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:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infusion of adenosine into the coronary arteries of isolated guinea pig hearts produced a dose-dependent inhibition of dP/dtmax caused by bolus injections of isoproterenol (4 X 10(-11) moles). Threshold concentration of adenosine was 10(-7) M and maximal inhibition (90%) occurred at 10(-5) M. Coronary dilation induced by papaverine did not influence the contractile response to catecholamines. In addition to its influence on cardiac performance, adenosine (10(-5) M) effectively inhibited the isoproterenol (10(-7)M) induced initial rise in myocardial levels of cyclic 3'5'-AMP, glucose-1-phosphate and glucose-6-phosphate. Adenosine also antagonized the effect of isoproterenol on adenylate cyclase activity in a crude membrane preparation from guinea pig ventricles; it was without effect on the activity of the membrane phosphodiesterase. Theophylline inhibited the actions of adenosine both on adenylate cyclase activity and on contractile force development. Upon infusion of isoproterenol (3 X 10(-7)M) into the coronary arteries of the isolated heart (perfusion at constant pressure), the adenosine concentration in the effluent perfusate increased within 45 s from 10(-8) M to about 10(-6) M. It thus appears conceivable that in ventricular myocardium endogenously formed adenosine may serve 2 functions: dilation of the coronary arteries and limitation of the inotropic and metabolic effects of catecholamines.
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PMID:Adenosine as inhibitor of myocardial effects of catecholamines. 20 20

Muscle and blood metabolites, plasma insulin and cyclic adenosine 3',5'-monophosphate (cAMP) levels were investigated in five male runners before and after strenuous intermittent running exercise of short duration. Immediately after the exercise, the mean muscle creatine phosphate level (CrP) had fallen by 74% (P less than 0.02) and 30 min later the initial level was regained in only one subject. Other immediate results were increases in mean muscle lactate (460%, P less than 0.005), glucose (130%), glucose-6-phosphate (G6P, 320%) and fructose-1,6-diphosphate (FDP, 32%). Muscle ATP and glycogen concentration had decreased by 31 and 23% (P less than 0.05), respectively. However, ATP, glucose, G6P and FDP changes were not significant owing to the great individual variation. This may have been due to the different training programmes of the runners. Immediately after the exercise mean plasma insulin was 210% (P less than 0.01), blood glucose 71% (P less than 0.005) and plasma cAMP concentration 260% (P less than 0.01) higher than the pre-exercise values. After running urinary excretion of cAMP was 29% higher than before the exercise. It is concluded that exhaustive, short-term exercise activates the liver adenylate cyclase system so giving rise to an increased level of blood glucose, which is an important source of energy during this type of exercise.
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PMID:Muscle metabolism during and after strenuous intermittent running. 21 Apr 97

1. Investigation of the ionic requirements of the in vitro insulin release system, which consists of cod islet plasma membrane and rabbit islet granules incubated at pH 6.5, showed that the presence of Ca(2+) was obligatory for the system to operate.2. Glucose-initiated insulin release was as effective in the presence of beta-gamma-methylene ATP, as it was in the presence of ATP. This analogue of ATP is a substrate neither for adenylate cyclase nor for any known animal membrane proteases. The effect of ATP on glucose mediated release is allosteric.3. Glucose (16 mM)-initiated insulin release was slower than that induced by glucose-6-phosphate (4 mM); 150 and 120 sec, respectively.4. The lag found with glucose-mediated insulin release was dependent upon glucose concentration. The lower the glucose concentration, the longer the lag. With 1 mM glucose the lag extended to 30 min.5. Once insulin release was initiated, the rate and amount of insulin release was independent of the glucose concentration.6. Pre-incubation of membranes with Ca(2+), glucose and ATP prior to the addition of granules, abolished the extended lag that had been obtained with 1 mM glucose. Events in the plasma membrane are the major contributor to the generation of the extended lag.7. The glucose analogue 5'thio-D-glucose, although not able to release insulin, was shown to compete with glucose for the glucoreceptor. By increasing the ratio of analogue to glucose the lag time increased. Thus, the lag time is dependent upon the ;effective' external glucose concentration.8. The max. amount of insulin released by 4 ng of membrane in the presence of glucose (16 mM) was 300 ng. The fact that membranes became refractory to glucose after this max. amount of insulin was released showed that recycling of release sites was not taking place in vitro and that granule: granule interactions were not occurring.9. The 120 sec lag before glucose-6-phosphate-initiated release was independent of glucose-6-phosphate concentration. The rate of insulin release with glucose-6-phosphate was concentration dependent.10. Glucose-6-phosphate did not cause further insulin release from a membrane that had released the max. amount of insulin it was capable of in the presence of glucose. The addition of tolbutamide (10 mM) to such a membrane did cause insulin release. This suggests that glucose and glucose-6-phosphate share a final common pathway.11. Adrenaline and somatostatin did not inhibit glucose-mediated insulin release.
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PMID:An in vitro system for studying insulin release: effects of glucose and glucose-6-phosphate. 33 48

