bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastric mucosal resistance to acute injury in experimental portal hypertension
Authors: Calatayud Sara , Ramírez M Carmen , Sanz M Jesús , Moreno Lucrecia , Hernández Carlos , Bosch Jaume , Piqué Jose M , Esplugues Juan V
Published: January 2005

The gastric mucosa of portal hypertensive rats exhibits important microvascular changes and a nitric oxide (NO)‐dependent hyperemia. This study analyses whether portal hypertensive mucosa exhibits changes in its ability to withstand aggression.

Portal hypertension was induced by partial portal vein ligation (PPVL) or common bile duct ligation (CBDL) and gastric damage was induced by oral administration of ethanol or aspirin. Experiments were performed in conscious or anaesthetized rats and some animals were pre‐treated with the NO‐synthesis inhibitor L‐NAME.

Conscious PPVL or CBDL rats showed an increased resistance to the damaging effects of ethanol. Oral administration of aspirin produced less gastric damage in PPVL conscious rats than in the control group.

The protective effects of portal hypertension were maintained in animals anaesthetized with ketamine and absent when pentobarbital was employed.

Pre‐treatment with L‐NAME restored the damaging effects of ethanol and aspirin in PPVL rats without modifying the level of damage in control animals.

Gastric bleeding induced by oral aspirin, as measured by the luminal release of 51Cr‐labelled erythrocytes, was significantly greater in PPVL rats than in control animals.

Semi‐quantitiative analysis by RT – PCR of the mRNA for endothelial NO‐synthase (eNOS), neuronal NOS (nNOS) and inducible NOS (iNOS) levels showed that the expression of iNOS was slightly increased in both the gastric mucosa and smooth muscle of PPVL rats. No changes were observed in eNOS and nNOS expression.

Conscious portal hypertensive rats exhibit an enhanced resistance to acute gastric damage which is absent under the influence of some types of anaesthesia and seems related to an increased synthesis of nitric oxide. However, mucosal lesions in these animals show an augmented bleeding per area of injury.

British Journal of Pharmacology (2001) 132, 309–317; doi:10.1038/sj.bjp.0703785
N‐acetylcysteine attenuates TNF‐α‐induced p38 MAP kinase activation and p38 MAP kinase‐mediated IL‐8 production by human pulmonary vascular endothelial cells
Authors: Hashimoto Shu , Gon Yasuhiro , Matsumoto Ken , Takeshita Ikuko , Horie Takashi
Published: January 2005

We have previously shown that tumour necrosis factor‐α (TNF‐α) activates p38 mitogen‐activated protein (MAP) kinase to produce interleukin‐8 (IL‐8) by human pulmonary vascular endothelial cells. Reactive oxygen species (ROS) including H2O2 generated by TNF‐α can act as signalling intermediates for cytokine induction; therefore, scavenging ROS by anti‐oxidants is important for the regulation of cytokine production. However, the effect of N‐acetylcysteine (NAC), which acts as a precursor of glutathione (GSH) synthesis, on TNF‐α‐induced activation of p38 MAP kinase pathway and p38 MAP kinase‐mediated IL‐8 production by human pulmonary vascular endothelial cells has not been determined. To clarify these issues, we examined the effect of NAC on TNF‐α‐induced activation of p38 MAP kinase, MAP kinase kinase (MKK) 3 and MKK6 which are upstream regulators of p38 MAP kinase, and p38 MAP kinase‐mediated IL‐8 production.

Human pulmonary vascular endothelial cells that had been preincubated with NAC were stimulated with TNF‐α and then the activation of p38 MAP kinase and MKK3/MKK6 in the cells and IL‐8 concentrations in the culture supernatants were determined.

Intracellular GSH levels increased in NAC‐treated cells.

NAC attenuated TNF‐α‐induced activation of p38 MAP kinase and MKK3/MKK6.

NAC attenuated p38 MAP kinase‐mediated IL‐8 production by TNF‐α‐stimulated cells.

These results indicate that the cellular reduction and oxidation (redox) regulated by intracellular GSH is critical for TNF‐α‐induced activation of p38 MAP kinase pathway and p38 MAP kinase‐mediated IL‐8 production by human pulmonary vascular endothelial cells, and we emphasize that anti‐oxidant therapy is an important strategy for the treatment of acute lung injury.

British Journal of Pharmacology (2001) 132, 270–276; doi:10.1038/sj.bjp.0703787
Modulation of BzATP and formalin induced nociception: attenuation by the P2X receptor antagonist, TNP‐ATP and enhancement by the P2X3 allosteric modulator, cibacron blue
Authors: Jarvis Michael F , Wismer Carol T , Schweitzer Edmund , Yu Haixia , Van Biesen Tim , Lynch Kevin J , Burgard Edward C , Kowaluk Elizabeth A
Published: January 2005

Exogenous ATP produces acute and localized pain in humans, and P2X receptor agonists elicit acute nociceptive behaviours in rodents following intradermal administration to the hindpaw. The predominant localization of P2X3 mRNA in sensory neurones has led to the hypothesis that activation of P2X3 and/or P2X2/3 receptors contributes to nociception.

The local administration of the P2X receptor agonist, BzATP (100 – 1000 nmol paw−1, s.c.) into the rat hindpaw produced an acute (<15 min) paw flinching response that was similar to that observed in the acute phase of the formalin (5%) test.

The co‐administration of the potent P2X receptor antagonist, TNP‐ATP (30 – 300 nmol paw−1), but not an inactive analogue, TNP‐AMP, with BzATP into the rat hindpaw attenuated BzATP‐induced nociception. Similarly, co‐administration of TNP‐ATP, but not TNP‐AMP, with 5% formalin reduced both acute and persistent nociception in this test.

Co‐administration of cibacron blue (30 and 100 nmol paw−1), a selective allosteric enhancer of P2X3 and P2X2/3 receptor activation, with BzATP (30 and 100 nmol paw−1) into the rat hindpaw produced significantly greater nociception as compared to the algogenic effects of BzATP alone. Intradermal co‐administration of cibacron blue (30 and 100 nmol paw−1) with formalin (1 and 2.5%) into the rat hindpaw also produced significantly greater nociceptive behaviour as compared to formalin alone.

