bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of eotaxin formation and eosinophil migration by selective inhibitors of phosphodiesterase type 4 isoenzyme
Authors: Silva Patrícia M R , Alves Alessandra C , Serra Magda F , Pires Ana Lucia A , Silva Juliane P , Barreto Emiliano O , Cordeiro Renato S B , Jose Peter J , Teixeira Mauro M , Lagente Vincent , Martins Marco A 
Published: January 2005

This study was undertaken to investigate the possible contribution of the blockade of eotaxin generation to the anti‐eosinophilotactic effect of phosphodiesterase (PDE) type 4 inhibitors. In some experiments, the putative synergistic interaction between PDE type 4 inhibitors and the β2‐agonist salbutamol was also assessed.Sensitized guinea‐pigs aerosolized with antigen (5% ovalbumin, OVA) responded with a significant increase in eotaxin and eosinophil levels in the bronchoalveolar lavage fluid (BALF) at 6 h. Eosinophil recruitment was inhibited by both PDE type 4 inhibitors rolipram (5 mg kg−1, i.p.) and RP 73401 (5 mg kg−1, i.p.) treatments. In contrast, only rolipram inhibited eotaxin production.Sensitized rats intrapleurally challenged (i.pl.) with antigen (OVA, 12 μg cavity−1) showed a marked eosinophil infiltration at 24 h, preceded by eotaxin generation at 6 h. Intravenous administration of a rabbit anti‐mouse eotaxin antibody (0.5 mg kg−1) significantly reduced allergen‐evoked eosinophilia in this model.Local pretreatment with rolipram (40 μg cavity−1) or RP 73401 (40 μg cavity−1) 1 h before challenge reduced eosinophil accumulation evaluated in the rat pleural effluent, but only the former was active against eotaxin generation. The inhibitors of PDE type 3 (SK&F 94836) and type 5 (zaprinast) failed to alter allergen‐evoked eosinophil recruitment in rats.Local injection of β2‐agonist salbutamol (20 μg cavity−1) inhibited both eosinophil accumulation and eotaxin production following pleurisy. The former was better inhibited when salbutamol and rolipram were administered in combination.Treatment with rolipram and RP 73401 dose‐dependently inhibited eosinophil adhesion and migrationin vitro. These effects were clearly potentiated by salbutamol at concentrations that had no effect alone.Our findings indicate that although rolipram and RP 73401 are equally effective in inhibiting allergen‐induced eosinophil infiltration only the former prevents eotaxin formation, indicating that PDE 4 inhibitors impair eosinophil accumulation by mechanisms independent of eotaxin production blockade.British Journal of Pharmacology(2001)134, 283–294; doi:10.1038/sj.bjp.0704233
Dependency of detrusor contractions on calcium sensitization and calcium entry through LOE‐908‐sensitive channels
Authors: Jezior James R , Brady Jeffrey D , Rosenstein Daniel I , McCammon Kurt A , Miner Amy S , Ratz Paul H 
Published: January 2005

The subcellular mechanisms regulating stimulus‐contraction coupling in detrusor remain to be determined. We used Ca2+‐free solutions, Ca2+ channel blockers, cyclopiazonic acid (CPA), and RhoA kinase (ROK) inhibitors to test the hypothesis that Ca2+ influx and Ca2+ sensitization play primary roles.
In rabbit detrusor, peak bethanechol (BE)‐induced force was inhibited 90% by incubation for 3 min in a Ca2+‐free solution. By comparison, a 20 min incubation of rabbit femoral artery in a Ca2+‐free solution reduced receptor‐induced force by only 5%.
In detrusor, inhibition of sarcoplasmic reticular (SR) Ca2+ release by 2APB, or depletion of SR Ca2+ by CPA, inhibited BE‐induced force by only 27%. The CPA‐insensitive force was abolished by LaCl3. By comparison, 2APB inhibited receptor‐induced force in rabbit femoral artery by 71%.
In the presence of the non‐selective cation channel (NSCC) inhibitor, LOE‐908, BE did not produce an increase in [Ca2+]i but did produce weak increases in myosin phosphorylation and force.
Inhibitors of ROK‐induced Ca2+ sensitization, HA‐1077 and Y‐27632, inhibited BE‐induced force by ∼50%, and in combination with LOE‐908, nearly abolished force.
These data suggest that two principal muscarinic receptor‐stimulated detrusor contractile mechanisms include NSCC activation, that elevates [Ca2+]i and ROK activation, that sensitizes cross bridges to Ca2+.

British Journal of Pharmacology (2001) 134, 78–87; doi:10.1038/sj.bjp.0704241
The role of the hydrophilic Asn230 residue of the μ‐opioid receptor in the potency of various opioid agonists
Authors: Pil Joost , Tytgat Jan 
Published: January 2005

To investigate the effect of the hydrophilic Asn amino acid at position 230 of the human μ‐opioid receptor (hMOR230) on the potency of various agonists, we mutated this residue to Thr and Leu (hMORN230T and hMORN230L respectively).
Taking advantage of the functional coupling of the opioid receptor with the heteromultimeric G‐protein‐coupled inwardly rectifying K+ (GIRK1/GIRK2) channel, either the wild type hMOR or one of the mutated receptors (hMORN230L or hMORN230T) were functionally coexpressed with GIRK1/GIRK2 channels and a regulator of G‐protein signalling (RGS4) in Xenopus laevis oocytes.
The two‐microelectrode voltage clamp technique was used to measure the opioid receptor‐activated GIRK1/GIRK2 channel responses. The potency of [D‐Ala2,N‐MePhe4,Gly5‐ol]‐enkephalin (DAMGO), remained unaffected as measured via hMORN230T and hMORN230L, while the potency of fentanyl and morphine significantly increased via these mutated receptors.
Our results are indicative for the existence of hydrophobic interactions between a methyl‐group of the side chain of Thr or Leu on the one hand and the piperidine‐ring of fentanyl and the hexene‐ring of morphine on the other. The mutations also had no influence on the potency of morphine‐6‐glucuronide (M6G) and morphine‐3‐glucuronide (M3G).
We conclude that the hydrophilic side chain of Asn in position 230 is not involved in the formation of a H‐bond with the aliphatic alcohol of morphine and that an enhancement of the potency of morphine and fentanyl can be explained by mutating this residue towards more hydrophobic amino acids.

