bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adenosine mediates relaxation of human small resistance‐like coronary arteries via A2B receptors
Authors: Kemp B K , Cocks T M 
Published: January 2005

The receptor subtype and mechanisms underlying relaxation to adenosine were examined in human isolated small coronary arteries contracted with the thromboxane A2 mimetic, 1,5,5‐hydroxy‐11α, 9α‐(epoxymethano)prosta‐5Z, 13E‐dienoic acid (U46619) to approximately 50% of their maximum contraction to K+ (125 mM) depolarization (Fmax). Relaxations were normalized as percentages of the 50% Fmax contraction.
Adenosine caused concentration‐dependent relaxations (pEC50, 5.95±0.20; maximum relaxation (Rmax), 96.7±1.4%) that were unaffected by either combined treatment with the nitric oxide inhibitors, NG‐nitro‐L‐arginine (L‐NOARG; 100 μM) and oxyhaemoglobin (HbO; 20 μM) or the ATP‐dependent K+ channel (KATP) inhibitor, glibenclamide (10 μM). The pEC50 but not Rmax to adenosine was significantly reduced by high extracellular K+ (30 mM). Relaxations to the adenylate cyclase activator, forskolin, however, were unaffected by high K+ (30 mM).
Adenosine and a range of adenosine analogues, adenosine, 2‐chloroadenosine (2‐CADO), 5′‐N‐ethyl‐carboxamidoadenosine (NECA), R(−)‐N6‐(2‐phenylisopropyl)‐adenosine (R‐PIA), S(+)‐N6‐(2‐phenylisopropyl)‐adenosine (S‐PIA), N6‐cyclopentyladenosine (CPA), 1‐deoxy‐1‐[6‐[[(3‐iodophenyl)methyl]amino]‐9H‐purin‐9‐yl]‐N‐methyl‐β‐D‐ribofuranuronamide (IB‐MECA), 2‐p‐(2‐carboxyethyl)phenethylamino‐5′‐N‐ethylcarboxamido adenosine hydrochloride (CGS 21680), relaxed arteries with a rank order of potency of NECA=2‐CADO>adenosine=IB‐MECA=R‐PIA= CPA>S‐PIA)>CGS 21680.
Sensitivity but not Rmax to adenosine was significantly reduced approximately 80 and 20 fold by the non‐selective adenosine receptor antagonist, 8‐(p‐sulphophenyl)theophylline (8‐SPT) and the A2 receptor antagonist, 3,7‐dimethyl‐1‐propargylxanthine (DMPX). By contrast, the A1‐selective antagonist, 1,3‐dipropyl‐8‐cyclopentylxanthine (DPCPX) had no effect on pEC50 or Rmax to adenosine.
These results suggest that A2B receptors mediate relaxation to adenosine in human small coronary arteries which is independent of NO but dependent in part on a K+‐sensitive mechanism.

British Journal of Pharmacology (1999) 126, 1796–1800; doi:10.1038/sj.bjp.0702462
Modification of membrane currents in mouse neuroblastoma cells following infection with rabies virus
Authors: Iwata M , Komori S , Unno T , Minamoto N , Ohashi H 
Published: January 2005

The effect on membrane currents of infection of mouse neuroblastoma NA cells with rabies virus was studied by using the whole‐cell patch clamp technique.
Three types of membrane currents, namely voltage‐dependent Na+ current (INa), delayed rectifier K+ current (IK‐DR) and inward rectifier K+ current (IK‐IR) were elicited in uninfected cells.
In cells 3 days after infection with the virus, no detectable change was observed in morphology and membrane capacitance, but INa and IK‐IR were significantly decreased in amplitude without any appreciable difference in the time course of current activation and inactivation. The voltage‐dependence of INa activation was significantly shifted in the positive direction along the voltage axis with a decreased slope. IK‐DR remained almost unaltered after the viral infection.
The resting membrane potential, measured with a physiological K+ gradient across the cell membrane, was decreased (depolarized) after the viral infection. The depolarization was associated with the decreased amplitude of IK‐IR.
These results suggest that infection of mouse neuroblastoma NA cells with rabies virus causes reduction of functional expression of ion channels responsible for INa and IK‐IR, and provide evidence for possible involvement of the change in membrane properties in the pathogenesis of rabies disease.