The ability of TNP‐ATP and cibacron blue to respectively attenuate and enhance nociceptive responses elicited by exogenous BzATP and formalin provide further support for the hypothesis that activation of peripheral P2X3 containing channels contributes specifically to both acute and persistent nociception in the rat.

British Journal of Pharmacology (2001) 132, 259–269; doi:10.1038/sj.bjp.0703793
Rho‐kinase inhibitors prevent agonist‐induced vasospasm in human internal mammary artery
Authors: Batchelor Timothy J P , Sadaba J Rafael , Ishola Adekunle , Pacaud Pierre , Munsch Christopher M , Beech David J
Published: January 2005

Vasospasm of arterial conduits used for coronary artery surgery is an important cause of graft failure and is likely to result partly from raised levels of vasoconstrictor substances such as thromboxane A2 and endothelin‐1. Our aim was to find pharmacological agents that could prevent agonist‐induced vasospasm.

Isometric tension was recorded from discarded segments of human left internal mammary artery (LIMA). Submaximal contraction evoked by the thromboxane A2 mimetic U46619 (10 nM) was not inhibited by a blocker of store‐ and receptor‐operated Ca2+ channels (30 μM SKF96365) in the presence of diltiazem. Furthermore, contractions to 1 nM U46619 were preserved when extracellular Ca2+ was reduced from 2.5 mM to 60 nM. Thus, sustained U46619‐evoked contraction occurred without Ca2+ influx.

We hypothesized that contraction might occur via Rho‐kinase‐mediated Ca2+‐sensitization of myofilaments. Inhibitors of Rho‐kinase (Y27632 and HA1077) were profound relaxants. If contraction was pre‐evoked by 10 nM U46619, Y27632 and HA1077 caused full relaxation with EC50s of 1.67±0.22 μM and 3.58±0.35 μM respectively. Y27632 was also effective if applied before U46619, but was less potent.

Y27632 abolished contraction evoked by endothelin‐1 and significantly reduced resting tone in the absence of a vasoconstrictor.

Rho‐kinase‐mediated Ca2+‐sensitization appears to be a major mechanism of vasoconstriction in human LIMA. Rho‐kinase inhibitors may have an important role in preventing vasospasm in arterial grafts used for coronary artery surgery.

British Journal of Pharmacology (2001) 132, 302–308; doi:10.1038/sj.bjp.0703809
Cardiostimulant effects of urotensin‐II in human heart in vitro
Authors: Russell Fraser D , Molenaar Peter , O'Brien Donalee M
Published: January 2005

The effects of the recently identified human peptide urotensin‐II (hU‐II) were investigated on human cardiac muscle contractility and coronary artery tone. In right atrial trabeculae from non‐failing hearts, hU‐II caused a concentration‐dependent increase in contractile force (pEC50=9.5±0.1; Emax=31.3±4.8% compared to 9.25 mM Ca2+; n=9) with no change in contraction duration. In right ventricular trabeculae from explanted hearts, 20 nM hU‐II caused a small increase in contractile force (7.8±1.4% compared to 9.25 mM Ca2+; n=3/6 tissues from 2 out of 4 patients). The peptide caused arrhythmic contractions in 3/26 right atrial trabeculae from 3/9 patients in an experimental model of arrhythmia and therefore has less potential to cause arrhythmias than ET‐1. hU‐II (20 nM) increased tone (17.9% of the response to 90 mM KCI) in 7/7 tissues from 1 patient, with no response detected in 8/8 tissues from 2 patients. hU‐II is a potent cardiac stimulant with low efficacy.

British Journal of Pharmacology (2001) 132, 5–9; doi:10.1038/sj.bjp.0703811
Formation of nitric oxide from nitroxyl anion: role of quinones and ferricytochrome c
Authors: Buyukafsar Kansu , Nelli Silvia , Martin William
Published: January 2005

Our previous finding that copper ions oxidize nitroxyl anion released from Angeli's salt to nitric oxide prompted us to examine if copper‐containing enzymes shared this property.

The copper‐containing enzyme, tyrosinase, which catalyses the hydroxylation of monophenols to diphenols and the subsequent oxidation of these to the respective unstable quinone, failed to generate nitric oxide from Angeli's salt by itself, but did so in the presence of tyrosine.

L‐DOPA, the initial product of the reaction of tyrosinase with tyrosine, was not the active species, since it failed to generate nitric oxide from Angeli's salt. Nevertheless, L‐DOPA and two other substrates, namely, catechol and tyramine did produce nitric oxide from Angeli's salt in the presence of tyrosinase, suggesting involvement of the respective unstable quinones. In support, we found that 1,4‐benzoquinone produced a powerful nitric oxide signal from Angeli's salt.

Coenzyme Qo, an analogue of ubiquinone, failed to generate nitric oxide from Angeli's salt by itself, but produced a powerful signal in the presence of its mitochondrial complex III cofactor, ferricytochrome c.

Experiments conducted on rat aortic rings with the mitochondrial complex III inhibitor, myxothiazol, to determine if this pathway was responsible for the vascular conversion of nitroxyl to nitric oxide were equivocal: relaxation to Angeli's salt was inhibited but so too was that to unrelated relaxants.

Thus, certain quinones oxidize nitroxyl to nitric oxide. Further work is required to determine if endogenous quinones contribute to the relaxant actions of nitroxyl donors such as Angeli's salt.

British Journal of Pharmacology (2001) 132, 165–172; doi:10.1038/sj.bjp.0703812
Constitutive neuropeptide Y Y4 receptor expression in human colonic adenocarcinoma cell lines
Authors: Cox Helen M , Tough Iain R , Zandvliet Dorothea W J , Holliday Nicholas D
Published: January 2005

Three human adenocarcinoma cell lines, Colony‐24 (Col‐24), Col‐6 and Col‐1 have been studied as confluent epithelial layers able to transport ions vectorially in response to basolateral vasoactive intestinal polypeptide (VIP) and pancreatic polypeptides (PP).