Glycogen content in the normal placenta decreases gradually towards term. However, in human diabetes and in rat streptozotocin diabetes two- to tenfold increases in placental glycogen level were found during the pregnancy. This elevation was evident in rats per tissue weight, protein or DNA content and was also seen in insulin-treated and gestational diabetics. Electron microscopic investigation of diabetic rat placenta revealed glycogen deposition in the typical glycogen cells, also in junctional zone cells and in all cells of the placental labyrinth. Placental glycogen accumulation in diabetes occurs in marked contrast to other tissues, such as maternal liver, from which glycogen disappears. Liver and muscle glycogenesis and glycogenolysis are under insulin control, by regulation of the activities of glycogen synthase and phosphorylase. However, in the placenta these enzymes are not meaningfully influenced by insulin in in vivo and in vitro studies. In our and other laboratories the activities of both enzymes somewhat increased or decreased, showing no trend conducive to glycogen accumulation. Placenta is glucose dependent, but the role of insulin in its carbohydrate metabolism is doubtful. Despite the high placental concentration of insulin receptors no metabolic outcome has yet been pointed out. Glycogen accumulation in the placenta of diabetic rats was found to be related to the extent of maternal hyperglycemia. The resultant markedly increased intracellular level of glucose-6-phosphate accelerates glycogen synthesis b. Glucose itself activates glycogen synthase and deactivates glycogen phosphorylase. Continuous glucose infusion to non-diabetic pregnant rats on gestation days 18-21 likewise also caused an increase in placental glycogen in correlation with hyperglycemia. The possibility that placental glycogen is under the control of fetal rather than maternal insulin was explored by producing insulin deficiency through intrafetal streptozotocin injection. There was no effect of fetal "diabetes" on placental glycogen synthesis or on the distribution of placental glycogen between the maternal and fetal segments of the placenta, while it caused a marked decrease in the fetal liver glycogen content and fetal body weight. To assess the availability of placental glycogen as an energy source the placental glycogenolysis was investigated after hormonal stimulation. Catecholamines were effective in inducing lactate formation both in vivo and in vitro in nondiabetic and diabetic rats. Protracted activation of the adenylate cyclase system by cholera toxin administration pronouncedly reduced placental glycogen in vivo.
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PMID:Placental glycogen metabolism in diabetic pregnancy. 183 20

Effect of collagen soluble forms of the I and III types on biosynthesis of DNA, RNA on activity of adenylate and guanylate cyclase as well as on activity of several key enzymes of energy metabolism was studied in bioptic samples of wound granulation tissue and in homogenates of intact rat liver tissue in vitro. Effects of the collagen soluble forms were shown to depend on their type and the step of wounds healing. Collagen of the III type stimulated DNA and RNA biosynthesis inhibited adenylate cyclase and activated guanylate cyclase within 3 days after the operation. Activities of lactate-, malate-, glucose-6-phosphate dehydrogenases and creatine phosphokinase were also dissimilarly altered in presence of collagens of the I and III types. The data obtained suggest that collagens of the I and III types affected dissimilarly the metabolic processes in wound tissues within various steps of their healing.
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PMID:[Differences between collagens of the the interstitial type and their effect on the biosynthesis of DNA and RNA and activity of various enzymes in biopsy specimens of wound tissues in rats]. 245 54

Changes in the contents of adenine nucleotides, creatine phosphate, inorganic phosphate, creatine, glucose-6-phosphate and glycogen and the activity of adenylate cyclase, creatine kinase, glycogen phosphorylase 31:51-AMP-phosphodiesterase and glycogen synthetase in muscles and of blood catecholamines were studied in adult rats before loading, immediately after the cessation of the muscular activity, and at rest. Adenine nucleotides are established to play a regulatory role in catabolic and anabolic processes nucleotides are established to play a regulatory role in catabolic and anabolic processes related to the muscular activity. It is established that compensation and supercompensation of the working losses of muscular creatine phosphate and glycogen are due to activation of anabolic processes under conditions of higher phosphorylation of the adenylic system.
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PMID:[Dependence of creatine kinase and glycogen synthetase activities of skeletal muscles on state of adenine nucleotide phosphorylation and cAMP metabolism]. 624 97

