Search Results
Results 401 - 450 of 793
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Bengtsson J - - 1995
BACKGROUND: The paramagnetic technique has made it possible to monitor the end-tidal oxygen concentration and P(1-ET)O2, i.e. inspiratory to end-tidal oxygen difference, breath-by-breath. Little is known about the implications of a changing P(1-ET)O2, but so far studies have shown it to be a quick and sensitive variable to detect hypoventilation. ...
Breen P H - - 1995
In a canine model of combined carbon monoxide (CO) and cyanide (CN) poisoning, cardiac output (QT) and oxygen consumption (Vo2) decreased but recovered to baseline values by 15 min after toxic exposure; elevated blood CN and lactic acidosis persisted for at least another 10 min. Given the rapid spontaneous recovery ...
Richardson R S - - 1995
The assumption that cellular oxygen pressure (PO2) is close to zero in maximally exercising muscle is essential for the hypothesis that O2 transport between blood and mitochondria has a finite conductance that determines maximum O2 consumption. The unique combination of isolated human quadriceps exercise, direct measures of arterial, femoral venous ...
Peschek G A - - 1995
Extraction and identification of the non-covalently bound heme groups from crude membrane preparations of photoheterotrophically grown Synechocystis sp. PCC 6803 by reversed phase high performance liquid chromatography and optical spectrophotometry led to the detection of heme O in addition to hemes B and A which latter was to be expected ...
Sakauchi M - - 1995
OBJECTIVE: To assess the factors limiting aerobic exercise capacity in patients with systemic lupus erythematosus (SLE). METHODS: The anaerobic threshold (AT) and O2 pulse, i.e., VO2/heart rate (HR), were measured in 21 patients with SLE without cardiopulmonary complications by the analysis of expired gas during incremental work load in exercise ...
Bhambhani Y N - - 1995
In this study, regression equations were derived to predict cardiac stroke volume (SV, mL/beat), measured by carbon dioxide rebreathing, from oxygen pulse (O2 pulse, mL/beat) measurements in healthy men (n = 25) and women (n = 12) during upper and lower body exercise at the ventilatory threshold. The equations for ...
Lahiri S - - 1995
High carbon monoxide (CO) gas tensions (> 500 Torr) at normoxic PO2 (125-140 Torr) stimulates carotid chemosensory discharge in the perfused carotid body (CB) in the absence but not in the presence of light. According to a metabolic hypothesis of O2 chemoreception, the increased chemosensory discharge should correspond to a ...
Mannix E T - - 1995
Inadequate O2 supply may impair intramuscular oxidative metabolism and O2 availability may modulate ATP production within exercising muscle. Therefore, we studied ATP flux from anaerobic glycolysis, the creatine kinase reaction, and oxidative phosphorylation using 31P-magnetic resonance spectroscopy kinetic data collected during exercise. We examined six chronic obstructive pulmonary disease (COPD) ...
Palange P - - 1995
We evaluated the effect of supplemental O2 on energy metabolism of hypoxemic humans by measuring O2 uptake (VO2) kinetics and other cardiorespiratory parameters in nine male chronic obstructive pulmonary disease (COPD) patients and seven age-matched control subjects (on air and on 30% O2) at rest and during moderate cycle ergometer ...
Zhu N - - 1995
The hypothesis tested was that myocardial venous O2 saturation (SvO2) heterogeneity, a measure of microregional O2 supply/consumption balance, would increase under hypoxic and CO-hypoxia conditions. Since we are able to determine both O2 supply and the O2 supply/consumption ratio, we could also determine whether regional myocardial O2 consumption was heterogeneous. ...
Wagner P D - - 1995
Perhaps the major points to be made from this review are the following: 1. Transport of O2 from the environment to the mitochondrion is accomplished in a well-described but not yet well-understood sequence of diffusive and convective steps that are highly interactive and thus integrative in their outcome. 2. Thus, ...
Clark J M - - 1995
Multiple physiological functions were monitored in ten men who performed two 30-min periods of 150-W ergometer exercise during 120-min exposures to O2 at 2.0 ATA. There were no convulsions or electroencephalographic manifestations of increased excitability. Sequential measurements of peripheral visual fields, pulmonary mechanical function, mental performance, and cardiovascular function during ...
