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)

A method for isolating a plasma membrane-enriched fraction and other subcellular fractions from rat mesenteric arteries by the use of a discontinuous sucrose density gradient is decribed. Electron microscopy showed both plasma membrane and endoplasmic reticulum fractions to be composed of vesicles. 5'-Nucleotidase, alkaline phosphatase, ouabain-sensitive (Na+ + K+)-ATPase and K+-phosphatase, and phosphodiesterase I were concentrated in the plasma membrane fraction. The increase in ATP-dependent calcium uptake in the presence of oxalate was greater in the endoplasmic reticulum than in the plasma membrane fraction. The lack of inhibition of active calcium uptake by azide suggests that the plasma membrane-enriched fraction was relatively free of mitochondrial contamination. Calcium uptake by the plasma membrane or the endoplasmic reticulum fraction was not enhanced by high-energy compounds other than ATP, and was little affected by 100 mM KCl or NaCl in the Mg++-containing medium. Subcellular fractions isolated by this method will be useful for investigating the biochemistry of small blood vessels of the rat.
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PMID:Isolation and characterization of plasma membrane from rat mesenteric arteries. 18 63

1. The role of adenosine 3':5'-phosphate (cyclic AMP) and guanosine 3':5'-phosphate (cyclic GMP) as second messengers for the enzyme secretory response evoked by the autonomic neurotransmitters, noradrenaline and acetylcholine, is examined in this in vitro study on the guinea-pig submandibular gland. 2. Noradrenaline increased enzyme (kallikrein) secretion. The initial stimulation of enzyme release appeared to be dose-dependent. The time course of cumulative kallikrein secretion revealed a complex pattern. Isoprenaline and phenylephrine were almost as potent as noradrenaline in releasing kallikrein. Both propranolol and phentolamine were required to fully inhibit the noradrenaline-stimulated enzyme secretion. 3. The cumulative secretion of kallikrein evoked by acetylcholine was dose-dependent. The onset of secretion showed a significantly greater time-lag than that observed with noradrenaline. Atropine effectively blocked the release of kallikrein by acetylcholine. 4. Dibutyryl cyclic AMP stimulated enzyme secretion. Dibutyryl cyclic GMP caused an initial increase which was not maintained. 5. The cyclic nucleotide phosphodiesterase inhibitors, theophylline and papaverine, increased basal kallikrein secretion. The action of the cyclic phosphodiesterase inhibitors on the secretory response to noradrenaline, acetylcholine, dibutyryl cyclic AMP and dibutyryl cyclic GMP was complex. In general, the increase in enzyme release produced by the secretagogues was additively enhanced by both inhibitors. 6. Omission of calcium inhibited both acetylcholine and dibutyryl cyclic GMP stimulated kallikrein release, but to a lesser degree than that of noradrenaline and dibutyryl cyclic AMP. High concentrations of extracellular calcium (10 mM) appeared to enhance the action of acetylcholine. 7. Noradrenaline produced a rise in the intracellular level of cyclic AMP. The increase preceded the stimulated secretion of kallikrein. Of the various adrenergic agonists, noradrenaline and isoprenaline were the most potent, whereas phenylephrine was significantly less effective in raising basal cyclic AMP values. Acetylcholine was without effect, even in the presence of a cyclic phosphodiesterase inhibitor. 8. Acetylcholine and noradrenaline raised intracellular levels of cyclic GMP only when the tissue incubations were performed in the presence of a cyclic phosphodiesterase inhibitor. The increase in cyclic GMP produced by acetylcholine preceded enzyme secretion. 9. Morphological data substantiated the finding that the in vitro release of kallikrein evoked by the secretagogues was associated with the depletion of secretory granules and vacuolations in acinar cells of the gland slices. 10. The molecular mechanisms which control enzyme secretion in the exocrine submandibular gland are discussed. Models are presented for the role of transmitter-specific cyclic nucleotides and calcium in stimulus-secretion coupling.
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PMID:Stimulus-secretion coupling: role of cyclic AMP, cyclic GMP and calcium in mediating enzyme (kallikrein) secretion in the submandibular gland. 18 62

