bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding of the prototypical adenosine A2A receptor agonist CGS 21680 to the cerebral cortex of adenosine A1 and A2A receptor knockout mice
Authors: Lopes Luísa V , Halldner Linda , Rebola Nelson , Johansson Björn , Ledent Catherine , Chen Jian Fan , Fredholm Bertil B , Cunha Rodrigo A 
Published: March 2004

2‐p‐(2‐carboxyethylphenethylamino‐5′‐ethylcarboxamidoadenosine) (CGS 21680) is considered the reference compound to study adenosine A2A receptors. However, CGS 21680 binding in the cerebral cortex, where adenosine A1 receptors are predominant, displays a mixed A2A/A1 receptor pharmacology. We now use adenosine A1 and A2A receptor knockout mice to investigate the characteristics of cortical [3H]CGS 21680 binding.
[3H]CGS 21680 binding to the cerebral cortex was strongly reduced in adenosine A1 receptor knockout mice, but only slightly reduced in A2A receptor knockout mice compared with the corresponding wild‐type littermates.
Another selective A2A receptor ligand, [3H]‐5‐amino‐7‐(2‐phenylethyl)‐2‐(2‐furyl)‐pyrazolo[4,3‐e]‐1,2,4‐triazolo[1,5‐c]pyrimidine ([3H]SCH 58261), displayed a saturable binding to mouse cortical membranes, albeit with a binding density 20 times lower than that of striatal membranes, and this [3H]SCH58261 binding was abolished in both striatal and cortical membranes of A2A receptor knockout mice and unchanged in A1 receptor knockout mice.
The presence of A2A receptors in cortical neurons was further confirmed by Western blot in mouse cortical nerve terminal membranes.
It is concluded that, although A2A receptors are present in the cerebral cortex, the purportedly selective A2A receptor agonist [3H]CGS 21680 binds in the cerebral cortex to an entity that requires the presence of adenosine A1 receptors. Thus, CGS 21680 should be used with care in all preparations where adenosine A1 receptors out‐number A2A receptors.

British Journal of Pharmacology (2004) 141, 1006–1014. doi:10.1038/sj.bjp.0705692
Selectivity of 3H‐MADAM binding to 5‐hydroxytryptamine transporters in vitro and in vivo in mice; correlation with behavioural effects
Authors: Larsen A K , Brennum L T , Egebjerg J , Sánchez C , Halldin C , Andersen P H 
Published: March 2004

Binding of the novel radioligand 3H‐2‐(2‐dimethylaminomethyl‐phenylsulphanyl)‐5‐methyl‐phenylamine (3H‐MADAM) to the serotonin transporter (SERT) was used to characterise a range of selective serotonin re‐uptake inhibitors (SSRIs) in vitro and in vivo.
3H‐MADAM bound with high affinity in a saturable manner to both human SERT expressed in CHO cells (Kd=0.20 nM (pKd=9.74±0.12), Bmax=35±4 fmol mg−1 protein) and mouse cerebral cortex membranes (Kd=0.21 nM (pKd=9.66±0.10), Bmax=50±24 fmol mg−1 protein).
Binding of 3H‐MADAM was highly selective for SERT in vitro as demonstrated by the in vitro profile of MADAM tested at 75 different receptors, ion channels and transporters. This was further substantiated by the pharmacological profile of the binding. Hence, the binding of 3H‐MADAM was potently inhibited by SSRIs but not by selective inhibitors of noradrenaline transport and dopamine transport. Likewise, a 5‐HT2A/2C receptor antagonist did not inhibit 3H‐MADAM binding.
3H‐MADAM binding in vivo was inhibited only by compounds which also inhibited the binding of 3H‐MADAM in vitro (the SSRIs, mixed SERT/noradrenaline transport inhibitors and clomipramine), confirming the selectivity of 3H‐MADAM for SERT also in vivo. Moreover, compounds effective in inhibiting 3H‐MADAM binding were the only ones found to be active in the mouse 5‐HTP potentiation test confirming the model as a behavioural correlate to in vivo 5‐HT uptake.
Finally, it was found that a SERT occupancy of 85–95% was necessary to produce 50% of the maximum behavioural response (ED50).

