We examined the rate and quantity of superoxide anion (O2-) generation by granulocytes harvested from the blood of patients before and after a 12-24 h constant intravenous infusion with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSFrh). Seven previously untreated patients with sarcomas who exhibited no bone marrow involvement by their disease ...

Hepatic oxygen delivery and consumption were assessed in mongrel dogs receiving 2MAC of halothane combined with graded hypoxic hypoxemia (21-8% oxygen). Hepatic blood flow was measured using electromagnetic flowmetry; hepatic oxygen delivery and consumption were calculated from measured hepatic blood flow and oxygen content in hepatic arterial, portal venous and ...

The role of thromboxane A2 (TXA2) in the control of O2 supply/consumption variables during pacing-induced ischemia was examined using the TXA2 receptor antagonist SQ 29,548. Anesthetized, open-chest dogs were subjected to left anterior descending coronary artery (LAD) stenosis that produced significant epicardial S-T segment elevation (12 mV) only when superimposed ...

Although patients using transtracheal oxygen (TTO2) frequently report decreased dyspnea and improved exercise tolerance, the mechanism for these effects is unknown. We hypothesized that these patients might have decreased inspired minute ventilation (VI), and this might be one mechanism for their decreased dyspnea and improved exercise tolerance. The effects of ...

The kinetics of O2 uptake into, and release from, the red blood cells (RBC) of the turtle Pseudemys scripta elegans were determined with a stopped-flow technique at varied temperature (10-30 degrees C) and pH (7.5-7.9). The results were compared to those obtained for RBC of other vertebrates and related to ...

We evaluated the possibility that massive, sympathetic nervous system (SNS) activation [as may precede the development of neurogenic pulmonary edema (NPE)] increases O2 demand. O2 consumption (VO2) and plasma concentrations of the calorigenic agents, epinephrine (EPI) and norepinephrine (NE) were measured in alpha-chloralose-anesthetized dogs under control conditions and for 3 ...

The effects of 3.0 mg.kg-1 fentanyl on cerebral and peripheral hemodynamics alone and when combined with subanesthetic doses of pentobarbital (4.0 mg.kg-1), were studied in 11 unanesthetized, newborn lambs, in whom catheters had been previously inserted. After a control period, drugs were administered at 20-min intervals by intravenous bolus injection. ...

Livers from well-fed female Sprague-Dawley rats (100-150 g) were perfused at flow rates of 4 or 8 ml.g liver-1.min-1 to deliver O2 to the organ at various rates. During perfusion at normal flow rates (4 ml.g-1.min-1), glucagon (10 nM) increased O2 uptake in perfused liver by approximately 40 mumol.g-1.h-1. In ...

We studied the independent and combined effects of feeding and environmental cold stress by measuring pre- and postprandial gastrointestinal blood flow (QGI), oxygen consumption (GIVO2), and oxygen extraction (GIO2ex) in seven awake 3- to 4-day-old piglets while in a thermoneutral environment (control phase, 31 degrees C) and during environmental cold ...

The effect of acetylcholine on the regional coronary perfusion and O2 consumption was determined in anesthetized open chest rabbits in order to compare its direct vasodilatory effects with the metabolic vasoconstriction it induces. Experiments were conducted in seven untreated controls and seven rabbits which were infused with acetylcholine (1 microgram/kg/min). ...

To determine the effects of hemodilution on gastric and intestinal oxygenation, isolated segments of canine stomach and small bowel were perfused by a pressurized reservoir with blood at hematocrits of 40 and 20%. Arteriovenous O2 difference, blood flow, and arterial and venous pressures were monitored continuously as perfusion pressure was ...

The relation between cerebral blood flow and oxygen consumption was studied in six children during cardiac operations with profound hypothermia. A combination of topical cooling and core cooling was used to reduce the nasopharyngeal temperature to 15 degrees C. The alpha-stat principle for pH management was used. Blood flow and ...

At least two investigators have demonstrated a reduction in O2 extraction during induced hypothermia (Cain and Bradley, J. Appl. Physiol. 55: 1713-1717, 1983; Schumacker et al., J. Appl. Physiol. 63: 1246-1252, 1987). We hypothesized that administration of pentoxiphylline (PTX), a theobromine that lowers blood viscosity and has vasodilator effects, would ...

Our studies demonstrate that in the explanation of the protective effect of the calcium antagonist (S)-emopamil the possibility of beneficial metabolic causes (lower O2 consumption) must also be considered beside of blood flow increasing effects. It is suggested that (S)-emopamil may be a useful drug for the treatment of cerebro-ischemic ...

Oxygen delivery and utilization is deranged in the setting of sepsis. The most likely cause is an inability of the microvasculature to provide sufficient oxygen to actively metabolize tissue, probably as a result of diminished autoregulatory control and capillary damage. This maldistribution of blood flow results in the development of ...

Cerebral oxidative metabolism was determined in 9 unanaesthetized fetal sheep near term, during a normoxic control period and during sustained hypoxaemia induced by lowering maternal inspired O2 concentration to 11-8% with 3% CO2 added. Preductal arterial and sagittal vein blood samples were analyzed for oxygen content, blood gas tensions and ...