British Journal of Pharmacology (1999) 126, 1691–1698; doi:10.1038/sj.bjp.0702473
Mechanism of verapamil block of a neuronal delayed rectifier K channel: active form of the blocker and location of its binding domain
Authors: Catacuzzeno L , Trequattrini C , Petris A , Franciolini F 
Published: January 2005

The mechanism of verapamil block of the delayed rectifier K currents (IK(DR)) in chick dorsal root ganglion (DRG) neurons was investigated using the whole‐cell patch clamp configuration. In particular we focused on the location of the blocking site, and the active form (neutral or charged) of verapamil using the permanently charged verapamil analogue D890.
Block by D890 displayed similar characteristics to that of verapamil, indicating the same state‐dependent nature of block. In contrast with verapamil, D890 was effective only when applied internally, and its block was voltage dependent (136 mV/e‐fold change of the on rate). Given that verapamil block is insensitive to voltage (Trequattrini et al., 1998), these observations indicate that verapamil reaches its binding site in the uncharged form, and accesses the binding domain from the cytoplasm.
In external K and saturating verapamil we recorded tail currents that did not decay monotonically but showed an initial increase (hook). As these currents can only be observed if verapamil unblock is significantly voltage dependent, it has been suggested (DeCoursey, 1995) that neutral drug is protonated upon binding. We tested this hypothesis by assessing the voltage dependence of the unblock rate from the hooked tail currents for verapamil and D890.
The voltage dependence of the off rate of D890, but not of verapamil, was well described by adopting the classical Woodhull (1973) model for ionic blockage of Na channels. The voltage dependence of verapamil off rate was consistent with a kinetic scheme where the bound drug can be protonated with rapid equilibrium, and both charged and neutral verapamil can unbind from the site, but with distinct kinetics and voltage dependencies.

British Journal of Pharmacology (1999) 126, 1699–1706; doi:10.1038/sj.bjp.0702477
Effects of the endogeneous cannabinoid, anandamide, on neuronal activity in rat hippocampal slices
Authors: Ameri Angela , Wilhelm Alwina , Simmet Thomas 
Published: January 2005

The arachidonic acid derivative arachidonylethanolamide (anandamide) is an endogeneous ligand of cannabinoid receptors that induces pharmacological actions similar to those of cannabinoids such as Δ9‐tetrahydrocannabinol (THC). We examined whether anandamide can influence excessive neuronal activity by investigating stimulation‐induced population spikes and epileptiform activity in rat hippocampal slices. For this purpose, the effects of anandamide were compared with those of the synthetic cannabinoid agonist WIN 55,212‐2 and its inactive S(−)‐enantiomer WIN 55,212‐3.
Both anandamide (1 and 10 μM) and WIN 55,212‐2 (0.1 and 1 μM) decreased the amplitude of the postsynaptic population spike and the slope of the field excitatory postsynaptic potential (field e.p.s.p.) without affecting the presynaptic fibre spike of the afferents. At a concentration of 1 μM, WIN 55,212‐2 completely suppressed the postsynaptic spike, whereas the S(−)‐enantiomer WIN 55,212‐3 produced only a slight depression. The CB1 receptor antagonist SR 141716 blocked the inhibition evoked by the cannabinoids. SR 141716 had a slight facilitatory effect on neuronal excitability by itself.
Anandamide shifted the input‐output curve of the postsynaptic spike and the field e.p.s.p. to the right and increased the magnitude of paired‐pulse facilitation indicating a presynaptic mechanism of action.
Anandamide and WIN 55,212‐2, but not WIN 55,212‐3, attenuated both stimulus‐triggered epileptiform activity in CA1 elicited by omission of Mg2+ and spontaneously occurring epileptiform activity in CA3 elicited by omission of Mg2+ and elevation of K+ to 8 mM. The antiepileptiform effect of these cannabinoids was blocked by SR 141716.
In conclusion, cannabinoid receptors of the CB1 type as well as their endogeneous ligand, anandamide, are involved in the control of neuronal excitability, thus reducing excitatory neurotransmission at a presynaptic site, a mechanism which might be involved in the prevention of excessive excitability leading to epileptiform activity.

