Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rise of hemoglobin concentration accompanied by an increase of the total iron in the blood serum of white mice was found under oxygen pressure of 4 atm for an hour (preconvulsive state) and 6 atm (convulsive state). Changes in correlations of hemoglobin fractions in the blood serum were detected in both stages of oxygen poisoning by disc-electrophoresis in 7.5% polyacrylamide gel. A rise of transferrin concentration under these conditions (hyperoxia) was observed. The deflections occurred were less pronounced following administration of urea to the animals before hyperbaric oxygenation.
 ...
PMID:[Hemoglobin, transferrin and total iron content in the blood serum in hyperoxia and during the protective action of urea]. 46 81

Published reports of oxygen consumption (VO2) during exercise in hyperoxia are equivocal. By and large, when measured at the lung using respiratory gas equations, VO2 is elevated in hyperoxia and, when measured at the blood-tissue level using the cardiovascular Fick (CVF) equation, it is unchanged. We sought to provide some insight into this problem by making through the use of both equations simultaneous determinations of VO2 during hyperoxia in exercising ponies. In normoxia, during treadmill exercise (115 m/min, 10% grade) of seven ponies, there was no difference in exercise VO2, whether it was measured by the Haldane transformation (HT) or CVF equations (P greater than 0.05). In hyperoxia, the exercise VO2 was significantly increased from the normoxia condition (P less than 0.05) when measured by the HT equation but not when measured by the CVF equation (P greater than 0.05). By use of the CVF equation as the method of choice for VO2 determinations in hyperoxia, the present data show no change in exercise VO2 in the hyperoxic condition.
 ...
PMID:Effect of hyperoxia on oxygen consumption in exercising ponies. 46 33

Using ten normal dogs, the right upper lobe of the lung was isolated in vivo by a balloon catheter and was artificially ventilated with nitrogen, air, 60% oxygen in nitrogen, and 60% oxygen and 20% carbon dioxide in nitrogen, while the rest of the lungs maintained a spontaneous breathing of ambient air. Aminophylline did not show a vasodilating action under severe alveolar hypoxia (PAO2: ca. 40 mmHg); on the contrary, it seemed to potentiate hypoxic pulmonary vasoconstriction. When the regional alveolar oxygen tension became less hypoxic (PAO2: ca. 70 mmHg) or higher than that in the rest of the lungs which spontaneously breathed ambient air, aminophylline showed a definite vasodilating action. Aminophylline also showed a vasodilating action in alveolar hypercapnia in the presence of alveolar hyperoxia.
 ...
PMID:Effect of aminophylline on regional perfusion distribution in the lungs. 48 2

The influence of regional alveolar oxygen and carbon dioxide tensions on the distribution of lung blood flow and gas exchange was studied in unanaesthetised sheep. Right apical lobe (RAL) hypoxia, induced by administering nitrogen or nitrogen/oxygen mixtures to the lobe, stimulated a prompt, graded and well sustained reduction in lobar blood flow. Maximum hypoxia was accompanied by an approximate 65% reduction in perfusion, a significant fall in RAL carbon dioxide tension and output, a reversal of lobar oxygen flux and an average 13 Torr fall in arterial oxygen tension. The reduction in perfusion and gas exchange persisted in the face of elevated systemic oxygen tensions produced by giving pure oxygen instead of air to the remainder of the lung (RL). Mild RAL hypercapnia potentiated the hypoxia-induced change in perfusion and gas exchange. During lobar hypoxia RL blood flow and gas exchange increased to maintain total pulmonary gas exchange at an essentially constant level. RAL hyperoxia did not significantly alter the distribution of perfusion or gas exchange.
 ...
PMID:Regional alveolar gas composition and lung function in sheep. 49 47

The reactivity of subpleural strips of lung parenchyma reflects primarily the tone of the smooth muscle in the peripheral airways. Lung strips taken from ten dogs relaxed when the oxygen level in the gas bubbling through the bath was reduced from 95% to 18%. Subsequent hypocapnia (carbon dioxide reduced from 5% to 0%) induced contraction of all strips. These changes were reversed when the oxygen or carbon dioxide tensions were restored to control levels. Addition of either indomethacin or meclofenamate, two chemically dissimilar inhibitors of prostaglandin synthetase, reduced the resting tone in each of six strips and prevented the hyperoxic constriction which was observed in paired, control strips (oxygen increased from 18% to 95%). Blockers of histamine and catecholamines had no effect. The reactivity of the distal airways to changes in gas tension provides a mechanism by which ventilation and perfusion can be matched. The action of indomethacin and meclofenamate indicates that a prostaglandin-like substance may be involved in the maintenance of distal airway tone and in the constriction produced by hyperoxia. The addition of prostaglandin F2 alpha or E1, after meclofenamate, in a further nine pairs of strips did not restore the hyperoxic constriction. This suggests that prostaglandins may mediate, rather than merely facilitate, the response.
 ...
PMID:Distal airway responses to changes in oxygen and carbon dioxide tensions. 52 47

Hyperoxia has been shown to enhance the toxicity of the herbicide paraquat. Experiments were conducted to learn more about the effects of oxygen following acute poisoning with paraquat as well as the structurally related herbicide, diquat. Rats were injected intravenously with various doses of diquat or paraquat and placed into an atmosphere of either 100% oxygen or room air. The time required for 50% lethality (LT50) of both diquat and paraquat was greatly diminished by hyperoxia and was dependent upon the herbicide dosage. Rats treated with 40 or 80 mg/kg diquat and exposed to 100% oxygen had a shorter LT50 than those treated similarly with paraquat. A dose of 20 mg/kg was equitoxic in 100% oxygen while rats treated with 5 or 10 mg/kg diquat had a longer LT50 than rats treated with the same dose of paraquat. All animals exhibited severe respiratory distress terminally. The plasma concentrations and tissue distribution of either herbicide at 20 mg/kg were the same in oxygen and air exposed animals. When oxygen concentrations were varied between 100% and 60% rats treated with 20 mg/kg diquat or paraquat exhibited increasing but equal LT50's. In 40% oxygen diquat treated rats died more rapidly than paraquat treated rats. These data demonstrate a toxic interaction between hyperoxia and diquat as well as paraquat.
 ...
PMID:The influence of hyperoxia on the acute toxicity of paraquat and diquat. 54 May 39

