Search Results
Results 601 - 650 of 1063
< 8 9 10 11 12 13 14 15 16 17 18 >
Helset E - - 1995
The release and vascular effects of calcitonin gene-related peptide (CGRP) and endothelin-1 (ET-1) during acute alveolar hypoxia (O2 2%) were examined in isolated blood-perfused rat lungs. In 10 lungs, repeatedly ventilated with hypoxic gas for 5 min, samples from effluent blood were taken during hypoxia and analysed for plasma levels ...
Archer S L - - 1995
Dithionite is a powerful reducing agent used to deoxygenate hemoglobin and create anaerobic conditions in vitro. Recently, dithionite has been used as a convenient means of creating "hypoxia" in experiments studying the O2 sensor in the pulmonary circulation and carotid body. We evaluated the hypothesis that hypoxia created by hypoxic ...
Abdalla S - - 1995
1. Isolated proximal and distal extralobar branches of the pulmonary artery of the guinea-pig develop slow and well-sustained contractions in response to hypoxia (PO2 11-15 mm Hg) without prior stimulation with an agonist. These contractions are readily reversible by readministration of oxygen. 2. Incubation of these preparations with diethyldithiocarbamic acid ...
Hughson R L - - 1995
The dynamic responses of expired ventilation (VE) following transitions in work rate were studied during step increases and decreases, and during pseudorandom binary sequence (PRBS) changes in work rate. Six healthy men completed multiple repetitions of each test type under conditions of hypoxia (fractional inspired O2, FIO2 = 0.14), room ...
Morgan B J - - 1995
We studied ventilatory and neurocirculatory responses to combined hypoxia (arterial O2 saturation 80%) and hypercapnia (end-tidal CO2 + 5 Torr) in awake humans. This asphyxic stimulus produced a substantial increase in minute ventilation (6.9 +/- 0.4 to 20.0 +/- 1.5 l/min) that promptly subsided on return to room air breathing. ...
Churchill T A - - 1995
This study was designed to address the reasons why glycolysis in mammalian liver is unable to function more efficiently during periods of cold hypoxia. Our hypothesis was that control of intracellular pH, by use of amino acid buffers with high pKa values, would allow prolonged flux through glycolysis and better ...
Zwemer C F - - 1995
Hyperoxic cardiopulmonary resuscitation (CPR) is associated with an increase in neurologic dysfunction upon successful resuscitation with much of the damage attributable to an increase in reperfusion oxidant injury. We hypothesized that by contrast, hypoxic ventilation during resuscitation would improve neurologic outcome by reducing available substrate necessary for oxidant injury. Specifically, ...
Hughson R L - - 1995
This study evaluated the dynamic response of VO2 in 6 healthy men at the onset and end of submaximal step changes in work rate during a pseudorandom binary sequence (PRBS) exercise test and during ramp incremental exercise to exhaustion while breathing three different gas mixtures. The fractional concentrations of inspired ...
Igarashi T - - 1995
The biphasic nature of the ventilatory response to sustained hypoxia (< 1 h) is thought to occur as a result of combined effects of stimulation and depression with hypoxia. If the depressant effect of hypoxia on ventilation occurs later than the stimulatory effect, the magnitude of the ventilatory response to ...
Jenden D J - - 1995
We have recently demonstrated an increase in arterial blood choline (Ch) concentration in normocapnic hypoxia and apnea. This could be due to enhanced release of free Ch from tissues, to decreased Ch clearance, or both. The present investigations was undertaken to determine the individual contributions of these processes to the ...
Chandel N - - 1995
During acute (< 30 min) hypoxia, cellular respiration is independent of the O2 concentration as long as PO2 remains above a critical value (5-10 Torr). Similarly, state 3 respiration by isolated mitochondria is independent of PO2 above a critical tension of 2-4 Torr. However, rat hepatocytes demonstrate a reversible suppression ...
Milerad J - - 1995
Decreased ability to generate a hyperventilatory response to hypoxemia is believed to be an important mechanism in the pathophysiology of sudden infant death syndrome, and maternal smoking is a leading risk factor. To investigate whether there may be a link between these two observations, we studied five lambs at mean ...
Hervant F - - 1995
Locomotory and ventilatory responses to severe hypoxia and subsequent recovery were investigated in 3 amphipod crustaceans: 2 hypogean species (1 interstitial species Niphargus rhenorhodanensis and 1 karstic species N. virei) and 1 epigean species (Gammarus fossarum), and in an epigean population of 1 isopod crustacean (Asellus aquaticus). These species displayed ...
