scholarly journals Effect of Astrocytic Energy Metabolism Depressant on 14C-Acetate Uptake in Intact Rat Brain

2004 ◽  
Vol 24 (2) ◽  
pp. 188-190 ◽  
Author(s):  
Rie Hosoi ◽  
Maki Okada ◽  
Jun Hatazawa ◽  
Antony Gee ◽  
Osamu Inoue
Keyword(s):  
Blood Flow ◽  
Energy Metabolism ◽  
Rat Brain ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Acetate Uptake ◽  
Minute Period ◽  
Intact Brain ◽  
The Right

Fluorocitrate, a selective astrocytic toxin, was microinjected into the right striatum of rat brain, and the regional distribution of 14C-acetate was measured using autoradiography. A significant reduction (more than 80%) in 14C-acetate uptake over a 5-minute period was observed in the right striatum, compared with that in the left striatum (saline infused), 4 hours after fluorocitrate (1 nmol/μL) infusion. This effect was transient, and 14C-acetate uptake had almost returned to normal at 24 hours after the fluorocitrate infusion. In contrast, the regional blood flow in the striatum, as determined using 14C-iodoamphetamine, was significantly increased by the fluorocitrate infusion. The present observations indicate that 14C-acetate uptake might be a useful characteristic for examining astrocytic energy metabolism in the intact brain.

Regional distribution of blood flow in awake heat-stressed baboons

1979 ◽  
Vol 237 (6) ◽  
pp. H705-H712 ◽  
Author(s):  
J. R. Hales ◽  
L. B. Rowell ◽  
R. B. King
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Renal Vasoconstriction ◽  
Suitable Animal Model ◽  
Mean Pressure ◽  
Subcutaneous Adipose ◽  
Arterial Po2 ◽  
The Brain

Radioactive microspheres (containing six different nuclide labels) were used to measure blood flow (BF) to most major organs of eight conscious baboons during heat stress. Cardiac output (CO), arterial mean pressure, and arterial PO2, PCO2, and pH did not change, but heart rate increased and stroke volume fell as body temperature increased by as much as 2.56 degrees C. Skin BF increased in all regions sampled so that the fraction of CO distributed to skin (not including feet and hands) increased from 3% (control) to 14%. Increased skin BF was compensated for by decreases in splanchnic (intestines, stomach, pancreas, and spleen) (35%), renal (27%), and possibly muscle BF. There was no change in BF to the brain, spinal cord, coronary, or subcutaneous adipose tissue during heating. Therefore, baboons show a generalized redistribution of BF during heat stress, so that increments in skin BF are provided without increases in CO, whereas man depends on changes in both; despite this latter difference between the baboon and man, the similarity in magnitude of the splanchnic and renal vasoconstriction between the two primates may indicate that the baboon would be a suitable animal model for investigations into mechanisms of changes in regional blood flow in man during heat stress.

Cardiovascular adjustments to laboratory diving in beavers and nutria

1982 ◽  
Vol 242 (5) ◽  
pp. R434-R440
Author(s):  
T. McKean
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Castor Canadensis ◽  
Venous Blood ◽  
Regional Distribution ◽  
Blood Gases ◽  
Myocastor Coypus ◽  
Recovery From Anesthesia ◽  
Rate Of Decline

Beavers (Castor canadensis) and nutria (Myocastor coypus) were anesthetized with halothane and catheters placed in the left ventricle, aorta and pulmonary artery, right ventricle or right atrium. The animals were strapped to a board and following recovery from anesthesia the following measurements were taken: regional distribution of blood flow, cardiac output, O2 consumption, arterial and venous blood gases, and pH. The animal was then immersed in 15-20 degrees C water for up to 2.75 min (nutria) or 4 min (beaver) and the measurements repeated. Heart rate and cardiac output decreased by 80 and 75%, respectively. Arterial and venous oxygen partial pressure and content fell as did pH whereas CO2 pressures rose during diving. Oxygen consumption at rest was 124 and 102% of that predicted on the basis of body mass for the beaver and nutria, respectively. Rate of decline of O2 stores during diving decreased by 93% in beavers and 89% in nutria compared to the predive value. Regional blood flow decreased to all organs except the adrenals, heart, and lungs. Blood flow to the brain increased during diving.

scholarly journals Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow

2006 ◽  
Vol 101 (2) ◽  
pp. 583-589 ◽  
Author(s):  
A. Cortney Henderson ◽  
David L. Levin ◽  
Susan R. Hopkins ◽  
I. Mark Olfert ◽  
Richard B. Buxton ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Normal Subjects ◽  
Relative Dispersion ◽  
Lung Water ◽  
Before And After ◽  
Capillary Pressures ◽  
The Right

