A continuous lysing and resealing procedure with erythrocytes permitted incorporation in these cells of inositol hexaphosphate (InsP6), a strong allosteric effector of Hb. This leads to significant rightward shifts of the HbO2 dissociation curves with in vitro P50 (partial pressure of O2 at 50% Hb saturation), values increasing from 32.2 ...

A mathematical model has been developed that permitted the calculation of the flow-weighted mean tissue O2 consumption (VO2T) at the onset of a step increase in work rate. From breath-by-breath measurements of alveolar O2 consumption (VO2A) and cardiac output (Q) by impedance cardiography and assumptions about the site of depletion ...

A simple method was developed to measure in vivo local oxygen consumption quantitatively in the brain cortex. Reflectance spectra of tissue hemoglobin at the brain's surface were measured for assessment of both local tissue hemoglobin content and its oxygen saturation. Local oxygen consumption was calculated from the spectral changes of ...

To assess the effect of brain blood flow on hypoxic ventilatory response, we measured arterial and internal jugular venous blood gases and ventilation simultaneously and repeatedly in eight healthy male humans in two settings: 1) progressive and subsequent sustained hypoxia, and 2) stepwise and progressive hypercapnia. Ventilatory response to progressive ...

We studied the response of O2 consumption, systemic O2 transport, arterial blood lactate concentration, base deficit, and respiratory exchange ratio (CO2 production/O2 consumption) to graded alveolar hypoxia (fractional concentration of inspired oxygen 0.21, 0.16, 0.12, and 0.08) in seven intact, conscious chronically catheterized lambs at less than 1 wk after ...

The consequences of a decreased O2 supply to a contracting canine gastrocnemius muscle preparation were investigated during two forms of hypoxia: hypoxic hypoxia (HH) (n = 6) and CO hypoxia (COH) (n = 6). Muscle O2 uptake, blood flow, O2 extraction, and developed tension were measured at rest and at ...

This study was designed to assess whether propranolol would improve the relationship between O2 supply and O2 consumption in the reperfused ischemic dog myocardium. In 14 dogs, the left anterior descending coronary artery was occluded for 2 hr, followed by a 4-hr period of reperfusion. In 7 of the 14 ...

The content of dissolved O2 (the major source of O2 for the myocardium) of dilute blood cardioplegic solution (dBCS) varied widely when oxygenated at 4 degrees C by surface flow of O2 in a Bentley BCR-3500 cardiotomy reservoir. We have modified the system to consistently deliver maximally oxygenated dBCS to ...

Oxygen tensions, cutaneous blood flow rate, and skin oxygen consumption rate were determined by tc-PO2 measurements at an electrode temperature of 45 degrees C. The epidermal surface was stripped by 50 applications of adhesive plaster to the surface. Ten healthy, normotensive adults were examined. Cutaneous blood flow rate was 41.2 ...

When systemic delivery of O2 (QO2 = QT X CaO2, where QT is cardiac output and CaO2 is arterial O2 content) is reduced by bleeding, the systemic O2 extraction ratio [ER = (CaO2 - CVO2)/CaO2, where CVO2 is venous O2 content] increases until a critical limit is reached below which ...

Whole blood oxygen equilibrium curves (O2 ECs), blood buffer lines, and several hematologic properties were determined for adult guinea pigs exposed to 700 ppm methyl isocyanate (MIC) for 15 min. MIC inhalation effected a significant reduction of blood O2 affinity; the half-saturation pressure (P50) at 38 degrees C increased from ...

Recessed oxygen microelectrodes (tip diameter less than 2 microns) were positioned stereotactically into either the cerebral cortex or the hippocampus of sodium pentobarbital anesthetized gerbils (n = 21). The mean tissue PO2 levels (+/- SEM) were not significantly different between cortex (35.4 +/- 1.7 torr) and hippocampus (33.6 +/- 1.4 ...

