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

Single injection to mice of a perified preparation of superoxide dismutase (1000 units, intravenously) combined with catalase (0.5 mg) or without it failed to protect from the toxic action of 100% oxygen under the pressure of 5 ata. 1,4-diazobicyclo (2.2.2) octane (6 mg, intraperitoneally) increased the preconvulsive survival period of mice under these conditions. The formation of single oxygen under hyperoxia in vivo is supposed.
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PMID:[Effect of exogenous superoxide dismutase and 1,4-diazobicyclo-(2,2,2,)-octane on the resistance of mice to acute oxygen poisoning]. 85 14

To study extension of O2 tolerance by interruption of hyperoxic exposure, as compared to previous studies of continuous oxygen exposure, five healthy volunteers were exposed to oxygen at 2 ATA on an intermittent schedule of 20 min breathing O2, alternating with 5 min on a normoxic N2-O2 mixture. The cycle was repeated until symptoms or signs of O2 toxicity caused cessation of the experiment. Tracheal irritation and burning on inspiration occurred after 6-9 "oxygen hours" of exposure and progressed to severe tracheobronchial burning sensation, chest pain, and dyspnea after 11-15 h of O2. Average duration of exposure was 13.7 O2 h, inducing a mean vital capacity decrease of 10.3%. The decrease began soon after onset of symptoms. With intermittent O2 administration, nearly a doubling of the average duration of actual oxygen breathing was required to induce marked vital capacity change (greater than 10%) as compared to the previous studies of continuous O2 exposure. The increased duration of tolerable O2 exposure in man resembles the extension of O2 tolerance known to occur in animals exposed to intermittent hyperoxia.
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PMID:Extension of pulmonary O2 tolerance in man at 2 ATA by intermittent O2 exposure. 86 21

The concentration-related viscosity (formula: see text) of DNP-solutions in 4.0 M urea, 0.0005 M tris-buffer (pH 7.5) isolated from cell nuclei of cerebral hemispheres and testicles was determined for mongrel and Wistar rats of 5 groups: I -- normal, II -- after the action of 6 gauge atmospheres of pure oxygen before convulsions beginning, III -- 1 hour, IV -- 4 hours, V -- 12 hours after decompression. It was noted that the concentration-related viscosity of these DNP was equal both for mongrel and inbred rats. No differences in the polymerity degree of brain DNP were detected in all groups of animals under study. The viscosity of testicular DNP was found to decrease by 13.3% 1 hour and 10.3% 4 hours after decompression, whereas 12 hours after it does not differ from the control. Differences in the resistance degree of the brain and testicular DNP to the action of hyperoxia may depend on the cell division rates in these tissues.
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PMID:[Degree of polymerization of rat cerebral hemisphere and testicular DNP-complex during hyperoxia and following it]. 86 17

100% oxygen breathing during submaximal exercise in patients with diffuse interstitial lung disease diminishes cardiac output and pulmonary artery hypertension. The pressure drop in the pulmonary artery is most marked in patients with concomitant bronchial obstruction. At rest hyperoxia produced only minimal cardiopulmonary changes. The ventilatory and hemodynamic responses are discussed to find out if differences in these variables during oxygen breathing could be a reliable index for functional classification.
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PMID:Oxygen breathing during exercise in patients with diffuse interstitial fibrosis. 88 Apr

Rabbits were exposed to 100% oxygen at pressures of 256 to 1520 mm Hg for up to 5 d and the blood and erythrocytes of these animals were examined for changes that could be related to hyperoxia. Glutathione reductase activity of erythrocytes was reduced 5 to 29% by hyperoxia, whereas that of the plasma was not significantly altered. Significant changes in red and white cell counts, including differential leukocyte count, could not be detected. Electrophoretic analysis of the proteins and esterases derived from plasma and membranes and cytoplasmic fractions of erythrocytes did not reveal changes attributable to hyperoxia.
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PMID:Effects of hyperoxia on glutathione reductase activity, membrane proteins, and esterases of rabbit erythrocytes. 88 26

Clearance of 5-hydroxytryptamine (5-HT) by the lungs of normal and vitamin E-deficient rats was evaluated following a 60-min exposure to 100% oxygen (O2) at 4 ATA (HBO). After exposure, lungs were isolated, ventilated, and perfused, with a recirculating system used for measurement of 5-HT clearance. Control lungs were obtained from rats exposed to air at 1 ATA. In control normal rats, fractional clearance of 5-HT was 0.78+/-0.03 (mean+/-SE). Following HBO 5-HT clearance was 0.55+/-0.04 (P less than 0.01). In control vitamin E-deficient rats. 5-HT clearance was 0.85+/-0.05 and was decreased to 0.46+/-0.03 (P less than 0.001) following HBO. To evaluate the effect of recovery time after HBO on 5-HT clearance, separate groups of rats were killed at varying intervals post-HBO. In normal rats, 5-HT clearance had returned to control levels by 3-4 after HBO; in vitamin E-deficient rats, clearance remained unchanged 4 h after HBO and was only 74% (P less than 0.001) of control values 24 h post-HBO. These results indicate that depression of pulmonary 5-HT clearance occurs in rats due to hyperoxia and is potentiated by vitamin E deficiency. This represents a reversible alteration of lung function which requires vitamin E for complete recovery.
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PMID:Effect of hyperbaric oxygen exposure on pulmonary clearance of 5-hydroxytryptamine. 89 79

