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)

When tracheas were isolated from rats pretreated with isoproterenol (ISO) or terbutaline, they were found to be considerably less sensitive to the relaxant action of ISO than tracheas which were isolated from saline-pretreated rats. The dissociation constant (Kb) for the propranolol-beta receptor complex was determined to be up to 400-fold larger in the tracheas isolated from beta agonist-pretreated rats (1.1 +/- 0.1 X 10(-6) M) than in tracheas isolated from saline-pretreated rats (3.0 +/- 0.3 X 10(-9) M). The longer the duration of pretreatment and the higher the dose of ISO or terbutaline used, the more attenuated was the response of tracheal smooth muscle to ISO, and the greater was the Kb for propranolol-beta receptor complex. These findings provide strong evidence which shows that desensitization, which occurs as a result of in vivo pretreatment with beta agonist drugs, results from pronounced reduction in this affinity of the beta receptors for beta agonist drugs. We observed that the in vivo treatment of rats with aminophylline (Amino), a phosphodiesterase inhibitor, did not affect the responsiveness of their isolated tracheas to either ISO or Amino. In addition, the responsiveness to Amino was determined in tracheal preparations taken from rats desensitized to ISO in vivo. The response to ISO was attenuated and the Kb for the propranolol-beta receptor complex was elevated (1.1 +/- 0.1 X 10(-6) M); however, Amino was half as effective in these tissues as in the saline control tissues. It is postulated, therefore, that the intracellular enzymes controlling the levels of cyclic adenosine monophosphate may be affected by the ISO-induced desensitization process, but are not affected by pretreatment with Amino.
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PMID:In vivo desensitization to beta receptor mediated bronchodilator drugs in the rat: decreased beta receptor affinity. 2 62

Adenylate cyclase activity as well as intracellular content of sAMP were decreased 2.5-4-fold, as compared with normal state, in plasmatic membranes (PM) of hepatoma 22 and of Ehrlich ascites carcinoma--the tumors characterized by high level- of malignancy. Activity of cAMP phosphodiesterase exceeded distinctly the normal value in all the tumors studied. In less malignant hepatoma 48 the adenylate cyclase activity and content of cAMP were similar to those found in normal liver cells. The guanylate cyclase activity did not differ markedly from values found in normal liver cells in PM of all the tumors studied and in liver tissue of the tumor-bearing animals. Distinct alterations were not found in content of cGMP in the tumors, except of hepatomas 60 and 22, in which the nucleotide level exceeded 2-fold the normal value. The ratio cAMP/cGMP was decreased in the most malignant tumors. At the same time, the ratio was distinctly elevated in tumors with the middle level of malignancy (hepatomas 60 and 61).
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PMID:[Concentration of cyclic nucleotides, activity of adenylate cyclase, 3',5'-AMP phosphodiesterase and guanylate cyclase in plasma membranes from liver and hepatomas of different degrees of malignancy]. 3 Feb 12

Cyclic AMP phosphodiesterase (PDE) in membrane fraction from rat cerebral cortex was activated by Triton X-100, and treatment at alkaline pH and with phospholipase C. These results suggest that membrane PDE exists in a latent form and is influenced by microenvironmental changes within the membrane. Furthermore, the PDE, unlike soluble enzyme, is not influenced by a protein activator and Ca++.
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PMID:Possible regulation of membrane-associated cyclic AMP phosphodiesterase in rat cerebral cortex by lipids. 3 Dec 95

