Search Results
Results 251 - 300 of 675
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Gosche J R - - 2000
BACKGROUND: Oxygen is a potent stimulus for pulmonary vasodilation in the perinatal period. Little information is available regarding mediators of oxygen-induced pulmonary vasodilation in fetal rats. We have investigated the effect of blocking several proposed mediators of oxygen-induced vasodilation on the responses of isolated, third-generation pulmonary arterioles from term fetal ...
Aguirre J I - - 2000
Chronic hypoxia leads to a greater degree of pulmonary hypertension in the Wistar-Kyoto (WKY) rat than in the Fischer 344 (F-344) rat. We questioned whether this difference is associated with baseline differences in pulmonary artery anatomy, a greater degree of hypoxia-induced pulmonary vascular remodeling in the WKY rat, and/or differences ...
Motoyama S - - 2000
OBJECTIVE: To investigate the heat shock protein (HSP) 72 expression and apoptosis induced by hydrogen peroxide in hypoxic rat liver. DESIGN: Prospective control study using the isolated rat liver. SETTING: Animal research facility. SUBJECTS: Fasted, pathogen-free specific, male Sprague-Dawley rats. INTERVENTIONS: A low-flow hypoxia model was made by reducing an ...
Harvey P J - - 2000
The oxygen limitation hypothesis states that hepatocyte hypoxia is the mechanism determining metabolic restriction in the cirrhotic liver. Therefore we studied markers of hepatocyte energy state and cellular hypoxia in livers of normal and cirrhotic rats before and after oxygen supplementation. Rats with carbon tetrachloride-induced cirrhosis and procedural control rats ...
Marin J G - - 2000
Formation of the lipid peroxidation product 8-epi-prostaglandin2alpha (8-epi-PGF2alpha) a bioactive marker of oxidative stress, was quantified in in vitro and in vivo models of neuronal death. In culture media of primary rat cortical neurones exposed to hypoxia followed by reoxygenation, a 3.7-fold increase of 8-epi-PGF2alpha concentration was observed in comparison ...
Obrezchikova M N - - 2000
A 3-week course of adaptation to high-altitude hypoxia (4500 m above sea level) inhibited baroreflex vagal bradycardia induced by a rapid rise of systemic blood pressure in conscious rats. Bradycardic responses to electrical stimulation of peripheral end of the right vagus nerve and methacholine (M(2) muscarinic receptor agonist) in hypoxia-adapted ...
Miyasaka N - - 2000
PURPOSE: To compare the apparent diffusion coefficients (ADCs) and histologic changes in young rats subjected to cerebral ischemic hypoxia (IH). MATERIALS AND METHODS: Fifteen 3-week-old rats were subjected to a 30-minute IH insult (unilateral common carotid arterial ligation and exposure to 8% oxygen) and were examined at diffusion-weighted magnetic resonance ...
le Cras T D - - 2000
Dexamethasone (Dex) treatment during a critical period of lung development causes lung hypoplasia in infant rats. However, the effects of Dex on the pulmonary circulation are unknown. To determine whether Dex increases the risk for development of pulmonary hypertension, we treated newborn Sprague-Dawley rats with Dex (0.25 microg/day, days 3-13). ...
Raff H - - 2000
Neonatal hypoxia increases aldosterone production and plasma lipids. Because fatty acids can inhibit aldosterone synthesis, we hypothesized that increases in plasma lipids restrain aldosteronogenesis in the hypoxic neonate. We exposed rats to 7 days of hypoxia from birth to 7 days of age (suckling) or from 28 to 35 days ...
Dorszewska J - - 2000
Cerebral sterols were examined in Wistar strain rats, subjected 4 h, 24 h, 14 days or 2 months earlier to severe (2% oxygen) and moderate (7% oxygen) experimental hypoxia. From brains of the experimental animals myelin was isolated and examined by gas chromatography coupled with mass spectrometry (GC-MS) to separate ...
Tang J R - - 2000
We hypothesized that disrupted alveolarization and lung vascular growth caused by brief perinatal hypoxia would predispose infant rats to higher risk for developing pulmonary hypertension when reexposed to hypoxia. Pregnant rats were exposed to 11% inspired oxygen fraction (barometric pressure, 410 mmHg; inspired oxygen pressure, 76 mmHg) for 3 days ...
Bigard A X - - 2000
This study investigated the effects of voluntary wheel running on the myosin heavy chain (MHC) composition of the soleus (Sol) and plantaris muscles (Pla) in rats developing under hypobaric choronic hypoxia (CH) conditions during 4 wk in comparison with those of control rats maintained under local barometric pressure conditions (C) ...
