Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The relationships between food intake self-selection and liver substrates (glycogen, fat) or activities of pyruvate kinase, glucose-6-phosphate dehydrogenase, malic enzyme, acetyl CoA carboxylase, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase were determined during the spontaneous variations of body weight in the dormouse. 2. The results show that during the phase of increasing body weight, carbohydrate intake and enzyme activities involved in lipogenesis are on a high level. 3. On the last part of the body weight increasing phase, when lipid intake occurs, lipogenesis is depressed and a gluconeogenetic activity is set on, while total caloric intake is important and body weight is still increasing. 4. These metabolic changes are interpreted as a preparation to hibernating conditions in the dormouse.
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PMID:Relationships between spontaneous food intake and metabolic activities in the dormouse (Glis glis L.). 31 73

To determine the fetal response to altered maternal fuel supply, the effects of prolonged maternal fasting, begun 24-96 h before term, were examined and compared with values from normally fed term animals. Fetal weight decreased only after 48 h of maternal fasting. Prolonged maternal fasting was associated with low blood glucose, high blood ketone bodies, and decreased gluconeogenic substrate in the fetus. Plasma insulin was decreased, whereas plasma glucagon was increased in the fetus of fasted mothers. Infusion of [2-3H]glucose into the mother to constant specific activity gave a ratio of maternal to fetal glucose activity of 1.0 in fed and 1.56 in fasted mothers. Fetal liver from fasted mothers showed both increase in activity of key gluconeogenic enzymes (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) and increased conversion in vitro of lactate, alanine, serine, and glycerol in glucose by liver slices. It is inferred that maternal fasting induces fetal substrate alterations and hormonal changes appropriate to premature appearance of hepatic gluconeogenesis. The priority for endogenous fuel provision in this state leads to impaired fetal growth.
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PMID:Fetal metabolic response to maternal fasting in the rat. 87 Nov 55

1. The metabolic response of livers to perfusion with ethanol with and without avenaciolide, has been followed by measuring the perfusate levels of glucose, lactate, pyruvate, beta-hydroxybutyrate, ethanol, amino acids, urea and lipid. 2. Analysis of the perfused livers showed changes in the activities of some of the key enzymes of glycolysis, gluconeogenesis and lipogenesis. Ethanol perfusion decreased the levels of phosphofructokinase, glucokinase and cytosolic isocitrate dehydrogenase, while avenaciolide lowered pyruvate carboxylase and phosphoenolpyruvate carboxykinase as well as glucokinase. Isocitrate dehydrogenase and phosphofructokinase were unchanged, but the ionophore increased the level of fructose-1,6-diphosphatase. Ethanol plus avenaciolide showed the same pattern as ethanol alone, together with the decrease in phosphoenolpyruvate carboxykinase found with avenaciolide. 3. Neither ethanol nor avenaciolide had any effect on kexokinase, pyruvate kinase or acetyl-CoA carboxylase. There were small changes in glucose-6-phosphatase and malic enzyme, and a tendency for citrate lyase levels to decline in avenaciolide perfusions.
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PMID:The actions of avenaciolide and ethanol on glucose metabolism and on related enzyme activities in the isolated perfused rat liver. 94 10

Insluin injected intravenously caused a rapid, marked decrease in hepatic glucose secretion in the rabbit, as determined by an isotope-dilution procedure. This was associated with a decrease in the concentrations of gluconeogenic intermediates from phosphoenolpyruvate to triose phosphates, inclusive, compatible with inhibition of gluconeogenesis at phosphoenolpyruvate carboxykinase. The concentration of glucose 6-phosphate was unaltered but that of hepatic glucose was reduced. The specific activities of the hexose phosphates, relative to that of liver glucose, were the same in control and insulin-treated animals. These observations can be explained by a decrease in the activity of glucose-6-phosphatase. It is concluded that this enzyme is a control point for hepatic glucose production and is inhibited by insulin. In the rat, insulin produced a rapid fall in blood sugar. The hepatic glucose output remained normal despite a fall in hepatic glucose 6-phosphate concentration during the initial period of insulin action. This suggests that glucose-6-phosphate returned to normal with no change in the rate of glucose production. The data suggest that in the rat, insulin produces a transient increase in glucose-6-phosphatase activity.
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PMID:Insulin control of hepatic glucose production. 112 Feb 88

