Astrocytes Function in Matching Blood Flow to Metabolic Activity

Physiology ◽  
2002 ◽  
Vol 17 (1) ◽  
pp. 27-31 ◽  
Author(s):  
David R. Harder ◽  
Chenyang Zhang ◽  
Debebe Gebremedhin
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Metabolic Activity ◽  
Regulatory Mechanism ◽  
Capillary Density ◽  
Epoxyeicosatrienoic Acids ◽  
Cell Type ◽  
Intermediary Cell ◽  
Cytochrome P 450 ◽  
The Brain

The brain possesses an intrinsic regulatory mechanism to maintain an adequate supply of O2 and nutrition despite local increases in neuronal activity. Brain astrocytes function as an intermediary cell type by responding to glutamate released from activated neurons, and they couple cerebral blood flow by producing cytochrome P-450-derived epoxyeicosatrienoic acids that induce vasodilation and increase capillary density.

Effect of hemorrhage on regional morphometric indexes of cerebral capillarity

1986 ◽  
Vol 61 (5) ◽  
pp. 1712-1719 ◽  
Author(s):  
G. J. Grover ◽  
E. Francois-Dainville ◽  
E. Buchweitz ◽  
H. R. Weiss
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Fluorescein Isothiocyanate ◽  
Capillary Density ◽  
Regional Cerebral Blood ◽  
Severe Hemorrhage ◽  
Fluorescein Isothiocyanate Dextran ◽  
The Brain

This study was performed to determine whether the brain can increase the number of perfused capillaries and arterioles supplying it regionally during hemorrhage. This was done using a technique to simultaneously determine total and perfused regional arteriolar and capillary morphology. Conscious Long-Evans rats served as unbled controls or were bled 65 mmHg or to 40–45 mmHg and stabilized for 30 min. Regional cerebral blood flow was determined using [14C]iodoantipyrine in half of these animals and fluorescein isothiocyanate-dextran was injected in the other half for determination of perfused cerebral microvascular morphometric indexes. The total microvasculature was labeled postmortem via an alkaline phosphatase stain. Regional cerebral blood flow was significantly increased in animals bled to 65 mmHg. During hemorrhage to 40–45 mmHg, cerebral blood flow was reduced 50% (from 59 +/- 28 to 26 +/- 11 ml X min-1 X 100 g-1, mean +/- SD) with no regional redistribution. For all treatments, total capillary density ranged from 400 to 500 capillaries/mm2, and in controls 47% were perfused. Animals bled to 65 mmHg did not mobilize their unperfused microvascular reserve even though they showed a slight tendency to do so. During hemorrhage to 40–45 mmHg, this percent increased significantly to 57% with the largest increase occurring in the pons. Approximately 51% of arterioles were perfused in controls and this was not different compared with the percent perfused during hemorrhage. Despite the overall lack of mobilization of unperfused arterioles, some regions within the brain significantly mobilized their reserves with severe hemorrhage, e.g., hippocampus (78%), hypothalamus (67%), and medulla (73%).(ABSTRACT TRUNCATED AT 250 WORDS)

Vorläufige Ergebnisse von 99mTc-HMPAO-SPECT-Untersuchungen bei endogenen Psychosen

1989 ◽  
Vol 28 (03) ◽  
pp. 88-91
Author(s):  
J. Schröder ◽  
H. Henningsen ◽  
H. Sauer ◽  
P. Georgi ◽  
K.-R. Wilhelm
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Regions Of Interest ◽  
Post Mortem ◽  
Regional Cerebral Blood ◽  
Hmpao Spect ◽  
Endogenous Psychoses ◽  
The Brain ◽  
99Mtc Hmpao