Head-down tilt has been shown to increase lung water content in animals and alter the distribution of ventilation in humans; however, its effects on the distribution of pulmonary blood flow in humans are unknown. We hypothesized that head-down tilt would increase the heterogeneity of pulmonary blood flow in humans, an effect analogous to the changes seen in the distribution of ventilation, by increasing capillary hydrostatic pressure and fluid efflux in the lung. To test this, we evaluated changes in the distribution of pulmonary blood flow in seven normal subjects before and after 1 h of 30° head-down tilt using the magnetic resonance imaging technique of arterial spin labeling. Data were acquired in triplicate before tilt and at 10-min intervals for 1 h after tilt. Pulmonary blood flow heterogeneity was quantified by the relative dispersion (standard deviation/mean) of signal intensity for all voxels within the right lung. Relative dispersion was significantly increased by 29% after tilt and remained elevated during the 1 h of measurements after tilt (0.84 ± 0.06 pretilt, 1.09 ± 0.09 calculated for all time points posttilt, P < 0.05). We speculate that the mechanism most likely responsible for our findings is that increased pulmonary capillary pressures and fluid efflux in the lung resulting from head-down tilt alters regional blood flow distribution.

Estimated regional blood flow by rubidium 86 distribution during arousal from hibernation

1962 ◽  
Vol 203 (2) ◽  
pp. 266-270 ◽  
Author(s):  
Robert W. Bullard ◽  
Gordon E. Funkhouser
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Ground Squirrel ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Arousal Level ◽  
Blood Flows

The local organ or tissue blood flows during the process of arousal from hibernation have been estimated in the 13-lined ground squirrel by the Sapirstein method, which consists of the measurement of the regional distribution of injected rubidium 86. The studies demonstrated that during arousal there is a confinement of blood flow to the thoracic regions. After the heart rate has attained 100 beats/min, blood flow increases to the anterior portions of the animal. At the arousal level characterized by a heart rate of 200 beats/min, blood flow to anterior and thoracic tissue had attained levels almost equal to control flows. Posterior tissue flows were still much lower than control flows. The centralization of blood flow to thoracic and anterior tissues did not occur in the rat in the hypothermic state.

Regional distribution of blood flow of dogs during graded dynamic exercise

1987 ◽  
Vol 63 (6) ◽  
pp. 2269-2277 ◽  
Author(s):  
T. I. Musch ◽  
D. B. Friedman ◽  
K. H. Pitetti ◽  
G. C. Haidet ◽  
J. Stray-Gundersen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Maximal Exercise ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Work Load ◽  
Work Intensity ◽  
Semitendinosus Muscle ◽  
Blood Flows ◽  
Flow Response ◽  
Semimembranosus Muscle

The regional blood flow response to progressive treadmill exercise was measured with radioactive microspheres in 25 untrained mongrel dogs. Incremental increases in work intensity resulted in corresponding increases in blood flows to the gracilis, gastrocnemius, semimembranosus, and semitendinosus muscles of the hindlimb and to the heart. During maximal exercise, blood flow was greatest in the semimembranosus muscle and lowest in the semitendinosus muscle (342 and 134 ml–1.100 g tissue-1.min-1, respectively). Exercise produced a decrease in blood flow to the temporalis muscle, which was classified as nonlocomotive in function. Blood flows to the stomach, pancreas, and large intestine decreased at the lowest exercise work load and remained diminished throughout the continuum to maximal exercise. Blood flows to the small intestine and spleen were maintained during submaximal exercise but were reduced by 50% at maximal O2 consumption (VO2max). No changes in blood flows to the kidneys, adrenal glands, liver, and brain were found. These results demonstrate that 1) renal blood flow is maintained at resting levels during exercise in untrained dogs; 2) blood flow changes in the various organs of the splanchnic region of dogs during exercise are heterogeneous; and 3) blood flows to the working skeletal muscles of dogs progressively increase with increasing work loads up to VO2max.

scholarly journals Asymmetric, dynamic adaptation in prefrontal cortex during dichotic listening tasks

2019 ◽  
Author(s):  
J. A. N. Fisher ◽  
I. Gumenchuk ◽  
O. Rogovin ◽  
A. G. Yodh ◽  
D. R. Busch
Keyword(s):  
Blood Flow ◽  
Prefrontal Cortex ◽  
Otoacoustic Emissions ◽  
Dichotic Listening ◽  
Right Hemisphere ◽  
Assessment Tool ◽  
Regional Blood Flow ◽  
Speech Comprehension ◽  
Distortion Product ◽  
The Right

