Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Twenty obese and 20 lean LA/N-cp male rats and 20 male Sprague-Dawley rats were fed a diet containing either 54 percent sucrose or starch for six weeks. After a 14-16 hour fast, rats were killed. Liver and kidney enzyme activities were determined in the LA/N-cp rats while plasma urea and selected amino acids were determined in all rats. 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), glucokinase (GK), pyruvate kinase (PK), phosphofructokinase (PFK), glutamic-oxaloacetic-transaminase (GOT), glutamic-pyruvic transaminase (GPT), arginase (ARGASE), arginine-synthase (ARG-SYN) and ornithine transcarbamylase (OTC) levels were significantly affected by phenotype (obese greater than lean). All the above changes in enzyme levels were exaggerated by sucrose-feeding with the exception of PK, PFK, GOT, GPT, ARGASE and ARG-SYN. Kidney cortex G6PASE, PEPCK and ARGASE activities were higher in the obese rats as compared to the lean littermates. Sucrose feeding resulted in higher cortex G6PASE, FBPASE and PEPCK as compared to starch-fed rats. A phenotype effect was noted with plasma glutamate, urea, leucine, isoleucine and valine (obese greater than lean) and a diet effect was seen with aspartate, phenylalanine, leucine and valine (sucrose greater than starch) concentration. Sprague-Dawley rats had higher plasma urea and lower alanine than lean LA/N-cp males. Metabolic obesity in the LA/N-cp rat appears to involve an elevated capacity for pathways of glycolysis, gluconeogensis, lipogenesis and amino acid catabolism in the liver.
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PMID:Effect of dietary carbohydrate on liver and kidney enzyme activities and plasma amino acids in the LA/N-cp rat. 204 12

Treatment of rats with diazinon (40 mg/kg, i.p.) resulted in hyperglycaemia and depletion of glycogen from the brain and peripheral tissues two hours after administration. The activities of glycogen phosphorylase and phosphoglucomutase were significantly higher in the brain and liver; that of glucose-6-phosphatase was not altered. The activities of the glycolytic enzymes hexokinase and lactate dehydrogenase were increased only in the brain. The cholinesterase activity in the brain was reduced by treatment with diazinon. The activities of the hepatic gluconeogenic enzymes fructose 1,6-diphosphatase and phosphoenolpyruvate carboxykinase were significantly increased. The lactate level was increased in the brain and blood, whereas that of pyruvate was not changed. The activity of glucose-6-phosphate dehydrogenase was not changed to any major extent. Cholesterol and ascorbic acid contents of adrenals were depleted in diazinon-treated animals. The changes were pronounced after intraperitoneal administration of 40 mg/kg diazinon, they were slight but significant after 20 mg/kg, and absent after 10 mg/kg. Hyperglycaemia and changes in carbohydrate metabolism were abolished by adrenalectomy suggesting possible involvement of adrenals.
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PMID:The role of adrenals in diazinon-induced changes in carbohydrate metabolism in rats. 209 50

1. The regulation of renal gluconeogenesis was studied in rats made septic by a caecal ligation and puncture technique. 2. Blood glucose concentrations were not markedly different in septic rats, but lactate, pyruvate and alanine concentrations were markedly increased, compared with sham-operated rats. Conversely, blood ketone body concentrations were significantly decreased in septic rats. Both plasma insulin and glucagon concentrations were markedly elevated in response to sepsis. 3. The maximal activities of glucose-6-phosphatase (EC 3.1.3.9), fructose-1,6-bisphosphatase (EC 3.1.3.11), pyruvate carboxylase (EC 6.4.1.1) and phosphoenolpyruvate carboxykinase (EC 4.1.1.49) were markedly decreased in kidneys obtained from septic rats, suggesting diminished renal gluconeogenesis. 4. Renal concentrations of lactate, pyruvate and other gluconeogenetic intermediates were markedly elevated in septic rats, whereas those of acetyl-CoA and fructose 2,6-bisphosphate were decreased and unchanged, respectively. 5. The rate of gluconeogenesis from added lactate, pyruvate and glycerol was decreased in isolated incubated renal tubules from septic rats. 6. Sepsis decreased the arteriovenous concentration difference for glucose, lactate, and alanine. Septic rats showed decreased net rates of glucose production and net rates of removal of lactate and alanine as compared with sham-operated controls. 7. It is concluded that the diminished capacity for renal gluconeogenesis in septic rats could be the result of changes in the maximal activities or regulation of key non-equilibrium gluconeogenic enzymes or both, but the effect of other factors (e.g. toxins) has not been excluded.
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PMID:Metabolic regulation of renal gluconeogenesis in response to sepsis in the rat. 217 16