Portman M A - - 1995
This study investigates the relation between myocardial oxygen consumption (MVO2), function, and high energy phosphates during severe hypoxia and reoxygenation in sheep in vivo. Graded hypoxia was performed in open-chested sheep to adjust PO2 to values where rapid depletion of energy stores occurred. Highly time-resolved 31P nuclear magnetic resonance spectroscopy ...
Hejal R - - 1995
The effects of moderate sustained normocapnic hypoxia on tracheal submucosal gland reflex responses were studied. Experiments were performed in anesthetized, paralyzed, and mechanically ventilated dogs. The changes in the number of secreting glands and volume of secreted fluid in the subsequent period of time were recorded after 15-30 min of ...
Peltonen J E - - 1995
The present study examined the effect of oxygen fraction in inspired air (FIO2) on exercise performance and maximum oxygen consumption (VO2max). Six national level male rowers exercised three 2500-m all-out tests on a Concept II rowing ergometer. Each subject performed one test in normoxia (FIO2 20.9%), one in simulated hyperoxia ...
Simon P M - - 1995
We assessed the cardiovascular responses to systemic normocapnic hypoxia in five normal subjects, five double lung transplant patients with lung denervation and intact hearts, and five patients with denervated hearts. Progressive normocapnic hypoxia was induced over 10-15 min and maintained for 2-3 min each at 90, 87, 84, and 80% ...
Long W - - 1995
We examined the effects of the dopamine blocker haloperidol (H) on the ventilatory response to sustained hypoxia in awake cats. Ventilation (VE) was measured plethysmographically, and end-tidal PO2 (PETO2) and PCO2 were measured by sampling tracheal gas. Measurements were made before, during, and after 30 min of isocapnic hypoxia after ...
Howard L S - - 1995
Almost all studies of the effects of prolonged hypoxia on ventilation (VE) in humans have been performed with the end-tidal PCO2 (PETCO2) left uncontrolled. The purpose of this study was to compare the effects of 8 h of hypoxia with PETCO2 held constant with 8 h of hypoxia with PETCO2 ...
Howard L S - - 1995
In the preceding companion paper (L. S. G. E. Howard and P.A. Robbins, J. Appl. Physiol. 78: 1092-1097, 1995), we showed that ventilation rises during 8 h of isocapnic hypoxia. In the present study we report the changes that occur in the ventilatory response to acute hypoxia (AHVR) over 8 ...
Yoshiike Y - - 1995
BACKGROUND: The effects of beta 2 adrenergic agonists on chemoreceptors remain controversial. This study was designed to examine whether fenoterol, a beta 2 adrenergic agonist, increases the ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) in normal subjects. METHODS: HCVR was tested with a rebreathing method and HVR was examined ...
Koistinen P - - 1995
We studied 12 highly trained athletes, 6 male ice-hockey players and 6 cross-country skiers (2 females, 4 males). All of them participated in a maximal electrically braked bicycle ergometer test in a hypobaric chamber at the simulated altitude of 3000m (520 mmHg) and in normobaric conditions two days apart in ...
Foo I T - - 1995
Twenty normal male subjects with brisk hypoxic ventilatory responses were recruited and ventilatory responses to sustained isocapnic hypoxia (SaO2 80.4 (SD 1.3)% for 20 min) were studied on separate days under four conditions: hypoxia alone, with or without domperidone, and 0.1 MAC of end-tidal isoflurane, with or without domperidone. Ventilatory ...
Benoit H - - 1995
The aim of this study was to evaluate the influence of peripheral chemosensitivity estimated by hypoxic ventilatory response (HVR) on arterial oxygen saturation (SaO2) during maximal exercise in acute hypoxia. A group of 16 healthy men performed maximal exercise in two conditions of partial pressure of inspired oxygen (PIO2/149 and ...
Gautier H - - 1995
Recently, we have described the effects of hypoxia and of hypercapnia on the metabolic (VO2) and ventilatory responses to cold in unanesthetized intact and carotid body-denervated (CBD) rats (Gautier et al., J. Appl. Physiol. 73: 847-854, 1992 and 75: 2570-2579, 1993). In the present paper, we have reanalyzed the above ...
