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Gonzalez N C - - 1994
Pulmonary gas exchange and O2 transport were studied at rest and during maximal treadmill exercise in rats in acute hypoxia (PIO2 approximately 71 Torr), and in littermates acclimatized to PB = 380 Torr (PIO2 approximately 71 Torr) for 3 weeks (chronic hypoxia). To obtain valid estimates of blood gas partial ...
Iwao T - - 1994
Oxygen saturation was studied with a pulse oximeter in 80 patients with cirrhosis (44 Pugh-Child's class A, 25 class B, and 11 class C) and 80 controls undergoing diagnostic esophagogastroduodenoscopy (EGD). No narcotic agent was used during the procedure. Baseline SaO2 was significantly lower in cirrhotics than in controls (97.7 ...
Tatsumi K - - 1994
Hypoxic (HVR) and hypercapnic ventilatory responses (HCVR) are known to be influenced by the administration of testosterone, but whether the hormone acts centrally or peripherally is unknown. To determine whether testosterone alters HVR, HCVR, and carotid sinus nerve (CSN) responsiveness to hypoxia, we compared the ventilatory and CSN responses of ...
Nagyova B - - 1994
To investigate the effects of enflurane on the control of breathing we have studied the ventilatory responses to isocapnic hypoxia in 12 adults with and without sedation with enflurane. Design 1 consisted of three steps into hypoxia (PE' O2 = 6.7 kPa), each lasting 3 min, separated by periods of ...
Whitson P A - - 1994
In an effort to understand the interaction between acute postural fluid shifts and hypoxia on hormonal regulation of fluid homeostasis, the authors measured the responses to head-down tilt with and without acute exposure to normobaric hypoxia. Plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP), plasma ...
Gentz E J - - 1994
The PCV of a llama increased from 50.8 to 74.0% during a 19-month period. The llama remained clinically normal unless stressed, when it would become dyspneic and tachypneic. Thoracic auscultation revealed sounds consistent with pneumonia, but were probably attributable to pulmonary congestion resulting from polycythemia. A diagnosis of secondary absolute ...
Suguihara C - - 1994
The purpose of this study was to evaluate the relationship between changes in minute ventilation (VE) and oxygen consumption (VO2) in response to acute hypoxia in the newborn piglet. Twenty-five (mean +/- SD; age, 4.7 +/- 1.1 d; weight, 1451 +/- 320 g) sedated, spontaneously breathing newborn piglets were studied. ...
Lowry T F - - 1994
To gain insight into central and peripheral contributions to changes in breathing during hypoxia, we compared effects on breathing of reducing inspired PO2 (hypoxic hypoxia) with reducing arterial O2 content (CaO2) through elevation of carboxy-hemoglobin (COHb) (CO hypoxia). Twelve awake ponies were studied during 1 h of breathing room air ...
Qayyum M S - - 1994
The purpose of this study was to determine whether changes in arterial plasma potassium concentration [K+]a affect expired ventilation (VE) in euoxia, hypoxia and hyperoxia during rest and light exercise in humans. Three periods of ventilatory measurements were undertaken in eight healthy subjects at rest and in seven other subjects ...
Dahan A - - 1994
BACKGROUND: The peripheral chemoreceptors are responsible for the ventilatory response to hypoxia (acute hypoxic response) and for 30% of the normoxic hypercapnic ventilatory response. To quantify the effects of subanesthetic concentrations of halothane on the respiratory control system, in particular on the peripheral chemoreceptors, we studied the response of humans ...
Bartlett D D - - 1994
In decerebrate, vagotomized cats, introduction of CO2 into the isolated laryngeal airway while systemic PCO2 is held constant evokes dose-related reflex changes in ventilatory activity. Because systemic hypoxia is known to exaggerate ventilatory responses to other types of laryngeal chemostimulation in neonates, we have compared the responses of phrenic and ...
Saiki C - - 1994
Previous studies have indicated that the hypometabolic response to hypoxia depends on ambient temperature (Ta), being more pronounced in the cold. If metabolic rate were an important contributor to the level of ventilation (VE), the magnitude of the hyperpneic response to hypoxia should also depend on Ta. We tested this ...
Schobel H P - - 1994
To investigate the effects of digitalis on chemoreflexes in humans, we measured muscle sympathetic nerve activity (microneurography), minute ventilation, oxygen saturation, end-tidal carbon dioxide, mean arterial pressure, heart rate, and central venous pressure during stimulation of peripheral chemoreceptors with hypoxia, during stimulation of central chemoreceptors with hypercapnia, and during a ...
