scholarly journals Relation between the content of acetyl-coenzyme A and acetylcholine in brain slices

1980 ◽  
Vol 188 (3) ◽  
pp. 683-688 ◽  
Author(s):  
J Rícný ◽  
S Tucek
Keyword(s):  
Incubation Medium ◽  
Brain Slices ◽  
Mass Action ◽  
Direct Relation ◽  
Law Of Mass Action ◽  
Acetyl Coa ◽  
Caudate Nuclei ◽  
High K ◽  
State Concentration

Slices of rat caudate nuclei were incubated in vitro in media containing, among other constituents, three different concentrations of glucose (0.5, 2 and 10 mM), 0.2 mM-choline, paraoxon as an inhibitor of cholinesterase, and 5 mM- or 30 mM-K+. After 30 and 60 min of incubation, the concentrations of acetyl-CoA, acetylcholine and choline in the tissue and of acetylcholine in the incubation medium were measured. The content of acetyl-CoA in the sliced varied in direct relation to the concentration of glucose in the incubation medium. The content of acetylcholine in the slices and, in experiments with high K+, also the amount of acetylcholine released into the incubation medium varied in direct relation to the concentration of glucose in the incubation medium and to the concentration of acetyl-CoA in the slices; the relation between the concentrations of acetyl-CoA and of acetylcholine in the slices was linear. It was concluded that the availability of acetyl-CoA had a decisive influence on both the rate of synthesis of acetylcholine and its steady-state concentration. The observations accord with the view that, at the ultimate level, the synthesis of acetylcholine is controlled by the Law of Mass Action.

scholarly journals Incorporation of isotopic carbon into cerebral glycogen from non-glucose substrates

1975 ◽  
Vol 146 (1) ◽  
pp. 185-189 ◽  
Author(s):  
M E Phillips ◽  
R V Coxon
Keyword(s):  
Guinea Pig ◽  
Incubation Medium ◽  
Specific Radioactivity ◽  
Brain Slices ◽  
Fresh Tissue ◽  
Radioactive Carbon ◽  
Glucose Carbon ◽  
Pig Brain ◽  
Guinea Pig Brain

1. Measurable incorporation of radioactive carbon from [U-14C]pyruvate, [U-14C]-glutamate and [14C]bicarbonate into the glycogen synthesized by brain slices in vitro was demonstrated. 2. The fructose diphosphatase activity of guinea-pig brain was determined and found to be about 0.03 μmol of substrate degraded/min per g of fresh tissue. 3. The specific radioactivity of the glucose carbon from glycogen relative to that of the precursor added to the incubation medium gave approximate values of 0.195 for glucose, 0.006 for pyruvate, 0.039 for glutamate and 0.001 for bicarbonate.

scholarly journals Ischemic Brain Slice Glucose Utilization: Effects of Slice Thickness, Acidosis, and K+

1991 ◽  
Vol 11 (3) ◽  
pp. 398-406 ◽  
Author(s):  
George C. Newman ◽  
Frank E. Hospod ◽  
Scott L. Schissel
Keyword(s):  
Brain Slice ◽  
Glucose Utilization ◽  
Brain Slices ◽  
Slice Thickness ◽  
Energy Demands ◽  
High K ◽  
Metabolic Products ◽  
Glucose Phosphorylation ◽  
Vitro Model

Brain slices of varying thickness were used to modify retention of metabolic products in an in vitro model of ischemia. Past and present results reveal increased anaerobic glycolysis in 660-μm slices with accumulation of lactate as slice thickness reaches 1,000 μm. Brain slice glucose utilization and lactate content were measured in buffers of various extracellular K+ levels and pH in 540-, 660-, and 1,000-μm slices. Acidosis suppresses glucose utilization at all slice thicknesses without affecting tissue lactate. Studies of 2-deoxyglucose metabolites establish that the suppression of glucose utilization by acidosis is due entirely to inhibition of glucose phosphorylation without any effect on glucose uptake into tissue. The inhibition is reversible after 45 min at pH 6.1. The experiments with acidosis also suggest that persistent energy demands continue to stimulate phosphofructokinase despite the low pH so that glycolysis continues, with potential for injury. Increasing K+ increases glucose utilization and tissue lactate at all three thicknesses. Correlations of glucose utilization with lactate accumulation support the possibility that high K+ may exert a dual influence on the tissue metabolism, not only stimulating glucose utilization by inducing depolarization but also by influencing the removal of metabolic products.

scholarly journals Tetrodotoxin-sensitive uptake of ions and water by slices of rat brain in vitro

