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)

In human D384 astrocytoma cells, cyclic AMP accumulation can be conveniently studied after labelling of the adenosine triphosphate pool (15 fmol cell-1) with [3H]adenine. In this study, adenosine had a biphasic effect on cyclic AMP accumulation, which was scarcely altered by blocking adenosine uptake and metabolism. Low concentrations of adenosine led to an inhibition of cyclic AMP accumulation, and higher concentrations led to stimulation. No effect of adenosine on cyclic AMP was observed unless phosphodiesterase was inhibited by rolipram. The A1 receptor antagonist DPCPX attenuated the inhibitory phase of adenosine response, and enhanced the cyclic AMP accumulation induced by adenosine analogues. The cyclic AMP accumulation was stimulated by NECA greater than ADO greater than CGS 21680 greater than CV 1808 greater than CPA greater than or equal to CHA, indicating mediation by A2 receptors. The stimulatory effect of NECA was much more effectively blocked by the combined A1 and A2 receptor antagonist CGS 15943 (KB 4 nmol l-1) than by the A1 antagonist DPCPX (KB 110 nmol l-1). Treatment of the cells with pertussis toxin (0.2 microgram ml-1 for 2.5 h) potentiated the cyclic AMP response to adenosine analogues significantly. The cyclic AMP response to NECA was enhanced by the protein kinase C activator phorbol dibutyrate even after pertussis toxin treatment. By contrast, nanomolar concentrations of bradykinin, which increases Ca(2+)-levels and protein kinase C activity in D384 cells, reduced NECA-induced cyclic AMP accumulation in control and pertussis toxin-treated cells. Thus, D384 cells possess both A1 and A2 adenosine receptors influencing cyclic AMP in opposite directions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adenosine receptor-induced cAMP changes in D384 astrocytoma cells and the effect of bradykinin thereon. 131 54

The phosphorylation of the 2 major phenobarbital-inducible cytochrome P450 isoenzymes IIB1 and IIB2 was increased in intact hepatocytes by the action of the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP. Under these conditions cyclophosphamide and ifosfamide (which are known to be activated by cytochrome P450 IIB1) were investigated for mutagenicity in Salmonella typhimurium TA1535 and TA100 and for cytotoxicity in TA1535. Cyclophosphamide and ifosfamide were transformed to mutagenic and cytotoxic metabolites by the hepatocytes. The activation of both drugs to mutagens was markedly reduced after pretreatment of the hepatocytes with the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP. Cyclophosphamide and ifosfamide activation were reduced to 51% and 38% of unstimulated controls respectively, when hepatocytes were incubated for 1 h with N6,O2'-dibutyryl-cAMP in the presence of the phosphodiesterase inhibitor theophylline, and Salmonella typhimurium TA1535 was used. A marked reduction in mutagenicity of cyclophosphamide (35% compared with unstimulated controls) was also observed under different experimental conditions, namely after pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP for 1.5 h without theophylline and using Salmonella typhimurium TA100 as target strain. Continued presence of the cytochrome P450 IIB1 and P450 IIB2 inducer phenobarbital in the stimulation medium increased the mutagenicity of cyclophosphamide and led to an even more marked reduction of mutagenicity by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline. In order to investigate whether the observed changes were metabolism-related, the ifosfamide metabolite ifosfamide mustard which does not require metabolic activation by cytochrome P450 was studied under the same conditions. Its mutagenicity was indistinguishable after incubation with N6,O2'-dibutyryl-cAMP-treated or with unstimulated hepatocytes. Also the metabolic formation of cytotoxic metabolites from cyclophosphamide and ifosfamide but not that of ifosfamide mustard was markedly decreased by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline. Thus the stimulation of protein kinase A in intact cells has important consequences for the control of genotoxic and cytotoxic metabolites and represents a fast and short-term regulation of it.
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PMID:Modulation of the control of mutagenic metabolites derived from cyclophosphamide and ifosfamide by stimulation of protein kinase A. 217 Aug 35

