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Paul, Michel
Introduction. In an effort to prolong airframe life of E model CCl30 aircraft, cabin pressure has been degraded to 10 PSI from the normal 15.3 PSI. This has resulted in higher cabin altitudes at operational altitudes. Whereas at normal operational altitudes, cabin altitudes used to be in the 1,500 ft ...
Huang Xiaoying - - 2002
To study the effect of carbon monoxide on pulmonary vessel remodeling of chronic pulmonary heart disease. Thirty-six sprague-dawley rats were randomly divided into three groups: control group, and hypoxic hypercapnic group, and hypoxic hypercapnia + hemin group. Blood CO concentration (COHb%), activity of HO-1 in blood serum and lung homogenate, ...
Germack R - - 2002
The usual model of intermittent hypoxia (sleep apnoea) corresponds to repeated episodes of hypoxia from a few seconds to a few hours interspersed with episodes of normoxia. The aim of this study was to evaluate in rats the effect of two periods of intermittent exposure for 2 months to hypoxia ...
Kiatchoosakun Pakaphan - - 2002
We have previously documented anatomic and functional relationships between ventilatory and autonomic neural output. Therefore, we hypothesized in this study that hypoxia-induced changes in respiratory neural output are associated with changes in autonomic regulation of lower esophageal sphincter (LES) pressure. Respiratory neural output, heart rate, and LES pressure were measured ...
Hutchison Alastair A - - 2002
This study tested the hypotheses that (1) acute cerebral hypoxia-ischemia changes laryngeal adductor, laryngeal abductor, and diaphragmatic activities, resulting in central apnea with laryngeal closure; and (2) these laryngeal muscle activities act to maintain absolute lung volume. The respiratory pattern was determined in three asphyxiated, awake preterm lambs after cesarean ...
Lighton John R B - - 2002
The discontinuous gas exchange cycle (DGC) of the pseudoscorpion Garypus californicus is characterized by periodic bursts of CO(2) emission and by high rates of interburst CO(2) emission. We investigated the mechanism that triggers the burst phase by manipulating ambient oxygen partial pressures (Po(2)). The ventilatory trigger in most land animals ...
Corno Antonio F - - 2002
OBJECTIVE: The postoperative course of cyanotic children is generally more complicated than that of acyanotic children. A possible reason is reoxygenation injury at the beginning of cardiopulmonary bypass. In this study we tested the hypothesis that reoxygenation of chronically hypoxic hearts is worse than that of normoxic hearts. METHODS: Two ...
Rouwet E V - - 2002
BACKGROUND: Low birth weight is associated with an increased incidence of cardiovascular diseases, including hypertension, later in life. This suggests that antenatal insults program for fetal adaptations of the circulatory system. In the present study, we evaluated the effects of mild hypoxia on cardiac function, blood pressure control, and arterial ...
Milano Giuseppina - - 2002
Chronic hypoxia (CH) is believed to induce myocardial protection, but this is in contrast with clinical evidence. Here, we test the hypothesis that repeated brief reoxygenation episodes during prolonged CH improve myocardial tolerance to hypoxia-induced dysfunction. Male 5-week-old Sprague-Dawley rats (n = 7-9/group) were exposed for 2 weeks to CH ...
Hirakawa Haruhisa - - 2002
The rebound tachycardia, transient increase in heart rate (HR) that was observed immediately after the cessation of hypoxia was investigated. Whether the cardiovascular responses induced by hypoxia depend on species difference is also discussed. Wistar rats were chronically instrumented for measurements of arterial blood pressure (ABP), HR and renal sympathetic ...
Jefferson J Ashley - - 2002
Chronic exposure to high altitude is associated with the development of erythrocytosis, proteinuria, and, in some cases, hyperuricemia. We examined the relationship between high-altitude polycythemia and proteinuria and hyperuricemia in Cerro de Pasco, Peru (altitude, 4,300 m). We studied 25 adult men with hematocrits less than 65% and 27 subjects ...
Grabellus Florian - - 2002
Left ventricular assist devices (LVAD) may improve cardiac function. The pathogenesis of this phenomenon, called 'reverse remodelling', is not completely elucidated. To examine the hypothesis that LVAD support eliminates tissue stress by reducing local hypoxia, the distribution of heme oxygenase-1 (HO-1), a stress protein inducible by hypoxia, was examined in ...
Balanos George M - - 2002
Hypoxia-inducible factor (HIF)-1 is stabilized by hypoxia and iron chelation. We hypothesized that HIF-1 might be involved in pulmonary vascular regulation and that infusion of desferrioxamine over 8 h would consequently mimic hypoxia and elevate pulmonary vascular resistance. In study A, we characterized the pulmonary vascular response to 4 h ...
