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Results 201 - 250 of 675
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Ip Siu Po - - 2002
INTRODUCTION: The circulating renin-angiotensin system (RAS) plays a crucial role in the regulation of blood pressure, electrolytes, and fluid homeostasis. In contrast to the circulating RAS, the presence of an intrinsic RAS has been demonstrated in different tissues/organs, which may affect both local and global functions of a biologic system. ...
Kitzmann Anna - - 2002
PURPOSE: We have previously described oxygen-induced retinopathy (OIR) and metabolic acidosis-induced retinopathy (MAIR) in the neonatal rat, both of which are analogous to human retinopathy of prematurity (ROP). Given that rats of identical strain from two commercial suppliers are phenotypically different, we investigated the incidence and severity of preretinal neovascularization ...
Hirai Kiyoshi - - 2002
Cellular injury was evaluated in superfused cerebrocortical slices (350 micro m) from 7-day-old Sprague-Dawley rats exposed to 30 min hypoxia followed by 4 h of reoxygenation. At the end of hypoxia homogenous cytosolic immunoreactivity of cytochrome c increased approximately fourfold, cytochrome c intensity in western blot analyses increased more than ...
Rauchová Hana - - 2002
The exposure to hypobaric hypoxia increased lipid peroxidation as indicated by thiobarbituric acid-reactive substances [TBARS] in rat brain. Plasma lactate/pyruvate ratio was used as a marker of hypoxia. We compared the protective effect of alpha-tocopherol with the effect of L-carnitine or phosphocreatine. Rats pretreated with alpha-tocopherol, L-carnitine, or phosphocreatine had ...
Chereshnev V A - - 2002
We studied changes in rat hemoglobin isoforms during acute adaptation to various hypoxic conditions. Erythrocytes were heterogeneous in the content of various hemoglobin isoforms. Changes in the hemoglobin profile during hypoxia are related to variations in the ratio between populations of erythrocytes differing in the content of individual hemoglobin isoforms.
Omata Naoto - - 2002
We prepared rat brain slices following sublethal hypoxic pretreatment (preconditioning) and untreated (control) rats, and measured the cerebral glucose metabolic rate (CMRglc) by dynamic positron autoradiography with [18F]2-fluoro-2-deoxy-D-glucose before and after originally lethal 20-min hypoxic loading. In the regions of interest such as the frontal cortex, the CMRglc before hypoxic ...
McGuire Michelle - - 2002
Episodic hypoxia induces a persistent augmentation of respiratory activity, termed long-term facilitation (LTF). Phrenic LTF saturates in anesthetized animals such that additional episodes of stimulation cause no further increase in LTF magnitude. The present study tested the hypothesis that 1) ventilatory LTF also saturates in awake rats and 2) more ...
Nishimaki Hironobu - - 2002
One of the serious problems that occurs after cardiopulmonary resuscitation is brain posthypoxic/ischemic deoxygenation. However, there has been no report concerning the effect of isoflurane (ISO) on the brain oxygenation during hypoxia-reoxygenation in relation to cell adhesion molecules (CD11b) in polymorphonuclear leukocyte. Rats were anesthetized with a low concentration of ...
Bavis Ryan W - - 2003
Episodic hypoxia elicits a long-lasting augmentation of phrenic inspiratory activity known as long-term facilitation (LTF). We investigated the respective contributions of carotid chemoafferent neuron activation and hypoxia to the expression of LTF in urethane-anesthetized, vagotomized, paralyzed, and ventilated Sprague-Dawley rats. One hour after three 5-min isocapnic hypoxic episodes [arterial Po(2) ...
Saul Gilbert D - - 2002
Involuntary hyperventilation is a critical factor in acclimatization to a high altitude. Unacclimatized subjects do poorly when acutely exposed to high altitude. This may not be due to hypocapnia itself, but rather an associated symptom which inhibits hypoxic respiratory stimulation. In an unacclimatized individual, voluntary hyperventilation may greatly relieve hypoxia ...
Khachatur'yan M L - - 2002
Resistance to acute hypoxia was evaluated by the life span after elevation to a simulated altitude of 11,500 m at 13.00-21.00 in different seasons of the same year. The period of investigation was divided into 3 parts: beginning (13.00-15.00), middle (16.00-18.00), and end (19.00-21.00) of the day. Animal life span ...
Khachatur'yan M L - - 2002
Resistance to acute hypoxia in rats was evaluated by the life span after elevation to an altitude of 11,500 m at 13.00-21.00 (local time) in different seasons of one year. Geomagnetic activity was evaluated using local K index for Moscow and planetary Kp index. Total 24-h geomagnetic activity had a ...