1. Adenylate cyclase (EC 4.6.1.1) activity has been determined in the parotid and sublingual glands of the mouse. Optimal activity of the enzyme was obtained at a Mg2+-concentration of 8 mM at pH 8.2, using AMP-PNP as the substrate. 2. Cyclic AMP degradation during the adenylate cyclase assay was relatively high in both the homogenate and the 40,000 g pellet-fraction of the glands. Theophylline was effective in inhibiting this degradation only in the parotid hemogenate, whereas isobutylmethylxanthine inhibited the cyclic AMP degradation in both salivary glands. Using the latter phosphodiesterase inhibitor, we observed a higher adenylate cyclase activity in the sublingual glands than in the parotid glands. 3. Various receptor-selective sympathetic and parasympathetic agonists and antagonists have been tested for their capacity to influence the adenylate cyclase activity and the glycoprotein secretion in the parotid and sublingual glands of the mouse, in vitro. (a) The parotid glycoprotein secretion was increased by beta-adrenergic agonists, which stimulate adenylate cyclase, and by cholinergic muscarinic drugs, which do not activate this enzyme. The adrenergic alpha-agonist phenylephrine appeared to be involved neither in the glycoprotein secretion nor in the direct regulation of the adenylate cyclase activity. (b) The sublingual protein and mucin secretion was increased by cholinergic muscarinic agents. The over-all protein secretion was stimulated also by phenylephrine, but this effect could be blocked by propranolol. The adenylate cyclase activity in membrane preparations was not stimulated by these secretogogues.
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PMID:Comparison of adenylate cyclase activity and in vitro secretion in the parotid and sublingual glands of the mouse. 3 65

By sequential acid treatment, gel filtration and KM-cellulose sorption a 18--20-fold purified preparation of ribonuclease with a yield of 50--60% was obtained from the culture liquid filtrate of Actinomyces rimosus 994. The preparation had a high specific activity of 450,000--600,000 units/mg protein, contained 85--98% protein, insignificant amounts of carbohydrates and hydroxytetracycline, and no quantities of DNase, phosphomonoesterases, phosphodiesterase or proteases. In RNA degradation (preparation of the total yeast RNA of the Sigma Co.) optimal results were obtained at 50 degrees C and pH 7.0--7.2 in phosphate buffer and 7.6--8.0 IN Tris-HCl buffer. The preparation was stable at high temperatures (80--100 degrees) in the wide pH range and during storage in the lyophilized form and in buffer solutions. RNase effect was inhibited by zinc, copper, iron and cobalt cations and activated by beta-mercaptoethanol, citrate and EDTA. Protamine sulphate and urea in low concentrations (0.01% and 1--4 M, respectively) accelerated and in high concentrations (1% and 8 M, respectively) terminated the enzyme reaction. With respect to many properties RNase from Act. rimosus 994 was similar to extracellular RNases, produced by other actinomycetes and fungi.
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PMID:[Preparation of extracellular ribonuclease form Actinomyces rimosus 994]. 3 16

Phosphodiesterase activity of cultured cells was determined with bis-(4-methylumbelliferyl) phosphate as substrate. In the presence of Triton X-100 an acid component was evident and results indicated that this enzyme was identical with sphingomyelinase. Acid phosphodiesterase activity was specifically inhibited by sphingomyelin. In fibroblasts from patients with Niemann-Pick diseases types A, B and C, acid phosphodiesterase activity was deficient whereas neutral activity was normal. Neutral activity could, however, be removed by acid precipitation or by binding to DEAE-cellulose. Hence a simple and sensitive fluorimetric method is described for the assay of sphingomyelinase activity in the diagnosis of Niemann-Pick disease.
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PMID:Diagnosis of Niemann-Pick disease using a simple and sensitive fluorimetric assay of sphingomyelinase activity. 3 94

An acidic, low molecular weight (18 400--19 100) protein capable of activating porcine brain phosphodiesterase in the presence of calcium has been purified 2700-fold from the anthozoan coelenterate, Renilla reniformis. The protein has physical, spectral, and chemical properties similar to those of modulator proteins isolated from mammalian species. Amino acid composition studies reveal no significant differences between the Renilla and mammalian modulator proteins. For example, we observed 1 mol of epsilon-N-trimethyllysine per mol of protein, no tryptophan or cysteine, and high levels of glutamic and aspartic acid residues. The protein from Renilla complexes with troponin I and T subunits in the presence of calcium and quantitatively replaces porcine brain modulator in the calcium-dependent activation of porcine brain phosphodiesterase. The protein has a high affinity for calcium as judged by the low levels of free calcium required for modulator-dependent activation of phosphodiesterase. The similarities in physical and chemical properties, high affinity for calcium, and identical calcium-dependent activities of this protein from Renilla (as compared with modulator protein purified from mammalian systems) suggest that a high degree of structural conservation has been retained in modulator proteins isolated from these diverse evolutionary forms.
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PMID:Isolation and characterization of Ca2+-dependent modulator protein from the marine invertebrate Renilla reniformis. 3 94