AbstractSpeech comprehension relies on highly distributed, dynamically interconnected neuroanatomical loci. Accordingly, performance on complex speech processing tasks such as dichotic listening can be used to assess the integrity and health of many functional and structural aspects of the brain. Despite the potential merits as a clinical assessment tool, however, the neural substrates activated during dichotic listening remain relatively opaque at higher processing levels. Ultimately, this knowledge gap limits diagnostic use of the task. At the level of the prefrontal cortex, dichotic listening induces an asymmetric response wherein regions on the right hemisphere exhibit a higher functional activation than on the left. Superficially, this finding is counterintuitive given the left hemisphere’s dominance for speech and language. To obtain a more in-depth perspective on the potentially distinct roles of the right and left prefrontal cortex, we optically monitored cerebral blood flow in the dorsolateral prefrontal cortex (DLPFC) during dichotic listening tasks in human subjects. The method permitted us to avoid systematic experimental confounds that functional magnetic resonance imaging (fMRI) measurements suffer from, namely the influence of scanner noise. In addition to reproducing the documented larger activation amplitude in the right hemisphere, we also found that repeated listening task blocks were associated with altered kinetics of blood flow in the right, but not the left DLPFC. Interestingly, subjects with the most prominent regional blood flow changes in the right hemisphere also displayed large distortion product otoacoustic emissions (DPOAEs) in the left ear, possibly signaling a correlation between prefrontal activity and top-down listening control infrastructure through medial olivocochlear efferent projections to the inner ear. Overall, our results suggest that the right prefrontal cortical regions play an active role in optimizing task performance.

Effect of hypoxemia and hypercapnia on regional distribution of myocardial blood flow

1965 ◽  
Vol 208 (6) ◽  
pp. 1211-1216 ◽  
Author(s):  
William D. Love ◽  
Myra D. Tyler
Keyword(s):  
Blood Flow ◽  
Left Ventricle ◽  
Right Ventricle ◽  
Coronary Blood Flow ◽  
Regional Distribution ◽  
Fick Principle ◽  
The Right ◽  
Isotope Content ◽  
Coronary Sinus Blood ◽  
Normal Difference

The effect of hypoxia and hypercapnia on regional coronary blood flow and vascular resistance (CVR) was studied in dogs without thoracotomy. Gas tensions were varied by ventilation at controlled rates with gas mixtures containing 4–100% O2 and 0–24% CO2. After 10 min intravenous infusion of Rb86, the animals were killed and the heart isotope content determined. Blood flow to the left ventricle was calculated by the Fick principle from the isotope uptake and the mean difference in radioactivity of arterial and coronary sinus blood. Patterns of flow elsewhere were estimated from the rates of regional Rb86 clearance. Myocardial Rb86 clearance in the right and left ventricles has been previously shown to be closely related to the rate of coronary blood flow. Hypoxemia and severe hypercapnia (pCO2 above 100 mm Hg) both produced a profound fall in CVR. With hypoxemia this decrease was more marked in the right ventricle. Elevation of pCO2 exaggerated the normal difference in Rb86 uptake between inner and outer thirds of the wall of the left ventricle, while hypoxemia reversed the normal gradients. Hypercapnia did not affect these gradients in the right ventricle, but hypoxemia significantly reduced them.

Spatial distribution of ventilation and perfusion in anesthetized dogs in lateral postures

2002 ◽  
Vol 92 (2) ◽  
pp. 745-762 ◽  
Author(s):  
Hung Chang ◽  
Stephen J. Lai-Fook ◽  
Karen B. Domino ◽  
Carmel Schimmel ◽  
Jack Hildebrandt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Regional Blood Flow ◽  
Linear Regression Analysis ◽  
Regional Distribution ◽  
Left Lung ◽  
Vertical Gradient ◽  
Fluorescent Microspheres ◽  
Lateral Decubitus ◽  
Ventilation And Perfusion

We aimed to assess the influence of lateral decubitus postures and positive end-expiratory pressure (PEEP) on the regional distribution of ventilation and perfusion. We measured regional ventilation (V˙a) and regional blood flow (Q˙) in six anesthetized, mechanically ventilated dogs in the left (LLD) and right lateral decubitus (RLD) postures with and without 10 cmH2O PEEP. Q˙ was measured by use of intravenously injected 15-μm fluorescent microspheres, and V˙a was measured by aerosolized 1-μm fluorescent microspheres. Fluorescence was analyzed in lung pieces ∼1.7 cm3 in volume. Multiple linear regression analysis was used to evaluate three-dimensional spatial gradients ofQ˙, V˙a, the ratio V˙a/Q˙, and regional Po 2 (PrO2 ) in both lungs. In the LLD posture, a gravity-dependent vertical gradient in Q˙ was observed in both lungs in conjunction with a reduced blood flow and PrO2 to the dependent left lung. Change from the LLD to the RLD or 10 cmH2O PEEP increased localV˙a/Q˙ and PrO2 in the left lung and minimized any role of hypoxia. The greatest reduction in individual lung volume occurred to the left lung in the LLD posture. We conclude that lung distortion caused by the weight of the heart and abdomen is greater in the LLD posture and influences both Q˙ andV˙a, and ultimately gas exchange. In this respect, the smaller left lung was the most susceptible to impaired gas exchange in the LLD posture.

