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Results 201 - 250 of 1063
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Bonetti Darrell L - - 2006
CONTEXT: Live-high train-low altitude training produces worthwhile gains in performance for endurance athletes, but the benefits of adaptation to various forms of artificial altitude are less clear. PURPOSE: To quantify the effects of intermittent hypoxic exposure on kayak performance. METHODS: In a crossover design with a 6-week washout, we randomized ...
Adamczyk W - - 2006
The purpose of the present study was to examine the influence of systematical training on the ventilatory response to hypoxia. A rebreathing technique - progressive isocapnic hypoxia - was used to measure hypoxic chemoreflex reactivity. The ventilatory response was measured in a group of 22 world class adult kayakers (22.6 ...
Aughey R J - - 2006
Hypoxia and exercise each modulate muscle Na(+), K(+)ATPase activity. We investigated the effects on muscle Na(+), K(+)ATPase activity of only 5 nights of live high, train low hypoxia (LHTL), 20 nights consecutive (LHTLc) versus intermittent LHTL (LHTLi), and acute sprint exercise. Thirty-three athletes were assigned to control (CON, n = ...
Qutub Amina A - - 2006
Hypoxia-inducible factor-1, HIF1, transcriptionally activates over 200 genes vital for cell homeostasis and angiogenesis. We developed a computational model to gain a detailed quantitative understanding of how HIF1 acts to sense oxygen and respond to hypoxia. The model consists of kinetic equations describing the intracellular variation of 17 compounds, including ...
Ogura Yuji - - 2006
The purpose of this study was to investigate whether hypoxia can alter anaerobic energy release during supramaximal exercise. Seven male subjects performed 12 submaximal cycling tests to establish the relationship between workload and O2 demand. The subjects also performed 40 s Wingate tests (WT) under normoxia (room air), two levels ...
Wilkins Brad W BW Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA. - - 2006
Exercise blunts sympathetic alpha-adrenergic vasoconstriction (functional sympatholysis). We hypothesized that sympatholysis would be augmented during hypoxic exercise compared with exercise alone. Fourteen subjects were monitored with ECG and pulse oximetry. Brachial artery and antecubital vein catheters were placed in the nondominant (exercising) arm. Subjects breathed hypoxic gas to titrate arterial ...
Woorons X - - 2007
During moderate exercise breathing a low inspired O(2) fraction (F(I)O(2)), arterial O(2) desaturation may depend on the fitness level. Seven trained (TM) and seven untrained men (UTM) cycled in normoxia and in hypoxia (F(I)O(2)=0.187, 0.173, 0.154, 0.13 and 0.117). We compared TM and UTM at submaximal intensities below the ventilatory ...
Gore Christopher J - - 2006
This study tested the hypothesis that athletes exposed to 4 wk of intermittent hypobaric hypoxia exposure (3 h/day, 5 days/wk at 4,000-5,500 m) or double-blind placebo increase their red blood cell volume (RCV) and hemoglobin mass (Hbmass) secondary to an increase in erythropoietin (EPO). Twenty-three collegiate level athletes were measured ...
Björkman S Tracey - - 2006
A comparison of a constant (continuous delivery of 4% FiO2) and a variable (initial 5% FiO2 with adjustments to induce low amplitude EEG (LAEEG) and hypotension) hypoxic/ischemic insult was performed to determine which insult was more effective in producing a consistent degree of survivable neuropathological damage in a newborn piglet ...
Potts Jeffrey T - - 2006
In severe hypoxia, respiratory rhythm is shifted from an eupneic, ramp-like motor pattern to gasping characterized by a decrementing pattern of phrenic motor activity. However, it is not known whether hypoxia reconfigures the spatiotemporal organization of the central respiratory rhythm generator. Using the in situ arterially perfused juvenile rat preparation, ...
Adachi Tetsuya - - 2006
Hypoxia causes a life-threatening situation, and the ventilatory response to hypoxia plays an important role in preventing death. We have hypothesized that persons with a blunted hypoxic ventilatory response may have a weak defense response to hypoxic episodes and be susceptible to fatal respiratory disturbances. However, precise correlations between the ...
Péronnet F - - 2006
Energy substrate oxidation was measured using indirect respiratory calorimetry combined with tracer technique in five healthy young male subjects, during a 80-min exercise period on ergocycle with ingestion of 140 g of (13)C-labelled glucose, in normoxia and acute hypobaric hypoxia (445 mmHg or 4,300 m), at the same relative [77% ...