British Journal of Pharmacology (2004) 141, 1015–1023. doi:10.1038/sj.bjp.0705693
Dual effects of adenosine on acetylcholine release from myenteric motoneurons are mediated by junctional facilitatory A2A and extrajunctional inhibitory A1 receptors
Authors: Duarte‐Araújo Margarida , Nascimento Carlos , Alexandrina Timóteo M , Magalhães‐Cardoso Teresa , Correia‐de‐Sá Paulo 
Published: March 2004

The coexistence of both inhibitory A1 and facilitatory A2 adenosine receptors in the rat myenteric plexus prompted the question of how adenosine activates each receptor subtype to regulate cholinergic neurotransmission.
Exogenously applied adenosine (0.3–300 μM) decreased electrically evoked [3H]acetylcholine ([3H]ACh) release. Blocking A1 receptors with 1,3‐dipropyl‐8‐cyclopentylxanthine (10 nM) transformed the inhibitory action of adenosine into a facilitatory effect. Adenosine‐induced inhibition was mimicked by the A1 receptor agonist R‐N6‐phenylisopropyladenosine (0.3 μM), but the A2A agonist CGS 21680C (0.003 μM) produced a contrasting facilitatory effect.
Increasing endogenous adenosine levels, by the addition of (1) the adenosine precursor AMP (30–100 μM), (2) the adenosine kinase inhibitor 5′‐iodotubercidin (10 μM) or (3) inhibitors of adenosine uptake (dipyridamole, 0.5 μM) and of deamination (erythro‐9(2‐hydroxy‐3‐nonyl)adenine, 50 μM), enhanced electrically evoked [3H]ACh release (5 Hz for 40 s). Release facilitation was prevented by adenosine deaminase (ADA, 0.5 U ml−1) and by the A2A receptor antagonist ZM 241385 (50 nM); these compounds decreased [3H]ACh release by 31±6% (n=7) and 37±10% (n=6), respectively.
Although inhibition of ecto‐5′‐nucleotidase by α,β‐methylene ADP (200 μM) or by concanavalin A (0.1 mg ml−1) attenuated endogenous adenosine formation from AMP, analysed by HPLC, the corresponding reduction in [3H]ACh release only became evident when stimulation of the myenteric plexus was prolonged to over 250 s.
In summary, we found that endogenously generated adenosine plays a predominantly tonic facilitatory effect mediated by prejunctional A2A receptors. Extracellular deamination and cellular uptake may restrict endogenous adenosine actions to the neuro‐effector region near the release/production sites.

British Journal of Pharmacology (2004) 141, 925–934. doi:10.1038/sj.bjp.141-0705697
Endothelium‐dependent smooth muscle hyperpolarization: do gap junctions provide a unifying hypothesis?
Authors: Griffith Tudor M 
Published: March 2004

An endothelium‐derived hyperpolarizing factor (EDHF) that is distinct from nitric oxide (NO) and prostanoids has been widely hypothesized to hyperpolarize and relax vascular smooth muscle following stimulation of the endothelium by agonists. Candidates as diverse as K+ ions, eicosanoids, hydrogen peroxide and C‐type natriuretic peptide have been implicated as the putative mediator, but none has emerged as a ‘universal EDHF’. An alternative explanation for the EDHF phenomenon is that direct intercellular communication via gap junctions allows passive spread of agonist‐induced endothelial hyperpolarization through the vessel wall. In some arteries, eicosanoids and K+ ions may themselves initiate a conducted endothelial hyperpolarization, thus suggesting that electrotonic signalling may represent a general mechanism through which the endothelium participates in the regulation of vascular tone.British Journal of Pharmacology (2004) 141, 881–903. doi:10.1038/sj.bjp.0705698
NPY presynaptic actions are reduced in the hypothalamic mpPVN of obese (fa/fa), but not lean, Zucker rats in vitro
Authors: Pronchuk Nina , Colmers William F 
Published: March 2004