The influence of isobaric hyperoxia (99% O2, 760 mm Hg, 3 hours a day for 2 weeks) on the respiratory function of the mongrel adult cats blood was investigated. An increase of the reticulocyte count (by 170%), and a fall of methemoglobin concentration in the blood (by 33%), and a decrease of the affinity of cat hemoglobin oxygen affinity (by 13%)8 and of the cooperation effect of Hill's constant (by 16%) were observed. Dialysis of hemoglobin solutions eliminated the difference in the hemoglobin oxygen affinity of control and experimental animals. The number of hemoglobin fractions and their mobility was found to be unchanged (according to the agar electrophoresis method). A conclusion was drawn that the cat erythrocytes reaction to hyperoxia was a typical autoregulation; on its basis hemoglobin acquired a lesser oxygen affinity under conditions of an excess of this gas.
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PMID:[Respiratory function of the blood in the cat in hyperoxia]. 90 16

Cardiorespiratory responses of four men to submaximal and maximal cycling exercise were observed during 17 days at 18.6 ATA. Inspired gas at pressure consisted of hyperoxic (PO2 = 232 mmHg) and normoxic (PO2 = 159 mmHg) helium mixtures with relative gas densities of 3.8 and 2.8, respectively. The average of pre- and postdive VO2max (1 ATA air), which were not significantly different, was 3.10 liters - min-1. During 5 min of submaximal exercise at 50% of VO2max, no significant difference in work rate, VO2, VCO2, VE, respiratory rate, heart rate (HR), stroke volume, blood pressures, or rectal temperature was noted at 18.6 ATA compared to 1 ATA with either gas mixture. Submaximal HR tended to decrease by 5 to 10 beats - min-1 at pressure, and in hyperoxia the VO2/HR ratio was significantly higher. Maximal exercise was performed to exhaustion at work rates requiring about 120% of VO2max. Significant increased in VO2max of 0.10 liter - min-1 (3%) and in endurance time of 2 min (48%) were found during hyperoxic gas breathing, whereas normoxic values at 18.6 ATA were similar to those at 1 ATA. Significant reductions in maximal HR of 8 beats - min-1 (4%) were observed with both gas mixtures at pressure, and VE was significantly decreased by 36 liters - min-1 (26%) in hyperoxia and 29 liters - min-1 (21%) in normoxia. No change was found in the calculated cardiac output. Maximal voluntary ventilation, which was measured only for the hyperoxic gas, fell significantly by 80 liters - min-1 (40%). Results indicate that aerobic power and endurance performance were affected by oxygen pressure. Normoxic work capacity, however, was not decreased at 18.6 ATA, despite marked reductions in HR and VE.
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PMID:Hana kai ii: a 17-day dry saturation dive at 18.6 ATA. V. Maximal oxygen uptake. 91 Mar 18

Transcutaneous oxygen blood tension (tcpO2), heart rate, respiratory amplitude, respiratory rate, and relative local perfusion have been monitored continuously during heart catheterization in 37 children with congenital heart disease. The tcpO2 method allows an adequate measurement of the severity and duration of hypoxemia following arrhythmias or injection of contrast medium. The extent of hyperoxia following diagnostic procedures can also be controlled by this method.
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PMID:[Transcutaneous PO2-measurement during heart catheterization in childhood (author's transl)]. 91 72

The rate of lipid peroxidation (by content of the lipid peroxide transformation end product--malonic dialdehyde) in homogenates of rat brain was studied as affected by hyperoxia and with a protective effect of urea in experiments in vivo and in vitro. In both cases an increase is observed in the malonic aldehyde yield with the effect of oxygen under higher pressure. Urea in physiological concentrations lowers the yield under the effect of hyperoxia in vitro. In experiments in vivo introduction of urea also evokes a decrease in the rate of peroxidation. It is established that hyperoxia and urea affect mainly the ascorbate-dependent system of peroxidation. The compositon of phospholipids in the rat brain was studied under the effect of hyperoxia and urea. No changes were found in the number of fractions under the effect of 6at oxygen, only quantitative changes are observed. With introduction of urea before hyperoxia there occurs a normalization in the phospholipid composition. The authors suppose the protective effect of urea to be due to its influence on membranes.
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PMID:[Change in peroxidation and in the phospholipid content in the brain in hyperoxia and the protective action of urea]. 94 11


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