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)

The mechanism of the inotropic effect of piroximone HCl [MDL 19205A, 4-ethyl-1,3-dihydro-5-(4-pyridinylcarbonyl)-2H-imidozol-2-on e HCl] was studied in the cat papillary muscle paced electrically in vitro. Piroximone produced a concentration-dependent positive inotropic effect accompanied by an increase in rate of contraction and rate of relaxation, but abbreviated time to peak tension and relaxation time. The positive inotropic effect produced by piroximone was antagonized by carbachol, 3 X 10(-6) M, whereas that produced by increasing calcium concentration was not affected by carbachol. In potassium chloride (22 mM) depolarized muscle, piroximone restored contractility, which was not affected by propranolol (10(-6) M) or by tetrodotoxin (2 X 10(-5) M), but was inhibited by nifedipine (10(-7) M). Piroximine also elevated tissue cyclic AMP (cAMP) content in the papillary muscle. Although nifedipine inhibited the restoration of contractility, it did so without altering the increase of cAMP produced by piroximone. These results suggest that piroximone causes an increase in calcium influx that is mediated by an increase in cAMP, and the results are consistent with the hypothesis that specific inhibition of the high affinity cAMP phosphodiesterase (PDE III) plays a role in the positive inotropic effect of piroximone.
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PMID:Studies on the mechanism of the positive inotropic effect of piroximone in cat papillary muscle. 241 Jul 17

The effects of pimobendan (UD-CG 115 BS) and UD-CG 212 Cl (2-(4-hydroxy-phenyl)-5-(5-methyl-3-oxo-4,5-dihydro-2H-6- pyridazinyl)benzimidazole X HCl) on force of contraction, beating frequency, and on adenylate cyclase and phosphodiesterase activity were investigated in isolated preparations from guinea-pig hearts. Both benzimidazole derivatives exerted a concentration-dependent positive inotropic effect in guinea-pig papillary muscles. The efficacies were similar to that of dihydroouabain. The positive inotropic effect of both benzimidazoles was accompanied by an enhancement of the rate of force development and a prolongation of the contraction. Both benzimidazole derivatives inhibited phosphodiesterase (PDE) activity in a crude preparation from guinea-pig ventricles. However, at the concentrations producing maximal positive inotropic effects in papillary muscles, pimobendan and UD-CG 212 Cl diminished PDE activity only by about 20-30%. Since both benzimidazoles did not affect adenylate cyclase in a particulate membrane preparation a stimulation of the cAMP synthesis can be ruled out. As recently reported for pimobendan, this study provides functional evidence that the positive inotropic effect of UD-CG 212 Cl is also at least partially mediated by cAMP. Firstly, the positive inotropic effect of UD-CG 212 Cl was inhibited by carbachol, adenosine and (-)-N6-phenyl-isopropyladenosine. Secondly, UD-CG 212 Cl potentiated the inotropic effects of isoprenaline and histamine. UD-CG 212 Cl had no positive chronotropic effect and pimobendan increased the beating frequency only slightly.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of the benzimidazole derivatives pimobendan and 2-(4-hydroxy-phenyl)-5-(5-methyl-3-oxo-4,5-dihydro-2H-6- pyridazinyl) benzimidazole . HCl on phosphodiesterase activity and force of contraction in guinea-pig hearts. 241 46

The effect of thiazinamium Cl (TCl) on histamine release from rat peritoneal mast cells (RPMC) was investigated. Although TCl inhibited compound 48/80-induced histamine release moderately (IC50 value 40 microM), the drug was a weaker inhibitor of ovalbumin-induced histamine release (100 microM, -21%). In contrast, promethazine HCl (PHCl) was more effective against antigen-induced histamine release (IC50 value 13 microM) than against compound 48/80-induced histamine release (100 microM, -53%). Disodium cromoglycate (DSCG) was effective against both antigen and compound 48/80-induced release of histamine with IC50 values of 7 and 1 microM, respectively. Neither TCl nor DSCG at 1 mM increased spontaneous release of histamine from RPMC, whereas PHCl induced spontaneous release by over 50% at 1 mM. TCl did not inhibit phosphodiesterase (PDE) activity in guinea pig lung at 1 mM, whereas theophylline and DSCG inhibited PDE with IC50 values of 1.1 and 0.32 mM, respectively. These data suggest that high local concentrations of TCl may reduce histamine release during an asthmatic attack and improve its effectiveness as a bronchoprotectant.
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PMID:Effects of thiazinamium chloride on histamine release from rat peritoneal mast cells and on phosphodiesterase activity in guinea pig lung. 243 Aug 93