Neuropeptide Y (NPY) profoundly enhances feeding when injected intracerebroventricularly, or directly into hypothalamic nuclei, such as the paraventricular nucleus (PVN). Paradoxically, NPY has a reduced action on feeding in obese Zucker rats relative to lean Zucker rats, although the obese rats have much higher levels of hypothalamic NPY expression. GABAergic inputs to a subpopulation of medial parvocellular PVN (mpPVN) neurons are sensitive to NPY. Here, we tested the hypothesis that the blunted eating response to NPY observed in obese Zucker rats will be reflected in a reduced NPY action at mpPVN GABAergic synapses.
‘Blind’ whole‐cell patch‐clamp recordings made from mpPVN neurons in acute brain slices of lean and obese Zucker rats revealed GABAergic inhibitory postsynaptic currents (IPSC) responses which were inhibited by NPY. While the maximum response in the obese Zucker rats was significantly less than in lean Zucker or Sprague–Dawley rats, there was no difference in the EC50.
Experiments using blocking concentrations of Y1‐ or Y5‐receptor antagonists revealed no differences between lean and obese Zucker rats in the contributions of either of these receptors to the total NPY response in mpPVN.
NPY is less effective at the mpPVN GABA synapse in obese than in lean Zucker rats. This is not associated with a change in the proportion of Y1 or Y5 receptors mediating the NPY response, and is consistent with the downregulation of NPY receptors or a reduction in receptor–effector coupling, and with the reduced sensitivity of obese rats to NPY.

British Journal of Pharmacology (2004) 141, 1032–1036. doi:10.1038/sj.bjp.0705699
The anti‐inflammatory carbazole, LCY‐2‐CHO, inhibits lipopolysaccharide‐induced inflammatory mediator expression through inhibition of the p38 mitogen‐activated protein kinase signaling pathway in macrophages
Authors: Ho Feng‐Ming , Lai Chih‐Chang , Huang Li‐Jiau , Kuo Tsun Cheng , Chao Chien M , Lin Wan‐Wan 
Published: March 2004

The present study was undertaken to investigate the anti‐inflammatory effects of a synthetic compound, LCY‐2‐CHO, on the expression of inducible nitric oxide synthase (iNOS), COX‐2, and TNF‐α in murine RAW264.7 macrophages.
Within 1–30 μM, LCY‐2‐CHO concentration‐dependently inhibited lipopolysaccharide (LPS)‐induced nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor‐α (TNF‐α) formation, with IC50 values of 2.3, 1, and 0.8 μM, respectively. Accompanying inhibition of LPS‐induced iNOS, cyclooxygenase‐2 (COX‐2), and pro‐TNF‐α proteins was observed.
Reverse transcription‐polymerase chain reaction (RT–PCR) and promoter analyses indicated that iNOS expression was inhibited at the transcriptional level (IC50=2.3 μM), that inhibition of COX‐2 expression only partially depended on gene transcription (IC50=7.6 μM), and that TNF‐α transcription was unaffected.
Transcriptional assays revealed that activation of AP‐1, but not NF‐κB, was concomitantly blocked by LCY‐2‐CHO. Our results showed that LCY‐2‐CHO was capable of interfering with post‐transcriptional regulation, altering the stability of COX‐2 and TNF‐α mRNAs.
Since the 3′‐untranslated region (3′ UTR) of both COX‐2 and TNF‐α mRNA contains a p38 mitogen‐activated protein kinase (MAPK)‐regulated element involved in mRNA stability, we assessed the effect of LCY‐2‐CHO on p38 MAPK. Our data clearly indicated an inhibition (IC50=1.7 μM) of LPS‐mediated p38 MAPK activity, but not of extracellular signal‐regulated kinase (ERK) or c‐Jun N‐terminal kinase (JNK) activity. However, kinase assays ruled out a direct inhibition of p38 MAPK action. The selective p38 MAPK inhibitor, SB203580, inhibited the promoter activities of iNOS and COX‐2 rather than that of TNF‐α.
In conclusion, LCY‐2‐CHO downregulates inflammatory iNOS, COX‐2, and TNF‐α gene expression in macrophages through interfering with p38 MAPK and AP‐1 activation.

