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)

Derivatives of adenosine 3',5'-cyclic phosphate (cAMP) with modifications in both the 2' and the 8 positions were synthesized and their enzymic activities as activators of cAMP-dependent protein kinase and as substrates for and inhibitors of cAMP phosphodiesterases were determined. Three types of derivatives were investigated: 8-substituted derivatives of O2'-Bt-cAMP, 8-substituted derivatives of 9-beta-D-arabinofuranosyladenine 3',5'-cyclic phosphate (ara-cAMP), and 8-substituted derivatives of 8,2'-anhydro-9-beta-D-arabinofuranosyladenine 3,'5'-cyclic phosphate (8,2'-anhydro-cAMP). The 8-substituted O2'-Bt-cAMP derivatives were synthesized by acylation of the preformed 8-substituted cAMP (8-HS-cAMP, 8-MeS-cAMP, and 8-PhCH2S-cAMP). 8-Br-O2'-tosyl-cAMP was sued as an intermediate for the preparation of 8,2'-anhydro-cAMP derivatives (8-HO-, 8-SH-, 8-H2N-, and 8-H3 CHN derivatives of 8,2'-anhydro-cAMP). 8-Substituted ara-cAMP derivatives were obtained by ring opening of 8-HO-8,2'-anhydro-cAMP with H+/H2O, NH3/MeOH, or MeONa/MeOH (to yield the 8-HO-, 8-H2N-, and 8-MeO-ara-cAMP derivatives). All of these doubly modified derivatives of cAMP are less than one-hundredth as active as cAMP at activating protein kinase and did not serve as substrates for the phosphodiesterase. These data show that the general inactivity of 2' derivatives of cAMP with kinase was not overcome by addition of an 8-substituent, even though many 8-substituted derivatives of cAMP activate the kinase more efficiently than does cAMP itself. In addition they show that while 2'-modification were tolerated by the phosphodiesterase, addition of an 8-substituent countermanded the allowable 2'-modification. The 8-substituted derivates of 02'-Bt-cAMP were found in general to be slightly better inhibitors of phosphodiesterase than the parent compounds containing no o2'-Bt substitution. As a group, the 8-substituted ara-cAMP derivatives were poorer inhibitors of phosphodiesterase than 8-substituted cAMP derivatives while the 8,2'-anhydro-cAMP derivatives were much poorer inhibitors than the 8-substituted ara-cAMP derivatives.
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PMID:8-Substituted derivatives of adenosine 3',5'-cyclic phosphate require an unsubstituted 2'-hydroxyl group in the ribo configuration for biological activity. 17 Sep 58

The radioactive adenosine 3',5'-monophosphate (cyclic AMP) level derived from 8-14C adenine in intact rabbit platelets decreased in the presence of mitochondrial inhibitor (potassium cyanide) or uncoupler (sodium azide), and markedly increased by the addition of NaF, monoiodoacetic acid (MIA), or 2-deoxy-D-glucose. The stimulative effect of the glycolytic inhibitors was distinctly enhanced by the simultaneous addition of sodium succinate. MIA did neither directly stimulate the adenyl cyclase activity nor inhibit the phosphodiesterase activity. These results suggest that cyclic AMP synthesis in platelets is closely linked to mitochondrial oxidative phosphorylation.
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PMID:Dependence of platelet adenyl cyclase system on oxidative phosphorylation. 17 98

Although beta-oxidation of fatty acids occurs in both peroxisomes and mitochondria, beta-oxidizing enzymes in these organelles have distinct differences in their specifity and sensitivity to inhibitors. In this study, the effects of the phosphodiesterase inhibitor enoximone on hepatic peroxisomal and mitochondrial beta-oxidation were investigated. In liver homogenates from control rats, cyanide-insensitive peroxisomal beta-oxidation of palmitoyl-CoA was inhibited progressively by increasing concentrations of enoximone. Similar results were obtained in liver homogenates from rats pretreated with the known peroxisomal proliferator diethylhexylphthalate. In contrast, mitochondrial beta-oxidation of palmitoyl-CoA was not inhibited by enoximone. These data show that enoximone selectively inhibits basal as well as induced peroxisomal, but not mitochondrial, beta-oxidation of the CoA thioester of long-chain fatty acids. The availability of specific inhibitors of peroxisomal beta-oxidation should prove useful in elucidating regulatory mechanisms operative in this pathway in normal as well as in proliferated peroxisomes.
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PMID:Selective inhibition of hepatic peroxisomal fatty acid beta-oxidation by enoximone. 153 8

