scholarly journals Persistent Resetting of the Cerebral Oxygen/Glucose Uptake Ratio by Brain Activation: Evidence Obtained with the Kety—Schmidt Technique

1995 ◽  
Vol 15 (3) ◽  
pp. 485-491 ◽  
Author(s):  
Peter Lund Madsen ◽  
Steen G. Hasselbalch ◽  
Lars P. Hagemann ◽  
Karsten Skovgaard Olsen ◽  
Jens Bülow ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Lactate Production ◽  
Brain Activation ◽  
Glucose Consumption ◽  
Wisconsin Card Sorting Test ◽  
Molar Ratio ◽  
Cerebral Oxygen ◽  
Uptake Ratio ◽  
Card Sorting ◽  
Cerebral Activation

Global cerebral blood flow (CBF), global cerebral metabolic rates for oxygen (CMRO2), and for glucose (CMRglc), and lactate efflux were measured during rest and during cerebral activation induced by the Wisconsin card sorting test. Measurements were performed in healthy volunteers using the Kety–Schmidt technique. Global CMRO2 was unchanged during cerebral activation, whereas global CBF and global CMRglc both increased by 12%, reducing the molar ratio of oxygen to glucose consumption from 6.0 during baseline conditions to 5.4 during activation. Data obtained in the period following cerebral activation showed that the activation-induced resetting of the relation between CMRglc and CMRO2 persisted virtually unaltered for ≥40 min after the mental activation task was terminated. The activation-induced increase in cerebral lactate efflux measured over the same time period accounted for only a small fraction of the activation-induced excess glucose uptake. These data confirm earlier reports that brain activation can induce resetting of the cerebral oxygen/glucose consumption ratio, and indicate that the resetting persists for a long period after cerebral activation has been terminated and physiologic stress indicators returned to baseline values. Activation-induced resetting of the cerebral oxygen/glucose uptake ratio is not necessarily accounted for by increased lactate production from nonoxidative glucose metabolism.

Regulation of glucose transport and GLUT1 glucose transporter expression by O2 in muscle cells in culture

1992 ◽  
Vol 262 (3) ◽  
pp. C682-C690 ◽  
Author(s):  
N. Bashan ◽  
E. Burdett ◽  
H. S. Hundal ◽  
A. Klip
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
De Novo ◽  
Lactate Production ◽  
Glucose Consumption ◽  
Glucose Deprivation ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Glut1 Glucose Transporter

The effect of varying cellular oxygenation on L6 muscle cell 2-deoxy-D-glucose transport, glucose utilization, lactate production, and expression of GLUT1 and GLUT4 transport proteins was investigated. Incubation of L6 myotubes in 3% O2 (mimicking a state of hypoxia) elevated glucose uptake by 6.5-fold over 48 h relative to cells incubated in 21% O2 (normoxia). Incubation of L6 cells in hyperoxic conditions (50% O2) significantly depressed glucose uptake by 0.4-fold. These effects were fully reversible. Incubation in 3% O2 also caused lactate accumulation and enhanced glucose consumption from the medium. Hypoxia elevated 2-deoxy-D-glucose transport even when the concentration of glucose in the medium was kept constant, suggesting that glucose deprivation alone was not responsible for increased cellular glucose uptake. Incubation in 3% O2 also elevated 3-O-methylglucose uptake but not amino acid uptake. Cycloheximide prevented the hypoxia-induced increase in glucose uptake, indicating that de novo synthesis of glucose transport-related proteins was the major means by which cells increased glucose uptake. The content of GLUT1 glucose transporter was significantly elevated in total membranes of cells incubated in 3% O2 and depressed in membranes from cells incubated in hyperoxic conditions, whereas GLUT4 expression was not affected. These results indicate that hypoxia induces an adaptive response of increasing cellular glucose uptake through elevated expression of GLUT1 in an attempt to maintain supply of glucose for utilization by nonoxidative pathways.

scholarly journals Activation-Induced Resetting of Cerebral Oxygen and Glucose Uptake in the Rat

1998 ◽  
Vol 18 (7) ◽  
pp. 742-748 ◽  
Author(s):  
Peter L. Madsen ◽  
Rasmus Linde ◽  
Steen G. Hasselbalch ◽  
Olaf B. Paulson ◽  
Niels A. Lassen
Keyword(s):  
Oxygen Uptake ◽  
Glucose Uptake ◽  
Precise Determination ◽  
Cerebral Oxygen ◽  
Uptake Ratio ◽  
Uptake Rates ◽  
Awake Rat ◽  
Baseline Conditions ◽  
Excess Glucose

