scholarly journals The development of gluconeogenesis in rat liver. Controlling factors in the newborn

1971 ◽  
Vol 124 (2) ◽  
pp. 265-274 ◽  
Author(s):  
F. J. Ballard
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Adenine Nucleotides ◽  
Relative Proportion ◽  
Rapid Change ◽  
Newborn Rats ◽  
Foetal Liver ◽  
Nadh Ratio ◽  
Old Rats ◽  
The Relationship ◽  
Stimulation Of

1. Measurements in livers of rats delivered by Caesarian section show a rapid change in the relative proportion of adenine nucleotides. By 20min the ATP/ADP ratio had increased from 1.76 to 8.7 and the value of the relationship [ATP][AMP]/[ADP]2increased from 1.0 to 4.4. These changes are dependent on the availability of oxygen to the animal. 2. The free [NAD+]/[NADH] ratio in the liver cytosol increases from 180 after delivery to reach a maximum of 1010 at 2h, before falling to 540 in the 24h-old animal. 3. The mitochondrial NAD redox potential also shows a sharp increase towards a more oxidized state in livers of delivered rats. 4. These results probably indicate that the foetal liver is hypoxic, with oxygenation occurring in the first hour after delivery. 5. Measurements in livers of naturally born rats 2min after birth also suggest that this tissue is hypoxic with an ATP/ADP ratio of 1.83 and a free [NAD+]/[NADH] ratio of 117. 6. Concentrations of intermediates in the gluconeogenic pathway have been determined in livers of foetal, 1h-old and 1-day-old rats. These experiments imply a facilitation of lactate dehydrogenase and glucose 6-phosphatase activities by 1h after birth, and a stimulation of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase steps by 1 day after birth. 7. The appearance of gluconeogenesis in livers of newborn rats seems therefore to involve an oxygenation stage followed by an increase in phosphoenolpyruvate carboxykinase activity.

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.

Abnormalities of Platelet Adenine Nucleotides in Patients with Myeloproliferative Disorders

1979 ◽  
Vol 41 (04) ◽  
pp. 787-795 ◽  
Author(s):  
Junji Nishimura ◽  
Seiki Okamoto ◽  
Hiroshi Ibayashi
Keyword(s):  
Platelet Aggregation ◽  
Marked Reduction ◽  
Adenine Nucleotides ◽  
Myeloproliferative Disorders ◽  
Normal Subjects ◽  
Platelet Dysfunction ◽  
Normal Functions ◽  
Induced Aggregation ◽  
The Relationship ◽  
Stimulation Of

SummaryPlatelet aggregation and adenine nucleotides in platelets have been studied in thirteen patients with myeloproliferative disorders. ADP induced aggregation was abnormal in two patients, but collagen induced aggregation was impaired in 11 patients. The concentrations of ATP and ADP in resting platelets in the patients with abnormal aggregation were significantly less than those in normal subjects. Marked reduction of the amounts of both nucleotides released into plasma was also observed after stimulation of collagen in these patients. Platelets in the patients with normal functions contained almost normal amounts of adenine nucleotides. We discussed the relationship between platelet dysfunction and adenine nucleotides in platelets of myeloproliferative disorders and concluded that platelet dysfunction was mainly attributable to reduction of releasable ADP.

scholarly journals Stimulation of mitochondrial calcium ion efflux by thiol-specific reagents and by thyroxine. The relationship to adenosine diphosphate retention and to mitochondrial permeability

1979 ◽  
Vol 182 (2) ◽  
pp. 455-464 ◽  
Author(s):  
E J Harris ◽  
M Al-Shaikhaly ◽  
H Baum
Keyword(s):  
Thyroid Hormones ◽  
Calcium Ion ◽  
Adenine Nucleotides ◽  
Adenosine Diphosphate ◽  
Ruthenium Red ◽  
Reduced Form ◽  
Factors Affecting ◽  
Ph Values ◽  
Rat Heart Mitochondria ◽  
The Relationship

Respiring rat heart mitochondria were loaded with Ca2+ and then treated with Ruthenium Red. The factors affecting the subsequent Ca2+-efflux were studied. Addition of rotenone or antimycin led to a decline of efflux except at pH values above 7.2, provided the load was less than about 80 nmol per mg of protein. Oligomycin reversed the effect of the respiratory inhibitors. Independently of respiration, efflux was stimulated by the uncoupler trifluoromethyltetrachlorbenzimadazole, by mersalyl and by thyroid hormones. The stimulated efflux could be diminished by ADP, with Mg2+ as cofactor if efflux was rapid. With respiration in progress, efflux could be stimulated by N-ethylmaleimide and 5,5′-dithiobis-(2-nitrobenzoate). The effects of mersalyl and of thyroid hormones could be diminished with dithiothreitol. In the absence of stimulating agents, the Ca2+ efflux was proportional to the load up to some critical amount, this critical amount was decreased by the agents. Thyroxine and mersalyl caused not only loss of Ca2+, but also simultaneous, but not necessarily proportional, loss of internal adenine nucleotides. Both efflux rates were kept at a low value by bongkrekic acid added before the stimulating agent. It is concluded that Ca2+ efflux is a measure of a permeability controlled by the binding of ADP (an Mg2+) to the inner membrane, and that this in turn depends on the maintenance of certain thiol gropus in a reduced form by a reaction that uses NADH and ATP and the energy-linked transhydrogenase.

scholarly journals The relationship between cobalt binding to tubulin and the stimulation of assembly.

