scholarly journals The rate of the AMP/adenosine substrate cycle in concanavalin-A-stimulated rat lymphocytes

1989 ◽  
Vol 261 (3) ◽  
pp. 739-742 ◽  
Author(s):  
Z Szondy ◽  
E A Newsholme
Keyword(s):  
Concanavalin A ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Fold Increase ◽  
Amp Deaminase ◽  
High Concentration ◽  
Trapping Effect ◽  
Atp Concentration ◽  
Rat Lymphocytes ◽  
Stimulation Of

The effect of adenosine on the metabolism of prelabelled adenine nucleotides was investigated in concanavalin-A-stimulated rat lymphocytes. Adenosine in the presence of the adenosine deaminase inhibitor, deoxycoformycin, caused a 2-fold increase in the ATP concentration. This effect was, in part, countereacted by an increased rate of adenine nucleotide catabolism, which could be explained by a stimulation of AMP deaminase (EC 3.5.4.6). At the same time a continuous rate of labelled adenosine production was found, which was not affected by the increased ATP concentration and which could only be detected by the trapping effect of a high concentration of added unlabelled adenosine. It is concluded that the rate of the substrate cycle between AMP and adenosine is low (1.9 +/- 0.2 nmol/h per 10(7) cells) in comparison to the rate of AMP deamination.

scholarly journals L-Arginine Intake Effect on Adenine Nucleotide Metabolism in Rat Parenchymal and Reproductive Tissues

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
G. Kocic ◽  
J. Nikolic ◽  
T. Jevtovic-Stoimenov ◽  
D. Sokolovic ◽  
H. Kocic ◽  
...  
Keyword(s):  
Adenosine Deaminase ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Tissue Growth ◽  
Nucleotide Metabolism ◽  
Amp Deaminase ◽  
Male Impotence ◽  
Adenine Nucleotide Metabolism ◽  
Adenosine Concentration ◽  
Male Wistar Rats

L-arginine is conditionally essetcial amino acid, required for normal cell growth, protein synthesis, ammonia detoxification, tissue growth and general performance, proposed in the treatment of men sterility and prevention of male impotence. The aim of the present paper was to estimate the activity of the enzymes of adenine nucleotide metabolism:5′-nucleotidase (5′-NU), adenosine deaminase (ADA), AMP deaminase, and xanthine oxidase (XO), during dietary intake of L-arginine for a period of four weeks of male Wistar rats. Adenosine concentration in tissues is maintained by the relative activities of the adenosine-producing enzyme,5′-NU and the adenosine-degrading enzyme-ADA adenosine deaminase. Dietary L-arginine intake directed adenine nucleotide metabolism in liver, kidney, and testis tissue toward the activation of adenosine production, by increased5′-NU activity and decreased ADA activity. Stimulation of adenosine accumulation could be of importance in mediating arginine antiatherosclerotic, vasoactive, immunomodulatory, and antioxidant effects. Assuming that the XO activity reflects the rate of purine catabolism in the cell, while the activity of AMP deaminase is of importance in ATP regeneration, reduced activity of XO, together with the increased AMP-deaminase activity, may suggest that adenine nucleotides are presumably directed to the ATP regenerating process during dietary L-arginine intake.

Regulation of hepatic gluconeogenesis in newborn rabbit: controlling factors in presuckling period

1985 ◽  
Vol 249 (5) ◽  
pp. E498-E505 ◽  
Author(s):  
W. A. Brennan ◽  
J. R. Aprille
Keyword(s):  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Mitochondrial Protein ◽  
Fold Increase ◽  
Insulin Injection ◽  
Pyruvate Carboxylation ◽  
Glucose Levels ◽  
Newborn Rabbit ◽  
Nucleotide Content