In vitro rates of lactate conversion to glucose and oxidation to CO2 were determined in livers of stress-susceptible (SS) and stress-resistant (SR) pigs because we hypothesized that livers of SS pigs had a lower capacity than livers of SR pigs to remove lactate from blood. Stress-susceptibility was determined by reaction to halothane at 7 weeks of age. At approximately 9 weeks of age, pigs were assigned to one of three experimental diets. Pigs weighing 95 kg were slaughtered immediately after stress, and liver samples were obtained. Incorporation of lactate into glucose in liver of SS pigs was 38% of that in SR pigs. Addition of either vitamin C or vitamins C and E plus magnesium oxide and collagen extract to a corn-soy diet did not alter lactate conversion to glucose, but depressed lactate oxidation to CO2. No differences were detected in either activities of lactate dehydrogenase, HAD-malate dehydrogenase, phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase, and glucose-6-phosphatase or concentration of glycogen in livers of SS and SR pigs. Our data indicate that livers of SS pigs possess a lower capacity to incorporate lactate into glucose and to oxidize lactate to CO2; maximal activities of enzymes measured in this study are not the cause of these differences. Reduced capacity of lactate metabolism in livers of SS pigs seems a part of the etiology of the porcine stress syndrome.
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PMID:Gluconeogenesis from lactate in liver of stress-susceptible and stress-resistant pigs. 126 79

The activities of glucose-6-phosphatase (G6P), fructose diphosphatase, phosphoenolpyruvate carboxykinase (PEPCK), aspartate and alanine transferases were measured in liver and kidney of fetal foals between 100-318 days of gestation (term approximately 335 days) and during the immediate postnatal period (0-48 h after birth). All 5 enzymes could be detected in the fetal liver and kidney at the youngest gestational age studied. Mean fetal activities were lower than those observed in their mothers and showed no change with gestational age for the majority of enzymes studied. However, renal PEPCK and renal and hepatic G6P did increase towards term. At birth, hepatic and renal activities of these two enzymes were higher than those found in late gestation or in the adult animals. There was no apparent change in the activities of any of the other enzymes at birth. In late gestation (80-90% gestation), the activities of G6P and PEPCK in the foal were low compared to those in other species at the same stage of gestation. Similarly, the perinatal increase in enzyme activity occurred closer to term in the foal than in most other species. These observations indicate that maturation of glucogenic capacity occurs relatively late in the fetal foal and suggests that this process may be dependent on the prepartum rise in fetal cortisol as occurs in other species.
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PMID:The development of gluconeogenic enzymes in the liver and kidney of fetal and newborn foals. 130 17

Twenty-four male (12 obese and 12 lean) and 21 female (11 obese and 10 lean) SHR/N-cp rats were fed a diet containing either 54% sucrose or starch for periods of 3-4 months. Rats were killed after a 14-16 h fast and liver enzyme activities were determined in both sex groups. Liver glucose-6-phosphatase (G6Pase), fructose 1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), malic enzyme (ME), phosphofructokinase (PFK), glucokinase (GK), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (per total liver capacity) were significantly affected by phenotype (obese > lean). Arginase and ornithine transcarbamylase levels were analysed only in male rats and were found to be elevated in obese rats as compared to lean littermates. Some of the above changes in enzyme levels were exaggerated by sucrose feeding but not the changes in FBPase, PEPCK, ME and GK (in both sexes) plus AST, arginase and arginine synthase activities in male rats and ALT levels in female rats. Results from SHR/N-cp rats published in this paper were compared to results obtained from LA/N-cp rats published previously. Comparison of the non-diabetic obese LA/N-cp with the diabetic obese SHR/N-cp male shows a greater excess in lipogenic capacity of the liver in the LA/N-cp male rat. The SHR/N-cp obese female also shows a greater liver lipogenic capacity as compared with the obese male SHR/N-cp rat. The results suggest that an adaptation of excessive lipogenesis in the liver of obese rats may be an anti-diabetogenic adaptation resulting in increased glucose conversion to lipids, thus reducing blood glucose levels.
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PMID:Adaptation in enzyme (metabolic) pathways to obesity, carbohydrate diet and to the occurrence of NIDDM in male and female SHR/N-cp rats. 133 Sep 56