British Journal of Pharmacology (1999) 126, 1831–1839; doi:10.1038/sj.bjp.0702478
Direct inhibition of the N‐methyl‐D‐aspartate receptor channel by dopamine and (+)‐SKF38393
Authors: Castro Newton G , De Mello Maria Christina F , De Mello Fernando G , Aracava Yasco 
Published: January 2005

Dopamine is known to modulate glutamatergic synaptic transmission in the retina and in several brain regions by activating specific G‐protein‐coupled receptors. We have examined the possibility of a different type of mechanism for this modulation, one involving direct interaction of dopamine with ionotropic glutamate receptors.
Ionic currents induced by fast application of N‐methyl‐D‐aspartate (NMDA) were recorded under whole‐cell patch‐clamp in cultured striatal, thalamic and hippocampal neurons of the rat and in retinal neurons of the chick. Dopamine at concentrations above 100 μM inhibited the NMDA response in all four neuron types, exhibiting an IC50 of 1.2 mM in hippocampal neurons. The time course of this inhibition was fast, developing in less than 100 ms.
The D1 receptor agonist (+)‐SKF38393 mimicked the effect of dopamine, with an IC50 of 58.9 μM on the NMDA response, while the enantiomer (−)‐SKF38393 was ineffective at 50 μM. However, the D1 antagonist R(+)‐SCH23390 did not prevent the inhibitory effect of (+)‐SKF38393.
The degree of inhibition by dopamine and (+)‐SKF38393 depended on transmembrane voltage, increasing 2.7 times with a hyperpolarization of about 80 mV. The voltage‐dependent block by dopamine was also observed in the presence of MgCl2 1 mM.
Single‐channel recordings showed that the open times of NMDA‐gated channels were shortened by (+)‐SKF38393.
These data suggested that the site to which the drugs bound to produce the inhibitory effect was distinct from the classical D1‐type dopamine receptor sites, possibly being located inside the NMDA channel pore. It is concluded that dopamine and (+)‐SKF38393 are NMDA channel ligands.

British Journal of Pharmacology (1999) 126, 1847–1855; doi:10.1038/sj.bjp.0702479
Effects of intrathecal administration of nitric oxide synthase inhibitors on carrageenan‐induced thermal hyperalgesia
Authors: Osborne Michael G , Coderre Terence J 
Published: January 2005

We examined the effects of various nitric oxide synthase (NOS) inhibitors on carrageenan‐induced thermal hyperalgesia.
First, we determined the time point at which a subcutaneous plantar injection of carrageenan into the rat hindpaw produced maximum thermal hyperalgesia. Subsequently, we demonstrated that intrathecal administration of the non‐selective NOS inhibitor L‐NG‐nitro‐arginine methyl ester (L‐NAME) produces a dose‐dependent reduction of carrageenan‐induced thermal hyperalgesia.
Four relatively selective NOS inhibitors were then tested for their efficacy at reducing carrageenan‐induced thermal hyperalgesia. Initially, the effects of prolonged treatment with inhibitors of neuronal [7‐nitroindazole (7‐NI) and 3‐bromo‐7‐nitroindazole (3‐Br)] and inducible [aminoguanidine (AG) and 2‐amino‐5,6‐dihydro‐methylthiazine (AMT)] NOS were examined. All agents were injected three times intrathecally during the course of inflammation caused by the plantar injection of carrageenan, and thermal hyperalgesia was measured at 6 h post‐carrageenan using a plantar apparatus.
All inhibitors, except for 7‐NI, were effective at attenuating the carrageenan‐induced thermal hyperalgesia when compared with vehicle treatment.
Finally, the effects of early versus late administration of neuronal and inducible NOS inhibitors on carrageenan‐induced thermal hyperalgesia were examined. We found that neither 3‐Br nor AG significantly affected thermal hyperalgesia when administered during the early phase of carrageenan inflammation, while only AG was able to reduce thermal hyperalgesia when administered during the late phase of the injury.
Our results suggest that inducible NOS contributes to thermal hyperalgesia in only the late stages of the carrageenan‐induced inflammatory response, while neuronal NOS likely plays a role throughout the entire time course of the injury.

