Po2 of cat cerebral cortex: Response to breathing N2 and 100% O2

Nair, P.; Whalen, William J.; Buerk, Donald G.

doi:10.1016/0026-2862(75)90077-1

Cited by 59 publications

(30 citation statements)

References 9 publications

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“…These results suggest that the ability of C. neoformans to grow under low oxygen conditions is associated with the ability to cause fatal infection in mice. Oxygen concentrations in the brain differ significantly among anatomical sites (15), and the mean tissue oxygen tension in the brain has been reported to range from 5 mm Hg to 40 mm Hg (14,27). We chose the very stringent 1% O 2 condition with which to examine the growth phenotypes of all the mutants.…”

Section: Discussionmentioning

confidence: 99%

Role of Actin-Bundling Protein Sac6 in Growth of Cryptococcus neoformans at Low Oxygen Concentration

2012

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ABSTRACTCryptococcus neoformans, the etiologic agent of cryptococcosis, is an obligately aerobic yeast that inhabits an environmental niche exposed to ambient air. The cell doubling time was significantly prolonged under 1% O2relative to that under normoxic conditions. No apparent cell cycle arrest occurred following a shift from ambient air to 1% O2. However, yeast cells became hypersensitive to the actin monomer-sequestering agent latrunculin A at 1% O2, indicating that proper actin function is critical for growth at low oxygen concentrations. We showed that Sac6, an actin-binding protein, played an important role in cell growth under low oxygen conditions. Sac6 colocalized with cortical actin patches and with the ring structures between mother cells and buds. Under low oxygen conditions, thesac6deletion mutant grew poorly, and accumulation of the actin capping protein Cap1 was observed in the vacuole of thesac6Δstrain. Furthermore, endocytic processes were hampered in thesac6Δmutant, but cell polarity and cytokinesis were not visibly disturbed. The deficiency of endocytosis in thesac6Δstrain could be rescued by 1 M sorbitol under 1% O2, but growth remained retarded. These results suggest an absence of a direct link inC. neoformansbetween endocytosis and coping with the stress of low oxygen conditions. This interpretation is further supported by the observation that deletion of three conserved genes,ABP1,CRN1, andSLA2, which play important roles in endocytosis, had no effect on growth under 1% O2. Interestingly, deletion ofSAC6inC. neoformanshad no effect on virulence in mice.

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Section: Discussionmentioning

confidence: 99%

Role of Actin-Bundling Protein Sac6 in Growth of Cryptococcus neoformans at Low Oxygen Concentration

2012

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“…e have previously used our recessed oxygen microelectrode 12 to measure tissue Po 2 distributions in vivo in cat cortex 3 and have determined metabolic parameters in vitro from slices of cat cortex, 4 rat cortex, 36 and guinea pig olfactory cortex 7 by fitting curves of measured Po 2 gradients to mathematical models for oxygen consumption, including Michaelis-Menten kinetics. We have also determined local metabolic rates in vivo by measuring oxygen disappearance following total blood flow occlusion in extensive studies of the cat carotid body.…”

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confidence: 99%

Comparisons of oxygen metabolism and tissue PO2 in cortex and hippocampus of gerbil brain.

Nair¹,

Buerk²,

Halsey³

1987

Stroke

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Recessed oxygen microelectrodes (tip diameter < 2 (j.m) were positioned stereotactically into either the cerebral cortex or the hippocampus of sodium pentobarbital anesthetized gerbils (n = 21). The mean tissue P02 levels (± SEM) were not significantly different between cortex (35.4 ± 1.7 torr) and hippocampus (33.6 ± 1.4 torr) although differences in the tissue P02 distributions were seen. The disappearance rate for oxygen ( -dPo^dt) was measured after brief (< 15 seconds) bilateral carotid artery (total brain blood flow) occlusion. The mean (±SEM) disappearance rate was significantly higher (p<0.05) in the cortex (Z3.8 ± 1.5 torr/sec, 160 locations in 21 gerbils) than In the hippocampus (17.0 ± 0.7 torr/sec, 119 locations in 16 gerbils). The maximum oxygen consumption rates (Vc^max) for Michaelis-Menten kinetics were calculated from the disappearance rates, correcting for gerbil oxyhemoglobin. The mean Vo^max was 8.28 ± 0.51 and 6.13 ± 0.25 ml O 2 /100 g/rain for the cortex and hippocampus, respectively. The apparent Michaelis-Menten kinetic constants (K_) for the 2 regions were not significantly different (overall mean 3.3 ± 0.4 torr The present study was undertaken to quantify oxygen metabolism at highly localized sites by the oxygen disappearance technique, correcting for the influence of oxyhemoglobin. Measurements were made in 2 regions of the gerbil brain, the cortex and the hippocampus, which are of interest due to marked differences in susceptibility to ischemic damage (selective vulnerability), even within a region. The gerbil model of ischemia was chosen because blood flow to the brain can be stopped completely with bilateral carotid artery occlusion since the circle of Willis has no connections to the basilar artery for a source of collateral blood flow. Materials and MethodsMongolian gerbils, aged 3-4 months, weighing 50-90 g, were maintained on standard laboratory food and water ad libitum. They were anesthetized with 30-40 mg/kg i.p. sodium pentobarbital, tracheotomized, and allowed to breathe spontaneously. Both common carotid arteries were exposed through ventral midline cervical incisions and isolated from the accompanying nerves and vein. Surgical sutures were placed around the arteries for causing occlusions. In by guest on May 9, 2018 http://stroke.ahajournals.org/ Downloaded from

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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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Po2 of cat cerebral cortex: Response to breathing N2 and 100% O2

Cited by 59 publications

References 9 publications

Role of Actin-Bundling Protein Sac6 in Growth of Cryptococcus neoformans at Low Oxygen Concentration

Role of Actin-Bundling Protein Sac6 in Growth of Cryptococcus neoformans at Low Oxygen Concentration

Comparisons of oxygen metabolism and tissue PO2 in cortex and hippocampus of gerbil brain.

Effect of Indomethacin on Cerebral Oxidized Cytochrome Oxidase in Preterm Infants

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