Kles K A - - 2002
BACKGROUND: Early enteral nutrition in patients following traumatic injury is an important intervention. However, after shock-resuscitation, intestinal hypoperfusion persists despite adequate systemic resuscitation. Our previous in vivo rat studies indicate that hypoperfusion impairs mucosal function in the small intestine. Therefore, the current study sought to improve previous in vitro models ...
Corpechot Christophe - - 2002
Hepatic resection in cirrhotic patients is associated with impaired liver regeneration and poor clinical outcome. Because experimental cirrhosis is associated with hepatic cell hypoxia, we herein investigated whether hypoxia might alter the mechanisms of liver regeneration in the cirrhotic liver. Cirrhosis was induced by diethylnitrosamine in rats. Immunohistochemistry was performed ...
Hattori Itaro - - 2002
Thioredoxin (TRX) is a 13 kDa protein with antioxidant effect and redox regulating functions. Peroxynitrite is a strong oxidizing and nitrating agent which can react with all classes of biomolecules. In the present study, we focused on the association between TRX and nitrotyrosine, which served as a marker of peroxynitrite ...
Cheng Deyun - - 2002
OBJECTIVE: To assess the effect of tetrandrine (Tet) pulmonary targeting microspheres on hypoxic pulmonary hypertension and evaluate its selective action on pulmonary circulation. METHODS: Twenty rats were exposed to hypoxic conditions for 3 weeks. Ten rats were used as normoxic controls. We administered Tet pulmonary targeting microspheres to 10 hypoxic ...
Ostojic Hrvoj - - 2002
Blood hemoglobin oxygen affinity (P50) was measured in three Andean species and in the laboratory rat (control), all raised near sea level. Chinchilla lanigera (Molina, 1792) has an altitudinal habitat range from low Andean slopes up to 3000 m., while Chinchilla brevicaudata (Waterhouse, 1848) has an altitudinal range from 3000 ...
Hasinoff Brian B - - 2002
Dexrazoxane is a cardioprotective antioxidant that is clinically used to reduce the cardiotoxicity of the chemotherapeutic drug doxorubicin. We examined the hypothesis that dexrazoxane also may be able to protect neonatal rat cardiac myocytes from hypoxia-reoxygenation damage. Hypoxia-reoxygenation damage is thought to involve oxidative stress on the heart muscle, possibly ...
Saiki C - - 2001
To examine the process of spontaneous autoresuscitation and the recovery of the hypoxic ventilatory response (HVR) after prolonged anoxia, we monitored respiratory frequency (f, by body plethysmography) and heart rate (HR, by ECG) in intact newborn rats (n = 12, day 2-4) before, during, and after 100% N2 exposure. The ...
Raff H - - 2001
Hypoxia from birth results in a decrease in body weight gain, body size, and bone mineral density (BMD). The purpose of the present study was to determine whether short-term administration of growth hormone (GH) (rat GH; 100 microg/d) could attenuate some of these effects of neonatal hypoxia. Rat pups (with ...
Vizek M - - 2001
We determined the effects of chronic hypoxia on end-expiratory lung volume (EELV), end-expiratory diaphragmatic activity (DE) and ventilation (VE) in 27 intact (awake and anesthetized) and six carotid body-denervated (CBD; anesthetized) rats. Twenty-nine control animals were also studied. Recordings were made during hypoxia and normoxia before and after 2 or ...
Karimov K Y - - 2001
We studied morphological changes in the myocardium during experimental myocardial infarction in rats with different resistance to hypoxia. Microscopic examination showed that morphological changes in the ischemic zone and adjacent tissues are different in rats with high and low resistance to acute ischemia. In highly resistant rats, necrotic changes in ...
Chernysheva G A - - 2001
Experiments on narcotized rats with crush syndrome showed that low resistant animals developed pronounced hypovolemia, hemoconcentration, blood hyperviscosity, impairment of oxygen metabolism, and central and peripheral hemodynamic disturbances, whereas in highly resistant rats the hemodynamics and oxygen supply to tissues were maintained at a sufficient level, while hemoconcentration and the ...
Serra A - - 2001
Carotid body denervation (CBD) in neonatal goats and piglets results in minimal irregular breathing and no fatalities. Redundancy and/or plasticity of peripheral chemosensitivity and a relatively mature ventilatory control system at birth may contribute to the paucity of CBD effects in these species. In the present study, we tested the ...