We have previously shown (Comp. Biochem. Physiol. 77B: 35-39, 1984) that a rapid postnatal increase in hepatic mitochondrial adenine nucleotide content activates pyruvate carboxylation and gluconeogenesis in the newborn rabbit. This study investigated factors limiting flux through the gluconeogenic pathway and examined the physiological stimuli responsible for the activation phenomenon. There is a 2.3-fold increase in total mitochondrial adenine nucleotides, along with a threefold increase in the matrix ATP/ADP ratio, by 2 h after birth, resulting overall in a sixfold increase in the amount of ATP/mg mitochondrial protein. Analysis of gluconeogenic intermediates, measured in freeze-clamped livers between birth and 4 h postnatal, suggests that pyruvate carboxylase controls gluconeogenic flux during this period. Newborn rabbits reared in an hypoxic environment (5% O2) exhibited decreased mitochondrial adenine nucleotide content, decreased rates of pyruvate carboxylation, and depressed blood glucose levels compared with littermates reared in room air or 95% O2. Manipulation of the insulin-to-glucagon ratio in vivo by injecting insulin at birth significantly delayed postnatal increases in the mitochondrial adenine nucleotide content and the rate of pyruvate carboxylation. Conversely, glucagon injection produced a supranormal increase in both mitochondrial adenine nucleotide content and pyruvate carboxylation. In addition, insulin injection prevented, whereas glucagon enhanced, the normal postnatal increase in tissue ATP/ADP. These results suggest that tissue oxygenation and a decreased insulin-to-glucagon ratio promote the rapid influx of adenine nucleotides from the liver cytosol into the mitochondrial matrix, thereby activating pyruvate carboxylation and gluconeogenesis during the presuckling period.

scholarly journals Glutamine metabolism in lymphocytes of the rat

1983 ◽  
Vol 212 (3) ◽  
pp. 835-842 ◽  
Author(s):  
M S M Ardawi ◽  
E A Newsholme
Keyword(s):  
Amino Acids ◽  
Concanavalin A ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Thymidine Incorporation ◽  
Adenine Nucleotides ◽  
Glutamine Metabolism ◽  
Mesenteric Lymph Nodes ◽  
Mesenteric Lymph ◽  
End Products ◽  
Stimulation Of

The metabolism of glutamine in resting and concanavalin-A-stimulated lymphocytes was investigated. In incubated lymphocytes isolated from rat mesenteric lymph nodes, the rates of oxygen and glutamine utilization and that of aspartate production were approximately linear with respect to time for 60 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 90 min. The major end products of glutamine metabolism were glutamate, aspartate and ammonia: the carbon from glutamine may contribute about 30% to respiration. When both glucose and glutamine were presented to the cells, the rates of utilization of both substances increased. Evidence was obtained that the stimulation of glycolysis by glutamine could be due, in part, to an activation of 6-phosphofructokinase. Starvation of the donor animal increased the rate of glutamine utilization. The phosphoenolpyruvate carboxykinase inhibitor mercaptopicolinate decreased the rate of glutamine utilization by 28%; the rates of accumulation of glutamate and ammonia were decreased, whereas those of lactate, aspartate and malate were increased. The mitogen concanavalin A increased the rate of glutamine utilization (by about 51%). The rate of [3H]thymidine incorporation into DNA caused by concanavalin A in cultured lymphocytes was very low in the absence of glutamine; it was increased about 4-fold at 1 microM-glutamine and was maximal at 0.3 mM-glutamine; neither other amino acids nor ammonia could replace glutamine.

Thrombin-Stimulated Myosin Phosphorylation in Intact Platelets and its Possible Involvement Secretion

1977 ◽  
Vol 38 (04) ◽  
pp. 0984-0989 ◽  
Author(s):  
James L. Daniel ◽  
Holm Holmsen ◽  
Robert S. Adelstein
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Adenine Nucleotide ◽  
Fold Increase ◽  
Acid Hydrolase ◽  
Myosin Phosphorylation ◽  
Stimulation Of ◽  
Platelet Secretion