DN-9693, c-AMP: phosphodiesterase inhibits platelet aggregation induced by metastasizing tumor cells and blood-borne metastases of these tumors. Effects of this drug on pulmonary metastases was studied in wKA rats, which were sc implanted with 4-dimethylaminoazobenzene (DAB) induced KDH-8 tumor cells. KDH-8 cells (10(5)) were sc inoculated on day 0 and excised on day 20. DN-9693 was ip injected at a dose of 150 micrograms twice a day for 7 days pre operatively (-7 - 0) or perioperatively (-3 - +3) or postoperatively (0 - +7). The rats were sacrificed on day 20 after surgery, and lung weight and the number of surface pulmonary nodules were measured. Both were significantly decreased in the group of perioperative and postoperative administration of DN-9693. The survival of these rats were furthermore prolonged when Cyclophosphamide (40 mg/kg) was sc injected 3 days after surgical resection. KDH-8 tumor cells (10(4)) were iv inoculated on day 0, and DN-9693 was ip injected at a dose of 150 micrograms twice a day for 7 days on day 0 approximately 7. Rats were sacrificed on day 20, and same studies as above were done. In this artificial pulmonary metastases, the decrease of the number of lung nodules was observed in WKA rat treated with DN-9693. Platelet aggregation induced by KDH-8 tumor cells was inhibited by ADP inhibitor (apyrase, CP/CPK) and thrombin inhibitor (heparin, MD-805); KDH-8 tumor cells induced platelet aggregation by two different mechanisms: ADP-mediated aggregation and thrombin-mediated aggregation. This platelet aggregation by KDH-8 tumor cells was inhibited by DN-9693 with dose-dependency. DN-9693 had no direct anti-tumor effects either in vivo or in vitro. The results indicates that this drug prevents pulmonary metastases by inhibiting platelet aggregation.
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PMID:[Effects of platelet aggregating inhibitor on pulmonary metastases of tumor cells after surgical resection]. 822 73

Adenosine causes airway obstruction in asthmatics and smokers. Theophylline and cromolyn, drugs used to treat these patients, bind to human lung adenosine receptors (ARs). This study investigated whether A1ARs and/or A2ARs are functionally present in human lung and airways, and whether theophylline and/or cromolyn antagonize their function. Peripheral lung or airway fragments from 21 people were incubated for 15 min with (1) an A1AR agonist, N6-cyclopentyladenosine (CPA, 5 to 1,000 nM), or (2) an A2AR agonist, either 5'-N-ethylcarboxamido adenosine (NECA, 0.5 to 20 microM) or 2-[p-(2-carboxyethyl)-phenethyl amino]-5'-N-ethylcarboxamido adenosine (CGS 21680, 0.5 to 28 microM), in the presence of the A1AR antagonist 8-cyclopentyl-1,3-dipropylxanthine (50 nM) and/or (3) theophylline (1 mM) and/or (4) cromolyn (500 microM). Adenosine deaminase (2 U/ml) and the phosphodiesterase inhibitor Ro 20-1724 (2 mM) were present in all incubations. Cyclic adenosine monophosphate (cAMP) was measured by radioimmunoassay. In peripheral lung, CPA did not change baseline or isoproterenol-stimulated cAMP content. However, both NECA (20 microM) and CGS 21680 (28 microM) significantly (P < 0.05) increased cAMP content 220 +/- 4% and 201 +/- 32%, respectively (mean +/- SEM). In airways, 20 microM NECA increased cAMP content 129 +/- 34%, and 28 microM CGS 21680 increased it 52 +/- 20% (both P < 0.05). In both peripheral lung and airway tissue, NECA-induced increase in cAMP was antagonized by theophylline (P < 0.05) but not cromolyn. The lungs of younger, nonsmokers had lower baseline cAMP content but did not respond differentially to A2AR stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of adenosine receptor ligands on cAMP content in human airways and peripheral lung. 839 27

This study characterized in rhesus monkeys the effects of selected adenosine agonists on ventilation during normal atmospheric conditions and during conditions of hypercapnia, hypoxia and hyperoxia. In seated, unanesthetized monkeys prepared with a head plethysmograph, ventilation during exposure to air, CO2 (3, 4 and 5%) mixed in air (hypercapnia), 10% O2 mixed in N2 (hypoxia) and 100% O2 (hyperoxia) was measured during cumulative dosing with each drug. The nonselective (A1/A2) agonist, 5'-N-ethylcarboxamidadenosine (NECA), the peripherally active, A2-selective agonist, CGS 21680 [2-(carboxyethylphenylamino)adenosine-5'-carboxamide], and the A1-selective agonists, N6-cyclohexyladenosine and N6-cyclopentyladenosine, increased respiratory frequency (f), but had no significant effect on minute volume (VE) during exposure to air. The relative potencies for increasing f corresponded closely with their potencies for binding at A2 receptors. NECA and CGS 21680 increased f in a dose-dependent manner during exposure to 3% CO2, but proportional increases in f were less pronounced as the concentration of CO2 increased. NECA and CGS 21680 also increased f during hypoxia, but neither had a significant effect on f during subsequent hyperoxia. The highest dose of CHA and CPA decreased f below control values during exposure to 5% CO2 and decreased f and VE during hyperoxia. In contrast, the adenosine antagonist, caffeine, and the selective phosphodiesterase inhibitor, rolipram, increased f and VE under all conditions. During hypercapnia, the magnitude of the increases in f was similar at each concentration of CO2 studied. Caffeine and rolipram increased f and VE during hypoxia, and f and VE remained elevated during hyperoxia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of adenosine agonists on ventilation during hypercapnia, hypoxia and hyperoxia in rhesus monkeys. 849 37

