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Bureau M A - - 1988
This study was undertaken to measure the neonate's response to CO-induced hypoxia in the first 10 days of life. CO breathing was used to induce hypoxia because CO causes tissue hypoxia with no or minimal chemoreceptor stimulation. An inspired gas mixture of 0.25 to 0.5% CO in air was used ...
Djelmis J - - 1988
As artefact-free recordings of the fetal brain bioelectric potentials can only be obtained by specially designed electrodes, an electrode for taking electroencephalogram (EEG) and cardiotocogram (CTG), according to the principle of vacuum electrode developed by Rosen and Scibetta, has been designed. The polygraphic technique was used to examine a total ...
Kraaier V - - 1988
A condition of hypobaric hypoxia was created in a low pressure chamber by reducing the atmospheric pressure to 46.5 kPa. Thirty-six subjects were exposed to hypobaric hypoxia during 19 min with a recovery period of 25 min. In 13 subjects the experiment was repeated after 1 week. Four EEG channels, ...
Lawler J - - 1988
The purpose of these experiments is to test the hypothesis that exercise-induced hypoxemia at sea level in highly trained athletes might be exacerbated during acute hypoxia and therefore result in correspondingly larger decrements in maximal O2 uptake (VO2max) compared with less trained individuals. Thirteen healthy male volunteers were divided into ...
Davis G M - - 1988
The diphasic ventilatory response to steady-state hypoxia has been reported in anesthetised, intubated newborn piglets. We questioned whether this diphasic response persisted in the awake, spontaneously breathing piglet. Nine piglets, at one day of age, breathing spontaneously through a fitted mask and pneumotachograph were examined, monitoring the minute ventilation. (VE) ...
Kjaer M - - 1988
Hypoxia and physical training alter the responses of glucoregulatory hormones to absolute work loads in opposite directions. These effects have tentatively been ascribed to changes in maximal O2 consumption (VO2 max) and ensuing changes in relative work loads. However, hypoxia as well as training may more specifically influence the hormonal ...
Bonora M - - 1988
The effects of intravenous administration of agonists and antagonists of dopamine (DA) and norepinephrine (NE) on the central ventilatory response to hypoxia were studied in unanesthetized cats. The experiments were performed in intact animals exposed to CO-hypoxia and in carotid-body denervated animals breathing a hypoxic mixture. The DA agonist, apomorphine ...
Schibye B - - 1988
The effect of acute hypoxia and CO2 inhalation on leg blood flow (LBF), on leg vascular resistance (LVR) and on oxygen supply to and oxygen consumption in the exercising leg was studied in nine healthy male subjects during moderate one-leg exercise. Each subject exercised for 20 min on a cycle ...
McMullin M F - - 1988
Animals subjected to hypoxia become hypocapnic and after some hours show an increase in circulating erythropoietin. The steps involved in the increased production of erythropoietin in response to hypoxia are not fully understood, although it has been postulated that changes in coincident variables such as acid-base balance may contribute to ...
Watchko J F - - 1988
We examined the separate effects of acute hypercapnia and acute hypoxia, on the electromyographic activity (EMG) of the costal and crural diaphragm in 6 anesthetized spontaneously breathing piglets (age 12-23 days, weight 3.00-4.37 kg). Bipolar wire electrodes were inserted into the anterior paratendinous costal diaphragm and the midportion of the ...
Côté A - - 1988
Newborn mammals respond to hypoxia with an immediate hyperventilation that is rapidly dampened. Changes in mechanical properties of the respiratory system during hypoxia have been considered an important reason for this fall in minute ventilation (VE). We have studied the dynamic mechanical behavior of the respiratory system in eight unanesthetized ...
Leiman B C - - 1987
To evaluate the effects of succinylcholine on cardiac arrhythmias and serum levels of potassium and catecholamines, dogs with hypoxia alone and with hypoxia and hypercarbia were studied during anesthesia with halothane or enflurane. After the injection of succinylcholine (0.3 mg/kg), cardiac arrhythmias occurred in all halothane:hypoxia dogs and in 70% ...
Moss I R - - 1987
Breathing response to 12% and 6% O2 in N2 (at isocapnia) was measured in anaesthetized piglets, 1-5 and 19-25 days old, before and after 3 mg kg-1 i.v. naltrexone. The degree of interaction between the anaesthetic and naltrexone was assessed. At the end of each hypoxic trial, arterial blood was ...