Treatment with diazinon (40 mg/kg, i.p.) resulted in hyperglycemia and depletion of glycogen from cerebral and peripheral tissues 2 hr after its administration in rats. The activities of the glycogenolytic enzymes glycogen phosphorylase and phosphoglucomutase were increased significantly in brain and liver, whereas that of glucose-6-phosphatase was not altered. The activities of the glycolytic enzymes hexokinase and lactate dehydrogenase were increased only in the brain. The cholinesterase activity of the brain was reduced by treatment with diazinon. The activities of the hepatic gluconeogenic enzymes fructose 1,6-diphosphatase and phosphoenolpyruvate carboxykinase were also increased significantly in diazinon-treated animals. The level of lactate was increased in brain and blood, whereas that of pyruvate was not changed. The activity of glucose-6-phosphate dehydrogenase was not changed significantly. The cholesterol and ascorbic acid contents of adrenals were depleted in diazinon-treated animals. The hyperglycemia and changes in carbohydrate metabolism were abolished by adrenalectomy, suggesting the possible involvement of the adrenals in the induced changes in diazinon-treated animals.
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PMID:Modification of diazinon-induced changes in carbohydrate metabolism by adrenalectomy in rats. 234 75

Treatment with diazinon resulted in hyperglycaemia and depletion of glycogen from cerebral and peripheral tissues 2 h after its administration in rats; the changes were maximal after 40 mg/kg diazinon, administered intraperitoneally. The activities of glycogen phosphorylase and phosphoglucomutase were significantly increased in brain and liver, while that of glucose-6-phosphatase was not altered. The activities of the glycolytic enzymes hexokinase and lactate dehydrogenase were increased only in brain. The cholinesterase activity of the brain was reduced by treatment with diazinon. The activities of hepatic gluconeogenic enzymes (fructose 1,6 diphosphatase and phosphoenolpyruvate carboxykinase) were also significantly increased in diazinon-treated animals. The level of lactate was increased in brain and blood while that of pyruvate was not changed. The activity of glucose-6-phosphate dehydrogenase was not significantly changed. Cholesterol and ascorbic acid contents of adrenals were depleted in diazinon-treated animals. Adrenalectomy abolished the hyperglycaemia and changes in carbohydrate metabolism, suggesting the possible involvement of adrenals in the induced changes in diazinon-treated animals.
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PMID:Effect of adrenalectomy on diazinon-induced changes in carbohydrate metabolism. 281 1