Kullmer T - - 1995
To assess whether acute alveolar hypoxia leads to the release of endothelin-1 (ET) in vivo, ET, cortisol (CORT), and lactate (LA) levels were determined in 15 healthy subjects at rest and during exhaustive incremental cycle ergometry on two separate test days. The subjects were to breathe a gas mixture with ...
Aljadeff G - - 1995
Carotid body afferent contributions to activity of the intermediate area of the ventral medullary surface (IVMS) following transient hypoxia and hyperoxia were examined in 6 spontaneously breathing, pentobarbital-anesthetized cats. Two tidal breaths of 100% N2, 100% O2, or room air, were randomly administered before and after carotid sinus denervation (CSD). ...
Takahashi H - - 1995
Five male subjects performed steady exercise on a cycle ergometer at an intensity of 60% maximal O2 uptake (VO2max) for 6 min on three separate occasions while breathing gas mixtures of 12,16 or 21% O2 in N2. Expired gas fractions, ventilation, heart rate, arterial O2 saturation (SaO2), blood lactate (La) ...
Walsh M L - - 1995
The relation between VO2 and work rate (WR) was examined in seven male subjects who performed ramp (1 W.3s-1) two-legged cycle ergometry to exhaustion while inspiring either hypoxic (12% O2), normoxic (21% O2), or hyperoxic (40% O2) air. The anaerobic threshold was estimated from respiratory gas exchange threshold (RGET). Prior ...
Saiki C - - 1995
Rat pups have a higher metabolic rate at night than in the morning; we questioned to what extent this was accompanied by changes in ventilation (Ve) and the effect of hypoxia on the morning-night differences. From birth, the pups were mother reared under a 12 h light: 12 h dark ...
Delacourt C - - 1995
The effect of vagal afferents on the ventilatory response to hypoxia was studied in eleven awake newborn lambs. Tests were repeated before and after vagotomy in the same lambs in two conditions: with intact upper airways and after intubation. During hypoxia, a diphasic pattern of ventilatory response was observed in ...
Suguihara C - - 1995
In order to evaluate the effects of epinephrine on the cardiorespiratory response to hypoxia in the neonate, 35 sedated, spontaneously breathing newborn piglets (mean +/- SD, age 5 +/- 0.8 days; weight 1.6 +/- 0.3 kg) with intact (ICB) or denervated (DCB) carotid bodies were studied before and during an ...
Nordsmark M - - 1995
Tumour oxygenation and bioenergetic status were measured in the same tumour and these results related to radiobiological hypoxia. A C3H mouse mammary carcinoma grown in the feet of CDF1 mice was used. Bioenergetic status was assessed by 31P MRS using a SISCO 7 Tesla magnet, oxygen measurements were done by ...
Frappell P B - - 1994
Oxygen consumption (VO2), CO2 production (VCO2), and minute ventilation (VE) together with breathing pattern were measured in echidnas during normoxia and hypoxia. In normoxia, VO2, VCO2, and VE were all found to be approximately 30% of the allometric prediction for a eutherian. As a consequence VE/VO2 and VE/VCO2 are as ...
Wanstall J C - - 1994
The effects of in vitro hypoxia on relaxant responses to various vasodilator drugs were examined on norepinephrine-contracted ring preparations of rat pulmonary artery. The physiological salt solution that bathed the tissues was equilibrated with gas mixtures that contained 95%, 12%, 6%, 4% or 0% oxygen (oxygen tension of solution, > ...
Howard L S - - 1994
This study examined whether the form of the acute ventilatory response to different levels of end-tidal PO2 (PETO2) could be determined from a progressive series of steps in PETO2 at constant end-tidal PCO2. Seven levels of PETO2 were employed each lasting 2 min. The steps were performed in both ascending ...
Perreault S - - 1994
Salbutamol is a potent beta 2-adrenoceptor agonist given to patients with bronchial asthma who are frequently hypoxemic. The aims of this study were to document the influence of chronic hypoxia on salbutamol tissue concentrations and on salbutamol effect on total respiratory resistance. To this purpose, salbutamol (60 micrograms/kg) was administered ...
Siim B G - - 1994
The 4-alkylamino-5-nitroquinolines (5NQs) are a new series of bioreductive drugs that exhibit varying degrees of selective toxicity (up to 60-fold) under hypoxic conditions in cell culture. This study tested the hypothesis that differences in hypoxia-selective cytotoxicity in this series reflect differences in the efficiency with which oxygen inhibits metabolic reduction. ...