British Journal of Pharmacology (1999) 126, 1840–1846; doi:10.1038/sj.bjp.0702508
Activation of nitric oxide synthase by β2‐adrenoceptors in human umbilical vein endothelium in vitro
Authors: Ferro Albert , Queen Lindsay R , Priest Rachel M , Xu Biao , Ritter James M , Poston Lucilla , Ward Jeremy P T 
Published: January 2005

Some animal studies suggest that β‐adrenoceptor‐mediated vasorelaxation is in part mediated through nitric oxide (NO) release. Furthermore, in humans, we have recently shown that forearm blood flow is increased by infusion of β2‐adrenergic agonists into the brachial artery, and the nitric oxide synthase (NOS) inhibitor NG‐monomethyl‐L‐arginine (L‐NMMA) inhibits this response.
The purpose of the present study was to determine whether stimulation of human umbilical vein endothelial β‐adrenoceptors causes vasorelaxation and nitric oxide generation, and whether this might be mediated by cyclic adenosine‐3′,5′‐monophosphate (cyclic AMP).
Vasorelaxant responses were determined in umbilical vein rings to the nonselective β‐adrenergic agonist isoprenaline and to the cyclic AMP analogue dibutyryl cyclic AMP, following precontraction with prostaglandin F2α.
NOS activity was measured in cultured human umbilical vein endothelial cells (HUVEC) by the conversion of [3H]‐L‐arginine to [3H]‐L‐citrulline, and adenylyl cyclase activity by the conversion of [α‐32P]‐ATP to [32P]‐cyclic AMP.
Isoprenaline relaxed umbilical vein rings, and this vasorelaxation was abolished by β2‐ (but not β1‐) adrenergic blockage, and by endothelium removal or 1 mM L‐NMMA. In addition, vasorelaxant responses to dibutyryl cyclic AMP were inhibited by 1 mM L‐NMMA, with a reduction in Emax from 90.0±9.3% to 50.5±9.9% (P<0.05).
Isoprenaline 1 μM increased NOS activity in HUVEC (34.0±5.9% above basal, P<0.001). Furthermore, isoprenaline increased adenylyl cyclase activity in a concentration‐dependent manner; this response was inhibited by β2 (but not β1‐) adrenergic blockade. Forskolin 1 μM and dibutyryl cyclic AMP 1 mM each increased NOS activity in HUVEC, to a degree similar to isoprenaline 1 μM. The increase in L‐arginine to L‐citrulline conversion observed with each agent was abolished by co‐incubation with NOS inhibitors.
These results indicate that endothelial β2‐adrenergic stimulation and cyclic AMP elevation activate the L‐arginine/NO system, and give rise to vasorelaxation, in human umbilical vein.

British Journal of Pharmacology (1999) 126, 1872–1880; doi:10.1038/sj.bjp.0702512
Enhancement of vascular permeability by specific activation of protease‐activated receptor‐1 in rat hindpaw: a protective role of endogenous and exogenous nitric oxide
Authors: Kawabata Atsufumi , Kuroda Ryotaro , Nishikawa Hiroyuki , Asai Toshiharu , Kataoka Kazuo , Taneda Mamoru 
Published: January 2005

To clarify the role of the first thrombin receptor/protease‐activated receptor (PAR)‐1 in an inflammatory process, we tested and characterized the effect of intraplantar (i.pl.) administration of the highly specific PAR‐1 agonist TFLLR‐NH2 in rat hindpaw.
TFLLR‐NH2 administered i.pl. at 0.01–0.03 μmol per paw enhanced vascular permeability in the hindpaw and produced paw oedema in a dose‐dependent manner. This effect was almost completely abolished by repeated pretreatment with compound 48/80 to deplete inflammatory mediators in mast cells.
The NO synthase inhibitor NG‐nitro‐L‐arginine methyl ester or N‐iminoethyl‐L‐ornithine, preadministered i.pl., stereospecifically potentiated the i.pl. TFLLR‐NH2‐induced permeability increase, while the NO donor sodium nitroprusside or NOC‐18, given i.pl., suppressed the effect of TFLLR‐NH2.
These findings demonstrate that specific activation of PAR‐1 produces increased vascular permeability accompanied by oedema formation in the rat hindpaw, predominantly via mast cell degranulation, and that endogenous and exogenous NO plays a protective role in the PAR‐1‐mediated inflammatory event.