The capacity for gluconeogenesis in the isolated amphibian retina was found to be approx. 70-fold greater with lactate than with glutamate as the gluconeogenic precursor, 1426 versus 21 pmol of glucose incorporated into glycogen/h per mg of protein. It was also found that 11-15% of the glucosyl units in glycogen are derived from C3 metabolites of the glycolytic pathway, suggesting that lactate is recycled within the retina. In concert with these metabolic observations, a full complement of the gluconeogenic enzymes was detected in retinal homogenates. These included: glucose-6-phosphatase, fructose-1,6-bisphosphatase, acetyl-CoA-dependent pyruvate carboxylase and phosphoenolpyruvate carboxykinase. Agents that regulate the rate of gluconeogenesis in hepatic tissue were tested on the retina. At concentrations of glutamate and lactate that are presumed to be relevant physiologically, it was found that vasoactive intestinal peptide, ionophore A23187 and elevated [K+] each enhanced the rate of gluconeogenesis in Ringer containing 50 microM-glutamate, whereas in Ringer containing 8.5 mM-lactate these agents inhibited the rate of gluconeogenesis. Further, it was found that the classic gluconeogenic hormone glucagon inhibited gluconeogenesis in both glutamate- and lactate-containing Ringer. Retinal energy metabolism was found to be altered in lactate-containing Ringer, in that lactate production was suppressed completely. In addition, glycogen metabolism appeared to be dependent on increased cytosolic Ca2+ and was insensitive to increased retinal cyclic AMP.
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PMID:Gluconeogenesis in the amphibian retina. Lactate is preferred to glutamate as the gluconeogenic precursor. 290 49

Glucose transport and metabolism, and the effect of insulin thereon, was studied using suspensions of rat renal tubules enriched in the proximal component. [U-14C]Glucose oxidation is a saturable process (Km 3.1 +/- 0.2 mM; Vmax 14 +/- 0.2 mumole 14CO2 formed/g tissue protein per h). Glucose oxidation and [14C]lactate formation from glucose are inhibited in part by phlorizin and phloretin: the data suggest that the rate-limiting entry of glucose into the cell metabolic pool occurs by both the Na-glucose cotransport system (at the brush border) and the equilibrating, phloretin-sensitive system (at the basal-lateral membrane). Raising external glucose from 5 to 30 mM markedly increases aerobic and anaerobic lactate formation. Gluconeogenesis from lactate is not affected by variations of glucose concentrations. 24 h after streptozotocin administration, aerobic lactate formation is enhanced, as is the uptake of methyl alpha-D-glucoside by the tubules, while anaerobic glycolysis is depressed. Streptozotocin treatment (ST) increases both the Km and Vmax of glucose oxidation; gluconeogenesis and lactate oxidation are not affected. The effect of streptozotocin treatment on lactate formation are abolished by 1 mU/ml insulin. Streptozotocin treatment increases tissue hexokinase activity, decreases glucose-6-phosphatase, but has no significant effect on fructose-1,6-diphosphatase; phosphoenolpyruvate carboxykinase and pyruvate dehydrogenase. The data demonstrate fast streptozotocin-induced changes in cellular enzymes of carbohydrate metabolism. The enhancing effect of streptozotocin on methyl alpha-glucoside uptake is transient: 8 days after administration of the agent, no significant difference from controls is found. It is concluded that under the given experimental conditions insulin enhances the equilibrating glucose entry by the phloretin-sensitive pathway at the basal-lateral membrane, and transiently inhibits the Na-glucose cotransport system.
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PMID:Glucose transport and metabolism in rat renal proximal tubules: multicomponent effects of insulin. 293 29

Glycerol, glycerol-3-phosphate (G3P), and dihydroxyacetone phosphate (DHAP) were evaluated as inhibitors of gluconeogenesis on rat liver enzymes in vitro, and for their effects on glucose formation in vivo in well-nourished and malnourished rats. DHAP was more potent as an inhibitor than G3P on fructose-1,6-diphosphatase (FDPase), phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase (G6Pase). The I50 for DHAP was 2, 8, and 9 x 10(-3) M, respectively. No effect was observed on rat liver pyruvate carboxylase (PC). Glycerol was a weak inhibitor of FDPase and PEPCK, but did not inhibit PC and G6Pase. In vivo, when G3P was injected before a parenteral L-alanine (Ala) challenge, it produced a hypoglycemic effect in malnourished rats and a lesser, but noticeable, blood glucose level reduction in well-fed animals. Glycerol caused a smaller reduction in glucose formation from Ala. No comparable effects were observed after a fructose pretreatment. These results underscore the potential hypoglycemic effects of phosphorylated glycerol metabolites and identify the steps in gluconeogenesis where this action is exerted. The study also stresses the nutritional component in the glycerol intolerance syndrome, apparent from the far more severe effects observed in malnourished rats given G3P or glycerol prior to Ala.
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PMID:Regulation of gluconeogenesis by glycerol and its phosphorylated derivatives. 298 19