1970 ◽  
Vol 120 (1) ◽  
pp. 37-47 ◽  
Author(s):  
K. Okamoto ◽  
J. H. Quastel
Keyword(s):  
Potassium Chloride ◽  
Rat Brain ◽  
Glial Cell ◽  
Water Uptake ◽  
Brain Slices ◽  
Caudate Nuclei ◽  
Anomalous Feature ◽  
K Concentration ◽  
Electrical Impulses

1. Under certain conditions the processes that bring about increased Na+ influx and water uptake into rat brain slices have a tetrodotoxin-sensitive component. 2. Incubation of slices in the absence of glucose, or in the presence of ouabain (0.1mm), protoveratrine (10μm) or electrical stimuli, leads to increased uptakes of water and Na+ that are partially suppressed by tetrodotoxin (3μm). 3. The increased water uptake and Na+ influx due to the presence of 30μm-2,4-dinitrophenol or of 100mm-potassium chloride are unaffected by tetrodotoxin. 4. The additional presence of 27mm-potassium chloride diminishes, or abolishes, the inhibitory effects of tetrodotoxin on the increased uptakes of water and Na+ found on incubation in the absence of glucose or in the presence of protoveratrine. 5. Ouabain increases Na+ influx into caudate nuclei from rat brain and this process is suppressed by tetrodotoxin. Ouabain does not increase water uptake in the caudate nuclei. 6. Diminution of Na+ influx in slices due to tetrodotoxin is not accompanied by an equal efflux of K+. 7. It is concluded that glial-cell membranes are permeable to K+ and Cl− and, as a consequence, when K+ is released from neurons in association with action potentials it, together with water, moves into the glial cells. The major consequence of K+ (and Cl−) permeability of the glial cell is therefore a buffering of the extracellular K+ concentration. 8. l-Glutamate presents an anomalous feature that may indicate that its effects are not restricted to neurons. 9. Calculations are made of the increase of K+ flux into the glia in the presence of ouabain or of protoveratrine or in the absence of glucose or on application of electrical impulses.

scholarly journals Control of synthesis and release of radioactive acetylcholine in brain slices from the rat. Effects of neurotropic drugs

1973 ◽  
Vol 132 (1) ◽  
pp. 1-14 ◽  
Author(s):  
D. S. Grewaal ◽  
J. H. Quastel
Keyword(s):  
Incubation Medium ◽  
Acetylcholine Release ◽  
Brain Slices ◽  
High Concentration ◽  
Choline Transport ◽  
Acetylcholine Synthesis ◽  
High K ◽  
Blocking Effects ◽  
Release Of Acetylcholine ◽  
Cortex Slices

1. Studies of the synthesis and release of radioactive acetylcholine in rat brain-cortex slices incubated in Locke–bicarbonate–[U-14C]glucose media, containing paraoxon as cholinesterase inhibitor, revealed the following phenomena: (a) dependence of K+-or protoveratrine-stimulated acetylcholine synthesis and release on the presence of Na+ and Ca2+ in the incubation medium, (b) enhanced release of radioactive acetylcholine by substances that promote depolarization at the nerve cell membrane (e.g. high K+, ouabain, protoveratrine, sodium l-glutamate, high concentration of acetylcholine), (c) failure of acetylcholine synthesis to keep pace with acetylcholine release under certain conditions (e.g. the presence of ouabain or lack of Na+). 2. Stimulation by K+ of radioactive acetylcholine synthesis was directly proportional to the external concentration of Na+, but some synthesis and release of radioactive acetylcholine occurred in the absence of Na+ as well as in the absence of Ca2+. 3. The Na+ dependence of K+-stimulated acetylcholine synthesis was partly due to suppression of choline transport, as addition of small concentrations of choline partly neutralized the effect of Na+ lack, and partly due to the suppression of the activity of the Na+ pump. 4. Protoveratrine caused a greatly increased release of radioactive acetylcholine without stimulating total radioactive acetylcholine synthesis. Protoveratrine was ineffective in the absence of Ca2+ from the incubation medium. It completely blocked K+ stimulation of acetylcholine synthesis and release. 5. Tetrodotoxin abolished the effects of protoveratrine on acetylcholine release. It had blocking effects (partial or complete) on the action of high K+, sodium l-glutamate and lack of Ca2+ on acetylcholine synthesis and release. 6. Unlabelled exogenous acetylcholine did not diminish the content of labelled tissue acetylcholine, derived from labelled glucose, suggesting that no exchange with vesicular acetylcholine took place. In the presence of 4mm-KCl it caused some increase in the release of labelled acetylcholine. 7. The barbiturates (Amytal, pentothal), whilst having no significant effects on labelled acetylcholine synthesis in unstimulated brain except at high concentration (1mm), diminished or abolished (at 0.25 or 0.5mm) the enhanced release of acetylcholine, due to high K+ or lack of Ca2+. The fall in tissue content of acetylcholine, due to lack of Ca2+, was diminished or abolished by pentothal (0.25 or 0.5mm) or Amytal (0.25mm).