Rapid, unidirectional Ca2+ influx was examined in isolated brown adipocytes by short incubations (30 s) with 45Ca2+. Ca2+ uptake was found to be large in the resting brown adipocyte, but was markedly inhibited when the cells were presented with norepinephrine. Specific alpha 1-adrenergic stimulation was without effect on Ca2+ uptake. The effect of norepinephrine (which had an EC50 of 140 nM) could be inhibited by beta-adrenergic blockade and could be mimicked by forskolin (an adenylate cyclase activator) and theophylline (a phosphodiesterase inhibitor). Exogenous free fatty acids such as octanoate and palmitate (classical stimulators of respiration in brown adipocytes) were also able to dramatically inhibit Ca2+ uptake by the cells. The artificial mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) induced a large reduction in cellular Ca2+ uptake (even in the presence of the ATPase inhibitor oligomycin), and in the presence of FCCP the inhibitory effect of norepinephrine on Ca2+ uptake was significantly reduced. The effect of beta-adrenergic stimulation on Ca2+ uptake was not directly caused by the large increase in respiration that occurs in response to norepinephrine because the respiratory inhibitor rotenone did not affect the Ca2+ response of the cells to the hormone. The evidence suggests that beta-adrenergic stimulation of brown adipocyte metabolism leads to a partial inhibition of Ca2+ uptake into the mitochondrial Ca2+ pool and we discuss the possibility that this represents the effect of a reduced membrane potential (and thus reduced Ca2+ uniport activity) in the partially uncoupled mitochondria of the thermogenically active brown adipocyte.
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PMID:Beta-adrenergic modulation of Ca2+ uptake by isolated brown adipocytes. Possible involvement of mitochondria. 283 96

To examine the involvement of Na+ ions in adrenergic responses in brown adipose tissue, a method is described for measuring Na+ influx into isolated brown adipocytes, using short (30 s) incubations with 22Na+, followed by a two-step centrifugation recovery procedure. Using this method, a clear norepinephrine-stimulated accumulation of intracellular 22Na+ was observed, which was enhanced by the addition of ouabain, was insensitive to amiloride (a Na+/H+ exchange blocker), and could not be mimicked by the total removal of oxygen from the incubation medium. The norepinephrine-stimulated Na+ influx was dose-dependent for the hormone with an EC50 of 250 nM, was blocked by the beta-antagonist propranolol but not by the alpha 1-antagonist prazosin, and could be induced by adrenergic agonists with the order of potency: isoproterenol greater than norepinephrine greater than phenylephrine, indicating a beta-receptor-mediated process. The Na+ influx was found to be cAMP-dependent since it could be induced by both theophylline (a phosphodiesterase inhibitor) and forskolin (an adenylate cyclase activator), but it was independent of other known cellular cAMP-dependent responses since neither addition of fatty acid substrates (octanoate or palmitate), nor of the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone could induce the phenomenon, despite having significant stimulatory effects on cellular respiration. Furthermore, total respiratory inhibition with rotenone, or total oxygen depletion of the medium with dithionite, did not prevent the normal norepinephrine-induced Na+ influx. The possibility that this beta-mediated norepinephrine-stimulated Na+ influx plays an important physiological role in brown adipose tissue activity is discussed, perhaps as one of the, as yet undefined, signals initiating tissue growth in the chronically beta-stimulated tissue of animals facing long-term increases in thermogenic demands.
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PMID:Norepinephrine-induced Na+ influx in brown adipocytes is cyclic AMP-mediated. 302 38

The changes in the cytosolic concentration of free calcium of adult rat cardomyocytes were monitored using aequorin incorporated by hypoosmotic shock. The majority of the myocytes retained their rod-like appearance and their tolerance to a normal concentration of extracellular calcium. The aequorin signal was increased by depolarization, by an increase in extracellular calcium, by substitution of extracellular sodium with either choline or tetramethylammonium, by 20 mM NH4Cl or by hypoxia. In these myocytes, isoproterenol or the phosphodiesterase inhibitor MIX (3-isobutyl-l-methylxanthine) enhanced the ability of the cells to buffer calcium loads while the mitochondrial inhibitor FCCP (carbonyl cyanide p-trifluoromethoxy-phenyl-hydrazone), decreased their calcium buffering capacity.
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PMID:Measurement of cytosolic calcium with aequorin in dispersed rat ventricular cells. 383 23

In order to resolve discrepancies in the literature concerning the subcellular localization of NADPH oxidase, we disrupted human neutrophils by nitrogen cavitation and fractionated the subcellular organelles on a discontinuous sucrose density gradient. The lightest fraction was 20- to 40-fold enriched for plasma membranes as determined by the marker enzymes alkaline phosphatase and phosphodiesterase I as well as by the ratio of lipid phosphorus to protein. There was a significant decrease in the specific activities of the granule markers myeloperoxidase, lysozyme, and beta-glucuronidase. An intermediate fraction was enriched in membrane markers but not to the extent the lightest fraction was enriched. This fraction contained more granular contamination, as shown by the marker enzymes. In contrast, the densest bands of the gradient were enriched for granule markers with little contamination by plasma membrane. Superoxide generation and NADP formation were primarily associated with the two membrane-enriched fractions from polymorphonuclear leukocytes stimulated with phorbol myristate acetate. The NADP formation associated with a dense granule fraction observed previously in our laboratory was probably due to a cyanide-stimulated oxidation of NADPH by myeloperoxidase.
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PMID:Co-localization of superoxide generation and NADP formation in plasma membrane fractions from human neutrophils. 609 76