Cordova A - - 1994
The aim of this study was to determine the influence of hypoxia and exercise in 65Zn distribution in various rat muscles. A total of 80 male wistar rats weighting 250 +/- 10 g were randomly separated into eight groups: four groups in air, two at rest, and the other two ...
Ward S A - - 1994
The inaccessibility of the peripheral chemoreceptors (carotid bodies) precludes their direct investigation in exercising humans. As a result, a range of indirect techniques has been developed to assess the carotid body contribution to ventilatory control in exercise. The considerable controversy surrounding their involvement in this control process is a reflection, ...
Barlow C W - - 1994
Hypoxia has been reported to increase arterial potassium concentration ([K+]a) in anaesthetized cats (Paterson, Estavillo & Nye, 1988). The purpose of this study was to determine whether this phenomenon occurs in humans. The effect of hypoxia on [K+]a was measured in ten male subjects, at rest and during light exercise, ...
Sjögren D - - 1994
Ventilatory responses to hypoxia (HVR) were investigated using poikilocapnic conditions (i.e. end-tidal CO2's allowed to seek it's own level) in 15 cardio-pulmonary healthy patients who were first studied awake and then at 0.85 MAC isoflurane. The influence of hypercapnia (HyperCapnic Ventilatory Response, HCVR) was also elucidated. Pneumotachography, capnography and airway ...
Matsuoka T - - 1994
We tested the hypothesis that the sinoaortic afferents may contribute to normoxic thermogenesis and to the magnitude of the hypometabolic response to hypoxia. Adult rats were either sinoaortic denervated (SAX; n = 20) or sham operated (Sham; n = 20). A few days after the operation, gaseous metabolism [O2 uptake ...
Lopes J M - - 1994
The role of intracerebral adenosine levels in the control of ventilatory response to hypoxia was explored in 15 spontaneously breathing intubated piglets, 1-5 days old, sedated with chloral hydrate. Respiration was recorded via by a pneumotachograph. In all animals exposed to hypoxia (12% O2) for 10 minutes. There was an ...
Kuno S - - 1994
Four well-trained combination skiers were studied through pre- and post-training for the effects of short-term intermittent training during hypoxia on muscle energetics during submaximal exercise as measured by Phosphorus-31 nuclear magnetic resonance and maximal aerobic power (VO2max). The hypoxia and training in the cold was conducted in a hypobaric chamber ...
Wardle C A - - 1994
Factors controlling hypoxia-induced myocardial glycerol release were studied in isolated, perfused rat hearts. A constant coronary flow rate 10 ml g-1 min-1 was maintained. The perfusion buffer was gassed with O2-N2 mixtures containing 5% CO2. The O2:N2 ratios were normoxia 95:0, hypoxia 30:65, and severe hypoxia 10:85 (v/v). Glycerol and ...
Dahan A - - 1994
To examine the effects of a sub-anaesthetic concentration of nitrous oxide on ventilation, we have studied the ventilatory response to carbon dioxide and isocapnic hypoxia (FIN2O 0.2). In five subjects, we performed step decreases in PE'O2 to 6.7 kPa for 15 min and step increases in PE'CO2 (delta PE'CO2 1.5 ...
Negoescu R - - 1994
ECGs of 21 candidate-pilots and 19 pilots were recorded during: 1) exposure to 5500 m hypobaric hypoxia (HH) while sitting, in the sequence: 1a) initial 7 min of adaptation (A); 1b) later 7 min of recovery (R) after short but intense tread-mill effort; and 2) final 7 min baseline (B), ...
Bonora M - - 1994
In conscious newborns, the ventilatory response to hypoxia is characterized by precocious hyperventilation followed by tardive hypoventilation, the latter disappearing with age. The hypoventilation could be mainly related to a weak peripheral drive and to the persistence of the diaphragmatic activity during expiration. Also, a decrease in metabolic rate and ...
Paterson D H - - 1993
This study assessed whether the form of the peripheral chemoreflex response to hypoxia depends on the magnitude of the stimulus. Two amplitudes of square-wave hypoxic stimulation were employed: small amplitude (SO) PETO2 from 63.2 to 54.9 Torr, and large amplitude (LO) PETO2 from 73.0 to 48.0 Torr. Each was studied ...