You Y - - 2000
The present study showed the expression of induced nitric oxide synthase (iNOS) immunoreactivity in amoeboid microglia following an exposure to transient hypoxia in postnatal rats. iNOS immunoreactivity was expressed mainly in the amoeboid microglia in corpus callosum and subependymal regions of the ventricles within 3 h after hypoxia. The expression ...
Thomas S - - 2000
Hypoxia and hypotension are both common findings following traumatic brain injury occurring with a frequency of up to 46% according to data of the Traumatic Coma Data Bank. In the present study the influence of secondary injury on intracranial pressure and the cardiovascular response is investigated in developing rats. Differences ...
Rasey J S - - 2000
The usefulness of radiolabeled nitroimidazoles for measuring hypoxia will be clarified by defining the relationship between tracer uptake and radiobiologically hypoxic fraction. We determined the radiobiologically hypoxic fraction from radiation response data in 36B10 rat gliomas using the paired cell survival curve technique and compared the values to the radiobiologically ...
Parthasarathi K - - 1999
The effect of reduced red blood cell (RBC) deformability on microvessel recruitment attendant to a reduction in tissue PO2 was studied in rat cremaster muscle using indicator-dilution techniques. Transit times (TT) of fluorescently labeled RBCs (TTRBC) and plasma (TTPl) between functionally paired arterioles and venules were obtained from their dispersion ...
Deshpande S B - - 1999
1. The involvement of pulmonary oedema produced by scorpion venom in augmenting a phenyldiguanide (PDG)-induced reflex response was evaluated in urethane-anaesthetized rats. 2. PDG-induced bradycardiac, hypotensive and apnoeic responses, expressed as time-response area, exhibited similarities before or after venom treatment. Hence, the time-response area of bradycardia was taken as a ...
Clayton R A - - 1999
We investigated the effect of chronic hypoxia (10% O(2) for 14 days) on airway responsiveness in rats. Chronic hypoxia significantly (P<0. 05, P<0.01, P<0.01, respectively) attenuated contractions evoked by methacholine (10(-9)-3x10(-4) M), endothelin-1 (10(-10)-3x10(-7) M) and potassium chloride (10(-3)-7x10(-2) M) in rat isolated trachea. To investigate this attenuation, we studied ...
Smith K - - 1999
1. We have investigated the physiological and structural changes that occur in skeletal muscle vasculature during acclimation to chronic hypoxia in rats exposed to 12 % O2 in a hypoxic chamber for 7 or 18 days (7CH and 18CH rats, respectively) and in age-matched normoxic (7N and 18N) rats. 2. ...
Merazzi D - - 1999
In a previous study in conscious normoxic newborn rats, we found that the strength of the Hering-Breuer reflex (HB reflex) was greater (188%) at high (36 degrees C) than at low (24 degrees C) ambient temperature (T(a); D. Merazzi and J. P. Mortola. Pediatr. Res. 45: 370-376, 1999). We now ...
Tomlinson L A - - 1999
Ascent to high altitude leads to pulmonary edema formation in some individuals. Recent laboratory evidence supports the hypothesis that hypoxia may impair the function of the alveolar epithelium and thus augment edema accumulation via reduced clearance of lung liquid. We investigated the effect of hypobaric hypoxia on epithelial sodium transport ...
Lopez-Gonzalez M A - - 1999
The ototoxicity of antibiotics, particularly of aminoglycosides, is a well-known undesirable side effect which may be based on a free radical mechanism. We studied the effect of different antibiotics in the production of reactive oxygen species in freshly isolated cochleas of mature and 2-10 weeks old developing rats. Phorbol myristate ...
Bayanov A A - - 1999
The hepatic cytochromes P450 1A1, 1A2, 2B1, and 2E1 activities have been investigated in the sublines of Wistar rats with principally different (high or low) resistance to hypoxia/stress. Repeated measurements in normoxic conditions showed a significant prevalence of total cytochrome P450 content, CYP 1A1, and CYP 2E1 activities in rats ...
Gralek M - - 1999
BACKGROUND: In experimental models of retinopathy of prematurity (ROP), a vasoproliferative disorder of the retina, retinal lesions are usually assessed by morphological examination. However, studies suggest that the polyamine system may be useful in monitoring proliferation processes. For this reason, polyamine concentrations in rat erythrocytes (RBC) and the regulation of ...
Whitbeck C - - 1999
PURPOSE: Studies indicate that bladder hypoxia may be an etiological factor for lower urinary tract dysfunction. Rat and rabbit are two species of experimental animals used frequently to study lower urinary tract function and dysfunction. The objective of this study was to compare directly effects of in vitro hypoxia on ...