Richardson R S - - 1995
Previously, a reduction in fractional inspired O2 (FIO2) during dynamic exercise of the human quadriceps muscles of one leg resulted in increased muscle blood flow (Q) and a fall in femoral venous O2 tension (PO2) but no change in peak O2 uptake (VO2). These data can be interpreted as reflecting ...
Braun R D - - 1995
PURPOSE: Oxygen consumption rate (QO2) was determined in the outer and inner halves of the cat retina in dark and light adaptation. METHODS: Double-barreled oxygen microelectrodes were used to measure oxygen tension (PO2) across the retina of anesthetized cats while the single retinal artery supplying that area was occluded. During ...
Freetly H C - - 1995
The objectives of this study were twofold: first, to estimate the time required to reach equilibrium in splanchnic tissue oxygen (O2) consumption rates after a feed restriction that maintained BW; and second, to estimate the time following a subsequent realimentation required to reach equilibrium. Catheters were placed in a cranial ...
Schlenker E H - - 1995
Male dystrophic hamsters (DH) were treated with pellets containing thyroxine (T hamsters) or placebo (P hamsters) for 8 wk. O2 consumption, ventilation, and ventilation in response to 8% CO2 in O2 and 10% O2 in N2 were evaluated 1 and 8 wk after treatment began. O2 consumption was elevated in ...
Ferretti G - - 1995
The response of the O2 transport system to acute changes in alveolar ventilation (VA) was analysed. The fractional limitations to maximal O2 consumption (VO2max) imposed by the lungs (ventilation, FV, and lung-blood transfer, FL), the cardiovascular system (FQ), and peripheral O2 diffusion (Fp) were calculated according to a multifactorial model. ...
Yamamoto M - - 1995
Eight male subjects were examined for the transition from anaerobic to aerobic energy supplies during supramaximal pedalling for 120 s on a cycle ergometer. The O2 debt and O2 deficit were measured for anaerobic supply, while O2 intake during exercise was measured for aerobic supply. The lactic acid system was ...
Jensen-Urstad M - - 1995
The influence of hypoxaemia on anaerobic energy production during arm exercise (AE) has been investigated. Six men were studied during maximal AE and during 10 min of sitting submaximal AE under both normoxic (AEN) and hypoxic (AEH, respiratory hypoxia, 12% O2) conditions. Peak pulmonary oxygen uptake (VO2) during maximal AE ...
Aguilaniu B - - 1995
Exercise-induced hypoxaemia (EIH) has been associated with an oxygen diffusion limitation. Because polyunsaturated fatty acids (PUFA) administration can modify cell membrane fluidity, we hypothesized that the importance of EIH could be reduced after a 6-week PUFA diet. Resting pulmonary functions and a maximal cycling test were performed before and after ...
Dempsey J A - - 1995
First we describe the changing site of limitation to maximal O2 transport with increasing fitness in mammals. The capacity for diffusion and airway/parenchymal flow rate and volume are markedly overbuilt in the sedentary subject's lung, but undergo little change with increased training/fitness; accordingly, as demand for O2 transport increases in ...
Babcock M A - - 1995
We examined the effects of hypoxia on exercise-induced diaphragmatic fatigue. Eleven subjects with a mean maximal O2 uptake of 52.4 +/- 0.7 ml.kg-1.min-1 completed one normoxic (arterial O2 saturation 96-94%) and one hypoxic (inspiratory O2 fraction = 0.15; arterial O2 saturation 83-77%) exercise test at 85% maximal O2 uptake to ...
Dulas D - - 1994
We examined the effects of the alpha-adrenergic blocking agent urapidil on coronary blood flow (CBF) and myocardial O2 consumption during exercise in 11 dogs trained to run on a motor-driven treadmill. Left circumflex coronary artery (LCX) BF was measured with an electromagnetic flowmeter, and aortic and coronary sinus electromagnetic flowmeter, ...
Fournier R A - - 1994
Marsupials have lower resting metabolic rates than placental mammals, but it is not clear whether particular species can extend this energetic advantage to locomotion. Some active marsupials have a low cost of locomotion, but other more sedentary species, such as the Virginia opossum, appear to run very inefficiently. Steady-state rates ...
Harris-Eze A O - - 1994
We examined whether arterial hypoxemia impairs incremental exercise performance in subjects with interstitial lung disease (ILD). Seven subjects underwent two incremental exercise tests on a bicycle ergometer in random order; one while breathing room air (RA), and the other while breathing 60% O2. Maximal exercise performance was impaired in all ...