Oltmanns Kerstin M - - 2006
Resting energy expenditure (REE) is known to be influenced by various ambient conditions such as oxygen supply. Investigations in healthy subjects during acute hypoxia revealed a drop in REE, but persistent effects after hypoxia had ended have not been examined so far. Although indirect calorimetry is a well-established method to ...
Kim Joo Han - - 2006
Transient recovery (TR) of evoked synaptic potential during the late stage of hypoxic hypoglycemia (HH) insult was investigated in rat hippocampal slices using extracellular recording methods. TR was observed in association with a rapid deterioration of antidromic population spikes (aPSs) following HH insult. TR was not elicited in normoglycemic hypoxia ...
Thomas Peter - - 2006
Although there is extensive evidence for impaired endocrine function in fishes exposed to environmental chemicals, information is currently lacking on reproductive endocrine effects of other environmental stressors such as hypoxia. The effects of ten weeks exposure to low dissolved oxygen (DO: 2.7 ppm and 1.7 ppm) on reproductive morphometric and ...
Angermann M - - 2006
We examined the effect of normobaric hypoxia (3200 m) on maximal oxygen uptake (VO2max) and maximal power output (Pmax) during leg and upper-body exercise to identify functional and structural correlates of the variability in the decrement of VO2max (DeltaVO2max) and of maximal power output (DeltaPmax). Seven well trained male Nordic ...
Manukhina Eugenia B - - 2006
Hypoxia is one of the most frequently encountered stresses in health and disease. The duration, frequency, and severity of hypoxic episodes are critical factors determining whether hypoxia is beneficial or harmful. Adaptation to intermittent hypoxia has been demonstrated to confer cardiovascular protection against more severe and sustained hypoxia, and, moreover, ...
Zoll Joffrey - - 2006
We hypothesized that specific muscular transcript level adaptations participate in the improvement of endurance performances following intermittent hypoxia training in endurance-trained subjects. Fifteen male high-level, long-distance runners integrated a modified living low-training high program comprising two weekly controlled training sessions performed at the second ventilatory threshold for 6 wk into ...
Agostoni Piergiuseppe - - 2006
To evaluate whether carvedilol influences exercise hyperventilation and the ventilatory response to hypoxia in heart failure (HF). Fifteen HF patients participated to this double blind, randomised, placebo controlled, cross-over study. Patients were evaluated by quality of life questionnaire, echocardiography, pulmonary function and cardiopulmonary exercise tests (ramp and constant workload) both ...
Harrison Jon - - 2006
Oxygen is critically important for catabolic ATP generation but is also a dangerous source of reactive oxygen species. Insects respond to short-term exposure to hypoxia or hyperoxia with compensatory changes in spiracular opening and ventilation that reduce variation in internal Po2. Below critical Po2 values (Pc), nitric oxide and hypoxia ...
Nesterov S V - - 2006
The effect of 15-min inhalation of 8% hypoxic gas mixture on stroke volume was studied in 17 healthy volunteers. The parameter decreased in all volunteers who endured this exposure to the end. At the beginning of exposure the decrease in stroke volume negatively correlated with HR changes, but this correlation ...
Lundby C - - 2006
Maximal aerobic power at high altitude (<4000 m) does not increase with altitude acclimatization. In order to investigate the isolated effects of increased arterial oxygen content (CaO2) on maximal oxygen uptake (VO2max) in hypoxia, we studied 10 subjects during exercise in acute exposure to 12.6% O2 before and after novel ...
Houssiere Anne - - 2006
PURPOSE: We tested the hypothesis that aging decreases the contribution of metaboreceptors to sympathetic responses during exercise in hypoxia. METHODS: We recorded sympathetic nerve traffic to muscle circulation (MSNA), heart rate (HR), blood pressure (BP), minute ventilation (VE), and blood lactate (BL) in 12 older (55 +/- 10 yr) and ...
Vulesevic B - - 2006
To determine whether development of ventilatory control in zebrafish (Danio rerio) exhibits plasticity, embryos were exposed to hypoxia, hyperoxia or hypercapnia for the first 7 days post-fertilization. Their acute reflex breathing responses to ventilatory stimuli (hypoxia, hypercapnia and external cyanide) were assessed when they had reached maturity (3 months or ...
Hu, Yang
HU, Y., ASANO, K., MIZUNO, K and USUKI S., Relationship between Serum Free and Total Testosterone after Exercise Training during Normoxia and Hypobaric Hypoxia in Rats. Adv. Exerc. Sports Physiol., Vol.7, No.1 pp17-20, 2001. The relationship between serum free testosterone (FT) and total testosterone (TT) was investigated after exercise training ...