Different species PP stimulated responses in Col‐24 with Y4‐like pharmacology. Bovine (b)PP, human (h)PP and porcine (p)PP were equipotent (EC50 values 3.0 – 5.0 nM) while rat (r)PP, avian (a)PP and [Leu31, Pro34]PYY (Pro34PYY) were significantly less potent. PYY was inactive. The PP pharmacology in Col‐1 was comparable with Col‐24. However, Col‐6 cells were different; pPP had an EC50 intermediate (22.0 nM) between that of bPP (3.0 nM) and hPP (173.2 nM), with aPP and rPP being at least a further fold less potent.

Deamidation of Tyr36 in bPP (by O‐methylation or hydroxylation) or removal of the residue resulted in significant loss of activity in Col‐24.

GR231118 (1 μM) had no PP‐like effects. In Col‐24 and Col‐1, GR231118 significantly attenuated bPP (30 nM) or hPP (100 nM) responses, but it did not alter bPP responses in Col‐6. BIBP3226 and GR231118 both inhibited Y1‐mediated responses which were only present in Col‐6.

RT – PCR analysis confirmed the presence of hY4 receptor mRNA in Col‐24 and Col‐1 epithelia but a barely visible hY4 product was observed in Col‐6 and we suggest that an atypical Y4 receptor is expressed in this cell line.

British Journal of Pharmacology (2001) 132, 345–353; doi:10.1038/sj.bjp.0703815
The critical role of adenosine and guanosine in the affinity of dinucleoside polyphosphates to P2X‐receptors in the isolated perfused rat kidney
Authors: Van Der Giet Markus , Westhoff Tim , Cinkilic Okan , Jankowski Joachim , Schlüter Hartmut , Zidek Walter , Tepel Martin
Published: January 2005

The activation of P2x‐receptors in the rat renal vasculature by dinucleoside polyphosphates with variable phosphate group chain length (XpnX; X=Adenin (A) /Guanin (G), n=4 – 6) was studied by measuring their effects on perfusion pressure of the isolated perfused rat kidney at constant flow in an open circuit.

Like Ap4A, Ap5A and Ap6A the dinucleoside polyphosphates Ap4G, Ap5G and Ap6G exerted a vasoconstriction which could be blocked by suramin and pyridoxal‐phosphate‐6‐azophenyl‐2; 4‐disulphonic acid (PPADS).

Gp4G, Gp5G and Gp6G showed only very weak vasoconstriction at high doses.

Ap6A and α, β‐meATP could not be blocked by the selective P2x1‐receptor antagonisten NF023 (30 μM), whereas Ap4A, Ap4G, Ap5A, Ap5G and Ap6G were partially blocked by NF023.

Inhibition of endothelial NO‐synthase by Nω‐nitro‐L‐arginine methyl ester (L‐NAME) did not affect vasoconstrictions induced by dinucleosidepolyphosphates.

P2x‐receptor can only be activated if at least one adenosine moiety is present in the molecule.

ApnG show a weaker vasoconstrictive action than corresponding ApnA, concluding that two adenosine moieties enhance the P2x‐receptor binding and activation.

XpnX containing five phosphate groups show the most pronounced vasoconstrictive effect whereas four phosphate groups show the less effect, therefore the number of phosphate groups critically changes receptor affinity.

Additional experiments using permanent perfusion with α, β‐methylene ATP (α,β‐meATP) and the selective P2x1‐receptor antagonist NF023 showed that the newly discovered human dinucleoside polyphosphates activated the vascular P2x1‐receptor and an recently identified new P2x‐receptor subtype.

The differential effects of dinucleoside polyphosphates allow a fine tuning of local perfusion via composition of XpnXs.

British Journal of Pharmacology (2001) 132, 467–474; doi:10.1038/sj.bjp.0703817
Chronic treatment with reboxetine by osmotic pumps facilitates its effect on extracellular noradrenaline and may desensitize α2‐adrenoceptors in the prefrontal cortex
Authors: Invernizzi R W , Parini S , Sacchetti G , Fracasso C , Caccia S , Annoni K , Samanin R
Published: January 2005

This study investigated the effect of acute (2 days) and chronic (14 days) treatment with a selective inhibitor of noradrenaline uptake, reboxetine (10 mg kg−1 day−1) by osmotic pumps, on extracellular noradrenaline and the sensitivity of α2‐adrenoceptors in the prefrontal cortex of rats.

The effect of continuous infusion of reboxetine for 14 days on cortical extracellular noradrenaline was significantly higher (599% of vehicle levels) than after 2 days (263% of vehicle levels).

Brain concentrations of reboxetine after 2 and 14 days of infusion were 37.9±17.8 and 37.1±7.7 ng g−1, respectively.

Reboxetine infused for 2 and 14 days significantly increased extracellular dopamine in the prefrontal cortex, to a similar extent (257 and 342% of vehicle levels, respectively), whereas extracellular 5‐HT was not modified by either treatment.

Clonidine (10 and 30 μg kg−1 i.p.) reduced cortical extracellular noradrenaline similarly in animals treated with reboxetine or vehicle for 2 days whereas the effects in rats infused with reboxetine for 14 days were markedly less than in vehicle‐treated animals.

Clonidine (0.05 and 0.2 μM), infused through the dialysis probe into the prefrontal cortex, reduced cortical extracellular noradrenaline much less in rats treated with reboxetine for 14 days than in vehicle‐treated animals.

Reboxetine's effect on extracellular noradrenaline in the prefrontal cortex was greater after chronic treatment and could be associated with desensitization of terminal α2‐adrenoceptors that normally serve to inhibit noradrenaline release.