British Journal of Pharmacology (2004) 141, 1037–1047. doi:10.1038/sj.bjp.0705700
Pharmacological activation of plasma‐membrane KATP channels reduces reoxygenation‐induced Ca2+ overload in cardiac myocytes via modulation of the diastolic membrane potential
Authors: Baczkó István , Giles Wayne R , Light Peter E 
Published: March 2004

The opening of cardiac plasma‐membrane ATP‐sensitive K+ channels (pmKATP) can protect the heart against ischaemia/reperfusion injury. We recently demonstrated that the resting membrane potential (Em) of ventricular myocytes strongly modulates reoxygenation‐induced Ca2+ overload. This led to the hypothesis that activation of pmKATP can influence the extent of chemically induced hypoxia (CIH)/reoxygenation Ca2+ overload via hyperpolarization of the diastolic membrane potential of ventricular myocytes.
The membrane potential (Em) of isolated rat myocytes was determined using the perforated patch‐clamp technique and DiBac4(3) imaging. Intracellular Ca2+ ([Ca2+]i) was monitored using FURA‐2 imaging.
CIH/reoxygenation caused a significant depolarization of Em and a substantial increase in [Ca2+]i. The KATP opener pinacidil (100 μM) and the pmKATP opener P‐1075 (100 μM) hyperpolarized the Em of normoxic myocytes. Pinacidil (100 μM) and P‐1075 (10 and 100 μM), applied during reoxygenation, hyperpolarized Em and prevented reoxygenation‐induced increases in [Ca2+]i.
Myocyte hypercontracture and death increased in parallel with an Em depolarization of 10–15 mV and increases in [Ca2+]i. Under these conditions, the selective pmKATP channel inhibitor HMR 1098 further depolarized myocyte membrane potential and increased hypercontracture.
In conclusion, activation of pmKATP channels can prevent CIH/reoxygenation‐induced Ca2+ overload via a mechanism that is dependent on hyperpolarization of diastolic membrane potential. Hyperpolarization toward normal resting membrane potential favours the Ca2+ extrusion mode of Na+/Ca2+ exchange.

British Journal of Pharmacology (2004) 141, 1059–1067. doi:10.1038/sj.bjp.0705702
Differential modulation of ATP‐induced calcium signalling by A1 and A2 adenosine receptors in cultured cortical astrocytes
Authors: Alloisio Susanna , Cugnoli Carlo , Ferroni Stefano , Nobile Mario 
Published: March 2004

Despite the accumulating evidence that under various pathological conditions the extracellular elevation of adenine‐based nucleotides and nucleosides plays a key role in the control of astroglial reactivity, how these signalling molecules interact in the regulation of astrocyte function is still largely elusive.
The action of the nucleoside adenosine in the modulation of the intracellular calcium signalling ([Ca2+]i) elicited by adenosine 5′‐triphosphate (ATP)‐induced activation of P2 purinoceptors was investigated on neocortical type‐1 astrocytes in primary culture by using single‐cell microfluorimetry.
Astrocyte challenge with ATP (1–10 μM) elicited biphasic [Ca2+]i responses consisting of an initial peak followed by a sustained elevation. The stable adenosine analogue 2‐chloroadenosine (2‐ClA) potentiated the transient [Ca2+]i rise induced by activation of metabotropic P2Y receptors. Among the various P1 receptor agonists tested, the nonselective agonist 5′‐N‐ethylcarboxamidoadenosine (NECA) mimicked the 2‐ClA action, whereas the selective A1 R(−) N6‐(2‐phenylisopropyl)‐adenosine (R‐PIA), the A2A 2‐[4‐(2‐carboxyethyl)phenethylamino]‐5′‐N‐ethylcarboxamidoadenosine (CGS‐21680) and A3 1‐deoxy‐1‐(6‐[([3‐lodophenyl]methyl)‐amino]‐9H‐purin‐9‐yl)‐N‐methyl‐β‐D‐ribofuranuronamide (IB‐MECA) agonists were ineffective.
Application of R‐PIA>NECA2‐ClA depressed the [Ca2+]i plateau reversibly. Moreover, in the presence of R‐PIA or 2‐ClA, the prolonged [Ca2+]i signal was maintained by application of the A1 antagonist 1,3‐diethyl‐8‐phenylxanthine (DPX). Finally, preincubation of the astrocytes with pertussis toxin abrogated the 2‐ClA inhibition of the ATP‐elicited sustained [Ca2+]i rise without affecting the transient [Ca2+]i potentiation.
Taken together, these findings indicate that stimulation of A1 and A2 adenosine receptors mediates a differential modulation of [Ca2+]i signalling elicited by P2 purinoceptors. Since variations in [Ca2+]i dynamics also affect cell proliferation and differentiation, our data suggest that tuning of the extracellular levels of adenosine may be relevant for the control of astrogliosis mediated by adenine nucleotides.

