to the loss of ATP and its conversion to large amounts of ADP and its breakdown products. ATP then stimulates glycolysis and results in a massive lactic acidosis. At the same time, the low thermodynamic capability of glycolytic metabolism is unable to prevent irreversible ion disequilibration, water movements, edema, and eventually rupture of the cell membrane. The pathway of resynthesis of ATP is then tortuous, particularly as AMP is deaminated and adenosine is converted eventually to hypoxanthine. Thus, NMR reports that metabolic control is operating in the region where homeostasis of biochemical parameters is feasible. It further reports regions where the metabolic control is susceptible to failure and most aggressive clinical care is require

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Cardiomyopathies; Electric Organ; Electrophorus; Humans; Hypoxia; Infant, Newborn; Kinetics; Magnetic Resonance Spectroscopy; Metabolic Diseases; Mitochondria; Muscular Dystrophies; Phosphates; Vitamin K

In vivo kinetics of mucosal uptake of luminal 59Fe2+ by tied segments of normal mouse duodenum are characterised by a Km of approx. 100 microM and a Vmax of approx. 9 pmol/min per mg wet weight of intestine. These values were determined at pH 7.25 in the presence of excess sodium ascorbate. Studies with luminal Fe2+ concentrations of 100 microM reveal: uptake is relatively independent of ascorbate: Fe ratio and luminal pH and uptake is potently inhibited by 1 mM Co2+ or Mn2+ and large luminal NaCl concentrations but not by Ca2+. 3 days of hypoxia (0.5 atmospheres) yields no significant increase in subsequent total mucosal uptake by in vivo tied segments while uptake is significantly reduced by semi-starvation. Quantitative comparison of in vivo mucosal uptake with subsequent determination of isolated brush-border membrane 59Fe2+ transport in individual mice reveals a positive correlation (P less than 0.01) between the two parameters. These results, in conjunction with studies of isolated mouse duodenal brush-border membrane (Simpson, R.J. and Peters, T.J. (1985) Biochim. Biophys. Acta, 814, 381-388 and (1986) Biochim. Biophys. Acta 856, 109-114) suggest that the Fe2+ transport properties of isolated brush-border membrane are quantitatively adequate to explain in vivo mucosal uptake in normal and hypoxic mice at Fe2+ concentrations up to 100 microM.

Topics: Animals; Ascorbic Acid; Biological Transport; Cobalt; Duodenum; Ferrous Compounds; Hydrogen-Ion Concentration; Hypoxia; Intestinal Absorption; Intestinal Mucosa; Iron; Iron Radioisotopes; Kinetics; Male; Manganese; Mice; Microvilli; Sodium Chloride

Levels of ascorbic acid (AA) in the plasma, brain, and adrenal gland of rats were determined after 15 min of hypoxia (PaO2 less than 25 mm Hg) and following asphyxia. In rabbits, AA plasma levels were followed up to 75 min of reoxygenation following 15 min of hypoxia of the same severity. A significant increase (approximately 70%) in AA levels was found in plasma of rats and rabbits after hypoxia and asphyxia. This increase was found to be transient, with a return to normal levels within 1 h after resumption of normal oxygenation. Pretreatment with dexamethasone reduced the increase in AA level in both rabbits and rats. Adrenalectomy in rats, performed 24 h before the experiment, abolished the response to hypoxia. Ascorbate levels in the cerebral cortex, hypothalamus, and adrenal gland of awake rats subjected to hypoxia or asphyxia were found to be the same as in normoxic rats. Our results suggest that the observed changes in plasma AA levels are probably mediated through adrenocorticotropic hormone and that the adrenal gland is the major source of ascorbate efflux into the circulation during oxygen deprivation.