The boiled supernatant fraction from rat cerebrum contained factors which inhibited the basal activity of a Ca2+-dependent phosphodiesterase from rat cerebrum. Two inhibitory fractions were isolated by DEAE-cellulose or Sephadex chromatography and were deemed proteins, based on their sensitivity to trypsin digestion. The inhibitory fractions eluted from DEAE-cellulose columns prior to the Ca2+-dependent activator protein. The inhibitory factors, unlike the activator protein, were stable to heat treatment under alkaline conditions. The inhibitory factors caused both an increase in Km for cyclic GMP and a decrease in V. In the presence of calcium ions and purified activator protein, the Ca2+-dependent phosphodiesterase was not inhibited by the factors, but instead was slightly stimulated. The inhibitory factors caused a slight apparent stimulation of a Ca2+-independent phosphodiesterase from rat cerebrum but this proved instead to be a nonspecific stabilizing effect which was minimicked by bovine serum albumin. After prolonged alkaline treatment, the purified activator protein caused a modest Ca2+-independent activation of Ca2+-dependent phosphodiesterase. The inhibitory factors antagonized the activation of Ca2+-dependent phosphodiesterase by alkaline treated activator protein or by lysophosphatidylcholine. The inhibitory factors had no effect on activity of trypsinized Ca2+-dependent phosphodiesterase. Of various other proteins, only casein mimicked the effects of the inhibitory factors on phoshodiesterase activity.
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PMID:Calcium-dependent cyclic nucleotide phosphodiesterase. Inhibition of basal activity by heat-stable factors from rat cerebrum. 3 21

Bronchial obstruction is mainly treated by bronchospasmolytics. They have different sites of action and work either by stimulating the beta-adrenergic receptors (beta-sympathicomimetics), by inhibiting the phosphodiesterase (theophylline-derivatives) or by blocking the cholinergic receptors (anticholinergica). Beta-sympathicomimetics do not only act via the beta-receptors but also by inhibiting the degranulation of the mast cells and thus preventing the liberation of spasmogenic substances. A very promising development is ipratropium bromide, an anticholinergic with a spasmolytic effect as pronounced as that of a beta2-adrenergic substance but with hardly any adverse side-effect. Glucocorticoids which are highly effective in bronchial asthma were shown to have also an "permissive effect" towards beta-sympathicomimetics.
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PMID:[New developments in the field of bronchospasmolytics]. 3 84

It is unclear what factors control the secretion of pulmonary surface active material from alveolar type II cells in vivo. Other workers have suggested that cholinergic stimuli, adrenergic stimuli, and prostaglandins may all stimulate secretion. We isolated type II cells from the lungs of rats by treatment with elastase, discontinuous density centrifugation, and adherence in primary culture. beta-Adrenergic agonists, but not cholinergic agonists, caused an increase in the release of [(14)C]disaturated phosphatidylcholine, the major component of surface-active material, from type II cells in culture. The beta-adrenergic effect was stereo-selective, (-)-isoproterenol being 50 times more potent than (+)-isoproterenol. Terbutaline, 10 muM, a noncatecholamine beta-2 adrenergic agonist, caused a release of 2.0+/-0.5 (mean+/-SD) times the basal release of [(14)C]disaturated phosphatidylcholine in 3 h; the concentration of terbutaline causing half maximal stimulation was 800 nM. The terbutaline effect was blocked by propranolol, a beta-adrenergic antagonist (calculated K(d) = 6 nM), but not by phentolamine, an alpha-adrenergic antagonist. Isobutylmethylxanthine, a phosphodiesterase inhibitor, and 8-Br cyclic AMP, but not 8-Br cyclic guanosine monophosphate, also stimulated release. We conclude that type II cells secrete disaturated phosphatidylcholine in response to treatment with adrenergic stimulation.
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PMID:Pulmonary alveolar type II cells isolated from rats. Release of phosphatidylcholine in response to beta-adrenergic stimulation. 3 31


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