British Journal of Pharmacology (2004) 141, 935–942. doi:10.1038/sj.bjp.0705707
Differential involvement of N‐type calcium channels in transmitter release from vasoconstrictor and vasodilator neurons
Authors: Morris Judy L , Ozols Daina I , Lewis Richard J , Gibbins Ian L , Jobling Phillip 
Published: March 2004

The effects of calcium channel blockers on co‐transmission from different populations of autonomic vasomotor neurons were studied on isolated segments of uterine artery and vena cava from guinea‐pigs.
Sympathetic, noradrenergic contractions of the uterine artery (produced by 200 pulses at 1 or 10 Hz; 600 pulses at 20 Hz) were abolished by the N‐type calcium channel blocker ω‐conotoxin (CTX) GVIA at 1–10 nM.
Biphasic sympathetic contractions of the vena cava (600 pulses at 20 Hz) mediated by noradrenaline and neuropeptide Y were abolished by 10 nM CTX GVIA.
Neurogenic relaxations of the uterine artery (200 pulses at 10 Hz) mediated by neuronal nitric oxide and neuropeptides were reduced <50% by CTX GVIA 10–100 nM.
Capsaicin (3 μM) did not affect the CTX GVIA‐sensitive or CTX GVIA‐resistant neurogenic relaxations of the uterine artery.
The novel N‐type blocker CTX CVID (100–300 nM), P/Q‐type blockers agatoxin IVA (10–100 nM) or CTX CVIB (100 nM), the L‐type blocker nifedipine (10 μM) or the ‘R‐type’ blocker SNX‐482 (100 nM), all failed to reduce CTX GVIA‐resistant relaxations. The T‐type channel blocker NiCl2 (100–300 μM) reduced but did not abolish the remaining neurogenic dilations.
Release of different neurotransmitters from the same autonomic vasomotor axon depends on similar subtypes of calcium channels. N‐type channels are responsible for transmitter release from vasoconstrictor neurons innervating a muscular artery and capacitance vein, but only partly mediate release of nitric oxide and neuropeptides from pelvic vasodilator neurons.

British Journal of Pharmacology (2004) 141, 961–970. doi:10.1038/sj.bjp.0705712
The fibrinolytic system attenuates vascular tone: effects of tissue plasminogen activator (tPA) and aminocaproic acid on renal microcirculation
Authors: Heyman Samuel N , Hanna Zohair , Nassar Taher , Shina Ahuva , Akkawi Sa'ed , Goldfarb Marina , Rosen Seymour , Higazi Abd‐Al Roof 
Published: March 2004

The renal medulla is a major source of plasminogen activators (PA), recently shown to induce vasodilation in vitro. Treatment with PA inhibitors has been associated with renal dysfunction, suggesting compromised renal microvasculature. We investigated the impact of the PA inhibitor epsilon amino‐caproic acid (EACA) upon vascular tone in vitro, and studied the effect of both tPA and EACA upon intrarenal hemodynamics in vivo.
In vitro experiments were carried out in isolated aortic rings and with cultured vascular smooth muscle cells. Studies of renal microcirculation and morphology were conducted in anesthetized Sprague–Dawley rats.
In isolated aortic rings, EACA (but not the other inhibitors of the fibrinolytic system PAI‐1 or α‐2 antiplasmin) reduced the half‐maximal effective concentration of phenylephrine (PE) required to induce contraction (from 32 nM in control solution to 2 and 0.1 nM at EACA concentrations of 1 and 10 μM, respectively). Using reteplase (retavase) in the same model, we also provide evidence that the vasoactivity of tPA is in part kringle‐dependent. In cultured vascular smooth muscle cells, Ca2+ internalization following PE was enhanced by EACA, and retarded by tPA.
In anesthetized rats, EACA (150 mg kg−1) did not affect systemic blood pressure, total renal or cortical blood flow. However, the outer medullary blood flow declined 12±2% below the baseline (P<0.03). By contrast, tPA (2 mg kg−1), transiently increased outer medullary blood flow by 8±5% (P<0.02). Fibrin microthrombi were not found within the renal microvasculature in EACA‐treated animals.
In conclusion, both fibrinolytic and antifibrinolytic agents modulate medullary renal blood flow with reciprocal effects of vasodilation (PA) and vasoconstriction (EACA). In vitro studies suggest that these hemodynamic responses are related to direct modulation of the vascular tone.