Barja G - - 1994
Birds are unique since they can combine a high rate of oxygen consumption at rest with a high maximum life span (MLSP). The reasons for this capacity are unknown. A similar situation is present in primates including humans which show MLSPs higher than predicted from their rates of O2 consumption. ...
Agustí A G - - 1994
To examine whether the tip of the femoral vein catheter used for sampling femoral venous PO2 during cycling exercise is contaminated by skin or saphenous vein blood, we studied 6 healthy volunteers [21.7 +/- 0.7 (SD) yr] during three identical incremental exercise tests while breathing room air on the same ...
Muth C M - - 1994
In five subjects we examined the effect of exercise on the pattern of central venous (right atrial) N2 tensions (PVN2) after ascent from simulated non-decompression dives. The dives consisted of exposure to air at 3 bar for 20 min with 10 min of exercise (workload 75 W) at depth to ...
Bengtsson J - - 1994
We assessed the inspiratory to end-tidal oxygen difference (PIO2-PE'O2) during voluntary hyperventilation in 10 healthy male volunteers. The oxygen difference was measured with a fast-response paramagnetic differential oxygen sensor. As simultaneous changes in metabolism and cardiac output also influence (PIO2-PE'O2), oxygen uptake was measured with indirect calorimetry and non-invasive transthoracic ...
Ward M E - - 1994
When tissue O2 delivery falls below a critical threshold, tissue O2 uptake (VO2) becomes limited. We compared critical O2 delivery and critical and maximum O2 extraction ratios of the resting and contracting left hemidiaphragm with those of nondiaphragmatic tissues in seven dogs. The left hemidiaphragm was perfused through the left ...
Severinghaus J W - - 1994
An analogy is drawn between cytochrome aa3 function and a polarographic cathode at which the potential of -0.6 V captures all O2 diffusing to the surface, achieving maximal O2 consumption (VO2max) by eliminating O2 backpressure and outward diffusion from the surface, defined herein as zero surface PO2. The relationship of ...
Anzueto A - - 1994
The association of oxygen radical generation with impaired diaphragm performance has previously been reported after inspiratory resistive loading (IRL). We hypothesized that exposure of rats to normobaric hyperoxia (O2) could produce impaired diaphragm function because of free radical production. Sprague-Dawley rats were divided into four groups: 1) room air (control), ...
Reed J Z - - 1994
When at sea, phocids dive for long periods and spend a high percentage of their time submerged. This behaviour requires some combination of an increased oxygen storage capacity, rapid oxygen loading at the surface and reduced oxygen utilisation when submerged. To assess these adaptations, breath-by-breath ventilation was studied in four ...
Lee H C - - 1994
Professional diving fishermen in the Pescadores Archipelago (119.30 degrees W, 23.30 degrees N) dive with a simple hookah system. Although they use modern equipment, such as wet suit, face mask, mouth piece with demand valve, spear gun, weight belt, and fins, their lack of knowledge of diving medicine is apparent. ...
Wolf J P - - 1994
The aim of this study was to examine the influence of water immersion to the chest on cardio-vascular adaptation to exercise. Upright or sitting immersion causes an increase in central blood volume, but it remains controversial whether central blood volume remains elevated during dynamic exercise in water and facilitates cardiac ...
Hannemann L - - 1994
OBJECTIVE: Investigation of the hypothesis that the infusion of 10 ng/kg/min prostacyclin (epoprostenol) (PGI2) improves O2 uptake in patients with hyperdynamic septic shock. DESIGN: Prospective, single cohort design. SETTING: ICU, university hospital. PATIENTS: Fifteen postoperative patients with septic shock. INTERVENTIONS: Infusion of 10 ng/kg/min of PGI2 for 60 min. MEASUREMENTS: ...
Wetterberg T - - 1994
Anesthetized, paralyzed and mechanically ventilated pigs were hypoventilated to extreme hypercapnia (PaCO2 approximately 20 kPa) at FiO2 0.5, and allotted to receive hypothermia (approximately 31.5 degrees C) and buffer infusion, (HB-group, n = 6) or to a hypothermic control group (H-group, n = 6). The HB-group had higher arterial pH ...