Sladek M - - 1993
To determine the influence of an altered carotid body function on the laryngeal chemoreflex (LCR) response, reflex apnea was induced by laryngeal water stimulation during normoxia or acute hypoxia in unanesthetized awake lambs in which the ventilatory response to acute hypoxia was attenuated by prolonged postnatal hypoxemia. Prolonged hypoxemia (H) ...
Kimura H - - 1993
We investigated whether selective depression of the genioglossus muscle (GG) activity could be associated with hypoxic ventilatory depression, which is developed in the late phase of the biphasic ventilatory response during sustained hypoxia. Eleven control subjects and 10 patients with obstructive sleep apnea syndrome (OSAS) were examined by an isocapnic ...
Young C H - - 1993
We selected nine normal subjects (8M, 1F; aged 25-43 yr) with brisk hypoxic ventilatory responses, and studied their ventilatory response to sustained isocapnic hypoxia (SaO2 82 (SEM 0.1) % for 25 min) in the presence and absence of 0.1% inspired halothane. Halothane had no significant effect on baseline ventilation or ...
Lahiri S - - 1993
The hypothesis that CO-binding pigments in the carotid body participate in O2 chemoreception was tested. The chemosensory nerve discharges of cat carotid body perfused and superfused in vitro at 36-37 degrees C with cell-free solution containing CO2-HCO3- (pH approximately equal to 7.39) were recorded to monitor O2 chemoreception. Several levels ...
Earley L - - 1993
The effects of cyanide and nitrogen on contractile activity in rat uteri was investigated. Hypoxia significantly reduced contractile activity produced either spontaneously, or by application of carbachol (50 mumol l-1) or oxytocin (20 nmol l-1) in preparations from pregnant and nonpregnant rats. Hypoxia had, however, significantly smaller effects on agonist-evoked ...
Myrmel T - - 1993
A phospholipase C specific for choline and ethanolamine acyl and plasmalogen glycerophospholipids (PC-PLC) has been described in myocardial tissue. In the present study we investigated whether an endogenous PC-PLC is activated in hypoxic, substrate-free incubations of rat ventricular myocytes. The phosphatidylcholine pool of the myocytes was prelabelled with [14C]choline during ...
Marshall J M - - 1993
1. In rats anaesthetized with Saffan, the spinotrapezius muscle was prepared for in vivo microscopy. Systemic hypoxia (breathing 8% O2 for 3 min) induced a fall in arterial pressure and tachycardia, together with constriction in some arterioles and venules of each section of the vascular tree and dilatation in others. ...
Kuna S T - - 1993
The electrical activity of the arytenoideus muscle, a vocal cord adductor, was measured in 14 normal adult humans during progressive isocapnic hypoxia and progressive hyperoxic hypercapnia. Electromyograms of the arytenoideus were obtained with intramuscular hooked-wire electrodes implanted by means of a fiber-optic nasopharyngoscope. Correct placement of the electrodes was confirmed ...
Penning D H - - 1993
Simultaneous assessment of synaptic activity and glutamate efflux in guinea pig hippocampal brain slices was made before, during and after a 10-min period of hypoxia. Spontaneous glutamate efflux was assessed by determining glutamate concentration in the superfusion medium at discrete times using high performance liquid chromatography (HPLC). Synaptic activity was ...
Mian R - - 1993
OBJECTIVE: The aim was to investigate the effect of acute systemic hypoxia on vascular permeability to macromolecules and on leucocyte adherence to vascular endothelium in vivo. METHODS: Experiments were performed on anaesthetised rats with either the intestinal mesentery or the spinotrapezius muscle prepared for in vivo microscopy. To quantify changes ...
Phillipson E A - - 1993
We examined the effects of aging on the metabolic respiratory control system by measuring changes with time in steady-state minute volume of ventilation (VI), alveolar carbon dioxide pressure (PACO2), and ventilatory and arousal responses to hypercapnia and hypoxia during slow-wave sleep (SWS). Studies were performed longitudinally in six healthy dogs ...
Clement I D - - 1993
Latencies for the ventilatory response to hypoxia have been estimated from data from experiments in which square waves of isocapnic hypoxia (periods 30 sec and 60 sec) were presented to 5 subjects. Distorted steps were excluded from the analysis, and the remaining steps were time-aligned relative to the step and ...
Canet E - - 1993
This study was designed to determine the effect of the removal of chemical stimuli on breathing rhythmicity in awake newborn lambs; it was also designed to define the chemical threshold below which breathing would stop [arterial PCO2 (PaCO2) apnea threshold]. We used a technique of graded extracorporeal CO2 removal with ...