Redistribution of pulmonary blood flow during unilateral hypoxia in prone and supine dogs

1998 ◽  
Vol 84 (6) ◽  
pp. 2010-2019 ◽  
Author(s):  
Christopher M. Mann ◽  
Karen B. Domino ◽  
Sten M. Walther ◽  
Robb W. Glenny ◽  
Nayak L. Polissar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Regional Distribution ◽  
Left Lung ◽  
Flow Distribution ◽  
Random Order ◽  
Total Flow ◽  
Hypoxic Vasoconstriction ◽  
Anesthetized Dogs ◽  
The Right

We used fluorescent-labeled microspheres in pentobarbital-anesthetized dogs to study the effects of unilateral alveolar hypoxia on the pulmonary blood flow distribution. The left lung was ventilated with inspired O2 fraction of 1.0, 0.09, or 0.03 in random order; the right lung was ventilated with inspired O2 fraction of 1.0. The lungs were removed, cleared of blood, dried at total lung capacity, then cubed to obtain ∼1,500 small pieces of lung (∼1.7 cm3). The coefficient of variation of flow increased ( P < 0.001) in the hypoxic lung but was unchanged in the hyperoxic lung. Most (70–80%) variance in flow in the hyperoxic lung was attributable to structure, in contrast to only 30–40% of the variance in flow in the hypoxic lung ( P < 0.001). When adjusted for the change in total flow to each lung, 90–95% of the variance in the hyperoxic lung was attributable to structure compared with 70–80% in the hypoxic lung ( P < 0.001). The hilar-to-peripheral gradient, adjusted for change in total flow, decreased in the hypoxic lung ( P = 0.005) but did not change in the hyperoxic lung. We conclude that hypoxic vasoconstriction alters the regional distribution of flow in the hypoxic, but not in the hyperoxic, lung.

Unsymmetrical alkyl aryl thiourea compounds for use as cerebral blood flow tracers

1980 ◽  
Vol 238 (6) ◽  
pp. H776-H787 ◽  
Author(s):  
S. S. Goldman ◽  
W. K. Hass ◽  
J. Ransohoff
Keyword(s):  
Blood Flow ◽  
Rat Brain ◽  
Regional Blood Flow ◽  
Alkyl Aryl ◽  
Flow Rates ◽  
Single Pass ◽  
Diffusion Limited ◽  
Brain Extraction ◽  
Plasma Distribution

The synthesis and characterization of an homologous series of inert nonvolatile 14C-labeled unsymmetrical alkyl aryl thiourea compounds is described for their use as regional blood flow (rCBF) tracers employing autoradiographic procedures. In alert normocapnic rats the single-pass extraction values into brain for these thioureas were found to be dependent on their respective lipid solubilities ranging from 0.497 for 1-methyl-3-phenylthiourea to 0.730 for 1-butyl-3-phenylthiourea. The commonly used rCBF tracers [14C]antipyrine and [14C]iodoantipyrine had single-pass extraction values of 0.451 and 0.553, respectively. The single-pass extraction value for n-butanol was found to be the same as that for 1-butyl-3-phenylthiourea indicating that both n-butanol and 1-butyl-3-phenylthiourea are mildly diffusion limited at normal rates of flow in rat brain. Since 1-butyl-3-phenylthiourea diffused most readily into rat brain it was chosen as a potentially valuable rCBF tracer. Its brain-blood partition coefficient was found to be 1.09. The plasma distribution of this thiourea in blood varied inversely with the hematocrit, and the compound was freely exchangeable between plasma and erythrocytes. Employing 1-butyl-3-phenylthiourea to measure rCBF and its empirically derived brain extraction values the following flow rates in normocapnic rats were found: 3.2 ml . g-1 . min-1 for cochlear nucleus: 3.0 for inferior colliculus; 2.5 for medical geniculate; 1.9 for pontine gray and hypothalamus; 1.7 for caudate and cerebral cortex; and 1.2 for cerebellar gray and 0.41-0.50 for white matter structures. It was concluded from these studies that 1-butyl-3-phenylthiourea is more advantageous than iodoantipyrine for measuring rCBF, especially in those areas that possess very rapid rates of flow.

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