Apneic, anesthetized patients frequently develop airway obstruction or may be disconnected from ventilatory support. The rate of PaCO2 rise is usually assumed to be equal to that of anesthetized humans who are receiving apneic oxygenation. Apneic oxygenation may eliminate CO2 because it requires a continuous O2 flow. The CO2 rate ...

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), ...

To estimate oxidative capacity of noncontracting rat skeletal muscle, the isolated gracilis muscle was perfused at various high flow rates with high-PO2 (88 kPa) saline-albumin solution and simultaneously perifused at either low (6.3 kPa) or high PO2 in a calorimeter at 28 degrees C. Under low-PO2 perifusion, specific O2 consumption ...

Minimum acceptable O2 delivery (DO2) during extracorporeal membrane oxygenation (ECMO) remains to be defined in a newborn primate model. The right atrium, carotid artery, and femoral artery were cannulated, and the ductus arteriosus, aorta, and pulmonary artery ligated in neonatal baboons (Papio cynocephalus) under a combination of ketamine, diazepam, and ...

The O2 uptake of chicken embryos confined in the eggshell (MO2) is governed by a shell diffusive conductance (GO2) and PO2 difference between ambience and air space, suggesting that a relation between GO2 and air space PO2 (PAO2) is hyperbolic at constant MO2. Upon wide alteration of GO2 from the ...

Our study tests the hypothesis that hyperviscosity independent of arterial O2 content reduces cerebral cortical blood flow, O2 delivery, and O2 uptake. After baseline determinations, ten 2- to 4-day-old awake spontaneously breathing piglets were given an intravenous infusion (5 ml.kg-1, body weight) of concentrated cryoprecipitate, whereas eight controls received normal ...

Male Sprague-Dawley rats (n = 18) weighing 548 +/- 30 g were anesthetized with pentobarbital sodium (40-65 mg/kg body wt ip), intubated via tracheotomy, and mechanically ventilated. After exposure of the great vessels in the thorax, blood was withdrawn from the pulmonary artery (PA), right ventricle (RV), right atrium (RA), ...

Rabbit hindlimb preparations perfused with blood from donor rabbits were used to determine whether O2 consumption (VO2) during hypoxemia is limited by total O2 transport (TO2) or by capillary O2 driving pressure, as reflected by the venous PO2 (PVO2). The preparations were randomized into two groups: low flow (LF) and ...

Acute obstruction of the middle cerebral artery (MCA) was obtained by injecting a single autologous blood clot into the internal carotid artery of dogs. The technique induced very reproducible unilateral ischemic lesions in the MCA territory; hemorrhagic transformation of the lesions was often seen. The hemodynamic and metabolic effects of ...

Acetazolamide (AZ), a potent carbonic anhydrase inhibitor in human and animal tissues, increases cerebral blood flow (CBF) by acidifying cerebral extracellular fluids. To demonstrate the relationship of increased CBF to brain O2 availability after AZ administration, a compensated fluorometer was used to study changes in the cerebrocortical redox balance in ...

When systemic delivery of oxygen (QO2 = blood flow X arterial O2 content) is reduced, the systemic O2 extraction ratio [(CaO2 - CVO2)/CaO2; where CaO2 is arterial O2 content and CVO2 is venous O2 content] increases until a critical limit is reached below which O2 uptake (VO2) becomes limited by ...

This review describes the transport of oxygen from ambient air to mitochondria in the cells. Using simple equations and diagrams, the presentation illustrates the variables which determine the magnitude of each of the three major steps in the partial pressure of O2 along the passage, from: (i) ambient air to ...

The contributions of five variables believed to influence the brain's metabolism of O2 during hypoxia [duration, PaO2, delta CMRO2 (the difference between normal and experimental oxygen uptake), O2 availability (blood O2 content.CBF), and O2 deficit (delta CMRO2.duration)] were assessed by stepwise and multiple linear regression. Levels of brain tissue carbohydrates ...

Oxygen consumption (Vo2) has been found to depend on oxygen delivery (Do2) following resuscitation from hemorrhage in both humans and animals. The relative influence of blood flow and arterial oxygen (O2) content, the components of Do2, has not been separately assessed. To determine the relative contribution of content and flow, ...

We studied the role of O2 supply and demand factors for producing diaphragmatic failure in a canine model of cardiogenic shock with pulmonary edema. We produced pulmonary edema with oleic acid and then hypotension with cardiac tamponade and followed the animals until respiratory failure began, which was defined by a ...

The objective of this experiment was to compare net nutrient absorption and oxygen consumption by portal-drained viscera (PDV) of catheterized Holstein steers (333 kg) when fed alfalfa or orchardgrass silage at two equalized intakes. The design was a 4 X 4 Latin square with a 2 X 2 factorial arrangement ...

The role of the adrenergic nervous system in the response to coronary artery occlusion has been examined using surgical and chemical denervation techniques. Experiments were conducted on four groups of dogs (n = 18): 1) untreated controls; 2) intrapericardial denervation immediately prior to coronary ligation; 3) surgical denervation 2 weeks ...

