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:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tolazoline (2-benzyl-2-imidazoline) activated adenylate cyclase in pig epidermal slices resulting in the accumulation of cyclic AMP. This effect was highly potentiated by the addition of the cyclic AMP-phosphodiesterase inhibitor, theophylline. Specific histamine (H2) receptor inhibitors (metiamide and cimetidine) completely blocked the tolazoline activation of adenylate cylase. At low concentrations (10-100 micrometer), a histamine (H1) receptor inhibitor (diphenhydramine) and a beta-adrenergic blocker (propranolol) did not inhibit this effect. The stimulation of cyclic AMP formation by the combination of tolazoline and histamine was about the same as the stimulation by histamine alone (nonadditive), whereas the stimulatory effects by tolazoline and epinephrine were additive. These data suggest that tolazoline, an alpha-adrenergic blocker, also activates adenylate cyclase at the histamine (H2) receptor site which is distinct from the beta-adrenergic receptor site. Another alpha-adrenergic blocker, phentolamine, did not have this effect.
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PMID:Epidermal adenylate cyclase: stimulation of the histamine (H2) receptor by tolazoline. 19 80

The effect of somatostatin on insulin release by incubated slices of rat pancreas was studied. Somatostatin inhibited insulin release induced by arginine/glucose (A/G), glucagon, glibenclamide, pentoxifyllin, 3',5'-adenosine monophosphate (cAMP), phentolamine, and KCl. When A/G was used as a stimulus, the quantial inhibitory effect of somatostatin was not neutralized by progressively increasing glucose concentrations. The alpha adrenergic blocking agent phentolamine, the phosphodiesterase inhibitors theophylline (10 mM) or pentoxifyllin (10 mM), and KCl partially reversed the inhibitory effect of somatostatin on A/G stimulation. The maximal reversal of somatostatin inhibition was obtained when the slices of pancreas were stimulated with A/G in the presence of the calcium ioniphore A23187 plus ATP. These results suggest that the inhibitory effect of somatostatin on insulin secretion could result from calcium translocation in pancreatic beta cells.
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PMID:Studies on the mode of action of somatostatin on insulin secretion. 19 19

The extreme sensitivity of chicken muscle fructose 1,6-bisphosphatase to inhibition by 5'-AMP has been utilized to develop a new method for the assay of cAMP phosphodiesterase activity. In this method, the substrate (cAMP) is first incubated with phosphodiesterase and the amount of 5'-AMP formed is then determined by measuring the degree of inhibition of fructose 1'6-bisphosphatase activity. The present method conveniently employs the spectrophotometric technique and is sensitive enough to detect the conversion of 50 pmol of cAMP to 5'-AMP in 1 ml of reaction mixture. This method is considered particularly valuable for those laboratories that are not equipped with facilities for measuring radioactivity.
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PMID:A new method for measurement of cyclic AMP phosphodiesterase activity. 19 81

The effect of lithium on cyclic 3',5'-adenosine monophosphate formation from precursor [8-14C]-adenine in guinea pig and rat brain slices and its influence on cAMP phosphodieesterase activity were studied. It was demonstrated that lithium stimulated cAMP formation in brain slices in correlation to its concentration. In guinea pig brain slices it stimulated cAMP formation in the presence of neurotransmitters and a phosphodiesterase inhibitor (histamine less than norepinephrine less than 5-OH-tryptamine). In rat brain slices, norepinephrine was also more effective than histamine. Phosphodiesterase inhibition was demonstrated only in preparations in which Triton X 100 was used.
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PMID:Effect of lithium on cyclic 3',5'-adenosine monophosphate formation in brain slices and its influence on phosphodiesterase. 20 Feb 49

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

A preparation of poly(adenosine diphosphoribose) synthase obtained from pigeon liver nuclei has been used to make poly(adenosine diphosphoribose) with an average chain length of 20. Digestion of the purified poly(adenosine diphosphoribose) with snake venom phosphodiesterase (oligonucleate 5'-nucleotidohydrolase; EC 3.1.4.1) gave the monomer, 2'-(5"-phosphoribosyl)-5-AMP. After purification of the monomer on a Dowex-1 column, further digestion with alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1] yielded the dephosphorylated product, 2'-ribosyl adenosine. Nuclear magnetic resonance spectra at 360 MHz of the 2'-ribosyl adenosine were obtained in [2H6]dimethylsulfoxide, which allows direct observation of the hydroxyl protons. These spectra show the absence of the adenosine 2'-hydroxyl proton, thus confirming the 2' position as the site of attachment of the ribose to the adenosine moiety. Comparison of the coupling constants and the chemical shifts of the ribose hydroxyl protons of 2'-ribosyl adenosine with the model compounds alpha- and beta-methylribofuranoside establishes an alpha (1" leads to 2') glycosidic linkage in the monomer. No evidence was found for heterogeneity in either the site of attachment or configuration of the linkage in the 2'-(5"-phosphoribosyl)-5'-AMP.
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PMID:Structure of a poly (adenosine diphosphoribose) monomer: 2'-(5"-hosphoribosyl)-5'-adenosine monophosphate. 20 34