Barros Renata C H - - 2002
Although intravenous (iv) injection of potassium cyanide (KCN) activates the arterial chemoreflex, it has been questioned whether cytotoxic hypoxia reproduces a physiological stimulus such as hypoxic hypoxia (low inspired O2 tension). Thus, the goal of the present study was to compare the cardiovascular responses elicited by intravenous injection of KCN ...
Rickards Caroline A - - 2002
BACKGROUND: Altitude-induced hypoxia is believed to decrease tolerance to orthostasis. This preliminary investigation assesses the interaction between low-level normobaric hypoxia and the cardiovascular responses to orthostasis. HYPOTHESIS: We hypothesize that low-level hypoxia at simulated altitudes up to 3350 m adversely affects cardiovascular responses to orthostasis. METHODS: Six women and eight ...
Güner Ibrahim - - 2002
Acute hypoxia produces an increase in ventilation. When the hypoxia is sustained, the initial increase in ventilation is followed a decrease in ventilation. The precise mechanism of this decline in ventilation during sustained hypoxia is unknown. Recent studies hypothesized that the accumulation of dopamine in the central nervous system might ...
Jounieaux Vincent - - 2002
OBJECTIVE: To confirm the hypothesis that the ventilatory response to hypoxia (VRH) may be abolished by hypocapnia. METHODS: We studied four healthy subjects during intermittent positive-pressure ventilation delivered through a nasal mask (nIPPV). Delivered minute ventilation (Ed) was progressively increased to lower end-tidal carbon dioxide pressure (PETCO(2)) below the apneic ...
Lai Yih-Loong - - 2002
We previously demonstrated that the pulmonary vascular response to substance P (SP) increased in chronically hypoxic rats. This study explored the temporal increase in reactivity of the pulmonary vascular response to SP and its underlying mechanisms. First, young female Wistar rats were exposed to sea level (SL) or simulated high ...
Moravec Mireille - - 2002
Effects of chronic hypoxia on capillary and myocyte growth were examined in rats born and raised in a low pressure chamber (equivalent of 3500 m a.s.l.). The animals were sacrificed at the age of 3 months and their hearts were used to study right ventricular growth and vascularization. The results ...
Baumgartner Ralf Werner - - 2002
To evaluate the role of acute mountain sickness (AMS) in the pathogenesis of stance abnormalities occurring at high altitude, static posturography was applied to 22 healthy subjects at an altitude of 450 m and during a 3-day sojourn at 4559 m. Subjects stood on a platform and sway velocity (S), ...
Peyronnet Julie - - 2002
To determine whether prenatal hypoxia increases the risk of developing cardiovascular disorders as an adult and, if so, the identity of the cell mechanisms involved in such dysfunction, we evaluated the sympathoadrenal system and central areas related to cardiovascular events during development and the cardiovascular parameters in adults. Pregnant rats ...
Frøen J Frederik - - 2002
Hypoxia-ischemia is a major cause of perinatal brain damage, but evidence shows that brain injury also is associated with intrauterine infections and maternal smoking. The mechanisms are not known, and we therefore explored the effects of experimental inflammation or nicotine on perinatal brain metabolism and injury during severe hypoxemia. Twenty-eight ...
Denton Kate M - - 2002
This study investigated the effects of graded reflex increases in renal sympathetic nerve activity (RSNA) on renal preglomerular and postglomerular vascular resistances. With the use of hypoxia to reflexly elicit increases in RSNA without affecting mean arterial pressure, renal function and stop-flow pressures were measured in three groups of rabbits ...
Maxová H - - 2002
To determine whether changes in partial pressure of CO2 participate in mechanism enlarging the lung functional residual capacity (FRC) during chronic hypoxia, we measured FRC and ventilation in rats exposed either to poikilocapnic (group H, F(I)O2 0.1, F(I)CO2 <0.01) or hypercapnic (group H+CO2, F(I)O2 0.1, F(I)CO2 0.04-0.05) hypoxia for the ...
DiPasquale Dana M - - 2002
Peripheral sweat rate was measured to determine if acute normobaric hypoxia exerted a local inhibition on sweat gland function. It was hypothesized that peripheral sweat rate would be reduced during hypoxia, following cholinergic stimulation. Nineteen subjects (24 +/- 3 yr; 177 +/- 9 cm; 75.5 +/- 20.1 kg), 8 females ...