Fukuda H - - 2001
The effects of hypothermia on caspase-3 activation were investigated in the newborn rat brain after hypoxia-ischemia (HI). Intense caspase-3 activation was observed in the control brains after HI, but this activation was significantly reduced by postischemic hypothermia. These findings suggest that the inhibition of caspase-3 activation may be an interventional ...
Olson E B EB - - 2001
We tested the hypothesis that unanesthetized rats exhibit ventilatory long-term facilitation (LTF) after intermittent, but not continuous, hypoxia. Minute ventilation (VE) and carbon dioxide production (VCO(2)) were measured in unanesthetized, unrestrained male Sprague-Dawley rats via barometric plethysmography before, during, and after exposure to continuous or intermittent hypoxia. Hypoxia was either ...
Nagaoka T - - 2001
The purpose of this study was to test whether the Tester Moriyama rat (TMR), a strain that has a serotonin platelet storage-pool deficiency similar to that of the fawn-hooded rat (FHR), develops severe pulmonary hypertension (PH) upon exposure to mild hypoxia. We compared hemodynamic parameters in catheterized 10-week-old FHR, TMR, ...
Trang A J - - 2001
The role of the thromboxane A(2)/prostaglandin H(2) receptor in endothelin-1 contraction was investigated in aortic rings from rats exposed to normoxia (21% O(2)) or hypoxia (10% O(2)) for 12 h. Indomethacin (10 microM) and SQ 29,548 (0.1 microM, thromboxane A(2)/prostaglandin H(2) receptor antagonist) reduced maximum tension and increased EC(50) in ...
Shirai M - - 2001
We measured internal diameter (ID) changes in resistance and conduit pulmonary arteries of 1- and 2-week hypoxic rats and normoxic control rats in response to nitric oxide synthase (NOS) inhibitors in vivo. At 2 weeks of hypoxic exposure, the ID reduction as a result of NOS inhibition was enhanced within ...
Svinov M M - - 2001
Quantitative analysis of synapses in layer I of the sensorimotor cortex in rats with low resistance to hypoxia revealed pronounced changes in the number of synaptic vesicles docked at the presynaptic membrane in active synaptic zones under conditions of acute hypobaric hypoxia. In high-resistant animals the number of docked synaptic ...
Holleran J - - 2001
Glia are thought to regulate ion homeostasis, including extracellular pH; however, their role in modulating central CO2 chemosensitivity is unclear. Using a push-pull cannula in chronically instrumented and conscious rats, we administered a glial toxin, fluorocitrate (FC; 1 mM) into the retrotrapezoid nucleus (RTN), a putative chemosensitive site, during normocapnia ...
Frisbee J C - - 2001
OBJECTIVE: To determine mechanisms underlying hypoxic dilation of skeletal muscle resistance arteries from normotensive (NT) and hypertensive (HT) Dahl salt-sensitive (SS) rats. METHODS: Isolated gracilis arteries (GA) from both rat groups were viewed via television microscopy and vascular responses to a reduction in PO2 from 145 mm Hg to 40 ...
Robertson T P - - 2001
OBJECTIVE: Sustained hypoxic pulmonary vasoconstriction is dependent upon the presence of an intact endothelium, strongly suggesting that an endothelium-derived constrictor factor is involved in this response. In the present study we have attempted to determine whether hypoxia induces the release of a vasoconstrictor(s) from the lung, and whether this vasoconstrictor ...
Coppola C P - - 2001
BACKGROUND/PURPOSE: Persistent pulmonary hypertension contributes to the high mortality rate associated with congenital diaphragmatic hernia (CDH). Oxygen is an important stimulus for pulmonary vasodilation in the perinatal period. The authors have investigated the responses of isolated pulmonary arterioles from fetal rats with and without CDH to an increase in oxygen ...
Grek O R - - 2001
We studied antipyrine metabolism in rats with different resistance to hypoxia during adaptation to cold stress. Changes in the concentrations of some antipyrine metabolites at low temperature were associated with individual resistance to hypoxia. In low-resistant rats, antipyrine metabolism was suppressed from day 5 of cold exposure to day 3 ...
Maslova M V - - 2001
Acute hypobaric hypoxia of pregnant rats led to a significant delay in body weight gain, growth and time of eye opening in newborn rat pups which was paralleled by behavioral changes. Preventive intranasal instillations of peptide mixture (semax and beta-casomorphine-7) to pregnant females prevented the effect of hypoxia on the ...
Fuller D D - - 2001
Long-term facilitation (LTF) is a prolonged, serotonin-dependent augmentation of respiratory motor output following episodic hypoxia. Previous observations lead us to hypothesize that LTF is subject to genetic influences and, as a result, differs between Sprague-Dawley (SD) rats from two vendors, Harlan (H) and Charles River Laboratories/Sasco (CRL/S). Using a blinded ...
