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

36 patients with essential hypertension and 15 of their adult descendants were investigated and compared with age-matched control groups of 33 and 15 healthy subjects, respectively. The ventilatory response to oxygen breathing and to progressive normo- und isocapnic hypoxia were studied. The reduction of ventilation during hyperoxia was significantly greater in all hypertensive patients. An augmented ventilatory response to hypoxia was found in 20- to 40-year-old patients whereas the older patients (41-60 years) were not different from the age-matched control subjects. Our results indicate that the augmented hypoxic sensitivity in early hypertension, as found also in the young adult descendants with family background of hypertension, is attenuated with age, similar to the normotensive subjects.
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PMID:Attenuation of augmented ventilatory response to hypoxia in essential hypertension in the course of aging. 263 44

The study was carried out in 30 subjects with mild primary hypertension and in 82 normotensive age-matched volunteers, 18-20 years of age. Hyperoxia test was used to withdraw the tonic chemoreceptor reflex drive. The following circulatory and respiratory effects of short lasting hyperoxia were observed in the hypertensive group and in most of the normotensive subjects yet with a family background of hypertension: a decrease in the mean arterial pressure, in total peripheral vascular resistance, and in forearm vascular resistance, and a significantly greater reduction of the resting ventilation as compared to the normotensive group. Our results suggest that the augmented arterial chemoreceptor drive is one of the mechanisms responsible for the elevated arterial blood pressure and total peripheral resistance in early human hypertension. The positive response to hyperoxia test in healthy subjects with a family background of hypertension suggests a familial occurrence of the hyperactivity of the arterial chemoreceptors.
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PMID:Augmented chemoreceptor reflex tonic drive in early human hypertension and in normotensive subjects with family background of hypertension. 383 54

Lipid peroxidation and some parameters of hemostasis were studied during exposure to various hyperoxia schemes combined with heparin therapy before and after treatment in 124 patients aged 16 to 69 with CNS involvement which developed as a result of atherosclerosis and essential hypertension, 60 of whom presented with initial manifestations of cerebral circulation insufficiency (IMCCI), 33 with posthypoxic encephalopathies (PE), and 31 with ischemic stroke (IS). Hyperoxia mechanisms were differently directed in the studied groups of patients, this necessitating a differentiated approach to the choice of schemes of hyperbaric oxygenation. Use of a short course of hyperbaric oxygenation (up to 3 sessions at 1.2 to 1.25 atA) is recommended for patients with IMCCI and PE. For patients with IS in the acute period hyperbaric oxygenation at 1.4 atA is advisable combined with heparin therapy in doses of 150 to 300 U/kg b.w. a day.
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PMID:[Effects of hyperoxia regimes on the state of lipid peroxidation and hemostasis in patients with lesions of the central nervous system]. 789 81

The aim of this study was to investigate whether there are differences between particular characteristics of breathing regulation in primary hypertensive and normotensive states which might indicate significant differences in arterial chemoreceptor reflex function. Under air-breathing conditions, minute ventilation was similar in adult spontaneously hypertensive rats (SHR) (50 +/- 2ml/min x 100 g) and in Wistar-Kyoto rats (WKY) (54 +/- 3 ml/min x 100 g) but significantly lower in randomly bred normotensive Wistar rats (NWR) (39 +/- 1 ml/min x 100 g). In seven-day-old rats minute ventilation was 10.5 +/- 1.2ml/min x 10 g in SHR and 10.2 +/- 1.4 ml/min x 10 g in WKY. Our data indicate that there is no elevation of the ventilatory drive under air-breathing conditions which can be unequivocally associated with primary hypertension in adult and neonatal animals. Acute inhibition of ventilation caused by hyperoxia indicated that oxygen dependent peripheral chemoreceptor activity during air-breathing was similar in SHR and normotensive controls both in the unanesthetized neonatal state and in anesthetized adult animals. No well defined association between the characteristics of the hypoxic ventilatory response and primary hypertension could be demonstrated although responses in adult anesthetized SHR tended to be faster and of higher amplitude than in normotensive controls.
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PMID:Cardiorespiratory responses to acute hypoxia and hyperoxia in adult and neonatal spontaneously hypertensive and normotensive rats. 855 2

