scholarly journals LIMITATIONS OF THE PYROANTIMONATE TECHNIQUE FOR LOCALIZATION OF SODIUM IN ISOLATED CEREBRAL TISSUES

1971 ◽  
Vol 19 (10) ◽  
pp. 605-610 ◽  
Author(s):  
S. M. SUMI ◽  
P. D. SWANSON
Keyword(s):  
Cerebral Cortex ◽  
Electron Microscope ◽  
Guinea Pig ◽  
Extracellular Space ◽  
Brain Slices ◽  
Intracellular Space ◽  
Thin Slices ◽  
Glutaraldehyde Solution ◽  
Potassium Pyroantimonate

Thin slices of guinea pig cerebral cortex incubated for 30-60 min with or without ouabain were analyzed for Na+, K+ and inulin contents. Other brain slices treated in a similar manner were fixed in potassium pyroantimonate-containing buffered glutaraldehyde solution and examined in the electron microscope. Slices incubated in the presence of ouabain contained considerably more Na+ in the non-inulin, presumably intracellular, space. However, precipitates of pyroantimonate which have been accepted by some to indicate the site of Na+ localization were almost entirely restricted to the extracellular space in both the control and experimental slices and appeared to reflect the method of fixation by immersion and not the movement of Na+. It is our conclusion that the lack of correlation between the chemical localization of Na+ and the pyroantimonate technique is due to the limitation of the latter method.

Comparison of changes evoked by GABA (γ-aminobutyric acid) and anoxia in [K+]o, [Cl-]o, and [Na+]o in stratum pyramidale and stratum radiatum of the guinea pig hippocampus

2000 ◽  
Vol 78 (5) ◽  
pp. 378-391 ◽  
Author(s):  
G V Obrocea ◽  
M E Morris
Keyword(s):  
Guinea Pig ◽  
Extracellular Space ◽  
Hippocampal Slices ◽  
Brain Slices ◽  
Receptor Activation ◽  
Ion Concentration ◽  
Aminobutyric Acid ◽  
Stratum Radiatum ◽  
Bicuculline Methiodide ◽  
Stratum Pyramidale

Ion-selective microelectrode recordings were made to assess a possible contribution of extracellular γ-aminobutyric acid (GABA) accumulation to early responses evoked in the brain by anoxia and ischemia. Changes evoked by GABA or N2 in [K+]o, [Cl-]o, [Na+]o, and [TMA+]o were recorded in the cell body and dendritic regions of the stratum pyramidale (SP) and stratum radiatum (SR), respectively, of pyramidal neurons in CA1 of guinea pig hippocampal slices. Bath application of GABA (1-10 mM) for approximately 5 min evoked changes in [K+]o and [Cl-]o with respective EC50 levels of 3.8 and 4.1 mM in SP, and 4.7 and 5.6 mM in SR. In SP 5 mM GABA reversibly increased [K+]o and [Cl-]o and decreased [Na+]o; replacement of 95% O2 -5% CO2 by 95% N2 -5% CO2 for a similar period of time evoked changes which were for each ion in the same direction as those with GABA. In SR both GABA and N2 caused increases in [K+]o and decreases in [Cl-]o and [Na+]o. The reduction of extracellular space, estimated from levels of [TMA+]o during exposures to GABA and N2, was 5-6% and insufficient to cause the observed changes in ion concentration. Ion changes induced by GABA and N2 were reversibly attenuated by the GABAA receptor antagonist bicuculline methiodide (BMI, 100 µM). GABA-evoked changes in [K+]o in SP and SR and [Cl-]o in SP were depressed by >=90%, and of [Cl-]o in SR by 50%; N2-evoked changes in [K+]o in SP and SR were decreased by 70% and those of [Cl-]o by 50%. BMI blocked Δ [Na+]o with both GABA and N2 by 20-30%. It is concluded that during early anoxia: (i) accumulation of GABA and activation of GABAA receptors may contribute to the ion changes and play a significant role, and (ii) responses in the dendritic (SR) regions are greater than and (or) differ from those in the somal (SP) layers. A large component of the [K+]o increase may involve a GABA-evoked Ca2+-activated gk, secondary to [Ca2+]i increase. A major part of [Cl-]o changes may arise from GABA-induced gCl and glial efflux, with strong stimulation of active outward transport and anion exchange at SP, and inward Na+/K+/2Cl- co-transport at SR. Na+ influx is attributable mainly to Na+-dependent transmitter uptake, with only a small amount related to GABAA receptor activation. Although the release and (or) accumulation of GABA during anoxia might be viewed as potentially protectant, the ultimate role may more likely be an important contribution to toxicity and delayed neuronal death. Key words: brain slices, ion-selective microelectrodes, stratum pyramidale, stratum radiatum, bicuculline methiodide, extracellular space shrinkage.