The effects of chloroquine on calmodulin (CaM)-related enzyme activities and the shape of human erythrocytes have been studied. It was found that the CaM activation of rat brain phosphodiesterase was abolished by the addition of chloroquine. CaM was included in the assay of phosphodiesterase activity at the concentration that gave half-maximal activation. The concentration of chloroquine that caused 50% inhibition of CaM stimulation of phosphodiesterase was 7 X 10(-5)M. The type of inhibition was competitive with respect to CaM. The CaM-stimulated Ca2+, Mg2+-ATPase in erythrocyte membrane was also inhibited by chloroquine, the 50% inhibitory concentration of which was about 2 X 10(-4)M. Its mode of action was also competitive with respect to CaM. The shapes of erythrocyte ghosts prepared by hypotonic hemolysis were examined in a solution consisting of 2 mM MgCl2, 154 mM NaCl and 10 mM Tris-HCl (pH 7.4); they were discocytic in the presence of 2 mM ATP and in its absence. They were converted to the invaginated form by the addition of chloroquine in the concentration range of 1 X 10(-4)-5 X 10(-4)M. This concentration is similar to that which caused the inhibition of CaM activation of Ca2+, Mg2+-ATPase.
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PMID:Inhibition of calmodulin stimulation of phosphodiesterase and Ca2+, Mg2+-ATPase activities and shape change of erythrocyte ghosts by chloroquine. 296 Mar 25

Griseolic acid, a potent inhibitor of cyclic adenosine 3',5'-monophosphate phosphodiesterase, was isolated from the fermentation broth of Streptomyces griseoaurantiacus SANK 63479. Treatment of griseolic acid with HCl-MeOH gave adenine and pseudo-sugar. The structure of griseolic acid, adenine nucleoside type structure, was elucidated by chemical degradation and X-ray analysis, and was shown to be structure 1.
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PMID:Griseolic acid, an inhibitor of cyclic adenosine 3',5'-monophosphate phosphodiesterase. II. The structure of griseolic acid. 299 19

The phosphodiesterase inhibitor and putative antidepressant rolipram (0.3-30 mg/kg i.p.) stimulated the accumulation of dopa following inhibition of the aromatic amino acid decarboxylase with 3-hydroxybenzylhydrazine HCl dose-dependently in all brain regions investigated, suggesting that both dopamine and noradrenaline synthesis was enhanced. The stimulatory effect of rolipram on dopa accumulation in dopamine rich regions persisted even after pretreatment with gamma-butyrolactone which by itself increased dopa accumulation three fold. Following inhibition of catecholamine synthesis with alpha-amethyl-p-tyrosine rolipram accelerated the disappearance of noradrenaline and slowed the disappearance of dopamine. At low doses rolipram tended to reduce the pargyline-induced accumulation of 3-methoxytyramine. Rolipram attenuated the accumulation of 5-hydroxytryptophan in the neocortex and the diencephalon of 3-hydroxybenzylhydrazine HCl pretreated rats. The data suggest that rolipram enhances noradrenergic transmission by direct stimulation of tyrosine hydroxylase and by an increase of neuronal activity. Despite a stimulatory effect on tyrosine hydroxylase rolipram does not appear to alter dopamine release and metabolism to a large extent. In view of the occurrence of head-twitches the rolipram-induced reduction of 5-hydroxytryptamine metabolism may be due to feedback inhibition.
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PMID:Effects of rolipram, a novel antidepressant, on monoamine metabolism in rat brain. 403 44

A macromolecule binding 3H-methylcholanthrene (3H-MCA) and 3H-benzo(a)pyrene (3H-BaP) and sedimenting in the 4-5 S region of sucrose gradient (4.5 S) was identified in rat liver cytosol. The binding was displaced by 100-fold molar excess unlabeled ligands whereas 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) was ineffective. The dissociation constant for both polycyclic aromatic hydrocarbons (PAHs) was of the order of 10(-8) M or lower. Both 3H-MCA and 3H-BaP bound to 4.5 S in a non covalent manner, since 92% of the bound radioactivity was extractable with ethyl ether. Furthermore the binding was strongly reduced by urea 8 M and by guanidine. HCl 4 M (99 and 70% respectively). Thin layer chromatography of the ethyl ether-solubilized radioactivity showed a peak comigrating with PAHs used as standards. When chromatographed on Sephadex G-200, 4.5 S was eluted as a sharp peak with an apparent molecular weight of 50-60,000 daltons. Enzyme treatment of liver cytosol showed that the 4.5 S binding sites were destroyed by micrococcal nuclease (92% of inhibition). Papain and phosphodiesterase I and II reduced the binding to 50%, whereas DNase I, DNase II, RNase, phospholipase A2 and C and trypsin were ineffective. These data suggest that the PAHs binding macromolecule of rat liver cytosol is a protein associated with a polynucleotide. The binding of both PAHs was enhanced by increasing the incubation temperature, the maximum being reached after 20-30 min at 37 degrees C. After 2.5 min at 65 degrees C, binding sites were completely destroyed. The same temperature-induced "activation" was obtained also by prewarming the cytosol at 37 degrees C in the absence of ligands.
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PMID:Polycyclic aromatic hydrocarbon binding macromolecules. Identification, characterization and temperature activation of a 4.5 S binding nucleoprotein. 406 Feb 44