British Journal of Pharmacology (2004) 141, 971–978. doi:10.1038/sj.bjp.0705714
Spatial Pricing in Interdependent Markets: A Case Study of Petrol Retailing in Sheffield
Authors: Ning Xiaoming , Haining Robert 
Published: March 2004

This paper reports the development of empirical models to explain spatial price variation in an urban area. Models are constructed for petrol price data collected in 1995 and 1997 in Sheffield, England. The 1995 data are modelled by using only supply-side predictors following the collection of supply-side information from field surveys of the retail sites, a site questionnaire survey, and interviews with site managers. The 1997 data are modelled by using supply-side predictors and demand-side predictors that relate to the economic characteristics of the population of consumers. This modelling is based on field surveys of the sites, a new site questionnaire survey, and a household survey. The purpose of this work is to assess supply-side and demand-side factors in explaining spatial price variation. Supply-side predictors are classified into site characteristics, location characteristics, and measures of spatial competition. We examine the relative importance of these different groups of supply-side variables in explaining price variation, with a particular interest in location and competition effects as these relate directly to the spatial and geographical aspects of the problem. Another contribution of the paper is to observe the stability of findings by contrasting the best-fitting models obtained for the 1995 price data to the best-fitting models obtained for the 1997 price data. We find that no demand-side factors are statistically significant. For 1995 a spatial competition variable and a location variable (whether a site is attached to a supermarket) are the consistently important supply-side variables. For 1997 all three categories of supply-side variables are important.
Bacterial Volatiles Induce Systemic Resistance in Arabidopsis
Authors: Ryu Choong-Min , Farag Mohamed A. , Hu Chia-Hui , Reddy Munagala S. , Kloepper Joseph W. , Paré Paul W. 
Published: March 2004

Abstract
Plant growth-promoting rhizobacteria, in association with plant roots, can trigger induced systemic resistance (ISR). Considering that low-molecular weight volatile hormone analogues such as methyl jasmonate and methyl salicylate can trigger defense responses in plants, we examined whether volatile organic compounds (VOCs) associated with rhizobacteria can initiate ISR. In Arabidopsis seedlings exposed to bacterial volatile blends from Bacillus subtilis GB03 and Bacillus amyloliquefaciens IN937a, disease severity by the bacterial pathogen Erwinia carotovora subsp. carotovora was significantly reduced compared with seedlings not exposed to bacterial volatiles before pathogen inoculation. Exposure to VOCs from rhizobacteria for as little as 4 d was sufficient to activate ISR in Arabidopsis seedlings. Chemical analysis of the bacterial volatile emissions revealed the release of a series of low-molecular weight hydrocarbons including the growth promoting VOC (2R,3R)-(-)-butanediol. Exogenous application of racemic mixture of (RR) and (SS) isomers of 2,3-butanediol was found to trigger ISR and transgenic lines of B. subtilis that emitted reduced levels of 2,3-butanediol and acetoin conferred reduced Arabidopsis protection to pathogen infection compared with seedlings exposed to VOCs from wild-type bacterial lines. Using transgenic and mutant lines of Arabidopsis, we provide evidence that the signaling pathway activated by volatiles from GB03 is dependent on ethylene, albeit independent of the salicylic acid or jasmonic acid signaling pathways. This study provides new insight into the role of bacteria VOCs as initiators of defense responses in plants.