Topics: Adrenal Glands; Adrenocorticotropic Hormone; Animals; Ascorbic Acid; Asphyxia; Cerebral Cortex; Guinea Pigs; Hypothalamus; Hypoxia; Male; Oxygen; Rabbits; Rats

Fe2+ uptake by mouse intestinal brush-border membrane vesicles consists of two components: a rapid, high affinity (Kd less than 1 microM), low capacity binding (less than 2 nmol/mg protein), presumably to the outside of the vesicles, and a second, large capacity component with an initial rate showing a hyperbolic dependence on medium Fe2+ (Km 35-90 microM). The latter, predominant process is relatively independent of medium ascorbate: Fe2+ ratio, is inhibited by Co2+ and Mn2+ but varies greatly from one membrane preparation to another. This component is strongly inhibited by large extravesicular NaCl and KCl concentrations and may represent transport into the vesicles. No significant change in uptake could be observed in vesicles prepared from hypoxic mice.

Topics: Animals; Ascorbic Acid; Cobalt; Ferrous Compounds; Hypoxia; Intestines; Iron; Manganese; Mice; Microvilli

High but well-tolerated doses of the nutritional antioxidants selenium and vitamins E and C have significant immunostimulant, anti-inflammatory, and anti-carcinogenic effects which are well documented in the existing biomedical literature. In addition, these antioxidants help to protect the structural integrity of ischemic or hypoxic tissues, and may have useful anti-thrombotic actions as well. Supplementation with high-dose nutritional antioxidants may eventually gain a broad role in the prevention, treatment, or palliation of cancer, cardiovascular disease, infection, inflammatory disorders, and certain diabetic complications.

Topics: Adjuvants, Immunologic; Animals; Anti-Inflammatory Agents; Antioxidants; Arthritis; Ascorbic Acid; Cardiovascular Diseases; Diabetes Mellitus; Free Radicals; Humans; Hypoxia; Ischemia; Mice; Neoplasms; Rabbits; Rats; Selenium; Superoxides; Thrombosis; Vitamin E

Some of the problems which appear during senescence, are said to be caused by cerebral oxygen deficiency and various experiments have been set up to try to imitate this particular aspect of the ageing process. We have already studied the action of many drugs with regard to acute repeated anoxia. Our work has given us clear evidence of the activity of ascorbic acid, which delays the moment of electroencephalographic silence in rats and decreases the latent period up to the reappearance of electrical activity. In order to pinpoint the mechanism of action, we compared the influence of lysine aceto-salicylate with that of hydroquinone. Very small doses of the latter drug produce a marked effect and lead us to put forward the hypothesis that it may be anti-oxydising. However, although all the drugs which proved effective in these experiments may be grouped together (despite their varying pharmacological profiles) and described as "anabiotic" drugs, it is not possible to revert to a single mechanism of action for the group as a whole.

Topics: Animals; Ascorbic Acid; Aspirin; Brain; Electroencephalography; Hydroquinones; Hypoxia; Lysine; Rats

Topics: Animals; Ascorbic Acid; Cyanides; Drug Evaluation, Preclinical; Humans; Hypoxia; Microsomes; Oxygen Consumption; Radiation-Sensitizing Agents; Radiotherapy

Topics: Animals; Ascorbic Acid; Catalase; Cell Survival; Cells, Cultured; Doxorubicin; Drug Interactions; Hypoxia; Radiation Tolerance; Vitamin E

Fatty acid metabolism was investigated in adult male albino rats exposed to hypobaric hypoxia at 25,000 ft simulated altitude for 6 h at 32 degrees C. Oxidation and esterification of palmitic acid-1-14C and de novo lipogenesis from acetate-1-14C were studied. Palmitic acid-1-14C oxidation in liver slices was normal while acetoacetate formation was increased. In vivo esterification of palmitic acid-1-14C to form triglycerides was increased while formation of phosphatidylcholine and phosphatidylethanolamine was observed to decrease. Decreased incorporation into plasma phosphatidylcholine with unaltered total activity in plasma triglycerides was observed. The incorporation of acetate-1-14C was observed to remain unaltered in triglycerides and phospholipids of liver with a similar pattern in the plasma indicating unaltered de novo lipogenesis. There appears to be increased esterification of fatty acids with probably impaired release of triglycerides into plasma while fatty acid biosynthesis remains unaffected.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Atmospheric Pressure; Cholesterol; Fatty Acids; Fatty Acids, Nonesterified; Hypoxia; Lipid Metabolism; Liver; Male; Palmitic Acids; Phospholipids; Phosphorus; Rats; Triglycerides