Brief pressure injections of aqueous solutions of cAMP in identified neurons of Helix pomatia caused depolarizations which lasted for tens of seconds. In voltage-clamped neurons an inward current of similar duration was induced which saturated at 10 microA/cm2 cell surface. In the range of negative membrane potentials with little voltage-dependent activation, this current was not accompanied by a change in membrane conductance. The inward current was not produced by injection of ATP, ADP, adenosine, inosine or cGMP. cAMP derivatives produced longer-lasting effects. Prolongation of the inward current was also observed after inhibition of the phosphodiesterase by IBMX. Drugs which block active transport had no effect on the response to cAMP injection. The inward current depended on extracellular sodium, and was maximal when all other mono- and divalent cations were replaced by Na+. The cAMP-induced current was accompanied by a transient increase in [Na+]i, but there was no change in [Cl-]i. Li+ could largely substitute for Na+; Ca2+ was less effective. Addition of Mg2+ or Ca2+ to solutions containing a high Na+-concentration inhibited the response. Internal acidification with HCl reversibly enhanced the inward current. These data indicate that the depolarizing effect of cAMP can be accounted for by an inward movement of Na-ions, and that the effect is augmented by H+-ions.
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PMID:Stimulation of a sodium influx by cAMP in Helix neurons. 619 63

The assay for cyclic nucleotide phosphodiesterase has been applied, with certain modifications, to the measurement of the soluble forms of these enzymes in the rat testis. The homogenization and incubation conditions were adjusted to achieve linear product formation as a function of time and protein concentrations and the resulting products were isolated by ion exchange chromatography using 5 mM HCl as the eluting agent. Phosphodiesterase activities were present in the testicular cytosol (105,000 g supernatant) of adult rats which were capable of hydrolyzing cAMP with a high (Km2 microM) and low Km20 microM) affinity and GMP with a relatively high affinity (Km3 microM). The low affinity cAMP enzyme activity could be stimulated with divalent ions such as calcium, magnesium, and manganese. At 18 days of age, all three enzyme activities were present in the testis, although both the high and low affinity cAMP phosphodiesterase displayed maximal rates (Vmax) that were only one third of the adult testis (when expressed per mg protein).
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PMID:Testicular cyclic nucleotide phosphodiesterase in the rat. Kinetic properties and changes with age. 626 77

Guinea pig epidermal DNAase I was purified from an epidermal extract by a procedure including DEAE-cellulose chromatography, Sephadex G-100 gel filtration and Con A-Sepharose affinity chromatography. The purified enzyme contained no detectable activities of acid DNAase, alkaline RNAase, phosphodiesterase or acid or alkaline phosphatase, but was contaminated with acid RNAase activity. The molecular weight of the enzyme was estimated to be 33 000 by sucrose density gradient centrifugation and Sephadex G-100 gel filtration. Its isoelectric point is 5.2 +/- 0.1. The enzyme requires divalent cations and exhibits two pH optima that are dependent on divalent cations: in the presence of Mn2+, the optimum pH is about 7.5 in 50 mM Tris-HCl buffer and in the presence of Mn2+, the pH is 6.4 in 50 mM cacodylate-HCl buffer. The enzyme hydrolyzes native DNA about 6-times faster than denatured DNA, producing 5'-phosphoryl and 3'-hydroxyl terminated oligonucleotides with an average chain length of about eight nucleotides, and converts double-stranded and circular DNA to relaxed and linear forms. The enzyme is inhibited by G-actin and antiserum against bovine pancreatic DNAase A. Thus this enzyme is classified as DNAase I.
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PMID:Purification and properties of a neutral endodeoxyribonuclease from guinea pig epidermis. 627 8


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