Lee, Ki-Chul
LEE, K.C., ASANO, K., HU, Y., SUNOO, S., RADAK, Z., MIMURA, T. and MIZUNO, K., AEffects of Combining of An Exercise Training and An Exposure to Hypoxia on Growth Rate, Food Intake, Oxygen Transporthing Capacity, Muscle Oxidative Capacity and Exercise Performance in Rat. Adv. Exerc. Sports Physiol., Vol.5, No.3 pp71-77, ...
Ciarka Agnieszka - - 2006
BACKGROUND: Heart failure is characterized by increased ventilation during exercise, which is positively related to increased peripheral and central chemoreceptor sensitivity. Heart transplantation does not normalize the ventilatory response to exercise, and its effects on the chemoreflex control of ventilation remain unknown. We tested the hypothesis that chemoreceptor sensitivity is ...
Hattink Jasper - - 2006
Zinc is an essential micronutrient that becomes toxic at elevated concentrations. Under hypoxic events, i.e., temporal depletion of oxygen, the toxicity of Zn increases for fish, apart from the direct effects of the reduced oxygen levels. This enhanced toxicity currently is explained by the increased ventilation rates under hypoxia, causing ...
Farias Jorge G - - 2006
Farias, Jorge G., Jorge Osorio, Gustavo Soto, Julio Brito, Patricia Siques, and Juan G. Reyes. Sustained acclimatization in Chilean mine workers subjected to chronic intermittent hypoxia. High Alt. Med. Biol. 7:302-306, 2006--We wanted to know if sea-level mine workers exposed previously to chronic intermittent hypoxia reached a steady acclimatization at ...
Zhou Hao - - 2006
As an important in vivo antioxidant, vitamin C is commonly used clinically to alleviate hypoxia-induced heart symptoms. To approach the protective mechanisms of vitamin C on hearts during hypoxia, we investigated the electrophysiological effects of vitamin C (1 mM: , pretreated before hypoxia) on Na(+) currents (including transient and persistent ...
Bernardi L - - 2006
A very high ventilatory response to hypoxia is believed necessary to reach extreme altitude without oxygen. Alternatively, the excessive ventilation could be counterproductive by exhausting the ventilatory reserve early on. To test these alternatives, 11 elite climbers (2004 Everest-K2 Italian Expedition) were evaluated as follows: 1) at sea level, and ...
Namdar Mehdi - - 2006
OBJECTIVES: We studied the acute effect of caffeine on myocardial blood flow (MBF) at rest and exercise in healthy volunteers at normoxia and during acute exposure to simulated altitude. BACKGROUND: Caffeine is a widely consumed stimulant, although its cardiovascular safety remains controversial and its effect on MBF is unknown. METHODS: ...
McAneney Jessica - - 2006
This study examined whether a hypoxia-tolerant amphibian, the Cane toad, undergoes mammalian-like ventilatory acclimatisation to hypoxia (VAH) and whether chronic hypoxia (CH) alters NMDA-mediated regulation of the acute hypoxic ventilatory response (HVR). Toads were exposed to 10 days of CH (10% O2) followed by acute hypoxic breathing trials or an ...
Spicuzza Lucia - - 2005
We investigated the interaction between hypoxia and hypercapnia on ventilation and on cerebro-cardio-vascular control. A group of 12 healthy subjects performed rebreathing tests to determine the ventilatory response to hypoxia, at different levels of carbon dioxide (CO(2)), and to normoxic hypercapnia. Oxygen saturation (SaO(2)), end-tidal CO(2) (et-CO(2)), minute ventilation, blood ...
Eckert Danny J - - 2006
RATIONALE: An intact cough reflex is important to protect the lung from injurious substances and to clear excess secretions. A blunted cough reflex may be harmful or even fatal in respiratory disease. Hypoxia is common in respiratory disorders and has been shown to have depressant effects on respiratory sensation and ...
Basset Fabien A - - 2006
This study aimed to determine the impact of short-term normobaric hypoxia on physiology and performance in highly trained athletes. Twelve (7 male and 5 female) athletes were randomly assigned into two groups and spent 8 h per night for two consecutive nights a week over 3 weeks under either short-term ...
Reeves Stephen R - - 2005
During development, windows of increased vulnerability to noxious stimulus occur. These critical periods of maturation represent times at which the maturing animal is uniquely susceptible to external perturbations that may alter the ultimate configuration of neural networks and their associated function(s), thereby inducing persistent (mal)adaptive changes. In contrast, when comparable ...