This research explored the possibility that cyclic nucleotides are part of the excitation-secretion sequence in mammalian motor nerve terminals. A series of reagents known to react with the enzymes that synthesize and degrade cyclic nucleotides or that are effectors of cyclic nucleotide actions were administered to in vivo cat soleus nerve-muscle preparations. The reagents were administered by rapid close intra-arterial injection while electrical activity in single motor axons and contractile activity of the muscle were monitored. NaF, an activator of adenylate cyclase, evoked bursts of action potentials in unstimulated axons and caused stimulus-bound repetitive activity in stimulated axons. It evoked vigorous asynchronous activity in the muscle and potentiated the force of muscle contraction. These effects are identical with those of cyclic N6-2'-O-dibutyryl adenosine 3':5'-monophosphate (dibutyryl cAMP). Prostaglandin E1 produced similar effects. Dithiobisnitrobenzoic acid and alloxan, inhibitors of adenylate cyclase, impaired neuromuscular transmission and prevented the effects of NaF, but they did not change the responses to dibutyryl cAMP. Theophylline, an inhibitor of phosphodiesterase, caused axons to respond repetitively to stimulation, but this activity had a different pattern from that produced by dibutyryl cAMP or NaF. Pretreatment with theophylline enhanced the responses to dibutyryl cAMP and NaF. Imidazole, an activator of phosphodiesterase, impaired neuromuscular transmission and prevented the effects of dibutyryl cAMP and NaF. Adenosine, an inhibitor of protein kinase, or verapamil, which inhibits calcium flux, impaired neuromuscular transmission and prevented the responses to dibutyryl cAMP, NaF and theophylline. These results are compatible with the hypothesis that cAMP is involved in the regulation of calcium flux and transmitter secretion in mammalian motor nerve terminals.
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PMID:A role of cyclic nucleotides in neuromuscular transmission. 18 85

Chlorphenesin inhibition of the hydrolysis of cyclic AMP by guinea-pig lung phosphodiesterase was reversed by the addition of exogenous magnesium ions. Chlorphenesin and theophylline inhibition of this enzyme was shown to be noncompetitive when the substrate concentration was low. Kinetic studies of the inhibition of beef heart phosphodiesterase by chlorphenesin and theophylline indicated that the substrate concentration was a factor in determining whether inhibition was competitive or noncompetitive. Calcium, cobalt and copper ions were inhibitory to guinea-pig lung phosphodiesterase. The inhibition due to chlorphenesin was partially reversed by low (40 mM or less) concentrations of barium ions; high concentrations of barium ions, or manganese ions, were inhibitory. The concentration of the divalent cation did not affect the type of inhibition that was observed.
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PMID:Interactions of chlorphenesin and divalent metal ions with phosphodiesterase. 18 30

The calcium ion concentration measured in rat kidney mitochondria, isolated from vasopressin treated tissue, has a dose response characteristic in which the calcium concentration reached a minimum at low doses of vasopressin (2 mU/ml), at higher doses of hormone the mitochondrial calcium ion concentration increases reaching a value close to that of the controls with vasopressin (100 mU/ml). This efflux and subsequent uptake of mitochondrial calcium has been shown to be a direct effect of the varying cyclic AMP concentrations. Sodium and water permeability effects of vasopressin have been shown in toad bladder to have different dose response characteristics. Maximum sodium transport occurs at a lower dose of vasopressin (2 mU/ml) and is believed to be associated with direct permeability effects of the hormone. Maximum water transport occurs at a higher dose of vasopressin (100 mU/ml) over a concentration range associated with hormone-stimulated adenylate cyclase activity. The water transport response to low doses of vasopressin may be potentiated by aldosterone treatment, an effect that can be related to the inhibition of tissue phosphodiesterase activity and subsequent increased cyclic AMP concentrations. In steroid depleted conditions the cyclic AMP medicate efflux of mitochondrial calcium ions, that occurs at low doses of vasopressin, may prevent the release of membrane bound calcium ions and thus inhibit the water permeability effect of the hormone. Higher levels of cyclic AMP reverse this inhibitory effect and give rise to an increased water flow. It is concluded that cyclic AMP and intracellular concentrations of calcium ion act as inter-related mediators of antidiuretic hormone action.
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PMID:Role of mitochondrial Ca2+ in antidiuretic hormone action. 18 79