1. Strips of muscle from sheep bladder neck were set up for tension recording and subjected to electrical field stimulation (EFS) to stimulate their intramural nerves. 2. In the presence of atropine (1 microM) and guanethidine (1 microM), the response to 1 Hz EFS was biphasic, characterized by a relaxation during the stimulus period, followed by a post-stimulus contraction. A similar biphasic response was also seen following bolus application of nitric oxide (NO). 3. In the absence of atropine and guanethidine, the relaxations were masked by contractions during stimulation; however, the post-stimulus contraction were unaffected. L-NAME (100 microM) blocked the post-stimulus contractions and L-arginine (1 mM) restored them, suggesting that they were NO-mediated. 4. M&B 22948, a phosphodiesterase inhibitor, prolonged the relaxations and abolished the post-stimulus contractions. This suggests that rapid removal of cyclic GMP is required for post-stimulus contraction to occur. 5. When the number of pulses in the stimulus train was kept constant, the size of the post-stimulus contraction increased as the duration of the preceding period of stimulation increased. Maximal post-stimulus contractions were obtained following stimulation for > 40 s. 6. The L-channel antagonist, nifedipine (1 microM) and verapamil (1 microM), had little effect on the amplitude of the post-stimulus contractions. 7. In contrast, ryanodine-(8 microM) reduced the post-stimulus contractions by over 90%. Caffeine (20 mM) also abolished the post-stimulus contractions and cyclopiazonic acid (CPA, 10 microM) reduced them by 76%. However, in the presence of CPA a slower post-stimulus contraction developed. Nifedipine (1 microM) reduced this by 40%. 8. In conclusion, these results support a role for NO in the post-stimulus contraction of the sheep bladder neck muscle. The post-stimulus contraction depends more on release of intracellular Ca2+, than Ca2+ influx through L-type channels.
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PMID:Characteristics of the NANC post-stimulus ('rebound') contraction of the urinary bladder neck muscle in sheep. 858 Dec 84

1. Either intrathecal (i.t.) or intracerebroventricular (i.c.v.) administration of morphine alone at the dose of 0.2 microgram slightly increased inhibition of the tail-flick response. However, combined i.t. and i.c.v. injections of morphine at the same dose increased the inhibition of the tail-flick response in a synergistic manner. 2. Cholera toxin (CTX, 0.05 to 0.5 microgram) pretreated i.t. or i.c.v. for 24 hr or pertussis toxin (PTX, 0.05 to 0.5 microgram) for 6 days dose-dependently attenuated inhibition of the tail-flick response induced by combined i.t. and i.c.v. injection of morphine. 3. 3-Isobutyl-1-methylxanthine (IBMX, 0.001 to 0.1 ng) pretreated i.t. for 10 min dose-dependently attenuated the inhibition of the tail-flick response induced by combined i.t. and i.c.v. injections of morphine. However, IBMX pretreated i.c.v. for 10 min was not effective in attenuating the inhibition of the tail-flick response induced by combined i.t. and i.c.v. injections of morphine. 4. It is concluded that both spinal and supraspinal CTX- and PTX-sensitive G-proteins are involved in the antinociception produced by morphine-induced multiplicative interaction between spinal and supraspinal sites. However, only spinal but not supraspinal cAMP phosphodiesterase is involved in mediating antinociception induced by morphine-induced multiplicative interaction.
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PMID:Multiplicative interaction between intrathecally and intracerebroventricularly administered morphine for antinociception in the mouse: effects of spinally and supraspinally injected 3-isobutyl-1-methylxanthine, cholera toxin, and pertussis toxin. 869 Feb 52

1. The cold (4 degrees C) water swimming stress (CWSS) for 3 min significantly increased the inhibition of the tail-flick response in ICR mice. 2. Pertussis toxin (PTX, 0.05-0.5 microgram) in mice pretreated intrathecally (IT) for 6 days attenuated the inhibition of the tail-flick response induced by CWSS. However, intracerebroventricular (ICV) pretreatment with PTX at the same doses did not affect CWSS-induced inhibition of the tail-flick inhibition. 3. 3-Isobutyl-1-methylxanthine (IBMX, 0.01-1 ng) in mice pretreated IT for 10 min dose-dependently attenuated the inhibition of the tail-flick response induced by CWSS. However, IBMX in mice ICV pretreated ICV at the same doses was not effective in attenuating the CWSS-induced inhibition of the tail-flick response. 4. Neither IT nor ICV pretreatment with cholera toxin (CTX, 0.05-0.5 microgram) for 24 hr affected the inhibition of the tail-flick response induced by CWSS. 5. The ICV or IT injection of PTX, CTX, or IBMX did not affect the basal tail-flick response latency. 6. It is concluded that spinal, but not supraspinal, PTX-sensitive G-proteins and cAMP phosphodiesterase may be involved in the antinociception produced by CWSS. However, neither spinal nor supraspinal CTX-sensitive G-proteins appear to be involved in mediating the antinociception induced by CWSS.
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PMID:Effects of spinally and supraspinally injected 3-isobutyl-1-methylxanthine, cholera toxin, and pertussis toxin on cold water swimming stress-induced antinociception in the mouse. 914 32