The content of glutamic, asparaginic and gamma-aminobutyric (GABA) acids in norm and under hyperoxia was determined in different cerebral areas of susliks living in places at different heights above sea level. In susliks at a height of 1700-2000 m above sea level the content of glutamate aspartate and GABA lowers significantly as compared to that in susliks at a height of 500-600 m above sea level. Under the effect of oxygen 6 at. ga at the 22nd minute on the average there occur convulsions in susliks living both in high mountains and middle mountains. Acute oxygen poisoning is not accompanied by noticeable shifts in the content of free dicarboxylic amino acids in the studied cerebral areas of middle-mountain susliks and is characterized only by an increase of the GABA content in the cerebellum. In high-mountain susliks the content of glutamate under these conditions increases in great cerebral hemispheres, while the asparate content lowers in cerebral hemispheres and cerebellum. In the latter the drop in the content of GABA is statistically significant.
 ...
PMID:[Content of dicarboxylic acids and GABA in normal suslik brain and under the effect of oxygen at higher pressure]. 55 58

Cidal activities of 24-h exposures to 100% O2 and 95% O2 + 5% CO2 were assayed at 1 and 3 ATA. Studied were 21 yeasts isolated from humans: Candida albicans (8 strains), C. tropicalis (3 strains), C. krusei (3 strains), C. parapsilosis (2 strains), C. guilliermondii (2 strains), and one strain each of C. pseudotropicalis, C. stellatoidea, and Torulopsis sp. Generally, these were extremely sensitive to hyperbaric oxygen, although species and strain differences were observed. Indices of kill from 80-100 (total kill) characterized 17 of the 21 yeasts (81%). Hyperoxia (O2 +/- CO2 at 1 ATA) was not lethal. Deprivation of CO2 as a consequence of hyperbaric exposure to 100% O2 enhanced cidal activity for only 2 of 21 yeasts, whereas hyperbaric exposure to the mixture enhanced activity against four yeasts. Cidal activities were not significantly different for the remaining 15 yeasts. This response to deprivation of CO2 is different from that of bacteria, and manifests fundamental differences between procaryotic and eucaryotic cells.
 ...
PMID:Quantitative cidal activity of hyperbaric oxygen for opportunistic yeast pathogens. 56 66

In anaesthetized rabbits the influence of vagal cold-block on the ventilatory response to lowered arterial oxygen pressure was investigated. With intact carotid chemoreflexes, lowered PaO2 caused hyperventilation, which was progressively intensified with the degree of hypoxia, regardless of whether the alveolar PCO2 was uncontrolled or kept constant at the hyperoxic control. The V-PaO2 response was to a greater extent due to an increase of respiratory rate than to one of tidal volume. During hyperoxia, vagal cold-block caused a distinct increase in ventilation provided the alveolar PCO2 was not allowed to decrease. During moderate hypoxia, vagal block caused only a slight increase in ventilation, when PACO2 was not controlled, but a distinct decrease in ventilation, when PACO2 was maintained at the hyperoxic level. Without carotid chemoreflexes, lowered PaO2 did not change ventilation at any level, provided the vagus nerves were left intact. This was due to a substantial increase in respiratory rate counteracting a corresponding decrease in tidal volume. Then vagal block led to a ventilatory depression depending on the degree of hypoxia, which was due to a simultaneous decline in respiratory rate and tidal volume. It is concluded that during hypocapnic hypoxia the vagal stretch reflex primarily inhibits the carotid chemoreflex drive of ventilation. During normocapnic hypoxia, however, the mode of interaction between the peripheral and the central chemical drive has to be considered, which without vagal feed-back is occlusive. This occlusion appears to be counteracted by a vagal mechanism sensitive to CO2 in the airways--and possibly also to a lack of O2--, mainly shortening respiratory cycle duration.
 ...
PMID:The role of the vagus nerves in the ventilatory response to lowered PaO2 with intact and eliminated carotid chemoreflexes. 57 48

Right and left gastrocnemius-plantaris muscle preparations in 20 dogs anesthetized with pentobarbital sodium were used to investigate the effect of hyperoxia on tension maintenance. Muscles were stimulated via the sciatic nerve for 20 min at 60 200-ms tetanic contractions/min (10 impulses/contraction). Direct muscle stimulation after the experimental period resulted in no significant change in tension. In control experiments the tension developed by the right or left muscles over the 20 min was not different. The tension developed by muscles perfused with hyperoxic blood decreased 14% after 20 min, whereas tension in the normoxic muscles decreased 35%. Blood flow in the hyperoxic muscles was significantly higher at 20 min (P less than 0.05). Pump perfusion of one of a pair of normoxic muscles resulted in a tension decrease of 13% in the pump-perfused muscles, whereas tension in the control muscles decreased 34%. Tension maintenance was flow dependent. The effect of hyperoxia could be mediated through the involvement of oxygen in the long-term control of muscle blood flow.
 ...
PMID:Interaction of hyperoxia and blood flow during fatigue of canine skeletal muscle in situ. 57 3


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>