Rohlicek C V - - 2002
OBJECTIVE: To determine the effects of chronic hypoxemia neonatally on the cardiovascular response to acute hypoxemia in adulthood. METHODS: Experiments were conducted on adult rats (82+/-2 days) which had been made chronically hypoxemic (hypobaric hypoxia equivalent to FiO(2)=0.14) during the first ten days of life but raised in room air ...
Filippelli M - - 2002
Chest wall compartment kinematics and respiratory muscle coordinate activity, during either hypercapnia or hypoxia, have not been comparatively assessed in healthy humans. We assessed the displacement volume of the chest wall (Vcw) in 5 normal subjects during hypoxic-normocapnic and hypercapnic-hyperoxic rebreathing by using linearized magnetometers. Vcw was divided into displacement ...
Gautier Henry - - 2002
Adult, conscious rats have been exposed to CO-induced hypoxia for 30 min in normoxia, ambient hypoxia (FI(O(2))=14%), or hyperoxia (FI(O(2))=40%). From arterial blood gas analyses, FICO was adjusted in all experimental conditions to obtain final arterial oxygen saturations (Sa(O(2))) of approximately 60%. Oxygen uptake (V(O(2))), ventilation (V) and colonic temperature ...
Klinger James R - - 2002
Targeted disruption of the gene for natriuretic peptide receptor-A (NPR-A) worsens pulmonary hypertension and right ventricular hypertrophy during hypoxia, but its effect on left ventricular mass and systemic pressures is not known. We examined the effect of 3 wk of hypobaric hypoxia (0.5 atm) on right and left ventricular pressure ...
Liu H Y - - 2001
Glycine content of the whole brain and subregions was measured by high pressure liquid chromatography (HPLC) in mice during their repetitive exposures to hypoxia. The contents of glycine in whole brain, diencephalon, and hippocampus and brain stem was significantly increased as the animals tolerance to hypoxia was increased. The results ...
Emery C J - - 2001
Intravascular radiographic contrast media (RCM) can be associated with significant morbidity in patients with pulmonary hypertension (PH). This study investigated the direct effect of the four main classes of RCM (high osmolar ionic monomer "diatrizoate"; low osmolar ionic dimer "ioxaglate"; low osmolar non-ionic monomer "iopromide"; and iso-osmolar non-ionic dimer "iotrolan") ...
Hirota K - - 2001
BACKGROUND: Apnea has been reported to produce bronchoconstriction and to cause hypoxia, hypercapnia, and modulation of vagal afferent nerves, which also change airway tone. In this study, the authors determined the mechanism of apnea-induced bronchoconstriction. METHODS: Twenty-eight dogs anesthetized and paralyzed were assigned to four groups (n = 7 each): ...
Foster K A - - 2001
The purpose of this study was to develop a newborn piglet model of hypoxia/ischaemia which would better emulate the clinical situation in the asphyxiated human neonate and produce a consistent degree of histopathological injury following the insult. One-day-old piglets (n=18) were anaesthetised with a mixture of propofol (10 mg/kg/h) and ...
Barak Y - - 2001
BACKGROUND: Acute hypoxia tolerance varies substantially among healthy individuals. We hypothesized that this variability results from a difference in autonomic (ANS) response to hypoxic stress. METHODS: Peripheral oxygen saturation, respiration and ECG were recorded from 21 healthy subjects (age, 29 +/- 7 yr) in an altitude chamber during normoxia, severe ...
Han F - - 2001
Given the environmental forcing by extremes in hypoxia-reoxygenation, there might be no genetic effect on posthypoxic short-term potentiation of ventilation. Minute ventilation (VE), respiratory frequency (f), tidal volume (VT), and the airway resistance during chemical loading were assessed in unanesthetized unrestrained C57BL/6J (B6) and A/J mice using whole body plethysmography. ...
Soares Barreto-Filho J A - - 2001
BACKGROUND: The peripheral and central chemoreflexes are important autonomic mechanisms for regulating breathing and cardiovascular function. Although pathological inflammatory infiltration of the peripheral chemoreceptors and central nervous system has been reported in Chagas' disease, functional evaluation of chemoreflexes has not yet been performed. METHODS AND RESULTS: The hypothesis that chemoreflex ...
Perreault T - - 2001
The pulmonary vasculature of newborns with persistent pulmonary hypertension is characterized by active vasoconstriction and vascular remodeling. It has been suggested that endothelin-1 (ET-1), a potent vasoconstrictor and growth promoter, may be involved in the pathogenesis of persistent pulmonary hypertension of the newborn. To determine whether treatment with an ET(A) ...