SummaryA 20,000 dalton polypeptide, which is phosphorylated in intact platelets pre-incubated with 32P-P04, has been identified as a platelet myosin light chain. Stimulation of intact platelets with thrombin produced a 5-fold increase in the amount of radioactive phosphate incorporated into the light chain. Myosin phosphorylation preceeded acid hydrolase secretion and occurred concomitantly with adenine nucleotide secretion. These results are suggestive of participation of contractile mechanisms in platelet secretion.

scholarly journals Mammalian adaptation to extrauterine environment: mitochondrial functional impairment caused by prematurity

1994 ◽  
Vol 303 (3) ◽  
pp. 855-862 ◽  
Author(s):  
C Valcarce ◽  
J M Izquierdo ◽  
M Chamorro ◽  
J M Cuezva
Keyword(s):  
Oxidative Phosphorylation ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Coupling Efficiency ◽  
Fold Increase ◽  
Liver Mitochondria ◽  
Postnatal Period ◽  
Preterm Neonates ◽  
Inner Mitochondrial Membrane ◽  
Adenine Nucleotide Pool

In this paper we report that, compared with term rat neonates, both mitochondrial content and function are diminished in liver of preterm neonates (delivered 24 h before full term) compromising cellular energy provision in the postnatal period. In addition, there is a parallel reduction in the content of mRNAs encoding mitochondrial proteins in preterm rats. Also, efficient oxidative phosphorylation is not attained in these pups until 3 h after birth. Although isolated liver mitochondria from preterm neonates show a two-fold increase in F1-ATPase beta-subunit and cytochrome c oxidase activity 1 h after birth, the abnormal coupling efficiency between respiration and oxidative phosphorylation (ADP/O ratio) is due to maintenance of high H(+)-leakage values in the inner mitochondrial membrane. Postnatal reduction of the H+ leak occurs concomitantly with an increase in intra-mitochondrial adenine nucleotide concentration. Accumulation of adenine nucleotides in preterm and term liver mitochondria parallels the postnatal increase in total liver adenine nucleotides. Delayed postnatal induction of adenine biosynthesis most likely accounts for the lower adenine nucleotide pool in the liver of preterm neonates. The delayed postnatal accumulation of adenine nucleotides in mitochondria is thus responsible for the impairment in oxidative phosphorylation displayed by organelles of the preterm liver.

scholarly journals Purine catabolism in isolated rat hepatocytes. Influence of coformycin

1980 ◽  
Vol 188 (3) ◽  
pp. 913-920 ◽  
Author(s):  
Georges Van Den Berghe ◽  
Françoise Bontemps ◽  
Henri-Géry Hers
Keyword(s):  
High Speed ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
Amp Deaminase ◽  
Purine Nucleotides ◽  
Isolated Rat Hepatocytes ◽  
Adenine Nucleotide Pool ◽  
Isolated Rat

1. The catabolism of purine nucleotides was investigated by both chemical and radiochemical methods in isolated rat hepatocytes, previously incubated with [14C]adenine. The production of allantoin reached 32±5nmol/min per g of cells (mean±s.e.m.) and as much as 30% of the radioactivity incorporated in the adenine nucleotides was lost after 1h. This rate of degradation is severalfold in excess over values previously reported to occur in the liver in vivo. An explanation for this enhancement of catabolism may be the decrease in the concentration of GTP. 2. In a high-speed supernatant of rat liver, adenosine deaminase was maximally inhibited by 0.1μm-coformycin. The activity of AMP deaminase, measured in the presence of its stimulator ATP in the same preparation, as well as the activity of the partially purified enzyme, measured after addition of its physiological inhibitors GTP and Pi, required 50μm-coformycin for maximal inhibition. 3. The production of allantoin by isolated hepatocytes was not influenced by the addition of 0.1μm-coformycin, but was decreased by concentrations of coformycin that were inhibitory for AMP deaminase. With 50μm-coformycin the production of allantoin was decreased by 85% and the formation of radioactive allantoin from [14C]adenine nucleotides was completely suppressed. 4. In the presence of 0.1μm-coformycin or in its absence, the addition of fructose (1mg/ml) to the incubation medium caused a rapid degradation of ATP, without equivalent increase in ADP and AMP, followed by transient increases in IMP and in the rate of production of allantoin; adenosine was not detectable. In the presence of 50μm-coformycin, the fructose-induced breakdown of ATP was not modified, but the depletion of the adenine nucleotide pool proceeded much more slowly and the rate of production of allantoin increased only slightly. No rise in IMP concentration could be detected, but AMP increased manyfold and reached values at which a participation of soluble 5′-nucleotidase in the catabolism of adenine nucleotides is most likely. 5. These results are in agreement with the hypothesis that the formation of allantoin is controlled by AMP deaminase. They constitute further evidence that 5′-nucleotidase is inactive on AMP, unless the concentration of this nucleotide rises to unphysiological values.