Frøbert Ole - - 2006
We tested whether hypoxia-induced coronary artery dilatation could be mediated by an increase in adenosine concentration within the coronary artery wall or by an increase in adenosine sensitivity. Porcine left anterior descendent coronary arteries, precontracted with prostaglandin F(2alpha) (10(-5) M), were mounted in a pressure myograph and microdialysis catheters were ...
Urquhart D S - - 2005
Hypoxia during sleep and exercise may occur in an important number of patients with cystic fibrosis (CF). Despite its recognition, no clear definition for hypoxia in CF exists, and nor do guidelines for commencing oxygen therapy. CF patients with hypoxia may have increased pulmonary artery pressure, reduced exercise ability, and ...
Foster Glen E - - 2006
It is not clear what the effects of different types of intermittent hypoxia have on human exercise ventilation. The purpose of this study was to determine whether short-duration intermittent hypoxia, and the subsequent augmentation of the hypoxic ventilatory response (HVR), would lead to an increase in ventilatory responses during exercise ...
Kirsch Karl A - - 2005
The intravascular volume consists of 40% to 45% red cells. Their production is controlled predominantly by erythropoietin (EPO), a hormone that is secreted particularly when tissue hypoxia is present. Because of this high percentage of the total intravascular volume the question comes to mind that, in addition to hypoxia, can ...
Wadley G D - - 2006
We compared in human skeletal muscle the effect of absolute vs. relative exercise intensity on AMP-activated protein kinase (AMPK) signaling and substrate metabolism under normoxic and hypoxic conditions. Eight untrained males cycled for 30 min under hypoxic conditions (11.5% O(2), 111 +/- 12 W, 72 +/- 3% hypoxia Vo(2 peak); ...
Morris S - - 2005
The concomitant effects of Pb and hypoxia on respiration and muscle energy status were examined in the freshwater crayfish Cherax destructor to determine if Pb intoxication exacerbated the effects of hypoxia. C. destructor, either intoxicated for 14 days with 0.5 mgL(-1)Pb, or from Pb-free control conditions, were subjected to progressive ...
Kerendi Faraz - - 2005
BACKGROUND: Prolonged deep hypothermic circulatory arrest is known to cause neurological injury. Hypoxia inducible factor, a transcription factor that mediates adaptive changes during hypoxia, is neuroprotective in models of ischemic brain injury, in part by upregulating erythropoietin. This study tested the hypothesis that upregulation of hypoxia inducible factor and erythropoietin ...
Favret Fabrice - - 2006
Our laboratory has previously shown an attenuation of hypoxic pulmonary hypertension by exercise training (ET) (Henderson KK, Clancy RL, and Gonzalez NC. J Appl Physiol 90: 2057-2062, 2001), although the mechanism was not determined. The present study examined the effect of ET on the pulmonary arterial pressure (Pap) response of ...
Baker D W - - 2005
Experiments were conducted to determine the behavioral and physiological responses to acute hypoxic challenges in Atlantic (Acipenser oxyrinchus) and shortnose (Acipenser brevirostrum) sturgeons. We measured the ventilatory rate following a 45-mmHg hypoxic challenge, as well as a variety of hematological parameters, including O2 transport and hormonal, ionic, and metabolic variables, ...
Friedmann B - - 2005
Heart rate monitoring and lactate measurements are used to control exercise intensity during training at moderate altitude although there is some uncertainty about hypoxia-induced changes in these parameters at equivalent submaximal exercise intensities compared to normoxia. To study the influence of acute normobaric hypoxia (FiO2 0.15) on heart rate and ...
Arkhipenko Yu V - - 2005
A novel principle of short-term periodic adaptive training by varying the oxygen level from hypo- to hyperoxia is substantiated both theoretically and experimentally. Short-term adaptation to hypoxia-normoxia produced a membrane-protective effect in the heart and cerebral cortex, but increased the sensitivity to free radical oxidation and decreased the level of ...
Heubert R A P - - 2005
The purpose of this study was to examine the influence of hypoxia on the O2 uptake response, on the arterial and muscular desaturation and on the test duration and test duration at VO2max during exhaustive exercise performed in normoxia and hypoxia at the same relative workload. Nine well-trained males cyclists ...
Han Feng - - 2005
Heme oxygenase cleaves heme to form biliverdin, carbon monoxide (CO), and iron, and consists of two structurally related isozymes, HO-1 and HO-2. HO-2 is also known as a potential oxygen sensor. Here we show that the relative CO content in arterial blood, which reflects the total amount of endogenous heme ...
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