British Journal of Pharmacology (2001) 132, 183–188; doi:10.1038/sj.bjp.0703821
Effect of the long‐acting tachykinin NK1 receptor antagonist MEN 11467 on tracheal mucus secretion in allergic ferrets
Authors: Khan Safina , Liu Yu‐Chih , Khawaja Aamir M , Manzini Stefano , Rogers Duncan F
Published: January 2005

We investigated the effect of MEN 11467 ((1R,2S)‐2‐N[1(H)indol‐3‐yl‐carbonyl]‐1‐N‐{Nα(p‐tolylacetyl)‐Nα(methyl)‐D‐3‐(2‐naphthyl)alanyl}diaminocyclohexane) on tachykinin‐induced mucus secretion in ferret trachea in vitro and determined its effect on secretion by tracheae from allergic ferrets in response to allergen challenge.

Repeated administration of [Sar9,Met(O2)11]‐substance P ([Sar9]SP, 1 μM) maintained mucus output above control values for at least 1.75 h. MEN 11467 inhibited secretion in a concentration‐dependent manner with maximal inhibition at 10 μM and an approximate IC50 of 0.3 μM. Inhibition by MEN 11467 (0.1 – 10 μM) was maintained, to varying degree, for at least 1.75 h after washout in the continued presence of [Sar9]SP.

In electrically stimulated tracheae, tachykininergic neural secretion was virtually abolished by 1 μM MEN 11467.

In tracheae from ovalbumin‐sensitised animals, repeated administration of ovalbumin maintained mucus output above controls for 1.5 h. MEN 11467 inhibited ovalbumin‐induced secretion in a concentration‐dependent manner, with complete inhibition at 1 μM. Inhibition by MEN 11467 (1 and 10 μM) was maintained, to varying degree, after drug washout for the 1.5 h of ovalbumin stimulation.

MEN 11467 1 μM did not affect secretion induced by either acetylcholine or histamine, whereas 10 μM MEN 11467 did inhibit agonist‐induced secretion.

We conclude that, in ferret trachea in vitro, MEN 11467 at concentrations of 0.1 – 1 μM is a long acting and selective inhibitor of tachykininergic‐induced mucus secretion, and may have therapeutic potential for bronchial hypersecretion associated with allergic conditions, for example in asthma.

British Journal of Pharmacology (2001) 132, 189–196; doi:10.1038/sj.bjp.0703822
Potentiation of halofantrine‐induced QTc prolongation by mefloquine: correlation with blood concentrations of halofantrine
Authors: Lightbown Ian D , Lambert James P , Edwards Geoffrey , Coker Susan J
Published: January 2005

The antimalarial drug halofantrine can prolong the QT interval and this may be enhanced by prior use of mefloquine. This possible interaction has been investigated by examining the effects of halofantrine and mefloquine alone and in combination.

In anaesthetized rabbits (n=6 per group), halofantrine given as bolus doses of 1, 3, 10, and 30 mg kg−1 at 25 min intervals dose‐dependently prolonged the rate‐corrected QT (QTc) interval from 313±12 ms pre‐drug to 410±18 ms after the highest dose. Similar doses of mefloquine did not alter QTc intervals significantly. The highest dose of mefloquine (30 mg kg−1) caused cardiac contractile failure.

Pretreatment with 3 mg kg−1 mefloquine 25 min before the first dose of halofantrine potentiated the effects of all doses of halofantrine on QTc intervals.

The blood concentrations of halofantrine were two to six times higher in the group pretreated with mefloquine compared to the halofantrine alone group; e.g. 1.03±0.17 and 0.16±0.02 μM respectively after 1 mg kg−1 halofantrine. There was a significant correlation between blood halofantrine concentrations and QTc intervals (r=0.673). Even after making allowance for overestimation of the potency of halofantrine that may result from the hypokalaemia that is prevalent in anaesthetized rabbits, these effects occurred with concentrations of halofantrine that are found in clinical use.

These data indicate clearly that while mefloquine does not alter QTc intervals itself, it does enhance the effects of halofantrine by increasing the circulating concentration of halofantrine.

British Journal of Pharmacology (2001) 132, 197–204; doi:10.1038/sj.bjp.0703823
Effects of γ‐HCH and δ‐HCH on human recombinant GABAA receptors: dependence on GABAA receptor subunit combination
Authors: Maskell P D , Wafford K A , Bermudez I
Published: January 2005

Human GABAA receptors containing different α and β subunits with or without the γ2S or γ2L subunits were expressed in Xenopus oocytes and the effects of the insecticides γ‐ and δ‐hexachlorocyclohexane (γ‐HCH and δ‐HCH, respectively) on these receptor subunit combinations were examined using two electrode voltage‐clamp procedures.

γ‐HCH produced incomplete inhibition of GABA responses on all receptor combinations examined with affinities in the range of 1.1 – 1.9 μM. Affinity was not dependent on subunit composition but the maximum percentage of inhibition was significantly reduced in β1‐containing receptors.

δ‐HCH both potentiated GABAA receptors and activated them in the absence of GABA at concentrations higher than those producing potentiation. Allosteric enhancement of GABAA receptor function by δ‐HCH was not affected by the subunit composition of the receptor, By contrast the GABA mimetic actions of δ‐HCH were abolished in receptors containing either α4, β1 or γ2L subunits.

Sensitivity to the direct actions were not restored in receptors containing the mutant β1(S290N) subunit, but α1β2γ2L receptors became sensitive to the direct actions of δ‐HCH when oocytes were treated for 24 h with the protein kinase inhibitor isoquinolinesulphonyl‐2‐methyl piperazine dihydrochloride (H‐7).

We have shown the influence of various α, β and γ subunits on the inhibitory, GABA mimetic and allosteric effects of HCH isomers. The data reveal that neither the inhibitory actions of γ‐HCH nor the allosteric effects δ‐HCH has a strict subunit dependency. By contrast, sensitivity to the direct actions of δ‐HCH are abolished in receptors containing α4, β1 or γ2L subunits.

British Journal of Pharmacology (2001) 132, 205–212; doi:10.1038/sj.bjp.0703824
Rasagiline [N‐propargyl‐1R(+)‐aminoindan], a selective and potent inhibitor of mitochondrial monoamine oxidase B
Authors: Youdim Moussa B H , Gross Aviva , Finberg John P M
Published: January 2005

Rasagiline [N‐propargyl‐1R(+)‐aminoindan], was examined for its monoamine oxidase (MAO) A and B inhibitor activities in rats together with its S(−)‐enantiomer (TVP 1022) and the racemic compound (AGN‐1135) and compared to selegiline (1‐deprenyl). The tissues that were studied for MAO inhibition were the brain, liver and small intestine.