Fructose-induced adenine nucleotide catabolism in isolated rat hepatocytes

1977 ◽  
Vol 55 (12) ◽  
pp. 1237-1240 ◽  
Author(s):  
Camilla M. Smith ◽  
Liisa M. Rovamo ◽  
Kari O. Raivio
Keyword(s):  
Adenosine Deaminase ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
Amp Deaminase ◽  
Isolated Rat Hepatocytes ◽  
Previous Hypothesis ◽  
Adenine Nucleotide Pool ◽  
Isolated Rat

The mechanism of fructose-induced nucleotide catabolism was studied using isolated rat hepatocytes in which the adenine nucleotide pool was prelabelled with [14C]adenine. Incubation of these cells with fructose caused a rapid depletion of the adenine nucleotides and a corresponding increase in allantoin. There was no accumulation of radioactivity in adenosine in the presence or absence of the adenosine deaminase inhibitor 9-erythro-(2-hydroxy-3-nonyl)adenine. This confirms the previous hypothesis that fructose-induced adenine nucleotide catabolism occurs by way of AMP deaminase (AMP amino-hydrolase, EC 3.5.4.6).

scholarly journals AMP deaminase as a cell-age marker in transient erythroblastopenia of childhood and its role in the adenylate economy of erythrocytes

Blood ◽  
1989 ◽  
Vol 74 (6) ◽  
pp. 2161-2165 ◽  
Author(s):  
DE Paglia ◽  
WN Valentine ◽  
M Nakatani ◽  
RA Brockway
Keyword(s):  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Direct Consequence ◽  
Nucleotide Metabolism ◽  
Amp Deaminase ◽  
Age Related ◽  
Cell Age ◽  
Reliable Marker ◽  
Salvage Pathways ◽  
Adenine Nucleotide Pool

Abstract Erythrocytes from 11 patients with presumptive diagnoses of transient erythroblastopenia of childhood were evaluated retrospectively (six) or prospectively (five) for a possible relationship between erythrocyte adenosine 5′-monophosphate aminohydrolase, adenylic acid deaminase (AMP deaminase) activity and intracellular concentrations of adenine nucleotides. Older red blood cell (RBC) cohorts in these patients consistently exhibited significantly decreased activities of AMP deaminase (approximately 5% to 70% of normal control mean) in association with increased concentrations (up to threefold) of adenosine triphosphate (ATP) and total adenine nucleotides. We postulate that the latter is a direct consequence of the former, since diminishing AMP deaminase activity in aging cells should reduce the drain on the adenine nucleotide pool imposed by irreversible deamination of AMP to inosine 5′-monophosphate. Consistent reductions in AMP deaminase activity indicate that this enzyme should also serve as a reliable marker of mean RBC age useful in diagnostic confirmation of transient erythroblastopenia. The observed increases in ATP and total adenine nucleotides in older RBCs require a reevaluation of the traditional view that age-related losses of these compounds mediate the ultimate demise of senescent erythrocytes. Similar alterations in the balance of degradative and salvage pathways in RBC nucleotide metabolism may also underlie certain cases of so-called “high ATP syndrome.”

scholarly journals Brain Injury Alters Ectonucleotidase Activities and Adenine Nucleotide Levels in Rat Serum / Povreda Mozga Menja Ektonukleotidazne Aktivnosti I Nivo Adeninskih Nukleotida U Serumu Pacova