In order to determine blood flow and oxygen consumption in the pelvic limb of fetal sheep, we applied the Fick principle of measurement of oxygen consumption in seven paired experiments in seven fetal sheep under normal conditions and after treatment with pancuronium bromide. Catheterization procedures, which minimized interference with the ...

To study the effect of genetic differences in the maternal oxyhemoglobin dissociation curve on fetal O2 supply, we compared eight pregnant ewes homozygous for high O2 affinity hemoglobin (A) with eight pregnant ewes homozygous for low O2 affinity hemoglobin (B). Each ewe carried a single fetus. Fetal weights were not ...

The effect of intravenous (i.v.) nifedipine (5 micrograms/kg/min) on regional O2 supply/consumption variables was determined in 14 anesthetized open-chest dogs subjected to left anterior descending coronary artery (LAD) stenosis sufficient to reduce blood flow 50%. Myocardial blood flow was measured using radioactive microspheres, and regional arterial and venous O2 saturations ...

The study of a number of parameters of placental function indicated that the perfused human placental lobe maintained its structural and functional integrity when PO2 levels in buffer perfusate were near physiological values, despite low O2 consumption. High O2 content in the perfusate may reduce placental transfer either through a ...

In 24 adult cats, the somatosensory-evoked potential (SEP) and cerebral blood flow (CBF) were measured under paralyzed, anesthetized conditions during exposure to two different ventilatory regimens. Group I cats (ventilated from 20 to 2% oxygen) responded with a significant increase in white matter blood flow from 25.0 +/- 7.8 to ...

The objective of this study was to measure acute (d 1) and chronic (d 9) effects of dietary clenbuterol on heart rate, blood flow, oxygen uptake, and net uptake/release of metabolites in the hindquarters of growing steers. The design was a single reversal with two 9-d periods of control or ...

In a postasphyxia neonatal lamb model, the responses of the cerebral circulation to hypoxic hypoxia and changes in systemic arterial blood pressure were examined. Ventilated newborn lambs (n = 14) were subjected to a gradual asphyxial insult, resuscitated, and returned to control ventilator settings. During the time 2-5 hours after ...

To clarify the influence of high O2-affinity blood on oxygen consumption by peripheral tissue, we perfused the dog gracilis muscle alternately with normal and low P50 blood at constant CaO2 and varying blood flows. VO2 was plotted against O2 delivery which was a product of CaO2 and blood flow. VO2 ...

1. We studied the haematology of the little penguin, Eudyptula minor, and measured red cell enzymes, and the rate of O2 and glucose consumption and CO2 and lactate production of whole penguin blood. 2. Little penguins have a very low RBC count (1.66 x 10(12) l-1) and very large red ...

In eight anesthetized spontaneously breathing dogs, we determined whether diaphragmatic blood flow is dependent on arterial blood pressure (Pa) or whether it is autoregulated. We also determined whether diaphragmatic muscular activity affects the degree of autoregulation. We measured blood flow through the left phrenic artery (Qphr) with an electromagnetic flow ...

A mathematical model is proposed to deal with the simultaneous transport of oxygen (O2) and carbon dioxide (CO2) in systemic capillaries and the surrounding tissue in a hyperbaric environment. The transport in the capillary region depends on molecular diffusion (radial as well as axial), the convective effect of the blood, ...

The two important blood properties that affect O2 delivery are the O2 equilibrium curve (OEC) and blood viscosity with its subsequent effect on flow (cardiac output). To quantitate these properties blood OEC's were analyzed in terms of the Adair 4-step oxygenation model and the resulting parameters were used to construct ...

We have shown that the fall in cerebral blood flow (CBF) as hematocrit (Hct) rises is due to the independent effects of increasing red blood cell (RBC) concentration and arterial O2 content (CaO2). In the present study, we tested the hypothesis that the magnitude of the effect of RBC concentration ...

For continuous measurement of both SO2 and [Hb] of whole blood, a hybrid type optical sensor was developed, tested in vitro and applied to the continuous measurement of arterial and mixed venous SO2 and [Hb] of awake live animals whose circulation was entirely supported by a pair of artificial hearts. ...

The objective of this investigation was to aid in the determination of the mechanism by which oxygen consumption changes in proportion to coronary perfusion pressure or coronary blood flow. A mathematical model of oxygen transport and consumption in the isolated-perfused heart was developed, based on data from an autoregulating, cell-free ...

The effects of acute asphyxia on both the time course of blood flow changes in central and peripheral organs, including the skin, and the time course of changes in oxygen consumption were studied in 9 unanaesthetized fetal sheep in utero at 130 +/- 2 days of gestation during 4-min arrest ...

The effect of beta-adrenoceptor blockade and activation on ischemic regional and microregional myocardial O2 supply/consumption parameters was assessed in 28 open chest, anesthetized dogs. Ten minutes after LAD occlusion, dogs were given i.v. saline, 2 mg/kg propranolol, 0.2 mg/kg pindolol, or 1 microgram/kg per min isoproterenol. Coronary blood flow was ...