ALDOSTERONE STIMULATION IN VITRO

1965 ◽  
Vol 50 (2) ◽  
pp. 301-309 ◽  
Author(s):  
Jürg Müller
Keyword(s):  
Ammonium Chloride ◽  
Human Urine ◽  
Incubation Medium ◽  
The Other ◽  
Ammonium Ions ◽  
Response Curves ◽  
Urine Extract ◽  
Similar Dose ◽  
Aldosterone Production

ABSTRACT An extract of human urine, which was previously shown to stimulate aldosterone production by rat adrenal sections, was further purified. Evidence was obtained that its aldosterone-stimulating effect was due to the presence of ammonium ions. Addition of ammonium chloride and of urine extract to the incubation medium caused identical increases in aldosterone production in vitro. In addition to ammonium ions, rubidium and caesium ions also stimulated aldosterone production up to 250% that of control values without a significant effect on corticosterone production. Similar dose-response curves were obtained when increasing concentrations of potassium, ammonium, rubidium and caesium ions were tested. Aldosterone production was maximal at concentrations of 7 mval/1 and was significantly lower at higher concentrations. When ammonium chloride and ACTH were simultaneously added to the incubation medium, the production of aldosterone and of corticosterone was lower than with ACTH alone. On the other hand, the stimulating activity on aldosterone and corticosterone production by »TPN« (NADP) and glucose-6-phosphate was enhanced by the simultaneous addition of ammonium chloride.

IN VITRO UPTAKE OF TRITIATED OESTRADIOL BY THE ANTERIOR HYPOTHALAMUS AND HYPOPHYSIS OF THE RAT

1970 ◽  
Vol 64 (4) ◽  
pp. 687-695 ◽  
Author(s):  
Junzo Kato
Keyword(s):  
Incubation Medium ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Ovariectomized Rats ◽  
Free Medium ◽  
Cortex Cerebri ◽  
Anterior Hypophysis ◽  
In Vitro Uptake

ABSTRACT The anterior, middle, and posterior hypothalamus, the cortex cerebri, the anterior hypophysis as well as the diaphragm of adult ovariectomized rats were incubated in vitro with tritiated 17β-oestradiol. The uptake of tritiated oestradiol was differentially distributed intracerebrally with higher accumulation in the anterior hypothalamus and the hypophysis. Lowering the temperature of the incubation medium caused a reduction in the uptake of radioactivity by the anterior hypothalamus as compared to that found in other brain tissues. Tritiated oestradiol taken up in vitro by the anterior hypothalamus and the hypophysis tended to be retained after further incubation in a steroid-free medium. The addition of non-radioactive 17β-oestradiol to the medium inhibited the uptake of tritiated oestradiol by these tissues. Moreover, pretreatment with non-radioactive 17β-oestradiol in vivo prevented the preferential accumulation of tritiated oestradiol in vitro in the anterior hypothalamus and the hypophysis. These results indicate that oestradiol is preferentially taken up in vitro by the anterior hypothalamus and the hypophysis of the rat.

ÉTUDE DE L'ACTIVITÉ BIOLOGIQUE IN VITRO DES HORMONES GONADOTROPES

1960 ◽  
Vol XXXIII (III) ◽  
pp. 444-450 ◽  
Author(s):  
Maria de la Luz Suarez Soto ◽  
Jean Legault Démare
Keyword(s):  
Paper Chromatography ◽  
Incubation Medium ◽  
Ultraviolet Absorption ◽  
Rat Ovary

ABSTRACT Serum gonadotrophin (PMS) when added to the incubation medium of rat ovary slices increases the amount of Δ4-3-ketosteroids produced. This enhancement is proportional to the logarithm of dose. The ketosteroids were determined by their ultraviolet absorption; paper chromatography has shown that only androst-4-en-3,17-dione is present.

scholarly journals A New Transgenic Mouse Line for Imaging Mitochondrial Calcium Signals

Function ◽  
2021 ◽  
Vol 2 (3) ◽  
Author(s):  
Nelly Redolfi ◽  
Elisa Greotti ◽  
Giulia Zanetti ◽  
Tino Hochepied ◽  
Cristina Fasolato ◽  
...  
Keyword(s):  
Transgenic Mouse ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Brain Slices ◽  
Resonance Energy ◽  
Mouse Line ◽  
Isolated Cells ◽  
Genomic Locus ◽  
Transgenic Mouse Line