Raff H - - 1999
Hypoxia leads to a decrease in food intake and attenuated weight gain in rats. The purpose of this study was to measure plasma leptin and insulin in young rats exposed to hypoxia for 7 d as compared to a normoxic control group of the same age. One group was exposed ...
Louajri A - - 1999
The influence of Vinburnine on red blood cell metabolism and hemoglobin oxygen affinity was investigated in normobaric rats (FiO2: 10%). Two periods of hypoxic exposure were performed (10-21 d). In each experimental series, rats were divided into two groups: Treated rats received a daily intraperitoneal injection of drug (4 mg/kg). ...
Itoh H - - 1999
To investigate the roles of endothelin-1 in the pathogenesis of hypoxic pulmonary hypertension, we studied the effects of a selective endothelin ET(A) receptor antagonist, TA-0201 (N-(6-(2-(5-Bromopyrimidin-2-yloxy) ethoxy)-5-(4-methylphenyl) pyrimidin-4-yl)-4-(2-hydroxy-1,1-dimethylethyl) benzensulfonamide sodium salt sesquihydrate), on helical strips of pulmonary arteries isolated from hypoxia-induced pulmonary hypertensive rats as compared with those of normoxic ...
Stieglerová A - - 1999
The aim of the present study was to compare the capacity of the oxidative metabolism (total activity of cytochrome c oxidase, COX) in the right and left ventricular myocardium of adult rats exposed to intermittent high altitude (IHA) hypoxia simulated in a barochamber (5,000 m, 8 h/day, 5 days/wk, for ...
Taki J i - - 1999
Cyanate derivatives such as NaOCN have been known to increase the hypoxia tolerance of animals by increasing the affinity of hemoglobin (Hb) to O(2). To clarify the mechanism of this increase in hypoxia tolerance, we examined changes in metabolic rate and cardiovascular parameters during a hypoxia test in halothane-anesthetized, NaOCN-treated ...
Wang Y - - 1999
OBJECTIVES: To study the interrelation between nitric oxide (NO) and endothelin-1 (ET1) in experimental acute hypoxic rats, and to evaluate the mechanism of acute hypoxic pulmonary hypertension affected by NO and ET1 and its intervention. METHODS: Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemical staining method, Griess biochemical assay and radioimmune ...
Conover C D - - 1999
The purpose of this study was to determine whether a six gram percent (g%) solution of the hemoglobin based oxygen carrier, polyethylene glycol conjugated bovine hemoglobin (PEG-Hb) could adequately deliver oxygen in both partial exchange transfusion and top-loaded rat models. This study measured tissue oxygen tension, circulatory retention and cardiovascular ...
De Sousa Pereira A - - 1999
BACKGROUND: Vibroacoustic disease (VAD) is a noise-induced pathology occurring in workers occupationally exposed to large pressure amplitude (> or =90 dB SPL) and low frequency (< or = 500 Hz) (LPALF) noise, over long periods of time (> or = 10 yr). Patient complaints frequently involve the respiratory tract. There ...
Varela A - - 1999
The aim of the investigation was to assess whether adenosine would ameliorate the hypoxic-induced disturbances of the isolated atria and ventricular strips from fed and 24 h fasted rats. Adenosine 100-50 microM exerted negative inotropic and chronotropic effects on the aerobic atria whereas 10 microM was ineffective. During hypoxia the ...
De Sousa Pereira A - - 1999
INTRODUCTION: Vibroacoustic Disease (VAD) is a multi-systemic entity caused by occupational or chronic exposure to large pressure amplitude and low frequency (LPALF) noise (> or = 90 dB SPL, < or = 500 Hz). The clinical picture involves extra-auditory pathology, such as neurological disturbances, respiratory disorders and cardiovascular problems. Among ...
Li X J - - 1999
AIM: To study the effect of melatonin on the production of hydroxyl radical (.OH) and lactate dehydrogenase (LDH) following hypoxia in cortical slice. METHODS: Cortical slice was incubated with artificial cerebrospinal fluid (ACSF) in tube. Hypoxia was achieved by substituting 91.6% N2 and 8.4% O2. The salicylate trapping method was ...
Davidson K G - - 1999
The application of impedance pneumography for monitoring respiration in small animals has been limited by problems with calibration. With improved instrumentation, we describe the calibration of tidal volume in anesthetized rats. The detection of changes in voltage, reflecting the electrical impedance variations associated with respiration, was optimized by using disposable ...