Conway M A - - 1987
1. The ventilatory responses to step changes from rest to 100 W cycling exercise were studied in five healthy human subjects. Exercise was performed in hypoxia (end-tidal O2 pressure, PET,O2, 50-55 mmHg), a condition characterized by a marked enhancement of arterial chemoreceptor activity, and in hyperoxia (PET,O2 greater than 250 ...
Young M L - - 1987
An isolated perfused heart model was used to assess the effects of hypoxia and adenosine on the adult and neonatal (1-5 days) rabbit atrioventricular (AV) node. The AV nodal function was assessed by the A-H interval at a constant atrial pacing cycle length and by the longest pacing cycle length ...
Severinghaus J W - - 1987
Oxygen saturation, SpO2%, was recorded during rapidly induced 42.5 +/- 7.2-s plateaus of profound hypoxia at 40-70% saturation by 1 or 2 pulse oximeters from each of six manufacturers (NE = Nellcor N100, OH = Ohmeda 3700, NO = Novametrix 500 versions 2.2 and 3.3 (revised instrumentation), CR = Criticare ...
Schramm C M - - 1987
To evaluate whether the influence of peripheral chemoreceptor (PCR) stimulation is centrally modulated by hypoxia, the respiratory effects of sodium cyanide (NaCN) infusion were compared during room air and 10% O2 inhalation in 18 lightly anesthetized, tracheotomized rabbits of varying postnatal age (1-33 days). During normoxia, noncumulative infusions of NaCN ...
Katz A - - 1987
Eight men cycled for 5 min at 120 +/- 6 W (mean +/- SE) at which O2 uptake was 50% of its maximal normoxic value, breathing room air (21% O2; normoxia) on one occasion and 11% O2 in N2 (respiratory hypoxia/hypoxic--Resp. Hx.) on the other. Biopsies were taken from the ...
Friedman B J - - 1987
To assess the effect of hypoxia on cellular thallium-201 (201Tl) uptake and washout independent of coronary flow, we studied thallium kinetics during normoxia and hypoxia in cultured chick ventricular cells. Monolayers of contracting ventricular cells grown on coverslips were placed in a chamber and perfused to asymptote with media containing ...
Fordyce W E - - 1987
Steady state breathing patterns, alveolar gases, and arterial blood gases and pH were measured during air, acute hypoxia, and acute hyperoxia in four awake cats 5 years after combined carotid body resection (CBR) and aortic depressor nerve section. Steady state breathing patterns and alveolar gases were also measured in these ...
Paterson D J - - 1987
Breathing frequency (f) is often reported as having an integer-multiple relationship to limb movement (entrainment) during rhythmic exercise. To investigate the strength of this coupling while running under hypoxic conditions, two male Caucasians and four male Nepalese porters were tested in the Annapurna region of the Himalayas at altitudes of ...
Fukuda Y - - 1987
The carotid chemoreceptor discharge responses to hypoxia and hypercapnia were quantitatively compared between normotensive (NTR) and spontaneously hypertensive rats (SHR). For this purpose we recorded afferent mass discharges from the carotid sinus nerve (CSN) at various levels of end-tidal O2 and CO2 concentrations (FetO2, FetCO2 (%)) in the urethane-anesthetized, vagotomized ...
Lee K - - 1987
The authors examined the effects of hypoxia (8% O2 in N2) on the turnover rates of norepinephrine (NE) and epinephrine (E) in the heart, adrenal gland, submaxillary gland and stomach. The turnover rates were estimated by measuring the decrease in the content of NE and E after an i.p. injection ...
Bouissou P - - 1987
Prolactin (PRL) secretion is regulated by a variety of factors, most of them being known for their enhancing effects on blood PRL levels. This study describes the inhibitory influence of an acute exposure to hypoxia (14.5% O2) on the blood PRL response induced by graded maximal exercise in eight trained ...
Paterson D J - - 1987
Three male and four female subjects were acutely exposed to normoxic and hypoxic gas mixtures (FIO2 = 17.39%, 14.40%, 11.81%) in a single-blind randomized fashion during four treadmill runs to volitional exhaustion. Maximal scores for oxygen consumption (VO2), carbon dioxide production and heart rate decreased linearly (p less than 0.01) ...