Using the uninvolved and involved skin from psoriatic patients, we investigated the effects of histamine and AMP (or adenosine) in vitro on the intracellular cyclic AMP levels. Both agents activated adenylate cyclase of the uninvolved and involved resulting in the accumulation of cyclic AMP. Without a cyclic nucleotide phosphodiesterase (PDE) inhibitor, these responses were biphasic and the maximal accumulation was observed in 5 min. With the PDE inhibitor both responses were markedly potentiated and high levels of cyclic AMP were observed for more than 20 min. The response to histamine by the involved skin was much greater than that by the uninvolved. The degree of the response to adenosine was approximately equal. In accordance with our previous work, the response to epinephrine by the involved skin was much less than that by the uninvolved. Thus adenylate cyclases of involved skin from psoriatic patients exhibit a markedly diminished response to epinephrine while at the same time exhibiting a markedly enhanced response to histamine. This precludes the possibility that the unresponsiveness to epinephrine can be due to a generalized inability of the epidermal psoriatic plaque cell to make a functioning cell membrane.
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PMID:Cyclic AMP accumulation in psoriatic skin: differential responses to histamine, AMP, and einephrine by the uninvolved and involved epidermis. 20 16

In the course of an investigation into the mode of action of phenylephrine using the radioimmunoisotope method, its influence on levels of cyclic 3'5'-AMP in the heart of rats was studied. Phenylephrine in the dose of 1 microgram/kg/min after five minutes lowered levels of this nucleotide by about 20%. Phenylephrine also inhibited the influence of theophyline, an inhibitor of phosphodiesterase which raises levels of c-AMP. The results suggest that the drop in c-AMP after phenylephrine is connected with lowered activity of adenyl cyclase, but do not exclude the possiblity of an interaction between theophylline and phenylephrine acting on phosphodiesterase, which could be referred to the observed effect.
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PMID:Influence of phenylephrine on levels of cyclic 3',5'-AMP in the heart of rats in vivo. 20 23

The adenylate cylcase (AC) and phosphodiesterase (PDE) activities, as well as the 3'5'-AMP (cAMP) fund were studied in the liver of newborn rats, intact, and after irradiation on the 9th day of the embryonic development. A decrease of AC and PDE activities was noted with a dose of 50 r. The stationary level of cAMP in the tissue remained unchanged. The adrenaline-stimulated AC activity only tended to decrease in case of irradiation. As suggested, during critical periods of development, in the presence of the hormone inductor in the liver of irradiated rats, conditions can be created for an increase of the cAMP pool.
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PMID:[Hepatic adenosine-3',5'-monophosphate metabolism in newborn rats irradiated during the period of organogenesis]. 20 38

1. A soluble phosphodiesterase is present in mammalian tissues which rapidly hydrolyses enantiomorphs of rac-glycerol 1:2-cyclic phosphate, producing rac-glycerol 1-phosphate. 2. The enzyme has been purified up to 1700-fold by a combination of acetone precipitation and chromatography on DEAE-Sephadex A-50, Sephadex G-150 and hydroxyapatite. 3. The Km with glycerol cyclic phosphate as substrate is 7.2 mM, and the pH optimum broad (6.9--7.5). The molecular weight (by gel filtration) of the enzyme is approx. 35500. 4. The phosphodiesterase has no requirement for Ca2+ or Mg2+, but is stimulated by reducing agents (cysteine, dithiothreitol) and Fe2+. 5. The purified phosphodiesterase preparation also hydrolysed 3':5'-cyclic AMP, producing 5'-AMP exclusively, and 2':3'-cyclic AMP, forming 3'-AMP and 2'-AMP in the ratio 7:3. Bis-(p-nitrophenyl) phosphate was slowly hydrolysed, but other phosphodiesters tested were not attacked. 6. The phosphodiesterase is inhibited by theophylline and o-phenanthroline. It is inhibited by Pi and by a variety of phosphomonoesters, of which certain aromatic primary phosphates are particularly effective.
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PMID:rac-Glycerol 1:2-cyclic phosphate 2-phosphodiesterase, a new soluble phosphodiesterase of mammalian tissues. 21 14


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