2015 ◽  
Vol 34 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Danijela Laketa ◽  
Jasmina Savić ◽  
Ivana Bjelobaba ◽  
Irena Lavrnja ◽  
Vesna Vasić ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Vascular System ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Fold Increase ◽  
Enzyme Assays ◽  
Cellular Functions ◽  
Rat Serum ◽  
Stab Injury ◽  
The Brain

Summary Background: Cortical stab injury (CSI) induces changes in the activity, expression and cellular distribution of specific ectonucleotidases at the injury site. Also, several experimentally induced neuropathologies are associated with changes in soluble ectonucleotidase activities in the plasma and serum, whilst various insults to the brain alter purine compounds levels in cerebrospinal fluid, but also in serum, indicating that insults to the brain may induce alterations in nucleotides release and rate of their hydrolysis in the vascular system. Since adenine nucleotides and adenosine regulate diverse cellular functions in the vascular system, including vascular tone, platelet aggregation and inflammatory responses of lymphocytes and macrophages, alterations of ectonucleotidase activities in the vascular system may be relevant for the clinical outcome of the primary insult. Methods: We explored ectonucleotidase activities using specific enzyme assays and determined adenine nucleotides concentrations by the UPLC method in the rat serum after cortical stab injury. while phosphodiesterase activity remained unchanged. Also, at 4-h postinjury a marked decrease in ATP concentration and more than 2-fold increase in AMP concentration were recorded. Conclusions: CSI induces rapid up-regulation of nucleotide catabolizing soluble ectonucleotidases in rat serum, which leads to the observed shift in serum nucleotide levels. The results obtained imply that ectonucleotidases and adenine nucleotides participate in the communication between the brain and the vascular system in physiological and pathological conditions and thereby may be involved in the development of various human neuropathologies.

scholarly journals The mechanism of adenosine triphosphate depletion in the liver after a load of fructose. A kinetic study of liver adenylate deaminase

1977 ◽  
Vol 162 (3) ◽  
pp. 601-609 ◽  
Author(s):  
G van den Berghe ◽  
M Bronfman ◽  
R Vanneste ◽  
H G Hers
Keyword(s):  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Transition Theory ◽  
Amp Deaminase ◽  
Rapid Degradation ◽  
Adenylate Deaminase ◽  
Assay Procedure ◽  
Kinetics Of ◽  
Low Activity ◽  
Simultaneous Accumulation

1. The hepatic concentration of several nucleotides and metabolites was measured during the first few minutes after an intravenous load of fructose to mice. The first changes, observed at 30s, were a decrease in the concentration of Pi and a simultaneous accumulation of fructose 1-phosphate. The decrease in the concentrations of ATP and GTP proceeded more slowly. An increase in the concentration of IMP was detected only after 1 min and could therefore not be considered to be the cause of the accumulation of fructose 1-phosphate. 2. To explain the temporary burst of adenine nucleotide breakdown that occurs after a load of fructose, the kinetics of AMP deaminase (EC 3.5.4.6) from rat liver were reinvestigated at physiological (0.2 mM) concentration of substrate. For this purpose, a new radiochemical-assay procedure was developed. At 0.2mM-AMP a low activity could be measured, which was more than 90% inhibited by 5mM-Pi. ATP (3MM) increased the enzyme activity over 200-fold. Pi alone did not influence the ATP-activated enzyme, but 0.5mM-GTP caused a 60% inhibition. The combined effect of both inhibitors at their physiological concentrations reached 95%. 3. It is proposed that the rapid degradation of adenine nucleotides that occurs after a load of fructose is caused by a decrease in the concentration of both inhibitors, Pi and GTP, soon counteracted by the decrease in the concentration of ATP. 4. Some of the kinetic parameters of liver AMP deaminase were computed in terms of the concerted transition theory of Monod, Wyman & Changeux (1965) (J. Mol. Biol. 12, 88-118).

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