In the clinical setting it has been shown that activation will increase cerebral glucose uptake in excess of cerebral oxygen uptake. To study this phenomenon further, this study presents an experimental setup that enables precise determination of the ratio between cerebral uptake of glucose and oxygen in the awake rat. Global CBF was measured by the Kety-Schmidt technique, and the ratio between cerebral uptake rates for oxygen, glucose, and lactate was calculated from cerebral arterial—venous differences. During baseline conditions, rats were kept in a closed box designed to minimize interference. During baseline conditions CBF was 1.08 ± 0.25 mL·g−1·minute−1, and the cerebral oxygen to glucose uptake ratio was 5.5. Activation was induced by opening the sheltering box for 6 minutes. Activation increased CBF to 1.81 mL·g−1·minute−1. During activation cerebral glucose uptake increased disproportionately to cerebral oxygen uptake, and the cerebral oxygen to glucose uptake ratio was 4.2. The accumulated excess glucose uptake during 6 minutes of activation amounted to 2.4 μmol/g. Activation was terminated by closure of the sheltering box. In the postactivation period, the cerebral oxygen to glucose uptake ratio rose to a maximum of 6.4. This response is exactly opposite to the excess cerebral glucose uptake observed during activation.

Cerebral blood flow, oxygenation, and carbohydrate metabolism in immature fetal sheep in utero

1989 ◽  
Vol 256 (6) ◽  
pp. R1264-R1268 ◽  
Author(s):  
C. A. Gleason ◽  
C. Hamm ◽  
M. D. Jones
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Glucose Uptake ◽  
Vena Cava ◽  
Lactate Production ◽  
Glucose Consumption ◽  
In Utero ◽  
Fetal Sheep ◽  
O2 Extraction ◽  
Near Term

Studies of cerebral blood flow (CBF) and metabolism in fetal sheep have been largely confined to late gestation, a time when brain development in this species is largely complete. Few studies have been done at a time when the fetal sheep brain is in the midst of rapid differentiation and development. We studied seven fetal sheep in utero at 91 days of gestation (term = 145-150 days) 24 h after catheters were placed into the sagittal sinus, axillary artery, and inferior vena cava. We measured CBF by the microsphere method and used arteriovenous differences of O2, lactate, and glucose to calculate cerebral O2 consumption (CMRo2), fractional O2 extraction, glucose consumption, O2-glucose index (OGI), and cerebral lactate production. Compared with near-term fetal sheep, we found lower CBF (33.9 +/- 5.3 ml.100 g-1.min-1), lower glucose consumption (8.5 +/- 1.25 mumol.100 g-1.min-1), and lower CMRo2 (41.8 +/- 8.8 mumol.100 g-1.min-1). Fractional O2 extraction was 0.29 +/- 0.04, which is similar to near-term fetal sheep. There was consistent cerebral lactate production (2.45 +/- 1.58 mumol.100 g-1.min-1). The OGI was 81 +/- 16%, i.e., oxidative metabolism could account for 81% of glucose uptake. Lactate production accounts for virtually all glucose uptake exceeding that required for oxidation.

Dynamic Assessment of Cognitive Rehabilitation Potential in Schizophrenic Persons and in Elderly Persons With and Without Dementia

2001 ◽  
Vol 17 (2) ◽  
pp. 112-119 ◽  
Author(s):  
Karl H. Wiedl ◽  
Henning Schöttke ◽  
M. Dolores Calero Garcia
Keyword(s):  
Cognitive Rehabilitation ◽  
Clinical Training ◽  
Dynamic Assessment ◽  
Verbal Learning ◽  
Verbal Working Memory ◽  
Wisconsin Card Sorting Test ◽  
Elderly Persons ◽  
Card Sorting ◽  
Static Test ◽  
Rehabilitation Potential

Summary: Dynamic assessment is a diagnostic approach in which specific interventions are integrated into assessment procedures to estimate cognitive modifiability. The study investigates the utility of this approach in persons with compelling rehabilitational needs. Samples of schizophrenic patients and of elderly with and without dementia were assessed with dynamic versions of the Wisconsin Card Sorting Test and the Auditory Verbal Learning Test. Both tests were administered by applying specific procedures of verbal mediation designed to increase performance. Results demonstrated superior predictive validity with regard to proficiency in a clinical training in schizophrenic subjects and better discrimination of nondemented and demented elderly with the help of dynamic measures compared to static test scores. Subsequent correlational analyses indicated that, for both tests, performance change following intervention is related to the processing of verbal context information. Results are discussed with respect to the concept of verbal working memory as one component of the patients' rehabilitation potential.

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