When the delivery of O2 to tissues (QO2 = blood flow X O2 content) falls below a critical threshold, tissue O2 uptake (VO2) becomes limited by QO2. The mechanism responsible for this extraction limitation is not understood but may involve molecular diffusion limitation as mean capillary PO2 drops below a ...

The effects of 1% CO on cerebral biogenic amine metabolism was studied by measurement of cerebral hemisphere contents of 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dihydroxyphenylalanine (DOPA) and dopamine (DA). The results indicated that 1% CO is associated with an increased cerebral hemisphere content of DA. In CO-exposed animals ...

The effects of norepinephrine infusion and fluid administration on diaphragmatic O2 consumption during endotoxic shock were assessed in spontaneously breathing anesthetized dogs. Blood flow was measured with the microsphere technique, and diaphragmatic venous blood was obtained via a catheter inserted into the left inferior phrenic vein. One group of dogs ...

The perfluorochemical O2-transport fluid, Fluosol-DA 20 percent (PFC), is being clinically evaluated as a volume expander in patients who are unable to receive blood products. Since patients treated with Fluosol-DA may be at risk of developing adult respiratory distress syndrome (ARDS) as a complication of the original disorder for which ...

Regional brain O2 consumption was determined in conscious Fischer-344 rats 3- and 33-months of age after intrahippocampal injection of the selective presynaptic cholinergic neurotoxin AF64A to investigate the influence of acetylcholine on this parameter. Regional cerebral blood flow (rCBF) was determined with 14[C]-iodoantipyrine. Regional arterial and venous oxygen saturation was ...

As a significant user of O2 at rest (20% of whole body), the gut may be subject to more severe limitation of O2 supply during global hypoxia than more vital areas because of preferential redistribution of blood flow. Accordingly, its accumulation of O2 deficit during hypoxia and its excess O2 ...

Cerebral partial pressure of O2 (PO2), relative changes in the ratio of reduced/oxidized cytochrome aa3, blood flow, and the arteriovenous difference in O2 content were measured during seizures with and without pulmonary edema. Seizures were induced with bicuculline (0.2-1.2 mg/kg iv) in rats anesthetized with 70% N2O and paralyzed with ...

Blood gases and electrolyte fluctuations were studied in arterial blood, after a single 35% CO2-65% O2 inhalation, which is known to trigger panic attacks in patients with panic disorder. The immediate effect of this maneuver was a brief hypercapnic acidosis followed by a slight alkalotic rebound, with shifts in Ca2+ ...

The purpose of this study was to determine whether depletion of serum complement can decrease the severity of an ischemic episode by improving regional O2 supply and consumption parameters in the ischemic region of the heart. Fourteen anesthetized dogs with serum complement intact or depleted (100 U/kg cobra venom factor ...

To estimate the advantage of the small red blood cells (RBC) of high-altitude camelids for O2 transfer, the kinetics of O2 uptake into and release from the RBC obtained from llama, vicuña and alpaca were investigated at 37 degrees C with a stopped-flow technique. O2 transfer conductance of RBC (G) ...

The physiological stress of anesthesia, hemorrhage, and operation can all contribute to postoperative morbidity and mortality in the patient who has experienced massive trauma. However, the problems of massive transfusion are not insurmountable. More important than achieving an adequate blood pressure in the hemorrhaging patient is the need to reestablish ...

Oxygen consumption and blood lactate concentration were measured in embryos (days 17-20) and chicks (days 0-7) in air and in 7-8% O2. The specific oxygen consumption in air increased up to day 4 after hatching. In 7-8% O2, the consumption decreased for all ages. The reduction was largest in the ...

Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of expiratory gas, one would predict that the time allowed for exhalation would have serious effects on cardiopulmonary function. To document these effects we lavaged the lungs of ten cats with 30 ml/kg of saline six ...