While rasagiline and AGN1135 are highly potent selective irreversible inhibitors of MAO in vitro and in vivo, the S(−) enantiomer is relatively inactive in the tissues examined.

The in vitro IC50 values for inhibition of rat brain MAO activity by rasagiline are 4.43±0.92 nM (type B), and 412±123 nM (type A). The ED50 values for ex vivo inhibition of MAO in the brain and liver by a single dose of rasagiline are 0.1±0.01, 0.042±0.0045 mg kg−1 respectively for MAO‐B, and 6.48±0.81, 2.38±0.35 mg kg−1 respectively for MAO‐A.

Selective MAO‐B inhibition in the liver and brain was maintained on chronic (21 days) oral dosage with ED50 values of 0.014±0.002 and 0.013±0.001 mg kg−1 respectively.

The degree of selectivity of rasagiline for inhibition of MAO‐B as opposed to MAO‐A was similar to that of selegiline. Rasagiline was three to 15 times more potent than selegiline for inhibition of MAO‐B in rat brain and liver in vivo on acute and chronic administration, but had similar potency in vitro.

These data together with lack of tyramine sympathomimetic potentiation by rasagiline, at selective MAO‐B inhibitory dosage, indicate that this inhibitor like selegiline may be a useful agent in the treatment of Parkinson's disease in either symptomatic or L‐DOPA adjunct therapy, but lack of amphetamine‐like metabolites could present a therapeutic advantage for rasagiline.

British Journal of Pharmacology (2001) 132, 500–506; doi:10.1038/sj.bjp.0703826
Impaired response to interferon‐γ in activated macrophages due to tyrosine nitration of STAT1 by endogenous nitric oxide
Authors: Llovera Marta , Pearson Jeremy D , Moreno Carlos , Riveros‐Moreno Valentina
Published: January 2005

Inducible NO synthase (iNOS) expression and activity were measured in the mouse macrophage cell line J774 after exposure to bacterial lipopolysaccharide (LPS) with or without interferon‐γ (IFN‐γ).

Inhibition of NOS activity by concomitant NG‐monomethyl‐L‐arginine (L‐NMMA) treatment further increased iNOS protein levels, with a substantial increase in iNOS half‐life.

Western blotting and ELISA demonstrated that several cell proteins were tyrosine‐nitrated when iNOS activity was high.

Rapid IFN‐γ‐induced phosphorylation of STAT1 was reduced by about 40% when cells were pretreated to induce iNOS, unless L‐NMMA was present during the pretreatment period. 2D gel electrophoresis demonstrated the presence of nitrotyrosine in STAT1 after iNOS induction, and confirmed the reduction in phospho‐STAT1 on subsequent stimulation with IFN‐γ for 15 min and its partial restoration when L‐NMMA was present during the pretreatment period.

We did not detect tyrosine nitration of the upstream kinase JAK2 in LPS+IFN‐γ pretreated cells, but JAK2 activity was also impaired, and was partially restored by concomitant L‐NMMA pretreatment.

We conclude that endogenous production of NO induces feedback inhibition of signalling pathways activated by IFN‐γ, at least in part by nitrating tyrosine residues in STAT1 which prevents phosphorylation.

British Journal of Pharmacology (2001) 132, 419–426; doi:10.1038/sj.bjp.0703838
Nedocromil sodium inhibits histamine‐induced itch and flare in human skin
Authors: Ahluwalia Poonam , McGill James I , Church Martin K
Published: January 2005

This study was designed to test the hypothesis that nedocromil sodium inhibits sensory nerve function to reduce flare and itch in human skin. Nedocromil sodium (2%) or water (control) was introduced into the volar forearm skin of eight non‐atopic volunteers by iontophoresis (8 mC) and histamine (20 μl of 1 μM and 300 nM) injected intradermally 10 min later at the same site. Itch was assessed on a visual analogue scale every 20 s for 5 min. Weal and flare areas and mean blood flux within the flare were assessed by scanning laser Doppler imaging at 10 min. The results showed that nedocromil sodium reduced itch scores, totalled over 5 min, by ∼74.0% (P<0.005) and flare areas by ∼65% (P<0.03). Neither weal areas nor blood flux within were reduced. These data demonstrate that nedocromil sodium is effective in reducing neurogenic itch and flare in the skin. We suggest that its mechanism of action is modulation of sensory neurone activation or conduction in the skin.

British Journal of Pharmacology (2001) 132, 613–616; doi:10.1038/sj.bjp.0703852
Indoxacarb, an oxadiazine insecticide, blocks insect neuronal sodium channels
Authors: Lapied Bruno , Grolleau Françoise , Sattelle David B
Published: January 2005

Decarbomethoxyllated JW062 (DCJW), the active component of a new oxadiazine insecticide DPX‐JW062 (Indoxacarb), was tested on action potentials and the inward sodium current recorded from short‐term cultured dorsal unpaired median neurones of the cockroach Periplaneta americana.

Under whole‐cell current‐clamp conditions, 100 nM DCJW reduced the amplitude of action potentials and induced a large hyperpolarization of the resting membrane potential associated with a 41% increase in input resistance.

In voltage‐clamp, DCJW resulted in a dose‐dependent inhibition (IC50 28 nM) of the peak sodium current. Based on IC50 values, the effect of DCJW was about 10 fold less potent than tetrodotoxin (TTX) but 1000 fold more potent than the local anaesthetic lidocaine. DCJW (100 nM) was without effect on activation properties of the sodium current, reversal potential, voltage dependence of sodium conductance and on both fast and slow steady‐state inactivations.