Risby T H - - 1999
Breath ethane, O2 consumption, and CO2 production were analyzed in 24-mo-old female Fischer 344 rats that had been fed continuously ad libitum (AL) or restricted 30% of AL level (DR) diets since 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then ...
Zengren Y - - 1999
It was found that cold injury in rats acclimated to hypoxia was more serious than that in nonacclimated ones. In order to go further into the cause, blood rheological parameters in rats of frostbite at normoxia (FN), frostbite during acute hypoxia (FAH) and frostbite during hypoxia after hypoxic acclimation (FHAC) ...
Fulton A B - - 1999
PURPOSE: To study in an infant rat model of retinopathy of prematurity, the rod photoreceptors, which are known to have attenuated photoresponses. METHODS: Rhodopsin was extracted from whole retinas, the thickness of the rod outer segment (ROS) layer was measured, large phagosomes were counted, and the ROS ultrastructure was examined ...
Ment L R - - 1998
Bronchopulmonary dysplasia remains a major cause of neurodevelopmental handicap in preterm infants. Because bronchopulmonary dysplasia may be associated with prolonged hypoxemia without obvious changes in systemic blood pressure, we developed an animal model of chronic sublethal hypoxia to test the hypothesis that this insult results in significant alterations in corticogenesis ...
Sakamoto K - - 1998
We investigated the possible changes in the distribution of HSP27 after a brief hypoxia-reoxygenation stress in the rat myoblast cell line, H9c2, as a model of ischemic preconditioning. Cells were exposed to 4 cycles of 5 min. of hypoxia and 5 min. of reoxygenation. In the normoxic condition, HSP27 was ...
Kusakabe T - - 1998
The abundance of substance P (SP)-, calcitonin gene-related peptide (CGRP)-, vasoactive intestinal polypeptide (VIP)-, and neuropeptide Y (NPY)-immunoreactive nerve fibers in the carotid body was compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). The immunoreactive fibers appeared as thin processes with many varicosities, ...
Newell M A - - 1998
BACKGROUND: Pulmonary hypertension and persistent fetal circulation contribute to the high mortality rate associated with congenital diaphragmatic hernia (CDH). Morphological alterations of the pulmonary vasculature in infants with CDH are thought to contribute to exaggerated vasoconstrictor responses to normal vasoconstrictor stimuli. In the pulmonary circulation, hypoxia is a potent vasoconstrictor. ...
Au-Fliegner M - - 1998
BACKGROUND: Infants born with congenital diaphragmatic hernias (CDH) frequently die as a result of pulmonary hypertension and persistent fetal circulation. The pulmonary vessels of infants with CDH have decreased total cross-sectional area, increased muscle content, and muscularization of intra-acinar arterioles that are normally not muscularized. These structural alterations are believed ...
Murasato Y - - 1998
The effects of systemic hypoxia with different levels of CO2 on R-R interval (RRI) and systolic blood pressure (SBP) variabilities were investigated in conscious rats. Wistar rats chronically instrumented for the measurement of blood pressure, electrocardiogram, and renal sympathetic nerve activity (RSNA) were exposed to hypocapnic (Hypo), isocapnic (Iso), and ...
Luo G - - 1998
AIM: To observe the effects of large dose of vitamin C (Vc) on myocardial mitochondrial function, ATP content, and myocardial structure in acute and chronic hypoxic rats. METHODS: Rats were exposed to a simulated altitude 4000 m (barometric pressure = 43 kPa) for 3 and 30 d. Vc (0.75 g.kg-1.d-1) ...
Di Giulio C - - 1998
Morphologic, physiological, and biochemical changes occur in the carotid body (CB) during postnatal development in relation to physiological requirements. Chronic normobaric hyperoxia attenuates the carotid chemosensory response to hypoxia. During aging there is less of a CB response to hypoxia, which results in a reduced ventilatory adaptation and chemosensory discharge. ...
Holmes J M - - 1998
PURPOSE: Hypercarbia has been suggested as a risk factor for retinopathy of prematurity (ROP). We investigated the effect of hypercarbia on the retinal vasculature of the neonatal rat to determine whether hypercarbia alone could induce preretinal neovascularization analogous to ROP. METHODS: In a preliminary blood gas study, 8-11-day-old rats were ...
Ge R L - - 1998
To investigate the possible mechanisms of adaptation to chronic hypoxia in the pulmonary circulation, we made direct measurements of pulmonary arterial pressure (Ppa) in 10 awake pika rodents that were transported to Xining, People's Republic of China (altitude 2,260 m) after being captured at 4,300 m and in 10 Wistar ...
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