The effects of feeding on gastrointestinal (GI) perfusion and oxygen transport in hypoxemic neonates is unknown. We evaluated these effects in unanesthetized, spontaneously breathing newborn piglets by comparing three experimental groups: nine hypoxemic piglets (mean PaO2 26 torr) which were fed with formula, six hypoxemic piglets (mean PaO2 27 torr) ...

Regional cerebral oxygen consumption and blood flow were determined and compared in conscious male Fischer-344 rats at 3, 12, 24 and 33 months of age to correlate the reported regional neurochemical and morphological changes which occur in these parameters during development, maturation, aging and senescence. Cerebral blood flow was determined ...

The gas exchange ratio (R) obtained from O2 and CO2 concentrations measured in rebreathing air usually shows a linear relation to the PCO2. By referring to this relation and the R which equals the Haldane effect coefficient and zero, the true- and oxygenated-venous PCO2 are obtained in addition to the ...

To examine the relation of oxygen delivery to uptake in normals, we have measured cardiac index, oxygen delivery and oxygen consumption directly and indirectly in two human volunteers before and during a prostacyclin (PGI2) infusion (5 ng/kg/min). We have also investigated the relation of direct and indirect measurements of delivery ...

The partition of O2 uptake between gills and skin was examined in the freshwater eel (Anguilla anguilla L.) at ambient PO2 ranging from hyperoxia (PO2 = 400 Torr) to severe hypoxia (PO2 = 10 Torr), using a technique of open-flow respirometry. All the expired water was collected, and the ventilatory ...

In 12 experiments on 9 chronically-cathetized pregnant sheep (116-143 days of gestation), fetal oxygen consumption, umbilical blood flow and blood gas values were measured before, during and after a 30-min period of hypercapnia, induced by having the ewes breathe 5% CO2 and 18% O2 in N2. During the large amplitude ...

This investigation determined the effects of withdrawal from chronic naltrexone administration on average and regional cerebral blood flow, oxygen extraction and oxygen consumption. The relationship between the effects of withdrawal from chronic administration of this opiate receptor antagonist, which may increase the numbers of postsynaptic opiate receptors, and these parameters ...

Lack of an adequate method for sampling venous blood from the brown adipose tissue (BAT) of conscious animals has impeded study of the in vivo metabolism of this tissue during physiological activation of its thermogenic function. This paper describes a technique for cannulating the main vein (Sulzer's) of the interscapular ...

Regional distribution of brain blood flow was examined in seven previously catheterized healthy isocapnic swine while awake (control), and during 1.0 and 1.5 minimum alveolar concentration (MAC--2.66 and 3.99% end-tidal, respectively) sevoflurane anesthesia using radionuclide-labeled 15-micron diameter microspheres that were injected into the left atrium. In six additional pigs, the ...

Liver from adult male rats were perfused in situ for 30 min with either undiluted, defibrinated rat blood (haematocrit value 38%) or the same blood diluted with buffer to give a haematocrit of 20%. Perfusion with diluted blood lowered the PO2 of the effluent perfusate but this was insufficient to ...

Starvation results in an energy-conserving reduction in metabolic rate that has features of an adaptive response. Tissue and organ sites of this response were investigated by examining the effects of starvation for 5 d on tissue blood flow (microsphere method) and regional arteriovenous O2 differences ((a-v)O2) in conscious rats resting ...

The hypothesis that hyperperfusion decreases muscle fatigue by increasing O2 and substrate delivery to the muscle was tested. Canine gastrocnemius-plantaris in situ preparations were stimulated at 5 Hz for 4 min during a free-flow control period and for 20 min during a pump-perfused experimental period. O2 delivery during these two ...

Using an X-ray TV system, we analyzed responses in the internal diameter (ID), flow velocity, and volume flow in small pulmonary vessels (100-600 microns ID) during unilobar hypoxia and hypercapnia in cats. In the hypoxic and hypercapnic lobes, the ID reduced in proportion to the degree of hypoxia and hypercapnia, ...