1. The aim of the present study was to investigate the role of adenosine A2b receptors in the anti-proliferative action of theophylline in human peripheral blood mononuclear cells (HPBMC) from healthy and asthmatic subjects. 2. Theophylline significantly inhibited PHA-induced proliferation of HPBMC from both healthy and asthmatic donors but only at relatively high concentrations at 1 mM (P<0.05). Enprophylline, a drug which also acts as a non-selective phosphodiesterase (PDE) inhibitor and is a selective A2b receptor antagonist, had no significant effect on proliferation of cells from either group at concentrations up to 10 microM (P>0.05; n=6). 3. Adenosine deaminase (2 u ml(-1)), which metabolizes adenosine, had no significant effect on PHA-induced HPBMC proliferation over a range of concentrations (0 - 8 microg ml(-1)) in cells from either healthy or asthmatic subjects. 4. The adenosine receptor agonists N(6)-cyclopentyladenosine (CPA, A1-selective) and 5'-N-ethylcarboxamidoadenosine (NECA, A1/A2) produced a small but significant inhibition of PHA-induced proliferation of HPBMC from healthy and asthmatic subjects (10 microM, P<0.05; n=6). In contrast, 5'-N-ethylcarboxamido-2-[4-(2-]carboxyethyl)phenethyl]adenosine (CGS21680, A2a-selective) was without significant effect (P>0.05; n=6). 5. The adenosine receptor antagonist alloxazine (A2b-selective) had no significant effect, while 8(3-chlorostyryl)caffeine,(CSC, A2a-selective) significantly inhibited PHA-induced proliferation of HPBMC from both groups (P<0.05; n=6). 6. Our results suggest that endogenous or exogenous adenosine has little effect on the proliferation of HPBMC obtained from healthy or asthmatic subjects. Thus it would appear that the effect of high concentrations of theophylline is not related to adenosine receptor antagonism.
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PMID:The role of adenosine receptors in the action of theophylline on human peripheral blood mononuclear cells from healthy and asthmatic subjects. 1072 62

1. Intracellular recordings were made from guinea-pig olfactory cortical brain slice neurones to assess the possible role of intracellular Ca(2+) stores in the generation of the slow post-stimulus afterdepolarization (sADP) and its underlying tail current (I(ADP)), induced by muscarinic receptor activation. 2. Caffeine or theophylline (0.5 - 3 mM) reduced the amplitude of the I(ADP) (measured under 'hybrid' voltage clamp) induced in the presence of the muscarinic agonist oxotremorine-M (OXO-M, 10 microM) by up to 96%, without affecting membrane properties or muscarinic depolarization of these neurones. 3. The L-type Ca(2+) channel blocker nifedipine (1, 10 microM) also inhibited I(ADP) (by up to 46%), while ryanodine (10 microM) (a blocker of Ca(2+) release from internal stores) produced a small ( approximately 10%) reduction in I(ADP) amplitude; however, neither 10 microM dantrolene (another internal Ca(2+) release blocker) nor the intracellular Ca(2+) store re-uptake inhibitors thapsigargin (3 microM) or cyclopiazonic acid (CPA, 15 microM) affected I(ADP) amplitude. 4. IBMX (100 microM), a phosphodiesterase inhibitor, also had no effect on I(ADP). Furthermore, inhibition of I(ADP) by caffeine was not reversed by co-application of 100 microM adenosine. 5. Caffeine (3 mM) or nifedipine (10 microM) reduced the duration of presumed Ca(2+) spikes revealed by intracellular Cs(+) loading. When applied in combination, nifedipine and caffeine effects were occlusive, rather than additive, suggesting a common site of action on L-type calcium channels. 6. We conclude that Ca(2+)-induced Ca(2+) release (CICR) from internal stores does not contribute significantly to muscarinic I(ADP) generation in olfactory cortical neurones. However caffeine and theophylline, which enhance CICR in other systems, blocked I(ADP) induction. We suggest that this action might involve a combination of L-type voltage-gated Ca(2+) channel blockade, and a direct inhibitory action on the putative I(ADP) K(+) conductance.
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PMID:Investigation of the role of intracellular Ca(2+) stores in generation of the muscarinic agonist-induced slow afterdepolarization (sADP) in guinea-pig olfactory cortical neurones in vitro. 1074 1


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