Ben-Yoseph O - - 1993
The incorporation of 13C from [1-13C]glucose and [2-13C]acetate into selected intermediary metabolites in extracts prepared from incubated cerebral-cortex slices was monitored by using 13C-n.m.r. spectroscopy under conditions of mild and severe hypoxia. Mild hypoxia had little effect on labelling of tricarboxylic-acid-cycle-related amino acids [glutamate, glutamine and gamma-aminobutyrate (GABA)], although the ...
Fregosi R F - - 1993
The slope of the relationship between ventilation (VI) and O2 consumption, as derived in progressive-intensity exercise tests, is increased markedly by systemic hypoxia. The mechanisms underlying the hypoxic potentiation of the ventilatory response to exercise have not been established, partly because several factors that can increase respiratory drive (e.g., metabolic ...
Hasegawa K - - 1993
Free radical generation in the neonatal mouse brain subjected to acute hypoxia was measured directly by using electron spin resonance spectroscopy (ESR). Free radical density, an index of free radical content, was investigated during exposure to nitrogen gas (N2 group) or carbon dioxide gas (CO2 group) of high purity, and ...
Moss I R - - 1993
To test the role of mu and delta opioid systems in neonates during hypoxia, a total of sixteen, 4-11 (n = 7) and 26-33-day-old piglets (n = 9) were instrumented aseptically for assessment of sleep/wake states (S/W), electromyographic activities of the diaphragm and posterior cricoarytenoid muscles (EMGdi, EMG-pca, respectively), heart ...
Blouin R T - - 1993
BACKGROUND: While flumazenil reverses benzodiazepine-induced sedation, its ability to antagonize the ventilatory depressant effects of benzodiazepines has not been fully established. A randomized, double-blind study was conducted to determine whether flumazenil effectively reverses midazolam-induced depression of the hypoxic ventilatory response. METHODS: Twelve healthy male volunteers received intravenous midazolam 0.12 +/- ...
Xi L - - 1993
1. We assessed short-term potentiation of ventilation in response to brief systemic normocapnic hypoxaemia in conscious dogs. Four recumbent dogs were exposed to Pa, O2 35-55 mmHg with Pa, CO2 maintained normocapnic for forty to fifty seconds and then abruptly returned to normoxia. Minute ventilation (VI) increased 4- to 5-fold ...
Damerau W - - 1993
The release of .OH and alkyl free radicals into the coronary flow were compared in Langendorff perfused and working rat hearts during normoxia (30 min), hypoxia (30 min) and reoxygenation (60 min) by means of spin-trapping techniques using 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). In Langendorff hearts, there was a small but steady increase ...
Meno J R - - 1993
We measured the changes in pial arteriolar diameter and CSF concentrations of adenosine, inosine, and hypoxanthine during hypoxia in the absence and presence of topically applied dipyridamole (10(-6) M) and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA; 10(-5) M). Closed cranial windows were implanted in halothane-anesthetized adult male Sprague-Dawley rats for the observation of the ...
Brown D R - - 1993
Periodic oscillations in pulmonary ventilation (VI), tidal volume (VT), and inspiratory and expiratory times (TI and TE) were studied during normoxia (arterial PO2 = 95 Torr) and 48 h of hypoxia (arterial PO2 = 40-50 Torr) in awake intact (n = 8) and carotid body-denervated (CBD; n = 8) ponies. ...
Elliott S L - - 1993
The effect of hypoxia and acidosis on the elimination of an oxidatively metabolized drug, S-propranolol, was examined in the single-pass isolated perfused rat liver (IPRL). The experiments (N = 6) consisted of four consecutive 30 min phases: normal pH (pH 7.4)/normal oxygen delivery, normal pH/hypoxia, hypercapnic acidosis (pH 7.1)/normal oxygenation ...
Taylor C P - - 1993
We performed experiments in vitro to observe electrophysiological events that may relate to the protective effect of decreased temperature during cerebral ischemia in vivo. Extracellular field potentials were recorded from area CA1 of rat hippocampal slices with reduced oxygen and 2.0 mM D-glucose, producing irreversible changes within c. 10 min ...
Trippenbach T - - 1993
Effects of 10% O2 on the response of the phrenic neurogram to vagal (VS) and saphenous stimulation (SS) were studied in anesthetized and artificially ventilated newborn (group 1: 1-3 days old, n = 13; group 2: 8-14 days old, n = 14) and adult (group 3, n = 12) rabbits. ...
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