The oxygen tension field within a discrete volume of cerebral cortex

Smith, Randolph H.; Guilbeau, Eric J.; Reneau, Daniel D.

doi:10.1016/0026-2862(77)90088-7

Cited by 45 publications

(11 citation statements)

References 5 publications

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“…However, the heterogeneity of oxygen tension in the brain precludes the use of absolute PTO for this measurement. For example, oxygen tensions may vary from 0 to over 9-0 kPa (68 Torr) depending on the geometric position in the capillary network (Silver, 1966;Smith, Guilbeau & Reneau, 1977) and oxygen tension can change as much as 9-0 kPa (68 Torr) in a distance of less than 0-5 mm (Lubbers, 1971). The recording field for the fluorometer was 3-5 mm or 2-3 mm in diameter, depending on the objective used, and fluorescence originated primarily from the top 0-5 mm of tissue .…”

Section: Polarographic Measurement Of Cortical Oxygen Tension (Pto)mentioning

confidence: 99%

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

Bryan¹,

Jones²

1980

The Journal of Physiology

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SUMMARY1. Cerebral energy metabolism during apnoeic asphyxia and steady-state hypoxia was compared in ducks and chickens; ducks tolerate apnoeic asphyxia 3-8 times longer than chickens.2. Fluctuations in the reduced form of respiratory chain nicotinamide adenine dinucleotide (NADH) were monitored from the left cerebral hemisphere by a noninvasive fluorometric technique and used as an indicator of mitochondrial hypoxia. NADH fluorescence was expressed in arbitrary units (a.u.) where 100 a.u. was defined as the fluorescence change from normoxia to anoxia. Electroencephalogram (e.e.g.) and surface P02 were recorded from the right hemisphere.3. After 1 min of asphyxia NADH fluorescence increased by 37 a.u. + 3-60 S.E. of mean (n = 54) in paralysed chickens and 8 a.u. + 1 41 (n = 55) in paralysed ducks. After 2 min the fluorescence increased by only 15 a.u. + 1P95 in ducks.4. Both species showed an isoelectric e.e.g. when fluorescence increased by approximately 35 a.u., indicating that anaerobic ATP production in ducks did not maintain brain function (e.e.g.) for a greater accumulation of respiratory chain NADH.5. At a given decrease in tissue P02 ducks and chickens showed the same level of NADH increase, indicating that both species are equally dependent on tissue P02 for the maintenance of redox state.6. We conclude that biochemical adjustments which enhance anaerobic ATP production and/or prolong oxidative phosphorylation during progressive hypoxia are not responsible for increased cerebral tolerance to apnoeic asphyxia in the duck.

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Section: Polarographic Measurement Of Cortical Oxygen Tension (Pto)mentioning

confidence: 99%

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

Bryan¹,

Jones²

1980

The Journal of Physiology

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“…Variations in oxygen delivery and consumption in brain produce heterogeneous tissue oxygen concentrations, distributed between 1 and 100 pM, with a median value of about 40 PM (34,35). Measurements in isolated mitochondria have shown that the concentration of oxidized cytochrome c begins to decrease at oxygen concentrations below 20 pM, although the respiration rate does not fall until the oxygen concentration is below 1 to 5 pM (23); thus, a decrease in oxidized cytochrome c is not necessarily equivalent to a fall in mitochondrial respiration rate.…”

Section: Discussionmentioning

confidence: 99%

Effect of Indomethacin on Cerebral Oxidized Cytochrome Oxidase in Preterm Infants

McCormick¹,

Edwards²,

Brown³

et al. 1993

Pediatr Res

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“…Evidence in support of this thesis comes from a study (Davis, 1977) of the apparent oxygen affinity of tyrosine hydroxylase activity in rat striatal synaptosomes. Davis found an apparent K,,, for oxygen of 12 mm Hg, a value that would correspond to 55% saturation in brain in vivo, as calculated from the distribution of oxygen tensions (in rabbit cortex) reported by Smith et al (1977). Contrary evidence comes from the work of Brown et al (1975), who reported that formation of 3methoxytyramine after inhibition of tyrosine hydroxylase and monoamine oxidase was inhibited by moderate hypoxia.…”

mentioning

confidence: 87%

Oxygen Affinity of Tyrosine and Tryptophan Hydroxylases in Synaptosomes

Katz

1980

Journal of Neurochemistry

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Tyrosine and tryptophan hydroxylase activities were studied in a synaptosome-enriched (P2) preparation from the rat striatum. Care was taken to avoid the potential diffusional artifacts to which measures of oxygenase activities in respiring tissue are, in general, subject. Tyrosine hydroxylase exhibited a Km for oxygen of 2 to 3 mm Hg under a variety of conditions. Tryptophan hydroxylase exhibited a Km of 3 to 4 mm Hg at C.S.F. levels of tryptophan (10 microM). The Km increased to 8 to 10 mm Hg at 2 microM tryptophan. These values are all consistent with some degree of unsaturation with respect to oxygen in vivo.

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The oxygen tension field within a discrete volume of cerebral cortex

Cited by 45 publications

References 5 publications

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

Effect of Indomethacin on Cerebral Oxidized Cytochrome Oxidase in Preterm Infants

Oxygen Affinity of Tyrosine and Tryptophan Hydroxylases in Synaptosomes

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