British Journal of Pharmacology (1999) 126, 1856–1862; doi:10.1038/sj.bjp.0702513
Ex vivo assay to determine the cyclooxygenase selectivity of non‐steroidal anti‐inflammatory drugs
Authors: Giuliano Francesco , Warner Timothy D 
Published: January 2005

In this study we describe experiments to establish ex vivo the selectivity of non‐steroidal anti‐inflammatory drugs (NSAIDs) given in vivo.
Anaesthetised (Inactin, 120 mg kg−1) male Wistar rats (220–250 g) received an i.v. dose of one of the following compounds (dose mg kg−1): aspirin (20), diclofenac (3), L‐745,337 (30), nimesulide (15), salicylate (20), sulindac (10). Blood samples were taken before and up to 6 h after dosing and the plasma obtained from it was tested for its ability to inhibit prostanoid formation in IL‐1β‐treated A549 cells (COX‐2 system) and human washed platelets (COX‐1 system). For control the same compounds were also added directly to the assay systems.
All drugs, except sodium salicylate, inhibited COX‐1 and COX‐2 when added directly to the test systems. Plasma from aspirin‐treated rats was without effect on either COX‐1 or COX‐2, consistent with the rapid in vivo metabolism to salicylate. Conversely, plasma from sulindac‐treated rats inhibited COX‐1 and COX‐2 with potencies according with in vivo metabolism to sulindac sulphide. Diclofenac was COX‐1/2 non‐selective when tested in vitro, but a slightly preferential inhibitor of COX‐2 when tested ex vivo. Nimesulide was confirmed as preferential inhibitor of COX‐2 both in vitro and ex vivo. L‐745,337 was a selective COX‐2 inhibitor when tested in vitro or ex vivo.
In conclusion, our experiments show clearly (a) NSAIDs inactivation, (b) activation of pro‐drugs, and (c) NSAIDs selectivity. Our assay provides useful information about the selectivity of NSAIDs that could be extended by the analysis of plasma samples taken from humans similarly treated with test drugs.

British Journal of Pharmacology (1999) 126, 1824–1830; doi:10.1038/sj.bjp.0702518
A comparison of the inhibitory activity of PDE4 inhibitors on leukocyte PDE4 activity in vitro and eosinophil trafficking in vivo
Authors: Cooper Nicola , Teixeira Mauro M , Warneck Julie , Miotla Jadwiga M , Wills Ruth E , Macari David M T , Gristwood Robert W , Hellewell Paul G 
Published: January 2005

Phosphodiesterase (PDE) 4 inhibitors have been shown to inhibit eosinophil PDE4 activity in vitro and accumulation of eosinophils in experimental airways inflammation. However, direct effects on eosinophil trafficking have not been studied in detail and it is not known if activity in vitro translates into efficacy in vivo. In the present study, we compared the activity of five PDE4 inhibitors in vitro and against trafficking of 111In‐eosinophils in cutaneous inflammation in the guinea‐pig.
The rank order of potency for inhibition of PDE4 activity in guinea‐pig eosinophil, neutrophil and macrophage, and human neutrophil lysates was RP73401>SB207499>CDP840>rolipram>LAS31025. On TNFα production by human PBMC, all inhibitors with the exception of rolipram showed potency similar to their effect on neutrophil lysates.
In a brain cerebellum binding assay, the rank order of potency at displacing [3H]‐rolipram was RP73401>rolipram>SB207499>CDP840>LAS30125.
Trafficking of 111In‐eosinophils to skin sites injected with PAF, ZAP or antigen in sensitized sites was inhibited by oral administration of all PDE4 inhibitors. The rank order of potency was RP73401=rolipram>LAS31025>SB207499>CDP840.
With the exception was RP73401, which was the most potent compound in all assays, there was no clear relationship between activity of PDE4 inhibitors in vitro and capacity to inhibit eosinophil trafficking in vivo. Thus, we conclude that in vitro activity of PDE4 inhibitors does not predict in vivo efficacy in an experimental model of eosinophil trafficking.