Darnall R A - - 1987
Neonates of animals and humans exhibit a paradoxical ventilatory response to hypoxia characterized by an initial increase in minute ventilation followed by a late, sustained decrease. Exogenous adenosine analogues cause respiratory depression, and the xanthine derivative aminophylline, a competitive inhibitor of adenosine receptors, decreases the amount of hypoxic ventilatory depression ...
Watchko J F - - 1987
The newborn infant monkey consistently demonstrates a biphasic ventilatory response to hypoxemia. We have previously shown that the ventilatory depression during the late portion of this biphasic response is secondary to a decline in inspiratory volume that cannot be explained solely by central neural depression. We hypothesized that hypoxemia caused ...
Angus P W - - 1987
Although studies in isolated hepatocytes have demonstrated that hypoxia adversely affects drug conjugation, the impact of hypoxia on drug elimination by conjugation in the intact liver has not been defined. This study in the isolated perfused rat liver examines the effect of acute hypoxia on the hepatic elimination of harmol, ...
Benzi G - - 1987
Synaptosomes were isolated from the motor area of the cerebral cortex of normoxic or hypoxic (PaO2 = 17-19 mmHg, for 15 min) beagle dogs of different ages. Synaptosomes were incubated in Krebs-Henseleit-Hepes buffer (for 10 min at 24 degrees C) and the energetic state was defined by: the balance of ...
Bender P R - - 1987
The relative contributions of breathing frequency and tidal volume to the increase in ventilation during acute or prolonged exposure to hypoxia is uncertain. We examined the changes in breathing pattern during hypoxic exposures lasting minutes, hours, and days using data from previous studies. Increased tidal volume accounted for the increased ...
Nakazono Y - - 1987
To clarify the role of the carotid body in the mechanism governing exercise hyperpnea, the effect of hypoxia and hyperoxia on ventilation and cardiac output was studied in four healthy men. The VE increased 10.7% in hypoxia and decreased 10.1% in hyperoxia from normoxia as judged from the steady-state values ...
Martin D - - 1987
Experiments were performed to check the tolerance to severe hypoxia of the tissue layers (compact and spongy) of the tortoise heart. The animals were subjected to hypoxia (7% O2) at 18 degrees C, 28 degrees C and 38 degrees C for 30, 6 and 2 hr respectively, or to anoxia ...
Moss I R - - 1987
In normoxia, the opioid antagonist naltrexone (3 mg/kg i.v.) increased respiratory drive (dITP/dt), frequency (f) and ventilation (V) and decreased tidal volume (Vt) in 1- to 4-day-old anesthetized piglets; it increased dITP/dt in 10- to 18-day-old piglets. During progressive and steady state hypoxia, naltrexone increased dITP/dt, f and V within ...
Garrett R C - - 1987
Lipoxygenase products (leukotrienes) have been proposed as the mediators of pulmonary hypoxic vasoconstriction. However, the supporting data are inconclusive because the lipoxygenase and leukotriene receptor blockers that reduce hypoxic vasoconstriction (such as diethylcarbamazine and the FPL's) have confounding effects. We investigated BW 755C, a potent inhibitor of both lipoxygenase and ...
Thys D M - - 1986
The pulse oximeter continuously and non-invasively measures arterial saturation. The objective of the current study was to assess the value of this monitor during thoracic surgery with one-lung ventilation. A total of 108 pulse oximeter saturation readings (SaO2[O]) were compared with PaO2 and calculated saturation (SaO2[C]) values. Hypoxia (PaO2 less ...
Burggren W - - 1986
Gill and lung ventilatory frequencies at 20-23 degrees C were recorded in five different larval stages and in the adults of the bullfrog, Rana catesbeiana (n = 101, body mass 40 mg-90 g). Ventilatory frequencies in unanesthetized, unrestrained animals were determined (1) after normoxic acclimation, (2) during acute hypoxic and ...
Maxwell D L - - 1986
Adenosine infusion (100 micrograms X kg-1 X min-1) in humans stimulates ventilation but also causes abdominal and chest discomfort. To exclude the effects of symptoms and to differentiate between a central and peripheral site of action, we measured the effect of adenosine infused at a level (70-80 micrograms X kg-1 ...
Shi Z Y - - 1986
This report deals with the study of electroencephalograms of 36 subjects who inhaled hypoxic mixture at the sea level (PO2 is as that at 7000 m above sea level) or in a hypobaric chamber with rapid decompression (as that at 5000-7500 m above sea level) and of 46 subjects who ...