The activities of glucose-6-phosphatase (G6Pase), fructose-1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate carboxylase (PC) were determined in homogenates of adult Schistosoma mansoni worms and compared with the activities in homogenates of rat liver and rat skeletal muscle, tissues with a high and a low gluconeogenic capacity, respectively. All four gluconeogenic enzymes were present in S. mansoni. The enzymes were less active than in rat liver, but the activities of G6Pase, PEPCK and PC were at least an order of magnitude higher than in rat skeletal muscle whereas FBPase was approximately equally active in S. mansoni and in rat muscle. Experiments with 14C-labelled substrates or [14C]NaHCO3 failed to demonstrate the actual occurrence of gluconeogenesis in S. mansoni. Some possible other functions of the gluconeogenic enzymes were investigated. Experiments with inhibitors of PEPCK gave no indications that this enzyme was involved in the degradation of glucose. This was confirmed by 13C-NMR experiments which indicated that lactate was formed from phosphoenolpyruvate via the actions of pyruvate kinase and lactate dehydrogenase, and that PEPCK did not participate in the formation of lactate. Substrate cycling between fructose-6-dehydrogenase, and fructose-1,6-bisphosphate was demonstrated to occur in adult S. mansoni. This shows that FBPase participates in the glucose metabolism of this parasite.
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PMID:The enigmatic presence of all gluconeogenic enzymes in Schistosoma mansoni adults. 164 28

Male Sprague--Dawley rats (350-375 g) were injected i.p. with TCDD (25 [sublethal dose] and 125 micrograms/kg [lethal dose], respectively, in corn oil/acetone), or vehicle only; vehicle-treated animals were pair-fed to their TCDD-treated counterparts. 1, 2, 4, 8, 16, and 32 days (28 days for lethal dose) thereafter, animals were sacrificed and activities of two key enzymes of gluconeogenesis determined in livers of rats. In livers of pair-fed rats both enzyme activities were little affected. In the livers of TCDD-treated animals the activity of phosphoenolpyruvate carboxykinase (PEPCK, EC 4.1.1.32) decreased rapidly, exhibiting significant losses by the 2nd day after treatment. Time course and extent of loss of PEPCK activity (about 50%) were similar after either dose. The activity of glucose-6-phosphatase (G-6-Pase, EC 3.1.3.9) decreased more slowly as a result of TCDD treatment; statistically significant losses were observed by 4 or 8 days after the lethal and sublethal dose, respectively. These results confirm the hypothesis that reduced in vivo rates of gluconeogenesis in TCDD-treated rats are due to decreased activities of gluconeogenic enzymes. In an additional set of experiments, rats were treated with 125 micrograms/kg TCDD, 25 micrograms/kg TCDD, or with vehicle alone. The 25 micrograms/kg or vehicle-treated rats were then pair-fed to rats dosed with 125 micrograms/kg of TCDD. Mean time to death and body weight loss at the time of death were essentially identical in all groups, lending additional support to the hypothesis that reduced feed intake is the major cause of TCDD-induced death in male Sprague--Dawley rats. Both appetite suppression and reduced total PEPCK activity in whole livers occurred in the same dose-ranges of TCDD, suggesting the possibility of a cause-effect relationship.
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PMID:Reduced activities of key enzymes of gluconeogenesis as possible cause of acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in rats. 184 69

Serum activity has been measured in three of the key enzymes in the gluconeogenic pathway in rats subjected to experimental hepatotoxicity after intraperitoneal administration of carbon tetrachloride. The levels of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-biphosphatase (FBPase) showed a similar behavior to the transaminase (AST and ALT), increasing markedly with respect to the controls at 12 h after administration of the poison, reaching their maximum peak of activity at between 24 and 36 h, and returning to normal values at 96 h. The activity of glucose-6-phosphatase was not significantly modified throughout the treatment. These results seem to demonstrate that the determination of the serum activity of PEPCK and FBPase could be a sensitive and specific marker of hepatic cytolysis.
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PMID:Serum activity of the key gluconeogenic enzymes in carbon-tetrachloride-induced experimental hepatotoxicity. 196 85


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