1982 ◽  
Vol 257 (10) ◽  
pp. 5839-5845
Author(s):  
R H Himes ◽  
Y C Lee ◽  
G R Eagle ◽  
K M Haskins ◽  
S D Babler ◽  
...  
Keyword(s):  
Cobalt Binding ◽  
The Relationship ◽  
Stimulation Of

scholarly journals The hormonal regulation of enzymes in prenatal and postnatal rat liver. Effects of adenosine 3′,5′-(cyclic)-monophosphate

1969 ◽  
Vol 115 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Olga Greengard
Keyword(s):  
Growth Hormone ◽  
Hormonal Regulation ◽  
Time Course ◽  
Tyrosine Aminotransferase ◽  
Cyclic Monophosphate ◽  
Sequential Development ◽  
Foetal Liver ◽  
Old Rats ◽  
Postnatal Rats ◽  
Do So

1. The administration of glucagon, cAMP [adenosine 3′,5′-(cyclic)-monophosphate], BcAMP [6-N-2′-O-dibutyryladenosine 3′,5′-(cyclic)-monophosphate] or adrenaline to foetal rats during the last 2 days of gestation evoked the appearance of tyrosine aminotransferase and enhanced the accumulation of glucose 6-phosphatase in the liver. In foetuses 1–2 days younger only BcAMP was effective. After birth liver glucose 6-phosphatase no longer responds to glucagon or BcAMP. Tyrosine aminotransferase is still inducible by these agents in 2-day-old rats, but not in 50-day-old rats. After adrenalectomy of adults glucagon or BcAMP can enhance the induction of the enzyme by hydrocortisone. The results indicate that the ability to synthesize tyrosine aminotransferase and glucose 6-phosphatase when exposed to cAMP develops sooner than the ability to respond to glucagon with an increase in the concentration of cAMP; the responsiveness of enzymes to different hormones changes with age. A scheme illustrating the sequential development of competence in regulating the level of an enzyme is presented. 2. Actinomycin inhibited the effects of glucagon and BcAMP on liver tyrosine aminotransferase and glucose 6-phosphatase in foetal rats. Growth hormone, insulin and hydrocortisone did not enhance the formation of these enzymes. 3. The time-course of accumulation of glucose 6-phosphatase in the kidney is different from that in the liver. Hormones that increase the accumulation in foetal liver do not do so in the kidney of the same foetus or in the livers of postnatal rats.

THE ROLE OF THE MOTHER IN 131I METABOLISM OF SUCKING AND WEANLING RATS

1965 ◽  
Vol 43 (3) ◽  
pp. 431-436 ◽  
Author(s):  
M. Samel ◽  
A. Caputa
Keyword(s):  
Urinary Bladder ◽  
In Utero ◽  
The State ◽  
Newborn Rats ◽  
Weanling Rats ◽  
Immature Rats ◽  
Other Substances ◽  
Old Rats

In newborn rats the mother provokes the emptying of the urinary bladder by stimulating the perineum with her tongue. The possibility that mothers may thereby ingest the urine of their young has been studied by means of 131I on nine litters of rats aged 10 to 29 days. The results indicate that a considerable quantity of 131I administered intraperitoneally to 10- and 18-day-old rats, which were then reunited with their mothers for 4 hours, reappears in the organism of uninjected nurslings after passing through the organism of the mother. The amount of 131I transferred from injected rats into the bodies of isolated uninjected rats of the same litter decreased during the period of weaning. The observed recirculation of 131I between immature rats and their mothers in both directions may represent a saving mechanism which might include several other substances and would compensate for their loss via the milk, and suggests a new aspect of maternal–neonatal interrelationship which appears as a continuation of the state existing in utero.

Cellular and molecular basis of increased ammoniagenesis in potassium deprivation

2011 ◽  
Vol 301 (5) ◽  
pp. F969-F978 ◽  
Author(s):  
Shaikh Abu Hossain ◽  
Farrukh A. Chaudhry ◽  
Kamyar Zahedi ◽  
Faraaz Siddiqui ◽  
Hassane Amlal
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Molecular Mechanisms ◽  
Intracellular Acidosis ◽  
Deficient Diet ◽  
Proximal Tubule Cells ◽  
Glutamine Transporter ◽  
Additive Increase ◽  
Acid Base Status ◽  
Low K ◽  
Stimulation Of