18 psychopharmacologically treated patients (7 schizophrenics, 5 schizoaffectives, 6 depressives) were studied using 99mTc-HMPAO-SPECT of the brain. The regional cerebral blood flow was measured in three transversal sections (infra-/supraventricular, ventricular) within 6 regions of interest (ROI) respectively (one frontal, one parietal and one occipital in each hemisphere). Corresponding ROIs of the same section in each hemisphere were compared. In the schizophrenics there was a significantly reduced perfusion in the left frontal region of the infraventricular and ventricular section (p < 0.02) compared with the data of the depressives. The schizoaffectives took an intermediate place. Since the patients were treated with psychopharmaca, the result must be interpreted cautiously. However, our findings seem to be in accordance with post-mortem-, CT- and PET-studies presented in the literature. Our results suggest that 99mTc-HMPAO-SPECT may be helpful in finding cerebral abnormalities in endogenous psychoses.

Neuroimaging in Drug Discovery and Development: Paradigms for Accelerating New Drug Availability

2001 ◽  
Vol 14 (5) ◽  
pp. 407-415
Author(s):  
John T. Metz ◽  
Malcolm D. Cooper ◽  
Terry F. Brown ◽  
Leann H. Kinnunen ◽  
Declan J. Cooper
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Glucose Metabolism ◽  
Phase Ii ◽  
New Drugs ◽  
Central Effects ◽  
Drug Discovery And Development ◽  
Psychological Tasks ◽  
The Brain ◽  
Phase Iv

The process of discovering and developing new drugs is complicated. Neuroimaging methods can facilitate this process. An analysis of the conceptual bases and practical limitations of different neuroimaging modalities reveals that each technique can best address different kinds of questions. Radioligand studies are well suited to preclinical and Phase II questions when a compound is known or suspected to affect well-understood mechanisms; they are also useful in Phase IV to characterize effective agents. Cerebral blood flow studies can be extremely useful in evaluating the effects of a drug on psychological tasks (mostly in Phase IV). Glucose metabolism studies can answer the simplest questions about whether a compound affects the brain, where, and how much. Such studies are most useful in confirming central effects (preclinical and early clinical phases), in determining effective dose ranges (Phase II), and in comparing different drugs (Phase IV).

Effects of Cytoflavin and Neuronol on Morphological Changes in the Brain and Survival of Rats with Ischemic Disturbances in Cerebral Blood Flow

2004 ◽  
Vol 137 (4) ◽  
pp. 411-414 ◽  
Author(s):  
V. V. Bulon ◽  
I. B. Krylova ◽  
N. R. Evdokimova ◽  
A. L. Kovalenko ◽  
L. E. Alekseeva ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Morphological Changes ◽  
The Brain

scholarly journals Use of 19F NMR Spectroscopy for Measurement of Cerebral Blood Flow: A Comparative Study Using Microspheres

1989 ◽  
Vol 9 (6) ◽  
pp. 886-891 ◽  
Author(s):  
David Barranco ◽  
Leslie N. Sutton ◽  
Sandra Florin ◽  
Joel Greenberg ◽  
Teresa Sinnwell ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood ◽  
Radioactive Microsphere ◽  
Low Concentrations ◽  
Cat Brain ◽  
Nmr Techniques ◽  
High Concentrations ◽  
Washout Curves ◽  
The Brain

19F NMR was used to determine washout curves of an inert, diffusible gas (CHF3) from the cat brain. The cerebral blood flow was estimated from a bi- or tri-phasic fit to the deconvoluted wash-out curve, using the Kety-Schmidt approach. Cerebral blood flow values determined by 19F NMR show the expected responsiveness to alterations in Paco2, but are approximately 28% lower than cerebral blood flow values determined simultaneously by radioactive microsphere techniques. High concentrations of CHF3 have little effect on intracranial pressure, mean arterial blood pressure or Paco2, but cause small changes in the blood flow to certain regions of the brain. We conclude that 19F NMR techniques utilizing low concentrations of CHF3 have potential for the noninvasive measurement of cerebral blood flow.