Arterial endothelial cells, which are capable of phagocytizing carbon particles of the same size as beta- and pre-beta-lipoprotein, were found only in endothelial cells of arterial segments susceptible to atheromatous changes in susceptible animal species, and the distribution closely corresponded to the susceptibility. The distribution of such endothelial cells is dense in large arteries, in the openings to their branches, especially in downstream portions, of rabbits, hens, and cocks; however, the distribution is relatively scanty in arteries of rhesus monkeys and is very scanty in dogs. Carbon particles were also rare in the suckling rabbit and tended to increase with age. They were not found in Wistar rats but were found in spontaneously hypertensive rats, which showed a characteristically diffuse distribution, even in relatively small arteries. The carbon particles, phagocytized, were released to the subendothelial space but were difficult to pass through the internal elastic lamina and tended to stagnate there for more than one month. The authors therefore call these cells hyperreactive endothelial cells. Various vasoactive substances, such as angiotensin II, histamine, and serotonin, significantly enhanced the phagocytic activities of arotic endothelial cells in rabbits; epinephrine and norepinephrine also slightly enhanced these activities. Various smooth muscle relaxants, such as ATP, pyridinol carbamate (ATP synthesis-enhancing substance), cycli-AMP, dibutyryl cycli-AMP, phthalazinol (cyclic-AMP phosphodiesterase inhibitor), iproveratril (calcium entry-inhibiting substance), colchicine, and vinblastine, with their different modes of action, commonly inhibited phagocytic activities, a finding that suggests a significant role for contractile protein in the permeability problem of atherogenesis. The atheromatous lesions of cholesterol-fed rabbits exhibited a striking increase in hyperreactive endothelial cells, accompanied by a marked rise in the activity of low-Km cyclic-AMP phosphodiesterase activity in atheromatous lesions and adjacent muscular layers, especially in rabbits with rapidly progressing atheroma.
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PMID:Hyperreactive arterial endothelial cells: a clue for the treatment of atherosclerosis. 18 68

A Ca2+-activatable cyclic nucleotide phosphodiesterase from bovine heart can be eluted from a DEAE-cellulose column either in the free form by buffers containing 0.1 mM ethylene glycol bis(beta-aminoethyl ether)N-N,N'N'-tetraacetic acid (EGTA) or as a complex of the enzyme with its protein modulator by buffers containing 0.01 mM CaCl2. A purification procedure based primarily on the significantly different affinity of the two forms of the enzyme for DEAE-cellulose was developed for the purification of the enzyme from bovine heart. The procedure involves ammonium sulfate fractionation, three chromatographic steps on DEAE-cellulose, and gel filtration on Sephadex G-200 with a 5000-fold purification over the crude extract. The purified enzyme has a specific activity of 120 mumol of cAMP/mg/min, can be activated 5-fold by Ca2+, but is only 80% pure as judged by analytical disc gel electrophoresis. The purified enzyme is unstable but can be stabilized by addition of Ca2+ and the protein modulator; this is in contrast to the less pure preparations of Ca2+-activatable phosphodiesterase which are destabilized by the protein modulator in the presence of Ca2+.
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PMID:Purification of a Ca2+-activatable cyclic nucleotide phosphodiesterase from bovine heart by specific interaction with its Ca2+-dependent modulator protein. 18 13

The properties of adenylyl cyclase and cyclic nucleotide phosphodiesterases from GH-strains of rat pituitary tumor cells have been investigated. Adenylyl cyclase was inhibited by calcium ion and stimulated by fluoride ion, 5'-guanylylimidodiphosphate and by prior treatment of intact releasing hormone (TRH), which stimulates prolactin releasing hormone (TRH), which stimulates prolactin release and synthesis in GH-cells, did not cause a significant stimulation of adenylyl cyclase activity under a wide variety of assay conditions; under the same conditions, [3H]TRH bound to a previously characterized membrane receptor. GH-cells contain phosphodiesterase activity catalyzing the hydrolysis of cAMP which gives nonliner Lineweaver-Burk plots with apparent Km's for cAMP of 1.5 muM and 4mM. TRH did not affect the activity of cyclic nucleotide phosphodiesterase at high or low cAMP concentrations when added to broken cell preparations. Treatment of intact cells with TRH caused no changes in the total adenylyl cyclase and cyclic nucleotide phosphodiesterase activites within the first 2 h of incubation, when stimulation of prolactin release occurs, but did lead to slight decrease in adenylyl cyclase and the apparent low Km phosphodiesterase after 72 h of treatment.
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PMID:Adenylyl cyclase and cyclic nucleotide phosphodiesterases in GH-Strains of rat pituitary cells. 18 95