Besch E L - - 1994
To determine the effects of varying inspired O2 on positive radial acceleration (+Gz; i.e., head-to-foot inertial load) duration tolerance, seven men were exposed to the +4.5- to +7.0-Gz simulated aerial combat maneuver (SACM) by use of the Armstrong Laboratory (Brooks Air Force Base) centrifuge. Exposures were repeated on different days ...
Bhambhani Y - - 1994
This study examined the relationship of oxygen pulse (O2 pulse) to stroke volume (SV) and arterio-venous oxygen difference [(a-v)O2 diff] during submaximal cycle exercise in untrained (UG) and trained (TG) males. Fourteen volunteers in each group completed an incremental VO2 max test and a submaximal test at 60% VO2 max ...
Chiu W C - - 1994
Despite apparently depressed function, stunned myocardium maintains oxygen consumption and has the capacity to increase contractility with inotropic stimulation. We hypothesized that during stunning, O2 demand is maintained because regional segment work is performed, but is asynchronous with global left ventricular contraction, and that inotropic stimulation would restore regional work ...
Vallet B - - 1994
Our question was whether inhibition of nitric oxide [endothelium-derived relaxing factor (EDRF)/NO] production in an in situ vascularly isolated but innervated canine hindlimb would prevent hypoxic vasodilation or interfere with O2 extraction during ischemic (IH) or hypoxic hypoxia (HH). After a control period, we gave NG-nitro-L-arginine methyl ester (L-NAME, 20 ...
Nawas Y N - - 1994
The hemodynamic alterations in elderly individuals when combined with their reduced functional capacity concerning specific organ systems places them at an increased risk of developing shock with certain disease processes. The initial management should be directed toward shock resuscitation with appropriate volume and/or vasopressor/inotropic support. Then attention must be given ...
Shen J M - - 1994
To test the influence of arterial O2 saturation (SaO2) on heart rate in cluster headache, changes in pulse rate induced by hyperoxia and hypoxia were monitored in 11 cluster headache patients (6 during cluster period, and 5 during remission). The results were compared with those obtained in 11 age and ...
Kayser B - - 1994
Exhaustive dynamic exercise with large muscle groups in chronic hypobaric hypoxia may be limited by central (nervous) rather than peripheral (metabolic) fatigue. Six males [32 +/- 4 (SD) yr] at sea level (SL) and after 1-mo acclimatization at 5,050 m (HA) performed exhaustive dynamic forearm exercise at a constant absolute ...
Richardson R S - - 1994
These data indicate that through the reduction in exercise time and recruitment of trained subjects, the exercising muscle in the human dynamic knee-extension model can reach even higher work rates, VO2, and Q than previously reported (Andersen & Saltin, 1985; Andersen et al., 1985; Rowell et al., 1986). Despite these ...
Maruyama R - - 1994
Physiological roles of ventilatory responses to acute hypoxia in the regulation of O2 transport and consumption were evaluated quantitatively in halothane anesthetized and spontaneously breathing rats with or without peripheral chemoreceptor afferents. Ventilation (VE), blood gas values, cardiac output (Q), and whole-body O2 consumption (VO2) were measured at various levels ...
Jones J H - - 1994
The cardiovascular system has frequently been hypothesized to be the limiting step for O2 transport that determines VO2 max in many species of mammals. Careful analysis of the factors that determine how O2 is transported by the circulation demonstrate that such a single-step limitation cannot exist. Evaluation of the results ...
Préfaut C - - 1994
To determine whether exercise induces hypoxemia in highly trained older "master" athletes (MA), as it does in certain elite endurance-trained young athletes (YA), 10 MA (65.3 +/- 2.6 yr), 10 control subjects (CS; 68.3 +/- 2.2 yr), and 10 endurance-trained YA (23.3 +/- 1.1 yr) performed an incremental exercise test. ...
Ku H H - - 1993
The objective of this study was to examine the possible involvement of oxygen free radicals in the aging process. Rates of mitochondrial O2.- and H2O2 production and oxygen consumption in the kidney and the heart were compared among seven different mammalian species namely, mouse, hamster, rat, guinea pig, rabbit, pig, ...
Escourrou P - - 1993
We previously reported that O2 diffusion was limited in piglets. To test the hypothesis of an inadequacy between diffusion and perfusion in piglets (< 4 wk) vs. older pigs (> 8 wk), we compared in these two age groups the effect of an increase (by opening an arteriovenous fistula) or ...
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