The activities and zonal distribution of key enzymes of carbohydrate metabolism were studied in livers of diabetic rats. 48 h after alloxan treatment the following alterations were observed, intermediate values being reached after 24 h: Blood glucose, acetoacetate and beta-hydroxybutyrate were increased to more than 500%; liver glycogen was reduced to about 10%. Portal vein insulin was reduced to below 10%, portal glucagon was increased to almost 200%. The glucogenic enzymes phosphoenolpyruvate carboxykinase and glucose-6-phosphatase were enhanced to 320% and 150%, respectively. The glycolytic enzymes glucokinase and pyruvate kinase L (differentiated from the M2 isoenzyme with a specific anti-L-antibody) were lowered to 50% and 75%, respectively. The citrate cycle enzyme succinate dehydrogenase remained unchanged. The normal periportal to perivenous gradient of phosphoenolpyruvate carboxykinase of about 3:1, as measured in microdissected tissue samples, was enhanced to about 4:1 with activities elevated to 230% and 190%, respectively, in the two zones. The normal periportal to perivenous gradient of pyruvate kinase L of about 1:1.7, as determined with the microdissection technique, was reduced to about 1:1.4 with levels lowered to 55% and 45%, respectively, in the two zones. The even zonal distribution of pyruvate kinase M2 remained unaltered.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolic zonation in liver of diabetic rats. Zonal distribution of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphatase and succinate dehydrogenase. 298 84

The activities and zonal distribution of key enzymes of carbohydrate metabolism were studied in livers of rats after end-to-side portocaval anastomosis. Sham-operated control animals with the same periods of interruption of hepatic blood supply as the shunted animals were pair-fed. The following alterations were observed: Food uptake was reduced to about 20% at the first postoperational day; it was then increased continuously to about 70% at day 8. Body weight, after a small 10% postoperational decrease, remained unaltered, but liver weight was lowered to 55% at day 8 and then stayed constant. The total glycogen reserves of the liver (g X 100 g body weight-1) were reduced, after a transient fall to about 10% at day 1-4, to about 25%. The total activity of the glucogenic phosphoenolpyruvate carboxykinase (mumol . min-1 X 100 g body weight-1) was diminished, after a transient increase to 190% and 150% at day 1 and 2 respectively, to about 55% from day 8 onwards. The total activity of the glucogenic glucose-6-phosphatase was lowered without a transient rise to about 30%. The total activities of the glycolytic pyruvate kinase isoenzyme L and glucokinase were decreased continuously to about 40% at day 8; that of the citrate cycle enzyme succinate dehydrogenase was lowered parallel with liver weight to 55%. The transient decrease of the glycogen reserves and the intermediate increase of the phosphoenolpyruvate carboxykinase capacity were due to the operational stress, since they were observed also in the sham-operated control animals. All other alterations, the decrease of liver weight and of the capacities of both gluconeogenic and glycolytic key enzymes, were specific for the portocaval anastomosis. The normal periportal to perivenous gradient of phosphoenolpyruvate carboxykinase of about 3.5:1, as measured in microdissected tissue samples, remained the same with specific activities reduced to about 80% each in the two zones. The normal periportal to perivenous gradient of pyruvate kinase L of about 1:1.7 was equalized with levels lowered to 35% and 23%, respectively, in the two zones. The normal periportal to perivenous gradients of glucose-6-phosphatase and succinate dehydrogenase, demonstrated histochemically, were essentially maintained with perivenous bridging occurring transiently at day 4 and 8.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Glucostat capacity and metabolic zonation in rat liver after portocaval anastomosis. 299 14


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