TTX (2 nM) resulted in 48% inhibition of the peak inward sodium current. Co‐application of TTX (2 nM) with various concentrations of DCJW produced an additional inhibition of the peak inward current, indicating that the blocking actions of DCJW and TTX were distinct. Co‐application of lidocaine (IC50 30 μM) with various concentrations of DCJW produced a reduction of the apparent potency of DCJW, suggesting that DCJW and lidocaine acted at the same site.

DCJW (100 nM) did not affect inward calcium or outward potassium currents.

This study describes, for the first time, the action on insect neuronal voltage‐dependent sodium channels of Indoxacarb, a new class of insecticides.

British Journal of Pharmacology (2001) 132, 587–595; doi:10.1038/sj.bjp.0703853
GABAB receptor autoradiography in hippocampal sclerosis associated with human temporal lobe epilepsy
Authors: Billinton Andrew , Baird Virginia H , Thom Maria , Duncan John S , Upton Neil , Bowery Norman G
Published: January 2005

Metabotropic γ‐aminobutyric acid receptors (GABAB) exist both pre‐ and postsynaptically throughout the brain, mediating the suppression of neurotransmitter release and late inhibitory postsynaptic potentials. Investigation of GABAB receptors in rodent models of temporal lobe epilepsy (TLE) suggests that expression or function of these receptors may be altered in the disorder.

The aim of the present study was to investigate the expression of GABAB receptors in samples of hippocampus surgically resected from patients with hippocampal sclerosis (HS) related intractable TLE, and compare this expression with samples of neurologically normal post‐mortem (PM) control hippocampal tissue. Appropriate measures of neuronal loss associated with HS were investigated for comparison with receptor binding data.

Receptor autoradiography with [3H]‐GABA in the presence of isoguvacine, and quantitative densitometric analysis were used to investigate GABAB receptor expression (Bmax) and affinity (KD) in 11 HS samples and eight controls. A three‐dimensional cell counting technique was used to assess neuronal density in both groups.

GABAB receptor density was significantly reduced in CA1, CA2, CA3, hilus and dentate gyrus, and increased in the subiculum, of HS cases as compared with PM controls. Neuronal loss was significant in all regions measured. When adjusted for neuronal loss, CA1 GABAB receptor expression appeared significantly upregulated (P<0.05).

In HS/TLE, GABAB receptor expression per remaining neurone appears increased in CA1. This finding, and increased [3H]‐GABA affinity at CA3 and hilar GABAB receptors, suggests altered GABAB receptor function may occur in human HS/TLE, possibly as a result of synaptic reorganization.

British Journal of Pharmacology (2001) 132, 475–480; doi:10.1038/sj.bjp.0703854
A novel activation of Ca2+‐activated Cl− channel in Xenopus oocytes by Ginseng saponins: evidence for the involvement of phospholipase C and intracellular Ca2+ mobilization
Authors: Choi Seok , Rho Seong‐Hwan , Jung Se‐Yeon , Kim Seok‐Chang , Park Chul‐Seung , Nah Seung‐Yeol
Published: January 2005

The signal transduction mechanism of ginsenosides, the active ingredients of ginseng, was studied in Xenopus oocytes using two‐electrode voltage‐clamp technique. Ginseng total saponin (GTS), i.e., an unfractionated mixture of ginsenosides produced a large outward current at membrane potentials more positive than −20 mV when it was applied to the exterior of oocytes, but not when injected intracellularly. The effect of GTS was concentration‐dependent (EC50: 4.4 μg ml−1) and reversible.

Certain fractionated ginsenosides (Rb1, Rb2, Rc, Rf, Rg2 and Ro) also produced an outward current in a concentration‐dependent manner with the order of potency of Rf>Ro>Rb1=Rb2>Rg2>Rc. Other ginsenosides (Rd, Re and Rg1) had little or no effect.

The GTS effect was completely blocked by bath application of the Ca2+‐activated Cl− channel blocker niflumic acid and by intracellular injection of the calcium chelator BAPTA or the IP3 receptor antagonist heparin. Also, the effect was partially blocked by bath‐applied U‐73122, a phospholipase C (PLC) inhibitor and by intracellularly injected GTPγS, a non‐hydrolyzable GTP analogue. Whereas, it was not altered by pertussin toxin (PTX) pretreatment.

These results indicate that: (1) interaction of ginsenosides with membrane component(s) at the extracellular side leads to Ca2+‐activated Cl− channel opening in Xenopus oocyte membrane; and (2) this process involves PLC activation, the release of Ca2+ from the IP3‐sensitive intracellular store and PTX‐insensitive G protein activation.

British Journal of Pharmacology (2001) 132, 641–648; doi:10.1038/sj.bjp.0703856
Somatostatin receptor‐mediated arachidonic acid mobilization: evidence for partial agonism of synthetic peptides
Authors: Alderton Forbes , Fan Tai‐Ping D , Humphrey Patrick P A
Published: January 2005

Somatostatin and the stable octapeptide analogues, octreotide and angiopeptin, were examined for their ability to stimulate the release of tritium from [3H]‐arachidonic acid pre‐loaded CHO‐K1 cells expressing human recombinant sst2, sst3 or sst5 receptors.

Somatostatin stimulated tritium release (pEC50) through the sst2 (7.8±0.1) and sst5 (7.3±0.2), but not the sst3 receptor. Octreotide behaved as a full (sst2 receptor) or partial agonist (sst5 receptor), whereas angiopeptin behaved as a weak partial agonist at both receptor types.

Maximum responses to somatostatin through both receptor types were significantly reduced by pertussis toxin, whereas pEC50 estimates were unaffected.

Inhibition of MEK1 or Src, but not PKA, PI 3‐kinases or tyrosine kinases, by reportedly selective inhibitors reduced sst2‐mediated responses by somatostatin, but not angiopeptin. A selective inhibitor of PKC (Ro‐31‐8220) reduced both somatostatin and angiopeptin responses.

These data provide further evidence for partial agonist activity of synthetic peptides of somatostatin. Furthermore, the somatostatin receptor signalling mechanisms which mediate arachidonic acid mobilization appear to be multiple and complex.