Variation of cerebral cortex fluid spaces in vivo as a function of species brain size

1965 ◽  
Vol 208 (4) ◽  
pp. 682-692 ◽  
Author(s):  
Robert S. Bourke ◽  
Edward S. Greenberg ◽  
Donald B. Tower
Keyword(s):  
Cerebral Cortex ◽  
Electron Microscope ◽  
Guinea Pig ◽  
Brain Size ◽  
Circulatory Arrest ◽  
Mammalian Species ◽  
Solute Distribution ◽  
Cellular Distribution ◽  
Experimental Conditions

Sizes of cerebral cortex fluid spaces accessible to chloride, thiocyanate-C14, sucrose-C14, and inulin-C14 were investigated in nine mammalian species. Indicator solutes were injected intracisternally, and after suitable intervals subarachnoid CSF and subadjacent cerebral cortex were sampled. Factors of site, time, and reproducibility of sampling were studied in detail. Despite influences of nonhomogeneous distribution in CSF of injected solutes and other factors on space measurements, appropriate attention to experimental conditions provided consistent, reproducible results. For a given species, there was identity of cortical chloride and thiocyanate spaces and identity of sucrose and inulin spaces, with the latter slightly but significantly smaller than the former. From smaller to larger species, all spaces exhibited parallel, significant increases (e.g., average sucrose-inulin spaces for guinea pig: 20.8%; cat: 27.4%; chimpanzee: 39.4%), varying as a function of the logarithm of the average, species brain weight. Findings are discussed relevant to CSF solute distribution and efflux and to electron microscope observations, glial and extra-cellular distribution of solutes, and abnormal conditions such as edema following circulatory arrest.

scholarly journals A study on the precursors of the acetyl moiety of acetylcholine in brain slices. Observations on the compartmentalization of the acetyl-coenzyme A pool

1970 ◽  
Vol 118 (3) ◽  
pp. 443-450 ◽  
Author(s):  
R. Nakamura ◽  
S.-C. Cheng ◽  
H. Naruse
Keyword(s):  
Cerebral Cortex ◽  
Guinea Pig ◽  
Specific Radioactivity ◽  
Brain Slices ◽  
Rat Cerebral Cortex ◽  
Rat Striatum ◽  
Metabolic Compartmentation ◽  
Cortex Slices ◽  
Guinea Pig Brain

1. A method was devised for the determination of the specific radioactivity of the acetyl moiety of acetylcholine synthesized from various 14C-labelled substrates. 2. The precursor for the acetyl moiety of acetylcholine was studied in slices of striatum and cerebral cortex from rat and guinea-pig brain. Incorporation of radioactivity into acetylcholine was determined after incubating the slices in the presence of [2-14C]acetate, [14C]bicarbonate, [1,5-14C]citrate, dl-[1- or 5-14C]glutamate or [1- or 2-14C]pyruvate. 3. After incubation for 1h, acetylcholine was accumulated significantly in both striatum slices (4.1nmol/mg of protein) and cerebral-cortex slices (0.57nmol/mg of protein) from the rat. Final concentrations were about 11 and 5 times respectively the initial values. 4. With slices from rat striatum, rat cerebral cortex and guinea-pig cerebral cortex, the specific radioactivity of acetylcholine derived from [2-14C]pyruvate was very high, reaching approx. 30, 20 and 6% respectively of the initial specific radioactivity of added pyruvate in the medium. With the striatum slices this high value was reached after incubation for 15min. Incorporation of radioactivity from [2-14C]acetate was only 1.25, 5.3 and 19.7% of that from [2-14C]pyruvate in rat striatum, rat cerebral-cortex and guinea-pig cerebral-cortex slices respectively. A small but definite incorporation was found from [5-14C]glutamate. No incorporation was found from the other substrates. The findings suggest that pyruvate is the most important precursor for the synthesis of the acetyl moiety of acetylcholine in brain slices. 5. The specific radioactivity of acetylcholine relative to that of citrate when [2-14C]pyruvate was used compared with that obtained when [2-14C]acetate was used. A marked difference was found in all slices, suggesting metabolic compartmentation of the acetyl-CoA pool.