Hypokalemia is associated with increased ammoniagenesis and stimulation of net acid excretion by the kidney in both humans and experimental animals. The molecular mechanisms underlying these effects remain unknown. Toward this end, rats were placed in metabolic cages and fed a control or K+-deficient diet (KD) for up to 6 days. Rats subjected to KD showed normal acid-base status and serum electrolytes composition. Interestingly, urinary NH4+ excretion increased significantly and correlated with a parallel decrease in urine K+ excretion in KD vs. control animals. Molecular studies showed a specific upregulation of the glutamine transporter SN1, which correlated with the upregulation of glutaminase (GA), glutamate dehydrogenase (GDH), and phosphoenolpyruvate carboxykinase. These effects occurred as early as day 2 of KD. Rats subjected to a combined KD and 280 mM NH4Cl loading (to induce metabolic acidosis) for 2 days showed an additive increase in NH4+ excretion along with an additive increment in the expression levels of ammoniagenic enzymes GA and GDH compared with KD or NH4Cl loading alone. The incubation of cultured proximal tubule cells NRK 52E or LLC-PK1 in low-K+ medium did not affect NH4+ production and did not alter the expression of SN1, GA, or GDH in NRK cells. These results demonstrate that K+ deprivation stimulates ammoniagenesis through a coordinated upregulation of glutamine transporter SN1 and ammoniagenesis enzymes. This effect is developed before the onset of hypokalemia. The signaling pathway mediating these events is likely independent of KD-induced intracellular acidosis. Finally, the correlation between increased NH4+ production and decreased K+ excretion indicate that NH4+ synthesis and transport likely play an important role in renal K+ conservation during hypokalemia.

scholarly journals The interaction between two trains of impulses converging on the same motoneurone

1929 ◽  
Vol 105 (738) ◽  
pp. 363-371 ◽  
Keyword(s):  
Mechanical Effect ◽  
The Other ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Afferent Pathways ◽  
Afferent Nerves ◽  
Maximal Stimulation ◽  
The Common ◽  
The Relationship ◽  
Stimulation Of

It was shown in an earlier paper (7) that if maximal stimulation of either of two different afferent nerves can reflexly excite fractions of a given flexor muscle, there are generally, within the aggregate of neurones which innervate that muscle, motoneurones which can be caused to discharge by either afferent (i. e., motoneurones common to both fractions). The relationship which two such afferents bear to a common motoneurone was shown, by the isometric method of recording contraction, to be such that the activation of one afferent, at a speed sufficient to cause a maximal motor tetanus when trans­mitted to the muscle fibres, caused exclusion of any added mechanical effect when the other afferent was excited concurrently. This default in mechanical effect was called “occlusion.” Occlusion may conceivably be due to total exclusion of the effect of one afferent pathway on the common motoneurone by the activity of the other; but facilitation of the effect of one path by the activation of the other when the stimuli were minimal suggests that, in some circumstances at least, the effect of each could augment and summate with th at of the other at the place of convergence of two afferent pathways. Further investigation, using the action currents of the muscle as indication of the nerve impulses discharged by the motoneurone units, has now given some information regarding the effect of impulses arriving at the locus of convergence by one afferent path when the unit common to both is already discharging in response to impulses arriving by the other afferent path. Our method has been to excite both afferent nerves in overlapping sequence by series of break shocks at a rapid rate and to examine the action currents of the resulting reflex for evidence of the appearance of the rhythm of the second series in the discharge caused by the first when the two series are both reaching the motoneurone.

scholarly journals Glucose stimulation of insulin secretion from the isolated pancreas of foetal and newborn rats

Diabetologia ◽  
1969 ◽  
Vol 5 (4) ◽  
pp. 260-262 ◽  
Author(s):  
K. Asplound ◽  
S. Westman ◽  
C. Hellerste�m
Keyword(s):  
Insulin Secretion ◽  
Newborn Rats ◽  
Glucose Stimulation ◽  
Isolated Pancreas ◽  
Stimulation Of

scholarly journals The mechanism by which adenosine decreases gluconeogenesis from lactate in isolated rat hepatocytes

1987 ◽  
Vol 246 (2) ◽  
pp. 449-454 ◽  
Author(s):  
A Lavoinne ◽  
H A Buc ◽  
S Claeyssens ◽  
M Pinosa ◽  
F Matray
Keyword(s):  
Ketone Body ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
Adenosine Kinase ◽  
Isolated Rat Hepatocytes ◽  
Adenosine Deaminase 2 ◽  
Body Production ◽  
Gluconeogenic Substrates ◽  
Isolated Rat ◽  
Stimulation Of

Incubation of hepatocytes from 24 h-starved rats in the presence of 0.5 mM-adenosine decreased gluconeogenesis from lactate, but not from alanine. The inhibition of gluconeogenesis was associated with a stimulation of ketone-body production and an inhibition of pyruvate oxidation. These metabolic changes were suppressed in the presence of iodotubercidin (an inhibitor of adenosine kinase), but were reinforced in the presence of deoxycoformycin (an inhibitor of adenosine deaminase); 2-chloroadenosine induced no change in gluconeogenesis from lactate. These data indicate that the inhibition of gluconeogenesis by adenosine probably results from its conversion into adenine nucleotides. In the presence of lactate or pyruvate, but not with alanine or asparagine, this conversion resulted in a decrease in the [ATP]/[ADP] ratio in both mitochondrial and cytosolic compartments. Adenosine decreased the Pi concentration with all gluconeogenic substrates.

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