Cerebral blood flow (CBF) and cerebral O2 transport (CBF X arterial O2 content) in the fetal sheep are nearly twice that in the adult, despite similar rates of cerebral O2 utilization. We tested the hypothesis that the difference depends on the increased oxyhemoglobin affinity in the fetus, using P50 (PO2 ...

Using the buttock flap in 29 white Yorkshire pigs, blood flow and O2 consumption were measured at dermal temperatures between 35 degrees C and 15 degrees C. Flow was measured with an electromagnetic flowmeter and O2 consumption was calculated as the product of blood flow and the difference in flap ...

A study was carried out to determine the effect of distal aortic constriction on the regional oxygen supply-consumption balance in ischaemic and non-ischaemic myocardium. Left anterior descending coronary artery flow was reduced by 50% in anaesthetised mongrel dogs, and half these animals were subjected to distal ascending aortic constriction (ventricular ...

The effects of hypothermia on oxygen delivery and tolerance to hypoxia were studied in 8 normothermic (36.8 degrees C) and 10 hypothermic (29.3 degrees C) pigs that had been anesthetized and surgically implanted with instruments. Cardiac output (QT), VO2 [oxygen consumption, or QT X C(a-v)O2, where C(a-v)O2 is arteriovenous oxygen ...

Continuous exposure of rabbits to 100% O2 at one atmosphere (1 ATA) for 48 h damages the alveolar epithelium increasing its permeability to lipid insoluble molecules. The purpose of this study was to quantify the reversibility of this injury upon resumption of air breathing, using a cytochemical technique. Rabbits were ...

Systemic distribution of blood flow was studied in 11 healthy adult grade ponies, using radionuclide-labeled microspheres (15 micron diameter) that were injected into the left ventricle. Measurements were made at rest, during severe exercise (SE) without furosemide, as well as during SE at 10 minutes and 120 minutes after furosemide ...

Systemic hemodynamic adjustments involved in the control of cardiac output (CO) were examined in chronically instrumented unanesthetized sheep inhaling gas mixtures resulting in hypocapnic hypoxia (H) [arterial pH (pHa) = 7.53, arterial partial pressure of O2 (Pao2) = 30 Torr, arterial partial pressure of CO2 (Paco2) = 29 Torr] or ...

Newborn mammals of medium or large sized species have ventilatory rates, expressed per kg body weight, larger than adults of corresponding size, while newborns of the smallest species do not. We hypothesized that the oxygen consumption of the smallest newborns is limited by the supply of oxygen and reasoned that ...

Selected blood parameters (arterial pH, O2 and CO2 tensions, oxygen content, bicarbonate and lactate concentrations, haematocrit, haemoglobin, red blood cell count, mean corpuscular haemoglobin, mean corpuscular volume and mean corpuscular haemoglobin concentration), oxygen consumption and ventilatory frequency were measured 0, 3 and 24 hours after cannulation of the dorsal aorta ...

Complex biochemical consequences are the result of a series of secondary biochemical changes caused by oxygen depletion. Hypoxia in the fetus and neonate results in decreased GI blood flow, especially to the GI mucosa. Although severe O2 deprivation cannot be entirely compensated for, an increase in tissue O2 extraction does ...

The effect of prolonged (2 h) hypocarbia on cerebral blood flow, oxygen delivery, extraction, and consumption was studied in eight, 1- to 4-day-old piglets. Hyperventilation to PaCO2 less than 20 mm Hg acutely (30 min) decreased cerebral blood flow and oxygen consumption. Cerebral oxygen consumption was subsequently restored via increases ...

We measured shunt in seven anesthetized, mechanically ventilated Pekin ducks by the multiple inert gas elimination technique (MIGET) and by the oxygen method during 100% O2 breathing (O2 shunt). MIGET shunt measures only intrapulmonary shunt but O2 shunt measures intra- and extrapulmonary shunt (e.g. bronchial drainage). O2 shunt was calculated ...