Glucose utilization and lactate formation in erythrocytes from normal and glutathione (GSH)-deficient sheep were similar. Significant differences were observed, however, between the 2 groups of sheep in the production of 14-CO2 from erythrocytes incubated with ascorbic acid or methylene blue, or both. The greater response of normal erythrocytes compared to erythrocytes deficient in GSH suggests that there are some metabolic differences in the pentose phosphate pathway (ppp) activity of the erythrocytes. The nature and site of these differences are, however, not known. When sheep were kept in a decompression chamber for 2 weeks and subjected to a simulated altitude of 7,000 m for 12 hours/day, the erythrocytes showed a four- to six-fold increase in the activity of the ppp.

Topics: Animals; Ascorbic Acid; Blood Glucose; Carbon Dioxide; Erythrocytes; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Glycolysis; Hypoxia; Lactates; Male; Methylene Blue; NADP; Oxidation-Reduction; Sheep; Sheep Diseases

Topics: Acclimatization; Adult; Altitude; Ascorbic Acid; Female; Humans; Hypoxia; Male

The effect of hypoxia, exercise, and thermal stress on myocardial metabolism have been widely investigated, but little attention has been paid to studying the effects of a combination of these stress. The influence of hypoxia as modified by physical exertion (swimming) and cold stress was therefore studied. The parameters investigated included myocardial glycogen and noradrenaline, serum free fatty acid, adrenal ascorbic acid, and adrenal weight. It was observed that maximal stress was produced when hypoxia was combined with physical exertion. No suppression of cold-induced lipolysis by hypoxia was observed, in contrast to previously reported observations. Maximal depletion of cardiac blycogen and cardiac noradrenaline was noted in hypoxic exercise. Adrenal overactivity was not found to be related to any particular stress but was seen to be proportional to the severity of the stress applied.

Topics: Adrenal Glands; Adrenocortical Hyperfunction; Animals; Ascorbic Acid; Cold Temperature; Fatty Acids, Nonesterified; Glycogen; Hypoxia; Lipid Metabolism; Male; Myocardium; Norepinephrine; Organ Size; Physical Exertion; Rats; Stress, Physiological

Topics: Administration, Oral; Anemia, Hypochromic; Animals; Ascorbic Acid; Biological Transport; Body Weight; Diet; Erythropoietin; Female; Genetic Linkage; Hematocrit; Hemorrhage; Hypoxia; Injections, Intraperitoneal; Intestinal Absorption; Iron; Iron Radioisotopes; Male; Mice; Mice, Inbred Strains; Phenobarbital; Sex Chromosomes; Statistics as Topic

Topics: Altitude; Animals; Ascorbic Acid; Blood Coagulation; Capillary Permeability; Dogs; Hypoxia

Topics: Adrenal Glands; Animals; Ascorbic Acid; Blood Glucose; Environment; Hypoxia; Liver Glycogen; Male; Mice; Temperature

Topics: Adrenal Glands; Animals; Animals, Newborn; Ascorbic Acid; Delivery, Obstetric; Female; Fetus; Gestational Age; Hypoxia; Kidney; Liver; Maternal-Fetal Exchange; Muscles; Myocardium; Pregnancy; Swine

Topics: Animals; Ascorbic Acid; Brain; Chlorine; Heart; Hypoxia; Kidney; Liver; Muscles; Potassium; Rats; Sodium; Water-Electrolyte Balance