Ultrastructure of the lesion induced by toxin T-514 isolated from K. humboldtiana in the alveolar region of the lung

1992 ◽  
Vol 50 (1) ◽  
pp. 640-641
Author(s):  
Julio Sepúlveda-Saavedra ◽  
Beatriz González-Corona ◽  
Víctor A. Tamez Rodríguez ◽  
Ma. Victoria Bermúdez de Rocha ◽  
Alfredo Piñeyro López
Keyword(s):  
Electron Microscope ◽  
Guinea Pig ◽  
Macaca Fascicularis ◽  
Osmium Tetroxide ◽  
Lead Citrate ◽  
Severe Damage ◽  
Thin Sections ◽  
Alveolar Region ◽  
Histopathological Findings

It has been shown in previous studies that the toxin T-514 isolated from K. humboldtiana induces severe damage to the lung in treated rodents. Histopathological findings include edema, and alveolar hemorrage. However, the ultraestructure of the lesion has not been investigated. In this study we used two species of rodents: Hamster and guinea pig, and a primate: Macaca fascicularis. Animals received different single dosis of the toxin via intraperitoneal. Control animals received only the vehicle (propylen glycol). Inmediately after spontaneous death, lung samples were fixed in Karnovsky-Ito fixative, post fixed in osmium tetroxide and embedded in epon. Thin sections were prepared with an Ultratome V LKB, stained with uranly acetate and lead citrate, and studied in an electron microscope Zeiss-EM109.

scholarly journals Turnover of protein-bound serine phosphate in respiring slices of guinea-pig cerebral cortex. Effects of putative transmitters, tetrodotoxin and other agents

1973 ◽  
Vol 132 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Martin Reddington ◽  
Richard Rodnight ◽  
Michael Williams
Keyword(s):  
Cerebral Cortex ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Electrical Pulses ◽  
Phosphorus Turnover ◽  
Serine Phosphate ◽  
Stimulation Of

1. The effect of various agents on the turnover of protein-bound phosphorus in respiring slices of cerebral cortex was studied. 2. Confirming previous work turnover was increased by the application of electrical pulses for 10s to the tissue. 3. Turnover was also increased by exposure of the slices for 10min to noradrenaline (0.5mm), 5-hydroxytryptamine (1μm) and histamine (0.1mm). 4. When slices were stimulated by electrical pulses in the presence of histamine the increase in turnover was the sum of the responses given by each agent above, suggesting that different phosphorylating systems were involved. 5. Tetrodotoxin (0.5μm) blocked the increased turnover due to electrical pulses, but not that due to histamine. Tetrodotoxin also prevented the increase in tissue cyclic AMP content caused by the application of electrical pulses. 6. Phosphoprotein turnover was not affected by adenosine, despite the increase in tissue cyclic AMP content given by this agent. 7. Adenosine blocked the phosphoprotein response to histamine, but did not affect the response to electrical pulses. 8. The results are discussed in relation to the hypothesis that the stimulation of protein phosphorus turnover by electrical pulses is secondary to the release of cyclic AMP in the tissue.

scholarly journals THE FINE STRUCTURE OF ASTROCYTES IN THE CEREBRAL CORTEX AND THEIR RESPONSE TO FOCAL INJURY PRODUCED BY HEAVY IONIZING PARTICLES

1965 ◽  
Vol 25 (2) ◽  
pp. 141-157 ◽  
Author(s):  
David S. Maxwell ◽  
Lawrence Kruger
Keyword(s):  
Cerebral Cortex ◽  
Fine Structure ◽  
Electron Microscope ◽  
Reactive Astrocytes ◽  
Lipid Bodies ◽  
Particle Irradiation ◽  
Fibrous Astrocytes ◽  
Primitive Forms ◽  
Focal Injury ◽  
Glycogen Particles

Normal and reactive astrocytes in the cerebral cortex of the rat have been studied with the electron microscope following focal alpha particle irradiation. The presence of glycogen and approximately 60-A fibrils identify astrocyte cytoplasm in formalin-perfused tissue. The glycogen particles facilitate the identification of small processes and subpial and perivascular end-feet. Both protoplasmic and fibrous astrocytes contain cytoplasmic fibrils and should be distinguished on the basis of the configuration of their processes and their distribution. Acutely reactive astrocytes are characterized by a marked increase in the number of glycogen granules and mitochondria from the first day after irradiation. These cells later hypertrophy and accumulate lipid bodies and increased numbers of cytoplasmic fibrils. The glial "scar" consists of a greatly expanded volume of astrocyte cytoplasm filled with fibrils and displays no signs of astrocyte death, reversion to primitive forms, or extensive multiplication.

Effect of (-)nicotine on GABA efflux from guinea pig cerebral cortex slices

1989 ◽  
Vol 21 ◽  
pp. 133-134 ◽  
Author(s):  
P. Spalluto ◽  
M. Morari ◽  
L. Ferraro ◽  
A. Nordberg ◽  
T. Antonelli ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Guinea Pig ◽  
Cortex Slices
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