Meehan R T - - 1986
The effect of hypoxia (H) on plasma renin (PRA), aldosterone (PA), and arginine vasopressin levels (AVP) was evaluated during 6 h of mild exercise (treadmill: 0 grade, 1 mph). A crossover study was performed on seven male volunteers during steady state conditions of H2O, Na+ and K+ balance while breathing ...
Gleeson M - - 1986
Respiratory, cardiovascular and blood gas responses of pigeons to spinal cord cooling (36 +/- 1 degrees C), to ambient cooling (Ta = 5 degrees C) and to simultaneous spinal cord and ambient cooling were measured at three different levels of fractional inspired oxygen concentration (FIO2 = 0.209, 0.10 and 0.07). ...
Matsuoka S - - 1986
Effects of glutamate on myocardial mechanical function and energy metabolism during 120 min of hypoxia and subsequent reoxygenation were studied in the isolated arterially perfused newborn and adult rabbit hearts. The muscle was perfused with a Krebs-Henseleit (KH) solution or KH solution which contained 1 mM glutamate. Glutamate attenuated the ...
Easton P A - - 1986
We examined the ventilatory response to moderate (arterial O2 saturation 80%), sustained, isocapnic hypoxia in 20 young adults. During 25 min of hypoxia, inspiratory minute ventilation (VI) showed an initial brisk increase but then declined to a level intermediate between the initial increase and resting room air VI. The intermediate ...
Lindefors N - - 1986
In vivo release of substance P (SP) was measured by microdialysis in the nucleus tractus solitarii (nTS) in adult cats. Small perfused semipermeable tubules (microdialysis probes) were implanted stereotaxically in the nTS, at the position of respiration-related neurons and perfused with artificial CSF. SP was determined by radioimmunoassay of the ...
Cooper D M - - 1986
The purpose of this study was to assess whether breathing high or low concentrations of O2 could affect glucose turnover during exercise in man. Ten healthy subjects performed two constant work-rate exercise tests, one when the fraction of inspired O2 (FIO2) was 0.15 and the other at the same work ...
Road J D - - 1986
In this study diaphragmatic length changes were measured during quiet breathing and during augmentation of breathing with hypoxia and hypercapnia in supine anesthetized dogs. The breathing pattern and the VT-TI relationship during hypoxia were different than those during hypercapnia. The crural diaphragm shortened more than the costal diaphragm with both ...
Gautier H - - 1986
The ventilatory response to CO hypoxia (FICO = 0.0025), hypercapnia, and hypoxia was studied in a group of intact, conscious cats before and during chronic administration of phenobarbital (60 mg/day). It was found that the ventilatory response to hypercapnia or hypoxia was not significantly modified during phenobarbital administration. However, the ...
Maxwell D L - - 1986
In seven normal subjects the ventilatory responses to progressive isocapnic hypoxia and hyperoxic hypercapnia were measured during rebreathing. During an infusion of somatostatin (10 nmol/min) the mean hypoxic response decreased by 66% (control: -1.6 SD 1.2 litres min-1 %-1 SaO2; somatostatin: -0.6 SD 0.7) but the mean hypercapnic response was ...
Mayock D E - - 1986
The effects of opiate receptor antagonism by naltrexone hydrochloride on the biphasic hypoxic ventilatory response in the infant Macaca nemestrina have been investigated. Minute ventilation, tidal volume, and respiratory frequency were measured in six animals from timed gestations before and during inhalation of a hypoxic gas mixture. All studies were ...
Smyth R J - - 1986
Adolescents with mild, asymptomatic scoliosis (thoracic curvature less than 35 degrees) may have little or no impairment of resting lung volumes. Progression to more severe disease may, however, be accompanied by lung restriction, impaired exercise tolerance, and respiratory failure with CO2 retention. We wished to see whether adolescents with mild ...
Beresewicz A - - 1986
The effect of calmodulin antagonists trifluoperazine (2.5 X 10(-7) M and 2.5 X 10(-6) M) and R 24571 (10(-8) M and 10(-7) M) on Langendorff-perfused rabbit hearts subjected to 180 min hypoxia and 30 min reoxygenation was studied. Coronary flow, force of contraction, oxygen consumption and release of lactate, noradrenaline ...
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