British Journal of Pharmacology (1999) 126, 1863–1871; doi:10.1038/sj.bjp.0702520
Tacrolimus suppresses tumour necrosis factor‐α and protects against splanchnic artery occlusion shock
Authors: Squadrito Francesco , Altavilla Domenica , Squadrito Giovanni , Ferlito Marcella , Campo Giuseppe M , Arlotta Mariarita , Grimaldi Serafino , Quartarone Cristina , Saitta Antonino , Caputi Achille P 
Published: January 2005

Tumour necrosis factor (TNF‐α) is a pleiotropic cytokine which is deeply involved in the pathogenesis of splanchnic artery occlusion (SAO) shock. Tacrolimus, formerly known as FK506, is a macrolide antibiotic, that blocks the transcription of several proinflammatory cytokines including TNF‐α.
Male anaesthetized rats were subjected to clamping of the splanchnic arteries for 45 min. This surgical procedure resulted in an irreversible state of shock (SAO shock). Sham operated animals were used as controls. SAO shocked rats had a decreased survival rate (0% at 4 h of reperfusion, while sham shocked rats survived more than 4 h), enhanced serum TNF‐α concentrations (415±12 U ml−1), decreased mean arterial blood pressure (MAP), leukopenia and increased ileal leukocyte accumulation studied by means of myeloperoxidase activity (MPO=7.5±0.3 U g−1 tissue). Moreover aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM–10 μM), reduced responsiveness to acetylcholine (ACh, 10 nM–10 μM) and increased staining for intercellular adhesion molecule‐1 (ICAM‐1). Furthermore increased mRNA for TNF‐α was observed in peritoneal macrophages of SAO shocked rats.
Tacrolimus (100 μg kg−1, 5 min after splanchnic arteries occlusion) increased survival rate (SAO+Tacrolimus=100% at 4 h of reperfusion), reverted the marked hypotension, reduced serum TNF‐α (15±3 U ml−1), ameliorated leukopenia, reduced ileal MPO (0.9±0.01 U g−1 tissue), restored to control values the hyporeactivity to PE, improved the reduced responsiveness to ACh and blunted the enhanced immunostaining for ICAM‐1 in the aorta. Finally tacrolimus suppressed cytokine mRNA levels in peritoneal macrophages.
The data suggest that tacrolimus may represent a new therapeutic approach in circulatory shock.

British Journal of Pharmacology (1999) 127, 498–504; doi:10.1038/sj.bjp.0702528
Effects of prolonged cold storage on double peaked vasoconstrictor responses to periarterial nerve stimulation in isolated canine splenic arteries
Authors: Yang Xiao‐Ping , Chiba Shigetoshi 
Published: January 2005

P2X‐Purinoceptors and α1‐adrenoceptors have previously been shown to involve in the double peaked vasoconstrictor responses to periarterial electrical nerve stimulation in the isolated and perfused canine splenic artery. The present study made an attempt to investigate effects of prolonged cold storage (7 days at 4°C) on vasoconstrictor responses to periarterial electrical nerve stimulation, tyramine, noradrenaline and adenosine 5′‐triphosphate (ATP) in the isolated canine splenic artery.
The periarterial nerve stimulation (1–10 Hz) readily causes a double peaked vasoconstriction in the non‐stored preparations. After cold stored for 7 days, the double peaked vasoconstriction was still recognized, although the response became significantly smaller. The first phase was decreased relatively greater than the second phase by the cold storage.
In the cold stored preparations, the dose‐response curve for tyramine was shifted to the right in a parallel manner. Prazosin almost completely inhibited tyramine‐induced vasoconstriction but α,β‐methylene ATP failed to influence the response to tyramine.
The vasoconstrictor responses to noradrenaline and ATP were not significantly modified by the prolonged cold storage.
From these results, it is concluded that the functions of sympathetic co‐transmission of purinergic components might be influenced more than that of adrenergic components in the cold storage canine splenic artery.

British Journal of Pharmacology (1999) 126, 1810–1814; doi:10.1038/sj.bjp.0702531