Kerbaul F - - 2001
PURPOSE: In vitro, halogenated agents reduce the pulmonary vasoconstrictor response to alveolar hypoxia in isolated perfused lungs. However, studies in intact animals have been less convincing. The aim of the present study was to assess the effect of sub-MAC concentrations of desflurane on hypoxic pulmonary vasoconstriction (HPV) in anesthetized piglets ...
Xie A - - 2001
1. Rhythmic breathing during sleep requires that P(CO2) be maintained above a sensitive hypocapnic apnoeic threshold. Hypoxia causes periodic breathing during sleep that can be prevented or eliminated with supplemental CO(2). The purpose of this study was to determine the effect of hypoxia in changing the difference between the eupnoeic ...
Holtzer S - - 2001
OBJECTIVE: To quantify the phenylephrine pressor responsiveness after severe brain injury combined with hypoxia-hypotension, and to study the respective roles of brain injury and hypoxia-hypotension in the observed alteration. DESIGN: Randomized study. SETTING: Accredited animal laboratory. SUBJECTS: Adult Sprague Dawley rats. INTERVENTIONS: Anesthetized animals were assigned to control, brain injury, ...
Yasuma F - - 2001
To test the hypothesis that hypoxia and hypercapnia have different effects on the genesis of respiratory sinus arrhythmia (RSA), the magnitude of RSA to these stimuli was compared in 3 unanesthetized dogs. Respiration was continuously monitored through a permanent tracheostomy, and the electrocardiogram and blood pressure were also monitored. The ...
de Salvo Souza R H - - 2001
The dourado, Salminus maxillosus, is an active and migratory teleost found in lotic waters of Southern Brazil. We have studied the relationships of gas transport in dourado to the specific ecophysiology of this-species. Measurements were performed of blood gases, O2 uptake, gill ventilation and perfusion at normoxia and various levels ...
McGuire M - - 2001
Sleep-disordered breathing is associated with pulmonary hypertension and raised haematocrit. The multiple episodes of apnoea in this condition cause chronic intermittent hypoxia and hypercapnia but the effects of such blood gas changes on pulmonary pressure or haematocrit are unknown. The present investigation tests the hypothesis that chronic intermittent hypercapnic hypoxia ...
Zhao L - - 2001
BACKGROUND: This study investigated the effect of the phosphodiesterase 5 inhibitor sildenafil on the pulmonary vascular response to hypoxia in humans and mice. METHODS AND RESULTS: In a randomized, double-blind study, sildenafil 100 mg or placebo was given orally to 10 healthy volunteers 1 hour before breathing 11% O(2) for ...
Vargas M - - 2001
Six men, normally working shifts of 7 days at high altitude (HA, 3800 m, approximately 480 mm Hg barometric pressure) followed by 7 days of rest at sea level (SL), were studied during the last days of their HA and SL shifts with a 24-h constant routine protocol of sustained ...
Benamou A E - - 2001
Elevated concentrations of endothelin (ET), a potent endothelium-derived vasoactive peptide, have been reported in a number of pathophysiological conditions associated with pulmonary hypertension, both in the horse and other species. We have previously shown, both in vitro and in vivo, that the pulmonary and systemic vascular response to exogenous ET ...
Ambalavanan N - - 2001
Levcromakalim (LKM; a K(ATP) channel opener) reverses hypoxic pulmonary vasoconstriction in isolated pulmonary arteries and perfused lungs. This vasorelaxation is blocked by glibenclamide (GLB; a K(ATP) channel blocker). We evaluated the hemodynamic effect of LKM followed by GLB in a chronically instrumented neonatal porcine model of pulmonary hypertension, created by ...
Jagolino A - - 2001
Previous studies in piglets show that hypercapnic pial artery dilation was blunted following cerebral ischemia. Unrelated studies show that the newly described opioid nociceptin orphanin FQ (NOC/oFQ) is released into cerebrospinal fluid and contributes to altered cerebral hemodynamics following hypoxia/ischemia. This study was designed to determine the contribution of NOC/oFQ ...
Clar C - - 2001
This study examined the role of muscarinic parasympathetic mechanisms in generating the progressive increases in ventilation (V(E)) and heart rate previously reported with 8 h exposures to hypoxia. The sensitivities of V(E) (G(p)) and heart rate (G(HR)) to acute variations in hypoxia, and V(E) and heart rate during acute hyperoxia ...
Ursino M - - 2001
The mathematical model of the respiratory control system described in a previous companion paper is used to analyse the ventilatory response to hypoxic stimuli. Simulation of long-lasting isocapnic hypoxia at normal alveolar PCO2 (40 mmHg=5.33 kPa) shows the occurrence of a biphasic response, characterized by an initial peak and a ...
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