AbstractMitochondria play a key role in cellular calcium (Ca2+) homeostasis. Dysfunction in the organelle Ca2+ handling appears to be involved in several pathological conditions, ranging from neurodegenerative diseases, cardiac failure and malignant transformation. In the past years, several targeted green fluorescent protein (GFP)-based genetically encoded Ca2+ indicators (GECIs) have been developed to study Ca2+ dynamics inside mitochondria of living cells. Surprisingly, while there is a number of transgenic mice expressing different types of cytosolic GECIs, few examples are available expressing mitochondria-localized GECIs, and none of them exhibits adequate spatial resolution. Here we report the generation and characterization of a transgenic mouse line (hereafter called mt-Cam) for the controlled expression of a mitochondria-targeted, Förster resonance energy transfer (FRET)-based Cameleon, 4mtD3cpv. To achieve this goal, we engineered the mouse ROSA26 genomic locus by inserting the optimized sequence of 4mtD3cpv, preceded by a loxP-STOP-loxP sequence. The probe can be readily expressed in a tissue-specific manner upon Cre recombinase-mediated excision, obtainable with a single cross. Upon ubiquitous Cre expression, the Cameleon is specifically localized in the mitochondrial matrix of cells in all the organs and tissues analyzed, from embryos to aged animals. Ca2+ imaging experiments performed in vitro and ex vivo in brain slices confirmed the functionality of the probe in isolated cells and live tissues. This new transgenic mouse line allows the study of mitochondrial Ca2+ dynamics in different tissues with no invasive intervention (such as viral infection or electroporation), potentially allowing simple calibration of the fluorescent signals in terms of mitochondrial Ca2+ concentration ([Ca2+]).

scholarly journals Genetic recombination as a generalised gradient flow

2021 ◽  
Author(s):  
Frederic Alberti
Keyword(s):  
Arbitrary Number ◽  
Genetic Recombination ◽  
Reaction Network ◽  
Gradient Flow ◽  
Mass Action ◽  
Gradient System ◽  
Gradient Structure ◽  
Law Of Mass Action ◽  
Reversible Chemical Reaction ◽  
Time Partitioning

AbstractIt is well known that the classical recombination equation for two parent individuals is equivalent to the law of mass action of a strongly reversible chemical reaction network, and can thus be reformulated as a generalised gradient system. Here, this is generalised to the case of an arbitrary number of parents. Furthermore, the gradient structure of the backward-time partitioning process is investigated.

Regulation of cytosolic free Ca2+ concentration in acinar cells of rat pancreas

1983 ◽  
Vol 245 (3) ◽  
pp. G347-G357 ◽  
Author(s):  
H. Streb ◽  
I. Schulz
Keyword(s):  
Steady State ◽  
Incubation Medium ◽  
Minimal Medium ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Atpase Inhibitor ◽  
Rat Pancreas ◽  
Mitochondrial Inhibitors ◽  
Pancreatic Cells ◽  
State Concentration

Ca2+ uptake into isolated exocrine pancreatic cells with highly permeable plasma membrane was determined by measuring the decrease in free Ca2+ concentration of the surrounding incubation medium with a Ca2+-specific electrode. In the presence of Mg-ATP and respiratory substrates the free Ca2+ concentration of the incubation medium decreased rapidly after addition of leaky cells until a stable medium free Ca2+ concentration of 4.2 +/- 0.1 X 10(-7) mol/l was obtained. Changes in the medium free Ca2+ concentration at steady state by addition of Ca2+ or EGTA were buffered by cellular uptake or release, respectively, until the steady-state free Ca2+ concentration was reestablished. When nonmitochondrial Ca2+ uptake was determined in the presence of a combination of mitochondrial inhibitors (10(-5) mol/l antimycin, 5 X 10(-6) mol/l oligomycin, and 10(-2) mol/l azide), the rate of uptake was considerably reduced, while the steady-state concentration was unaltered. In contrast, mitochondrial uptake that could be observed in the presence of the ATPase inhibitor vanadate (2 X 10(-3) mol/l) proceeded at the same rate as the control, but the minimal medium free Ca2+ concentration reached was 2.4 +/- 0.1 X 10(-7) mol/l higher than the control. Addition of secretagogues at steady-state free Ca2+ concentration resulted in a Ca2+ release of 0.73 +/- 0.08 nmol/mg protein. The increase in medium free Ca2+ concentration was entirely transient and followed by reuptake to the prestimulation level. The data indicate that a cytosolic free Ca2+ concentration of 4 X 10(-7) mol/l can be regulated in pancreatic acinar cells by a nonmitochondrial Mg2+-dependent Ca2+ pool.

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