Vasodilation of cat cerebral arterioles by prostaglandins D2, E2, G2, and I2

1979 ◽  
Vol 237 (3) ◽  
pp. H381-H385 ◽  
Author(s):  
E. F. Ellis ◽  
E. P. Wei ◽  
H. A. Kontos
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Blood Pressure ◽  
Standard Error ◽  
Arterial Blood ◽  
Cerebral Arterioles ◽  
The Mean ◽  
Dose Dependent ◽  
The Brain

To determine the possible role that endogenously produced prostaglandins may play in the regulation of cerebral blood flow, the responses of cerebral precapillary vessels to prostaglandins (PG) D2, E2, G2, and I2 (8.1 X 10(-8) to 2.7 X 10(-5) M) were studied in cats equipped with cranial windows for direct observation of the microvasculature. Local application of PGs induced a dose-dependent dilation of large (greater than or equal to 100 microns) and small (less than 100 microns) arterioles with no effect on arterial blood pressure. The relative vasodilator potency was PGG2 greater than PGE2 greater than PGI2 greater than PGD2. With all PGs, except D2, the percent dilation of small arterioles was greater than the dilation of large arterioles. After application of prostaglandins in a concentration of 2.7 X 10(-5) M, the mean +/- standard error of the percent dilation of large and small arterioles was, respectively, 47.6 +/- 2.7 and 65.3 +/- 6.1 for G2, 34.1 +/- 2.0, and 53.6 +/- 5.5 for E2, 25.4 +/- 1.8, and 40.2 +/- 4.6 for I2, and 20.3 +/- 2.5 and 11.0 +/- 2.2 for D2. Because brain arterioles are strongly responsive to prostaglandins and the brain can synthesize prostaglandins from its large endogenous pool of prostaglandin precursor, prostaglandins may be important mediators of changes in cerebral blood flow under normal and abnormal conditions.

scholarly journals Effects of Gastric Bypass Surgery on the Brain; Simultaneous Assessment of Glucose Uptake, Blood Flow, Neural Activity and Cognitive Function during Normo- and Hypoglycemia

2021 ◽  
Author(s):  
Kristina E. Almby ◽  
Martin H. Lundqvist ◽  
Niclas Abrahamsson ◽  
Sofia Kvernby ◽  
Markus Fahlström ◽  
...  
Keyword(s):  
Blood Flow ◽  
Gastric Bypass ◽  
Cerebral Blood Flow ◽  
Cognitive Function ◽  
Counterregulatory Hormones ◽  
Fdg Uptake ◽  
Post Surgery ◽  
Total Brain ◽  
Underlying Mechanisms ◽  
The Brain

While Roux-en-Y Gastric Bypass (RYGB) surgery in obese individuals typically improves glycemic control and prevents diabetes, it also frequently causes hypoglycemia. Previous work showed attenuated counter-regulatory responses following RYGB. The underlying mechanisms as well as the clinical consequences are unclear. <p>In this study, 11 non-diabetic subjects with severe obesity were investigated pre- and post-RYGB during hyperinsulinemic hypoglycemic clamps. Assessments were made of hormones, cognitive function, cerebral blood flow by arterial spin labeling, brain glucose metabolism by FDG PET and activation of brain networks by functional MRI. Post- vs pre-surgery, we found a general increase of cerebral blood flow but a decrease of total brain FDG uptake during normoglycemia. During hypoglycemia, there was a marked increase in total brain FDG uptake and this was similar for post- and pre-surgery, whereas hypothalamic FDG uptake was reduced. During hypoglycemia, attenuated responses of counterregulatory hormones and improvements in cognitive function were seen post-surgery. In early hypoglycemia, there was increased activation post- vs pre-surgery of neural networks in CNS regions implicated in glucose regulation such as the thalamus and hypothalamus. The results suggest adaptive responses of the brain that contribute to lowering of glycemia following RYGB, and the underlying mechanisms should be further elucidated.</p>

Sign in / Sign up

Export Citation Format

Share Document