British Journal of Pharmacology (2001) 132, 760–766; doi:10.1038/sj.bjp.0703862
Pharmacological characterization and antithrombotic effect of agkistin, a platelet glycoprotein Ib antagonist
Authors: Yeh Chia‐Hsin , Chang Mei‐Chi , Peng Hui‐Chin , Huang Tur‐Fu
Published: January 2005

Agkistin, purified from the snake venom of Formosan Agkistrodon acutus, belongs to the family of C‐type lectin GPIb binding proteins. It is a heterodimeric molecule, consisting of α‐ (16.5 kDa) and β‐ (15.5 kDa) subunits with a molecular mass of 32,512 Daltons examined by SDS – PAGE and mass spectrometry.

In vitro, agkistin concentration‐dependently inhibited ristocetin‐induced human platelet agglutination and aggregation in the presence of vWF. It also inhibited TXA2 formation and prolonged the latent period in triggering aggregation by a low concentration of thrombin (0.03 u ml−1).

125I‐agkistin specifically bound to unactivated human platelets in a saturable manner with a KD value of 223±10.6 nM. This binding reaction was rapid and reversible. Monoclonal antibodies, AP1 and 6D1 raised against platelet GPIb, almost completely blocked 125I‐agkistin binding to platelets. However, monoclonal antibody 7E3 raised against GPIIb/IIIa complex, trigramin, a GPIIb/IIIa antagonist, ADP and EDTA did not affect 125I‐agkistin binding reaction.

Agkistin (250 μg kg−1) significantly prolonged the bleeding time and induced transient thrombocytopenia of mice when given intravenously. Furthermore, it markedly inhibited platelet plug formation in irradiated mesenteric venules of fluorescein‐treated mice in vivo.

In conclusion, agkistin inhibits ristocetin induced platelet aggregation mainly through its specific binding to platelet GPIb, thereby blocking the interaction between GPIb and vWF. In addition, agkistin exhibits antithrombotic activity in vivo.

British Journal of Pharmacology (2001) 132, 843–850; doi:10.1038/sj.bjp.0703865
β2‐Adrenoceptor agonists inhibit release of eosinophil‐activating cytokines from human airway smooth muscle cells
Authors: Hallsworth Matthew P , Twort Charles H C , Lee Tak H , Hirst Stuart J
Published: January 2005

Airway smooth muscle (ASM) is a potential source of multiple pro‐inflammatory cytokines during airway inflammation. β‐Adrenoceptor agonist hyporesponsiveness is a characteristic feature of asthma, and interleukin (IL)‐1β and tumour necrosis factor (TNF)‐α are implicated in its cause. Here, the capacity of β‐adrenoceptor agonists to prevent release of GM‐CSF, RANTES, eotaxin and IL‐8, elicited by IL‐1β or TNFα, was examined in human ASM cells.

Isoprenaline (∼EC50 150 nM), a non‐selective β‐adrenoceptor agonist, and salbutamol (∼EC50 25 nM), a selective β2‐adrenoceptor agonist, attenuated release of GM‐CSF, RANTES and eotaxin, but not IL‐8 (EC50 >1 μM). The maximum extent of attenuation was RANTES eotaxin > GM‐CSF >> IL‐8, and was prevented by either propranolol (1 μM), a non‐selective β‐adrenoceptor antagonist, or ICI 118511 (IC50 15 nM), a selective β2‐adrenoceptor antagonist.

The cyclic AMP‐elevating agents, dibutyryl cyclic AMP (∼EC50 135 μM), forskolin (∼EC50 530 nM) and cholera toxin (∼EC50 575 pg ml−1) abolished IL‐1β‐induced release of GM‐CSF, RANTES and eotaxin, but not IL‐8.

IL‐1β (1 ng ml−1) attenuated early increases (up to 1 h) in cyclic AMP formation induced by salbutamol (1 μM), but not by forskolin (10 μM). The cyclo‐oxygenase inhibitor, indomethacin (1 μM) prevented later increases (3 – 12 h) in IL‐1β‐stimulated cyclic AMP content, but did not prevent the attenuation by salbutamol of IL‐1β‐induced cytokine release.

We conclude in human ASM cells that activation of β2‐adrenoceptors and generation of cyclic AMP is negatively‐linked to the release, elicited by IL‐1β or TNFα, of eosinophil‐activating cytokines such as GM‐CSF, RANTES and eotaxin, but not IL‐8.

British Journal of Pharmacology (2001) 132, 729–741; doi:10.1038/sj.bjp.0703866
Orphenadrine prevents 3‐nitropropionic acid‐induced neurotoxicity in vitro and in vivo
Authors: Pubill David , Verdaguer Ester , Canudas Anna Ma , Sureda Francesc Xavier , Escubedo Elena , Camarasa Jordi , Pallàs Merce , Camins Antoni
Published: January 2005

Previous studies indicate that 3‐nitropropionic acid (3‐NPA) neurotoxicity involves the excitotoxic activation of N‐methyl‐D‐aspartate (NMDA) receptors. Thus, we examined the effect of orphenadrine (an anticholinergic drug with NMDA receptor antagonist properties) on 3‐NPA neurotoxicity in both cultured rat cerebellar granule cells (CGCs) and in rats.

Orphenadrine protected CGCs from 3‐NPA‐induced mortality, as assessed by both the neutral red viability assay and laser scanning cytometry, using propidium iodide staining.

For rats, two indirect markers of neuronal damage were used: the binding of [3H]‐PK 11195 to the peripheral‐type benzodiazepine receptor (PBR), a microglial marker, and expression of the 27 kD heat‐shock protein (HSP27), a marker of activated astroglia. Systemic administration of 3‐NPA (30 mg kg−1 per day for 3 days) induced a 170% increase in [3H]‐PK 11195 binding, and expression of HSP27.

Both the increase in [3H]‐PK 11195 and HSP 27 expression were prevented by previous administration of 30 mg kg−1 per day of orphenadrine for 3 days. Lower doses (10 and 20 mg kg−1) had no protective effect. Orphenadrine also reduced 3‐NPA‐induced mortality in a dose‐dependent manner.