Hemodynamic consequences of the withdrawal of arterial chemoreceptor drive (ACD) by brief systemic hyperoxia were studied in 16 mild hypertensive subjects (HT) and in 16 healthy subjects (NT) in horizontal position at resting metabolic rate. In another 9 mild HT and match NT measurements were made in resting sitting position and during steady-state mild physical exercise on cycloergometer, (30% of VO2 max.) Tidal volume, minute ventilation, end tidal CO2 and O2 concentration, K+, Na+, pO2, pCO2 values in blood were recorded. Impedance reography was used for recording stroke volume (SV) and arm blood flow (ABF). Cardiac output (CO), ABF and arterial blood pressure (ABF) values were used for calculation of the total peripheral resistance (TPR) and vascular resistance in the arm (AVR). To assess the neurogenic circulatory response to withdrawal of ACD in HT attenuated by opposite peripheral effects of high oxygen, the values of AVR, ABP, TPR and AVR changes during brief hyperoxia in NT, assumed to be of peripheral origin, were subtracted from respective values in HT, assumed to be of mixed neurogenic and peripheral origin. In HT hyperoxia applied in sitting position produced a brief decrease in systolic and diastolic ABP by 5.4 +/- 0.8% and 3.4 +/- 1.1% respectively, of TPR by 12.4 +/- 3% and of AVR by 4.7 +/- 4.6%. Decrease in AVR during hyperoxia was significantly greater in sitting than in horizontal position. In NT hyperoxia produced opposite effects in ABP, TPR and AVR, as compared to those in HT. In HT subjects during steady-state exercise the TPR decreased by 21 +/- 3.7% reaching a value no different from that in NT. We suggest, that in primary hypertension neurogenic sympathoexcitatory ACD is augmented and interacts with the peripheral mechanisms related to tissue oxygen supply.
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PMID:Hemodynamic responses to brief hyperoxia in healthy and in mild hypertensive human subjects in rest and during dynamic exercise. 880 52

The aim of this study was to investigate whether there are differences between particular characteristics of the ventilatory responses to acute hypoxia and hyperoxia in primary hypertensive and normotensive states which might indicate significant differences in arterial chemoreceptor reflex function. Pneumotachographic monitoring of ventilation was carried out in anesthetized, spontaneously breathing, normotensive randomly bred Wistar rats (NWR), Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Under air breathing conditions, minute ventilation in SHR (50 +/- 2 ml/min per 100 g) was not significantly different from that of WKY (54 +/- 3 ml/min per 100 g) but NWR had a significantly lower minute ventilation (39 +/- 1 ml/min per 100 g) than both SHR and WKY. Our data indicate that there is no elevation of the ventilatory drive under air breathing conditions which can be unequivocally associated with primary hypertension in adult animals. During acute hypoxia, minute ventilation increased by a similar magnitude in SHR and NWR (by 97 and 77%, respectively, above baseline values), whereas in WKY the increase was only 58%. When exposed to acute hyperoxia, minute ventilation was inhibited by a similar degree in all animals investigated. We conclude that there is no characteristic pattern of peripheral chemoreceptor-mediated ventilatory responses in close association with primary hypertension.
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PMID:Effects of acute hypoxia and hyperoxia on ventilation in spontaneously hypertensive and normotensive rat. 896 45

Heart transplantation initially normalizes sympathetic hyperactivity directed at the muscle circulation. However, sympathetic activity increases with time after transplantation and the exact mechanisms responsible for sympathetic control in heart transplant recipients remain unclear. We examined the effects of peripheral chemoreflex deactivation caused by breathing 100% oxygen on muscle sympathetic nerve activity (expressed as number of burst per minute and mean burst amplitude), heart rate, and mean blood pressure in 13 heart transplant recipients, 13 patients with essential hypertension, and 10 controls. Heart transplant recipients disclosed the highest sympathetic activity, whereas it did not differ between controls and patients with essential hypertension (51+/-16 versus 37+/-14 versus 39+/-12 burst/min, respectively; P<0.05). Breathing 100% oxygen, in comparison with 21% oxygen, reduced sympathetic activity (-4+/-4 versus -1+/-2 burst/min, P<0.01; 85+/-9 versus 101+/-8% of amplitude at baseline, P<0.001) and mean blood pressure (-4+/-5 versus +3+/-6 mm Hg; P<0.05) in heart transplant recipients, decreased sympathetic activity (-4+/-4 versus 0+/-3 burst/min, P<0.05; 90+/-16 versus 101+/-9% of amplitude at baseline, P<0.05) in patients with essential hypertension, but did not reduce sympathetic activity (2+/-4 versus 3+/-3 burst/min, P=NS; 95+/-11 versus 95+/-13% of amplitude at baseline, P=NS) in control subjects. The sympathetic response to hyperoxia was more marked in heart transplant recipients than in controls (85+/-9 versus 95+/-11% of baseline amplitude; P<0.05). The decrease in sympathetic activity was most evident in patients with the longest time after heart transplantation (r=-0.75, P<0.01). In conclusion, tonic chemoreflex activation increases resting muscle sympathetic nerve activity and favors blood pressure elevation after heart transplantation.
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PMID:Effects of peripheral chemoreceptors deactivation on sympathetic activity in heart transplant recipients. 1579 65