Blonc S - - 1994
The effect of acute hypoxia (FIO2 = 0.137 +/- 0.001) at Low Altitude (LA: Clermont-Ferrand, 330 m) and acute normoxia (FIO2 = 0.306 +/- 0.006) at High Altitude (HA: La Paz, 3600 m) on performance during a 30-s Wingate test has been investigated in prepubertal children (Tanner stage 1). Twenty ...
Dahan A - - 1994
BACKGROUND: In humans the ventilatory response to isocapnic hypoxia is biphasic: an initial increase in minute ventilation (VE) from baseline, the acute hypoxic response, is followed after 3-5 min by a slow ventilatory decay, the hypoxic ventilatory decline, and a new steady state, 25-40% greater than baseline VE, is reached ...
Igarashi T - - 1994
To examine the role of endogenous adenosine on the hypoxic ventilatory response (HVR) enhanced during exercise, we measured HVR at rest and during mild exercise (12.5 W) in nine healthy men in a supine position after pretreatment with aminophylline (5 mg/kg), an adenosine receptor blocker, or dipyridamole (0.6 mg/kg), an ...
Linseman D A - - 1994
Neonatal rat cardiac myocytes were subjected to 5 h of hypoxia (PO2 < 5 mmHg) in glucose-free, modified Tyrodes solution. Prior to hypoxic exposure, cells were pretreated for 90 min with media alone or containing the trolox analog, U-78517F, at 0.3, 1, or 3 microM. Hypoxic injury was characterized by ...
Koshiya N - - 1994
The mass discharges of the splanchnic sympathetic (SND) and phrenic nerves (PND) were recorded in urethananesthetized rats with resected vagal and aortic nerves. Carotid chemoreceptor (CC) stimulation with N2 inhalation (4-12 s) or cyanide (50-100 micrograms/kg iv) activated SND in bursts synchronized with the postinspiratory phase (mean SND increase: 105 ...
McIlroy W E - - 1994
Characterizing the postural perturbation due to a transient support-surface displacement in terms of acceleration and deceleration events leads to a new framework for understanding the control of the stabilizing response. This study documents the existence of a 'deceleration response', which has not been reported previously, and explores the control of ...
Mizusawa A - - 1994
1. An attempt has been made to test the hypothesis that, in the caudal part of nucleus tractus solitarii (NTS) where carotid sinus nerve (CSN) afferents project, L-glutamate (Glut) modulates the hypoxic ventilatory response. 2. Unanaesthetized, peripherally chemodenervated (carotid body denervated; CBD) and sham-operated, freely moving rats were used. During ...
Charoenpan P - - 1994
Sudden nocturnal deaths among "healthy" workers in Southeast Asia have been termed "sudden unexplained nocturnal death syndrome (SUNDS)" or "sudden unexplained death syndrome (SUDS)". The pathogenesis is still unknown. The paucity of publications on nocturnal monitoring and scientific data stimulated us to perform this study, which included biochemical tests and ...
Gershan W M - - 1994
This study was done to determine 1) whether goats demonstrate the roll-off phenomenon, i.e., a secondary decrease in minute ventilation (VE), after an initial hyperventilation during various levels of hypoxia and, if so, 2) whether roll-off could be due to changes in metabolic rate. We hypothesized that roll-off occurs in ...
Long W - - 1994
In humans and cats the ventilatory response to 30 min of isocapnic hypoxia is biphasic with an initial increase followed by a decrease, termed "hypoxic depression." In humans, 30 min of hypoxia reduces the initial response to a subsequent hypoxic exposure. These experiments were to determine whether the same occurred ...
Korducki M J - - 1994
To determine the effect of hypoxia on metabolic rate (VO2) of ponies, on 2 days we studied ponies that were breathing room air for 1 h followed by 5 h of either hypoxic hypoxia (fractional concn of inspired O2 = 0.126) or 5 h of CO hypoxia. Control arterial PO2 ...
Pandit J J - - 1994
1. The acute ventilatory response to 3 min periods of hypoxia (AHR) was examined in nine patients with clinically complete spinal cord transection (T4-T7) during (a) rest and (b) electrically induced leg exercise (EEL). 2. EEL was produced by surface electrode stimulation of the quadriceps muscles so as to cause ...
< 8 9 10 11 12 13 14 15 16 17 18 >