We propose that orphenadrine or orphenadrine‐like drugs could be used to treat neurodegenerative disorders mediated by overactivation of NMDA receptors.

British Journal of Pharmacology (2001) 132, 693–702; doi:10.1038/sj.bjp.0703869
Prostaglandin E2 increases cyclic AMP and inhibits endothelin‐1 production/secretion by guinea‐pig tracheal epithelial cells through EP4 receptors
Authors: Pelletier Stéphane , Dubé Jean , Villeneuve Annie , Gobeil Fernand , Yang Quan , Battistini Bruno , Guillemette Gaétan , Sirois Pierre
Published: January 2005

Prostaglandin E2 (PGE2) increased adenosine 3′ : 5′‐cyclic monophosphate (cyclic AMP) formation in tracheal epithelial cells and concomitantly decreased the production/secretion of immunoreactive endothelin (irET).

Naturally occurring prostanoids and selective and non‐selective EP receptor agonists showed the following rank order of potency in stimulating cyclic AMP generation by epithelial cells: PGE2 (EP‐selective)>16,16‐dimethyl PGE2 (EP‐selective)>11‐deoxy PGE2 (EP‐selective)>>>iloprost (IP/EP1/EP3‐selective), butaprost (EP2‐selective), PGD2 (DP‐selective), PGF2α (FP‐selective). The lack of responsiveness of the latter prostanoids indicated that the prostanoid receptor present in these cells is not of the DP, FP, IP, EP1, EP2 or EP3 subtype.

Pre‐incubating the cells with the selective TP/EP4‐receptor antagonists AH23848B and AH22921X antagonized the PGE2‐evoked cyclic AMP generation. This suggested that EP4 receptors mediate PGE2 effects. However, in addition to any antagonistic effects at EP4‐receptors, both compounds, to a different extent, modified cyclic AMP metabolism. The selective EP1, DP and EP2 receptor antagonist (AH6809) failed to inhibit PGE2‐evoked cyclic AMP generation which confirmed that the EP2 receptor subtype did not contribute to the change in cyclic AMP formation in these cells.

The PGE2‐induced inhibition of irET production by guinea‐pig tracheal epithelial cells was due to cyclic AMP generation and activation of the cyclic AMP‐dependent protein kinase since this effect was reverted by the cyclic AMP antagonist Rp‐cAMPS.

These results provide the first evidence supporting the existence of a functional prostaglandin E2 receptor that shares the pharmacological features of the EP4‐receptor subtype in guinea‐pig tracheal epithelial cells. These receptors modulate cyclic AMP formation as well as ET‐1 production/secretion in these cells.

British Journal of Pharmacology (2001) 132, 999–1008; doi:10.1038/sj.bjp.0703886
Inhibition of capacitative calcium entry is not obligatory for relaxation of the mouse anococcygeus by the NO/cyclic GMP signalling pathway
Authors: Ayman Sinem , Gibson Alan , McFadzean Ian , Reynolds Martyn , Wallace Pat
Published: January 2005

The object of this study was to determine whether inhibition of capacitative calcium entry is essential for relaxation of the mouse anococcygeus via the NO/cyclic GMP signalling pathway.

In intact muscles, thapsigargin (Tg; 100 nM)‐induced tone was relaxed by NO, sodium nitroprusside (SNP), 8‐Br‐cyclic GMP, and nitrergic field stimulation. The relaxations were similar in magnitude to those observed against carbachol (50 μM) tone and, with the exception of those to 8‐Br‐cyclic GMP, were reduced by the soluble guanylyl cyclase inhibitor 1H‐[1,2,4]oxodiazolo[4,3‐a]quinoxalin‐1‐one (ODQ, 5 μM).

In single smooth muscle cells, loaded with Fura‐2, both carbachol and Tg produced sustained elevations in cytoplasmic calcium levels ([Ca2+]i). SNP inhibited the rise in [Ca2+]i produced by carbachol, an effect attenuated by ODQ. In contrast, neither SNP nor 8‐Br‐cyclic GMP reduced the elevated [Ca2+]i associated with Tg.

In β‐escin skinned preparations, NO had no effect on tone induced by calcium (1 μM in the presence of 100 μM GTP). Carbachol and Tg produced further increases in calcium/GTP‐induced tone and, in both cases, this additional tone was relaxed by NO and 8‐Br‐cyclic GMP.

The results support the hypothesis that the NO/cyclic GMP pathway inhibits capacitative calcium entry by refilling the internal stores, since reduction in [Ca2+]i was not observed in the presence of Tg. However, as muscle relaxation was still observed, impairment of capacitative calcium entry cannot be considered obligatory for relaxation. Results from skinned tissues suggest that inhibition of calcium sensitization processes, perhaps associated with store‐depletion, may be an important mechanism of NO/cyclic GMP‐induced relaxation.

British Journal of Pharmacology (2001) 132, 807–814; doi:10.1038/sj.bjp.0703888
Anandamide activates peripheral nociceptors in normal and arthritic rat knee joints
Authors: Gauldie S D , McQueen D S , Pertwee R , Chessell I P
Published: January 2005

The effects of the endogenous cannabinoid anandamide were studied on peripheral, polymodal nociceptors recorded from normal and chronically inflamed (Freund's adjuvant) knee joint afferents in rats anaesthetized with pentobarbitone. Anandamide (860 nmol) caused a rapid, short lasting excitation of a sub‐population of capsaicin‐sensitive nociceptive afferents in normal knee joints (7.2±2.3 impulses s−1; n=15 units from five animals). In arthritic joints there were 9.7±3.0 impulses s−1 (n=11 from six animals), which was not significantly different from normal joints. The excitation was dose dependent (8.6 – 2900 nmol) and mediated by activation of the vanilloid receptor (VR1) as it was abolished by the VR1 antagonist capsazepine (1 mg kg−1). Our results show that anandamide, at high doses, can activate nociceptive afferents innervating the rat knee joints, in contrast with its widely described analgesic actions.

British Journal of Pharmacology (2001) 132, 617–621; doi:10.1038/sj.bjp.0703890