Topics: Acute Disease; Animals; Ascorbic Acid; Glyceraldehyde-3-Phosphate Dehydrogenases; Hypoxia; Isocitrate Dehydrogenase; Isoenzymes; L-Lactate Dehydrogenase; Myocardium; NAD; Oxidoreductases; Rats; Stimulation, Chemical

Topics: Adrenal Glands; Altitude; Animals; Ascorbic Acid; Atmospheric Pressure; Blood; Blood Pressure; Carbon Dioxide; Electrocardiography; Ganglia, Autonomic; Geniculate Bodies; Hydrogen-Ion Concentration; Hypoxia; Male; Nictitating Membrane; Oxygen; Partial Pressure; Phenformin; Rats; Respiration; Stereotaxic Techniques

Topics: Animals; Ascorbic Acid; Brain; Hypoxia; Mitochondria; Oxidative Phosphorylation; Oxygen Consumption; Phosphorus; Rats; Stimulation, Chemical

Topics: Animals; Ascorbic Acid; Autonomic Nervous System; Female; Hypoxia; Male; Oxygen; Parasympathetic Nervous System; Prostaglandins; Rats; Scopolamine; Stomach; Sympathetic Nervous System; Vagus Nerve

Topics: Adult; Ascorbic Acid; Barbiturates; Caffeine; Female; Humans; Hypoxia; Male; Middle Aged; Oxygen Consumption; Respiratory Insufficiency; Strychnine; Thiamine; Vascular Resistance

Topics: Animals; Ascorbic Acid; Depression, Chemical; Hypoxia; Liver; Muscles; Myocardium; NAD; NADP; Nicotinic Acids; Oxidation-Reduction; Rats; Stimulation, Chemical

Topics: Animals; Antimetabolites; Ascorbic Acid; Biological Transport, Active; Citrates; Duodenum; Ferritins; Hydrochloric Acid; Hydrogen-Ion Concentration; Hypoxia; Ileum; Intestinal Absorption; Intestinal Mucosa; Iron; Iron Isotopes; Ketoglutaric Acids; Methylene Blue; Perfusion; Rats

Topics: Ascorbic Acid; beta-Aminoethyl Isothiourea; Cell Nucleus; Chromium; Chromium Isotopes; Cyanides; Cysteamine; Cysteine; Dinitrophenols; Hypoxia; Iodoacetates; Lymphocytes; Metabolism; Mitochondria; Nucleoproteins; Pharmacology; Radiation Injuries; Radiation Injuries, Experimental; Radiation Protection; Rats; Research; Serotonin; Sodium; Thiourea; Thymocytes; Thymus Gland; Vanadium

Topics: Ascorbic Acid; Fetal Death; Guinea Pigs; Hypoxia; Liver Diseases; Lung Diseases; Pathology; Pharmacology; Pregnancy; Pregnancy, Animal; Research; Toxicology

Topics: Ascorbic Acid; Cysteine; Glycerol; Hypoxia; Pharmacology; Radiation-Protective Agents; Research; Serratia marcescens; Sulfhydryl Compounds; Sulfur

Topics: Animals; Antioxidants; Ascorbic Acid; Asphyxia Neonatorum; Female; Glucose; Humans; Hypoxia; Infant, Newborn; Maternal-Fetal Exchange; Pharmacology; Phenothiazines; Pregnancy; Pregnancy, Animal; Rats; Research; Vitamin E

Topics: Ascorbic Acid; Atmospheric Pressure; Carbohydrate Metabolism; Erythrocyte Count; Hypoxia; Vitamins

Topics: Aerospace Medicine; Ascorbic Acid; Hypoxia

Topics: Ascorbic Acid; Drug Tolerance; Hypoxia; Vitamins

Topics: Adrenal Glands; Ascorbic Acid; Hyperoxia; Hypoxia; Oxygen

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Carbohydrate Metabolism; Carbohydrates; Guinea Pigs; Hypoxia; Oxygen; Scurvy