Abstract:
:1. Diadenosine tetraphosphate (Ap4A) a dinucleotide stored and released from rat brain synaptic terminals presents two types of affinity binding sites in synaptosomes. When [3H]-Ap4A was used for binding studies a Kd value of 0.10 +/- 0.014 nM and a Bmax value of 16.6 +/- 1.2 fmol mg-1 protein were obtained for the high affinity binding site from the Scatchard analysis. The second binding site, obtained by displacement studies, showed a Ki value of 0.57 +/- 0.09 microM. 2. Displacement of [3H]-Ap4A by non-labelled Ap4A and P2-purinoceptor ligands showed a displacement order of Ap4A > adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-S) > 5'-adenylyl-imidodiphosphate (AMP-PNP) > alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP) in both sites revealed by the Ki values of 0.017 nM, 0.030 nM, 0.058 nM and 0.147 nM respectively for the high affinity binding site and values of 0.57 microM, 0.87 microM, 2.20 microM and 4.28 microM respectively for the second binding site. 3. Studies of the P2-purinoceptors present in synaptosomes were also performed with [35S]-ADP-beta-S. This radioligand showed two binding sites the first with Kd and Bmax values of 0.11 +/- 0.022 nM and 3.9 +/- 2.1 fmol mg-1 of protein respectively for the high affinity binding site obtained from the Scatchard plot. The second binding site showed a Ki of 0.018 +/- 0.0035 microM obtained from displacement curves. 4. Competition studies with diadenosine polyphosphates of [35S]-ADP-beta-S binding showed a displacement order of Ap4A > Ap5A > Ap6A in the high affinity binding site and Ki values of 0.023 nM, 0.081 nM and 5.72 nM respectively. The second binding site potency order was Ap5A> Ap4A > Ap6A,with Ki values of 0.28 microM, 0.53 microM and 5.32 microM respectively.5. Displacement studies of [35S]-ADP-beta-S with P2-purinoceptor agonists showed the following potency pattern: ADP-beta-S > AMP-PNP >alpha,beta-MeATP with Ki values of 0.021 nM, 0.029 nM 0.215 nM respectively in the high affinity binding site. 2-Methylthio-adenosine 5'-triphosphate (2MeSATP) was unable to displace [35S]-ADP-beta-S in this binding site. The second binding site showed a profile of ADP-beta-S> a,beta-MeATP> AMP-PNP > 2MeSATP and Ki values of 0.0 18 microM, 0.212 microM, 0.481 microM and 18.04 microM respectively.6. These studies suggest the presence of a new P2-purinoceptor in rat brain synaptosomes with high affinity for diadenosine polyphosphates which we tentatively designate as P2d.
journal_name
Br J Pharmacoljournal_title
British journal of pharmacologyauthors
Pintor J,Díaz-Rey MA,Miras-Portugal MTdoi
10.1111/j.1476-5381.1993.tb13510.xsubject
Has Abstractpub_date
1993-04-01 00:00:00pages
1094-9issue
4eissn
0007-1188issn
1476-5381journal_volume
108pub_type
杂志文章abstract::Cholesterol and oxysterol sulfates are important regulators of lipid metabolism, inflammation, cell apoptosis, and cell survival. Among the sulfate-based lipids, cholesterol sulfate (CS) is the most studied lipid both quantitatively and functionally. Despite the importance, very few studies have analysed and linked th...
journal_title:British journal of pharmacology
pub_type: 杂志文章,评审
doi:10.1111/bph.15227
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abstract::1. The effects of 5-hydroxytryptamine (5-HT) uptake inhibitors, agonists and antagonists have been evaluated on mouse marble-burying behaviour, a putative test for anxiolytic agents. The high levels of locomotor activity occurring on first exposure to a circular runway (runway were used as a separate test of non-speci...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1991.tb12392.x
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abstract::1 Subcutaneous administration of glucagon (1 and 0.5 mg/kg) 30 min before the injection of carrageenin or dextran into the rat's paw reduced oedema and the local exudation of Evans blue previously given intravenously. 2 The effect persisted after removal of the adrenal medulla but not after adrenalectomy. 3 When gluca...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1975.tb07611.x
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abstract::The vanilloid receptor (VR1) is a ligand-gated ion channel, which plays an important role in nociceptive processing. Therefore, a pharmacological characterization of the recently cloned rat VR1 (rVR1) was undertaken. HEK293 cells stable expressing rVR1 (rVR1-HEK293) were loaded with Fluo-3AM and then incubated at 25 d...
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doi:10.1111/bph.12160
更新日期:2013-06-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1038/sj.bjp.0700964
更新日期:1997-03-01 00:00:00
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journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1973.tb08339.x
更新日期:1973-02-01 00:00:00
abstract::1. The study was designed to test the hypothesis that nitric oxide (NO)-releasing compounds increase guanosine 3':5'-cyclic monophosphate (cyclic GMP) production in human polymorphonuclear leucocytes (PMNs) and concomitantly inhibit PMN functions, i.e. leukotriene B4 (LTB4) synthesis, degranulation, chemotaxis and sup...
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更新日期:1993-07-01 00:00:00
abstract::1. A study has been made of the effects of cocaine and sympathetic denervation on responses of the cat spleen to (-)-noradrenaline and (-)-isoprenaline.2. Responses of isolated strips of spleen capsule to (-)-noradrenaline or to (-)-isoprenaline were not affected by reserpine-pretreatment.3. In adult cats, cocaine (1 ...
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pub_type: 杂志文章
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更新日期:1973-08-01 00:00:00
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journal_title:British journal of pharmacology
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更新日期:1994-06-01 00:00:00
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更新日期:2003-05-01 00:00:00
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pub_type: 杂志文章
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更新日期:1999-11-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1988.tb11657.x
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abstract::1. We have investigated the effects of RP 73401, a novel, potent and highly selective cyclic nucleotide phosphodiesterase (PDE) type IV inhibitor, in guinea-pig and rat models of bronchoconstriction and allergic inflammation. In some models, the effects of RP 73401 have been compared with those of the standard PDE typ...
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doi:10.1111/j.1476-5381.1994.tb17156.x
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更新日期:1981-02-01 00:00:00
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更新日期:2004-11-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1111/bph.13616
更新日期:2016-12-01 00:00:00
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journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1993.tb12797.x
更新日期:1993-02-01 00:00:00
abstract::1. Involvement of cholinergic mechanisms in the contractile response to Leu13-motilin (LMT, KW-5139) was investigated in rabbit duodenal segments, and longitudinal muscle-myenteric plexus (LM-MP) preparations preincubated wtih [3H]-choline. 2. Contractile response to LMT (0.1 nM-1 microM) consisted of an initial rapid...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1993.tb13536.x
更新日期:1993-05-01 00:00:00
abstract::1. The aim of this study was to characterize the pharmacological profile of the GABA(B1)/GABA(B2) heterodimeric receptor expressed in Chinese hamster ovary (CHO) cells. We have compared receptor binding affinity and functional activity for a series of agonists and antagonists. 2. The chimeric G-protein, G(qi5), was us...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0703682
更新日期:2000-11-01 00:00:00
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journal_title:British journal of pharmacology
pub_type: 杂志文章,评审
doi:10.1038/sj.bjp.0707672
更新日期:2008-04-01 00:00:00