Maxová H - - 2001
Hypoxia stimulates ventilation, but when it is sustained, a decline in the ventilatory response is seen. The mechanism responsible for this decline lies within the CNS, but still remains unknown. In this study, we attempted to elucidate the possible role of hypoxia-induced depression of respiratory neurons by comparing the ventilatory ...
Maresová D - - 2001
Pregnant rats were exposed to intermittent hypobaric hypoxia (at a simulated altitude of 7000 m or 5000 m) and the excitability of cortical neurons of their pups was tested. Stimulation of the sensorimotor cortex of rats prenatally exposed to hypoxia shortened the duration of cortical afterdischarges in 12-day-old rats, but ...
Maruoka N - - 2001
Seven-day-old rat brain slices were incubated at 36C in oxygenated Krebs-Ringer solution containing [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG), and serial two-dimensional time-resolved images of [(18)F]FDG uptake by the slices were obtained. The Gjedde-Patlak graphical method was applied to the image data, and the duration limit of hypoxia loading that allowed recovery of the ...
Sun Z Y - - 2000
A series of diaryl and alkylaryl sulfoxide-containing nitrogen mustards were synthesized and evaluated for their hypoxia-selective cytotoxicity against V-79 cells in vitro as well as for their metabolism profiles with the rat S-9 fractions. In general, the diaryl sulfoxides (4, 5, and 7-9) showed much greater hypoxia selectivity (11-27-fold) than ...
Yu D Y - - 2000
PURPOSE: To measure the intraretinal oxygen environment at different stages in the Royal College of Surgeons (RCS) rat model of retinal degeneration to determine whether changes in oxygen level are an important aspect of the disease. METHODS: Oxygen-sensitive microelectrodes were used to measure oxygen tension as a function of depth ...
St-John W M - - 2000
In vivo mammalian preparations can exhibit eupnea, apneusis and gasping. In vitro mammalian preparations exhibit only a single invariant pattern, which appears identical to gasping. We characterized the patterns of ventilatory activity of a perfused heart-brainstem preparation of the juvenile rat. In this preparation, phrenic activity has a 'ramp-like' rise ...
Rauca C - - 2000
To clarify the question whether the duration of hypoxia exposure has an influence on the point in time or the strength of hypoxic preconditioning, hypoxia exposure of rats lasting 1 and 8 h was tested regarding the modification of susceptibility to acute pentylenetetrazol-induced seizures. Following the short-lasting (1 h) hypoxia, ...
Keith I M - - 2000
To increase understanding of persistent pulmonary hypertension, we examined chronic pulmonary effects of hypoxia at birth and their relationships with immunoreactive levels of the potent vasodilator, calcitonin gene-related peptide (CGRP). Rats were born in 10% hypobaric hypoxia, where they remained for 1-2 days, or in 15% hypoxia, where they remained ...
Roux J C - - 2000
Ventilatory responses to acute and long-term hypoxia are classically triggered by carotid chemoreceptors. The chemosensory inputs are carried within the carotid sinus nerve to the nucleus tractus solitarius and the brainstem respiratory centres. To investigate whether hypoxia acts directly on brainstem neurons or secondarily via carotid body inputs, we tested ...
Powell F L - - 2000
Acclimatization to hypoxia increases the hypoxic ventilatory response (HVR) in mammals. The literature on humans shows that several protocols can quantify this increase in HVR if isocapnia is maintained, regardless of the exact level of Pa(CO(2)). In rats, the isocapnic HVR also increases with chronic hypoxia and this cannot be ...
Bondarenko N A - - 2000
Locomotor activity in the open field test did not correlate with rat resistance to acute hypobaric hypoxia; there was a correlation between this resistance and rat behavior during acute stress. Immobility was characteristic of rats with low and particularly medium resistance to hypoxia; this reaction can be abolished by antidepressants. ...
McCormack D G - - 2000
A variety of pulmonary microvascular changes occur during sepsis. These include abnormal vascular reactivity, leukocyte sequestration, and leakage of protein into the alveoli. Based on intravital videomicroscopy we have developed a method to directly assess in vivo the changes that occur in the pulmonary microcirculation in a rat model of ...
Hu B R - - 2000
The involvement of caspase-3 in cell death after hypoxia-ischemia (HI) was studied during brain maturation. Unilateral HI was produced in rats at postnatal day 7 (P7), 15 (P15), 26 (P26), and 60 (P60) by a combination of left carotid artery ligation and systemic hypoxia (8% O2). Activation of caspase-3 and ...
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