Phosphodiesterase activities for adenosine and guanosine 3':5'-monophosphates (cyclic AMP and cyclic GMP) were demonstrated in particulate and soluble fractions of rat anterior pituitary gland. Both fractions contained higher activity for cyclic GMP hydrolysis than that for cyclic AMP hydrolysis when these activities were assayed at subsaturating substrate concentrations. Addition of protein activator and CaCl2 to either whole homogenate, particulate or supernatant fraction stimulated both cyclic AMP and cyclic GMP phosphadiesterase activities. Almost 80% of cyclic AMP and 90% of cyclic GMP hydrolyzing activities were localized in soluble fraction. Particulate-bound cyclic nucleotide phosphodiesterase activity was completely solubilized with 1% Triton X-100. Detergent-dispersed particulate and soluble enzymes were compared with respect to Ca2+ and activator requirements and gel filtration profiles. Particulate, soluble and partially purified phosphodiesterase activities were also characterized in relation to divalent cation requirements, kinetic behavior and effects of Ca2+, activator and ethyleneglycol-bis-(2-aminoethyl)-N,N'-tetraacetic acid. Gel filtration of either sonicated whole homogenate or the 10500 X g supernatant fraction showed a single peak of activity, which hydrolyzed both cyclic AMP and cyclic GMP and was dependent upon Ca2+ and activator for maximum activity. Partially purified enzyme was inhibited by 1-methyl-3-isobutylxanthine and papaverine with the concentration of inhibitor giving 50% inhibition at 0.4 muM substrate being 20 muM and 24 muM for cyclic AMP and 7 muM and 10 muM for cyclic GMP, respectively. Theophylline, caffeine and theobromine were less effective. The rat anterior pituitary also contained a protein activator which stimulated both pituitary cyclic nucleotide phosphodiesterase(s) as well as activator-deficient brain cyclic GMP and cyclic AMP phosphodiesterases. Chromatography of the sonicated pituitary extract on DEAE-cellulose column chromatography resolved the phosphodiesterase into two fractions. Both enzyme fractions hydrolyzed cyclic AMP and cyclic GMP and had comparable apparent Km values for the two nucleotides. Hydrolysis of cyclic GMP and cyclic AMP by fraction II enzyme was stimulated 6--7-fold by both pituitary and brain activator in the presence of micromolar concentrations of Ca2+.
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PMID:Cyclic nucleotide phosphodiesterases from rat anterior pituitary. Characterization of multiple forms and regulation by protein activator and Ca+. 19 11

The response to combinations of gastric acid secretagogues was studied in isolated glands from the rabbit gastric mucosa in terms of changes in oxygen consumption and accumulation of the weak base aminopyrine (AP). The latter reflects the acid secreting status of the glands. The following secretagogues were investigated: histamine, carbachol, aminophylline and db-cAMP. The histamine respiratory dose-response curve was shifted to the left in the presence of the phosphodiesterase inhibitor aminophylline. Both ED-50 and maximum response were significantly increased. Histamine-induced AP accumulation was also strongly enhanced by aminophylline (5 X 10(-4) M). These results are consistent with the hypothesis that histamine stimulation of acid secretion is mediated by cyclic AMP. Carbachol-stimulated oxygen consumption could not be potentiated by aminophylline and the combined effect was only additive. The response to a combination of histamine and carbachol was a significant increase in oxygen consumption above what could be expected from an additive effect alone. Carbachol addition to glands prestimulated with histamine gave a rapid increase in the respiratory rate resulting in a new steady state level within 10-15 min, as compared with a time constant of about 40 min when both drugs were added simultaneously. Likewise AP accumulation increased more rapidly and reached a higher value after addition of histamine + carbachol as compared with histamine alone. The db-cAMP-stimulated oxygen consumption was in all respects equally affected by carbachol as was histamine stimulation. This indicates that the well known cholinergic potentiation of histamine stimulation is not due to an increased sensitivity of the histamine receptor but is of a more general nature. A mechanism involving intracellular availability of Ca2+ is proposed as one possible explanation of this potentiation.
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PMID:Potentiation by carbachol and aminophylline of histamine- and db-cAMP-induced parietal cell activity in isolated gastric glands. 19 Aug 65


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