At the onset of pentylenetetrazole induced convulsions, the adenylate cyclase activity and phosphodiesterase activity were increased. The former was markedly stimulated in the brain stem of rats. In the cerebral cortex and brain stem, the glucose level was significantly decreased, and the concentration of glucose-6-phosphate was increased. However, the definite changes in energy reserve system of the brain could not be observed at the onset of penetylentetrazole induced seizures. The present study revealed some correlation between pentylenetetrazole convulsions and the adenylate cyclase activity and glycometabolism.
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PMID:Biochemical aspects of pentylenetetrazole induced seizure. 629 19

Space flight factors did not influence activity of glycogen phosphorylase and adenylate cyclase in skeletal muscles of rats. Activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases increased noticeably in the most active muscles (gastrocnemius and tibialis anterior muscles). Activation of enzymes involved in the pentosephosphate pathway of glucose conversion may be associated with compensatory processes induced by muscle changes due to diminished motor activity of animals in space flight.
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PMID:[Enzyme activity of carbohydrate metabolism in rat skeletal muscle after space flight]. 728 70

The formation of glycerol-3-phosphate (G3P) in cells growing on TB causes catabolite repression, as shown by the reduction in malT expression. For this repression to occur, the general proteins of the phosphoenolpyruvate-dependent phosphotransferase system (PTS), in particular EIIA(Glc), as well as the adenylate cyclase and the cyclic AMP-catabolite activator protein system, have to be present. We followed the level of EIIA(Glc) phosphorylation after the addition of glycerol or G3P. In contrast to glucose, which causes a dramatic shift to the dephosphorylated form, glycerol or G3P only slightly increased the amount of dephosphorylated EIIA(Glc). Isopropyl-beta-D-thiogalactopyranoside-induced overexpression of EIIA(Glc) did not prevent repression by G3P, excluding the possibility that G3P-mediated catabolite repression is due to the formation of unphosphorylated EIIA(Glc). A mutant carrying a C-terminally truncated adenylate cyclase was no longer subject to G3P-mediated repression. We conclude that the stimulation of adenylate cyclase by phosphorylated EIIA(Glc) is controlled by G3P and other phosphorylated sugars such as D-glucose-6-phosphate and is the basis for catabolite repression by non-PTS compounds. Further metabolism of these compounds is not necessary for repression. Two-dimensional polyacrylamide gel electrophoresis was used to obtain an overview of proteins that are subject to catabolite repression by glycerol. Some of the prominently repressed proteins were identified by peptide mass fingerprinting. Among these were periplasmic binding proteins (glutamine and oligopeptide binding protein, for example), enzymes of the tricarboxylic acid cycle, aldehyde dehydrogenase, Dps (a stress-induced DNA binding protein), and D-tagatose-1,6-bisphosphate aldolase.
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PMID:Glycerol-3-phosphate-induced catabolite repression in Escherichia coli. 1200 46

The metabolic regulation of Escherichia coli lacking a functional pykF gene was investigated based on gene expressions, enzyme activities, intracellular metabolite concentrations and the metabolic flux distribution obtained based on (13)C-labeling experiments. RT-PCR revealed that the glycolytic genes such as glk, pgi, pfkA and tpiA were down regulated, that ppc, pckA, maeB and mdh genes were strongly up-regulated, and that the oxidative pentose phosphate pathway genes such as zwf and gnd were significantly up-regulated in the pykF mutant. The catabolite repressor/activator gene fruR was up-regulated in the pykF mutant, but the adenylate cyclase gene cyaA was down-regulated indicating a decreased rate of glucose uptake. This was also ascertained by the degradation of ptsG mRNA, the gene for which was down-regulated in the pykF mutant. In general, the changes in enzyme activities more or less correlated with ratios of gene expression, while the changes in metabolic fluxes did not correlate with enzyme activities. For example, high flux ratios were obtained through the oxidative pentose phosphate pathway due to an increased concentration of glucose-6-phosphate rather than to favorable enzyme activity ratios. In contrast, due to decreased availability of pyruvate (and acetyl coenzyme A) in the pykF mutant compared with the wild type, low flux ratios were found through lactate and acetate forming pathways.
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PMID:Effect of a pyruvate kinase (pykF-gene) knockout mutation on the control of gene expression and metabolic fluxes in Escherichia coli. 1515 58


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