Tissue Oxygen Tension in the Cerebral Cortex of the Rabbit

Fennema, M.; Wessel, Jennifer; Faithfull, N. S.; Erdmann, W.

doi:10.1007/978-1-4684-5643-1_50

Cited by 27 publications

(11 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, we have further quantified these observations and have demon strated in rats that heterogeneity was significantly curtailed by anesthesia (Sinha et aI., 1992). Other investigators (Kozniewska et aI., 1987;Fennema et 24.9% and the average venous O2 saturation was 53.8%. During hypoxia, venous O2 saturation was significantly decreased to 43.1% without a change in CV (24.5%).…”

mentioning

confidence: 79%

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins

Wei¹,

Chen²,

Sinha³

et al. 1993

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

This study evaluated the hypothesis that the sympathetic nervous system was one of the factors increasing the heterogeneity of cerebrocortical venous O2 saturation and this heterogeneity would be greater during hypoxia when cervical sympathetic activity was elevated. Thirty-two male Long-Evans rats were either sham operated (n = 16) or received bilateral cervical sympathectomy (n = 16). One-half of the animals (n = 8) in each treatment were challenged by hypoxia (8% O2 in N2). Cerebral blood flow was determined in five brain regions with [14C]iodoantipyrine. Oxygen saturation was measured microspectrophotometrically in small cerebrocortical arteries and veins. The degree of hypoxic hyperemia was not significantly different between sham-operated and sympathectomized rats. Cortical venous O2 saturations, indicating the balance between O2 supply and consumption, were significantly more heterogeneous in the sham-operated group under both normoxic and hypoxic conditions. The coefficient of variation (CV = 100 x SD/mean) for the normoxic sham-operated animals was 24.9% and the average venous O2 saturation was 53.8%. During hypoxia, venous O2 saturation was significantly decreased to 43.1% without a change in CV (24.5%). Sympathectomy significantly reduced this heterogeneity through a reduction in the number of low O2 saturation veins (CV = 13.2%) under normoxic conditions and the effect was similar under hypoxic conditions (CV = 15.3%). In both sham-operated and sympathectomized groups, hypoxia elicited a significantly higher cerebrocortical O2 consumption. Thus, bilateral cervical sympathectomy improved the O2 supply in selective cerebrocortical regions with high O2 extraction. However, the effect of sympathetic innervation on the heterogeneity of cerebrocortical venous O2 saturation was not potentiated by hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

mentioning

confidence: 79%

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins

Wei¹,

Chen²,

Sinha³

et al. 1993

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

show abstract

“…A nearly exhausted cerebrovascular reserve would produce a ceiling effect on the CBF response to behavioral activation, and the constrained CBF response would in turn constrain the BOLD response. The oxygen limitation model is based on the observation that there is little oxygen reserve for neurons to use when increased neural activity increases oxygen demand (Buxton and Frank, 1997;Fennema et al, 1989). Consequently, increased cerebral oxygen consumption during behavioral activation would require an increased flux of oxygen from the capillaries to neural tissue (Raichle, 1998).…”

Section: Discussionmentioning

confidence: 99%

BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

Brown

Zorrilla

Georgy

et al. 2003

J Cereb Blood Flow Metab

125

View full text Add to dashboard Cite

Summary:The authors studied the effects of altering global cerebral blood flow on both blood oxygen level-dependent (BOLD) response and perfusion response to finger-thumb apposition. A PICORE/QUIPSS II protocol was used to collect interleaved BOLD-weighted and perfusion-weighted images on eight finger-thumb apposition trials. Subjects were studied on a drug-free day and on a day when acetazolamide was administered between the second and third trials. After acetazolamide administration, resting cortical perfusion increased an average of 20% from preadministration levels, whereas the BOLD response to finger-thumb apposition decreased by an average of 35% in the S1M1 hand area. Contrary to predictions from the exhausted cerebrovascular reserve hypothesis and the oxygen limitation model, an effect of acetazolamide on cerebral blood flow response in the S1M1 hand area was not observed. Across the acetazolamide trials, BOLD response was inversely correlated with resting cortical perfusion for individual subject data. These results suggest that resting perfusion affects the magnitude of the BOLD response and is thus an important confounding factor in fMRI studies, and that the physiologic systems that increase cerebral blood flow in response to acetazolamide administration and systems that increase cerebral blood flow in response to altered neural activity appear to have additive effects.

show abstract

“…The ratio of substrate to oxygen is therefore reduced to such a level that the supply of oxygen to the enzyme layer is abundant, and the sensor can work reliably at Po 2 levels as low as 10 mm Hg. Tissue Po2 has been demonstrated to vary dramatically from 2 to >90 mm Hg throughout the capillary zone in the brain owing to the distributions of diffusion zones of oxygen in tissue around capillaries (Silver, 1965;Fennema et al, 1989). Based on the same considerations of the dimensions of the sensor and capillary zone as mentioned above, the sensor's performance is more likely dependent on the local average oxygen tension.…”

Section: Methodsmentioning

confidence: 99%

Rapid Changes in Local Extracellular Rat Brain Glucose Observed with an In Vivo Glucose Sensor

Wilson

1997

Journal of Neurochemistry

183

138

View full text Add to dashboard Cite

A needle‐type electrochemically based microsensor for glucose (110 µm o.d.) is described. This sensor, designed for monitoring transient glucose content changes in response to neural stimuli, has a response time of ∼5 s and has been shown to be free of interference from endogenous electroactive species such as ascorbate, urate, and various neurotransmitters. It exhibits linear response to glucose up to 10 mM. The usefulness of the sensor has been demonstrated by examining the time‐dependent interstitial glucose concentration in the rat hippocampus in response to KCl depolarization and by stimulation of glutamate neurons through a perforant pathway. Simultaneous monitoring of oxygen is also carried out and demonstrates that for both oxygen and glucose there is substantial local depletion of both species and that their pools are replenished by increased regional cerebral blood flow. The transient initial rapid (10–13 s) decrease up to 20–34%, observed on a time scale comparable to that for neurotransmitter release, may be involved in a recently suggested astrocytic uptake for glutamate‐stimulated aerobic glycolysis possibly needed to meet energy homeostasis in brain. These studies demonstrate the importance of microsensors in monitoring transient events linked to neuronal stimulation.

show abstract

Tissue Oxygen Tension in the Cerebral Cortex of the Rabbit

Cited by 27 publications

References 9 publications

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins

BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

Rapid Changes in Local Extracellular Rat Brain Glucose Observed with an In Vivo Glucose Sensor

Contact Info

Product

Resources

About

Tissue Oxygen Tension in the Cerebral Cortex of the Rabbit

Cited by 27 publications

References 9 publications

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O2 Saturation of Small Cerebrocortical Veins

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O2 Saturation of Small Cerebrocortical Veins

BOLD and Perfusion Response to Finger-Thumb Apposition after Acetazolamide Administration: Differential Relationship to Global Perfusion

Rapid Changes in Local Extracellular Rat Brain Glucose Observed with an In Vivo Glucose Sensor

Contact Info

Product

Resources

About

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins

Effect of Cervical Sympathectomy and Hypoxia on the Heterogeneity of O₂ Saturation of Small Cerebrocortical Veins