[2-Cyano-3-(methylamino)phenylamino]oxoacetic acid, sodium salt (Wy-41,195) was found to be a potent oral inhibitor (viz., ED50, 0.3 mg/kg) of IgE-mediated release in the rat passive cutaneous anaphylaxis (PCA) model and was very effective by the aerosol and oral route in the rat passive lung anaphylaxis model. High doses (25-50 mg/kg p.o.) were effective when administered up to 180 min before antigen challenge in the rat PCA model. The compound had minimal phosphodiesterase activity and demonstrated no bronchodilator or antihistamine activity. In the dog, Wy-41,195 inhibited histamine-induced reflex bronchoconstriction but had little effect on Ascaris-induced bronchoconstriction. No significant ancillary pharmacology was observed for Wy-41,195 except for inhibition of gastric secretion in the rat. The compound is relatively nontoxic and possesses a very high therapeutic index (greater than 10 000). Activity in these animal systems indicates that Wy-41,195 may hold promise in the treatment of bronchial asthma and other allergic diseases in man.
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PMID:The pharmacologic profile of wy-41,195, a new orally effective antiallergic agent. 618 61

1. Acid extrusion through Na(+)-H+ exchange was studied in the sheep cardiac Purkinje fibre (bathed in Hepes-buffered solution, nominally free of CO2-HCO3-) by examining (i) intracellular pH (pHi) recovery from an intracellular acid load (induced by 20 mM NH4Cl prepulse) and (ii) the rate of rise of intracellular Na+ activity (aiNa) following the ammonium prepulse (used as an estimate of apparent Na+ influx on Na(+)-H+ exchange). The pHi and aiNa were recorded using ion-selective microelectrodes. 2. The pHi recovery and rise of aiNa were both greatly slowed in the presence of 2-deoxyglucose (DOG; glucose-free solution), an inhibitor of glycolysis, indicating inhibition of Na(+)-H+ exchange. 3. Cyanide moderately slowed pHi recovery rate but did not significantly affect the rise of aiNa. Estimates of beta 1 (intracellular buffering power) indicated an increase of approximately 50% in the presence of cyanide; such an increase accounts for most of the observed slowing of pHi recovery. It is concluded that oxidative inhibition with cyanide does not inhibit Na(+)-H+ exchange. 4. Intracellular ATP, measured from luciferin-luciferase luminescence, was reduced by a similar amount (approximately 70%) by either DOG or cyanide. This suggests that, if intracellular ATP (ATPi) reduction is the cause of exchanger inhibition by metabolic inhibitors, then ATPi generated glycolytically is more important for activation of the exchange. 5. 3-Isobutyl-1-methylxanthine (IBMX; a non-specific phosphodiesterase inhibitor which can elevate intracellular [cAMP]) slowed acid extrusion and reduced apparent Na+ influx by a similar amount, whereas addition of sodium nitroprusside (to elevate intracellular [cGMP]) had no effect, suggesting that raising intracellular [cAMP] downregulates Na(+)-H+ exchange, whereas raising intracellular [cGMP] does not. 6. Application of trifluorperazine (TFP; a non-specific calcium-calmodulin inhibitor) completely reversed the inhibitory effects of IBMX upon pHi recovery and aiNa. Under control conditions (no IBMX), TFP had no effect on pHi recovery or upon resting pHi. 7. The phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) had no significant effect on pHi recovery or apparent Na+ efflux. 8. We conclude that inhibition of glycolysis or elevation of cAMP produces downregulation of Na(+)-H+ exchange in the cardiac Purkinje fibre. Possible reasons for the lack of inhibitory effect of oxidative inhibitors are discussed.
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PMID:Effect of metabolic inhibitors and second messengers upon Na(+)-H+ exchange in the sheep cardiac Purkinje fibre. 752 44

The ED50 value of cyanide as measured by induction of convulsions (tonic seizure) was significantly increased by 80% or 69% when trifluoperazine (TFP) or chlorpromazine (CHP), a specific calmodulin inhibitor was preinjected intracerebroventricularly (i.v.t.) at a dose of 0.09 mumol/body of mice. However, the ED50 of cyanide was not significantly changed by the same dose of promethazine (PMZ), another calmodulin inhibitor. Since it is known that the inhibitory effect of TFP or CHP against calmodulin-dependent enzymes such as phosphodiesterase is 100-400-fold higher compared to PMZ, it is speculated that the inhibitory effect of TFP or CHP against cyanide-induced convulsions may be based on its strong inhibitory properties into calmodulin-dependent enzymes. On the other hand, the LD50 value of cyanide was significantly increased by i.v.t. preadministration of TFP or CHP (0.045 mumol/body). Furthermore, the LD50 value of cyanide was also significantly increased by the same dose of PMZ. These results suggest that there is no positive correlation between mortality and convulsions induced by cyanide.
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PMID:Protective effect of calmodulin inhibitors against acute cyanide-induced lethality and convulsions in mice. 842 23


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