British Journal of Pharmacology (2001) 134, 496–506; doi:10.1038/sj.bjp.0704263
A1‐, A2A‐ and A3‐subtype adenosine receptors modulate intraocular pressure in the mouse
Authors: Avila Marcel Y , Stone Richard A , Civan Mortimer M 
Published: January 2005

Despite the potential importance of the mouse in studying the pharmacology of aqueous dynamics, measurement of intraocular pressure (IOP) in its very small eye has been problematic. Utilizing a novel servo‐null electrophysiologic approach recently applied to the mouse, we have identified a diversity of adenosine‐receptor mechanisms in modulating IOP in this species. We report the first evidence that A3 receptors increase IOP in any species, and verify in the mouse reports with larger mammals that A1 receptors lower and A2A receptors increase IOP.British Journal of Pharmacology (2001) 134, 241–245; doi:10.1038/sj.bjp.0704267
Increased contractile response to 5‐hydroxytryptamine1‐receptor stimulation in pulmonary arteries from chronic hypoxic rats: role of pharmacological synergy
Authors: MacLean Margaret R , Morecroft Ian 
Published: January 2005

5‐Hydroxytryptamine (5‐HT)1‐receptor‐induced contraction is enhanced, or uncovered, by elevated vascular tone in many arteries including pulmonary arteries. In hypoxia‐induced pulmonary hypertension, the endogenous tone of pulmonary arteries is elevated and this may contribute to increased 5‐HT1‐receptor‐induced contraction. Here we investigate the influence of vascular tone induced by endothelin‐1 (ET‐1), neuropeptide Y (NPY), KCl, 4‐aminopyridine (inactivator of Kv channels, 4‐AP) or the calcium ionophore A23187 on contractile responses to the 5‐HT1‐receptor agonist 5‐carboxamidotryptamine (5‐CT) in small muscular pulmonary arteries from control rats and rats exposed to chronic hypoxia. The influence of the nitric oxide synthase inhibitor Nω‐nitro‐L‐arginine methyl ester (L‐NAME, 100 μM) was also studied. These conditions were chosen to mimic those that influence pulmonary vascular tone in hypoxia‐induced pulmonary hypertension.
In control rat small pulmonary arteries, only high concentrations of 5‐CT (>1 μM) induced vasoconstriction. Tone induced by NPY, 4‐AP and A23187 had no effect on responses to 5‐CT whilst responses to 5‐CT were increased by ET‐1‐ and KCl‐induced tone. In the presence of L‐NAME these responses to 5‐CT were enhanced further.
Responses to 5‐CT were enhanced 3 – 4 fold in small pulmonary arteries from hypoxia‐exposed, pulmonary hypertensive rats and neither L‐NAME nor increasing tone with NPY, 4‐AP, A23187, ET‐1 or KCl had any further effect on responses to 5‐CT.
The results suggest that inhibition of nitric oxide synthase combined with KCl‐ or ET‐1‐induced vascular tone potentiates responses to 5‐HT1‐receptor‐induced contraction in pulmonary arteries in a synergistic fashion and this mimics the effects of chronic hypoxic exposure.

British Journal of Pharmacology (2001) 134, 614–620; doi:10.1038/sj.bjp.0704273
Effects of potassium channel and Na+‐Ca2+ exchange blockers on the responses of slowly adapting pulmonary stretch receptors to hyperinflation in flecainide‐treated rats
Authors: Matsumoto Shigeji , Nishikawa Toshimi , Yoshida Shinki , Ikeda Mizuho , Tanimoto Takeshi , Saiki Chikako , Takeda Mamoru 
Published: January 2005

The effects of K+ channel blockers, such as 4‐aminopyridine (4‐AP) and tetraethylammonium (TEA), and a reverse‐mode Na+ – Ca2+ exchange blocker, 2‐[2‐[4‐(4‐nitrobenzyloxyl) phenyl] ethyl] isothiourea methanesulphonate (KB‐R7943), on the responses of slowly adapting pulmonary stretch receptor activity to hyperinflation (inflation volume=3 tidal volumes) were investigated in anaesthetized, artificially ventilated, unilaterally vagotomized rats after pretreatment with a Na+ channel blocker flecainide. The administration of flecainide (9 mg kg−1) at a dose greater than that which abolished 50 μg kg−1 veratridine‐induced SAR stimulation also inhibited hyperinflation‐induced stimulation of SARs.
In flecainide‐treated animals, administration of 4‐AP (0.7 and 2 mg kg−1) stimulated SAR activity during normal inflation and also caused a partial blockade of hyperinflation‐induced SAR inhibition.
The discharges of SARs during normal inflation in flecainide‐treated animals were not significantly altered by administration of either TEA (2 and 7 mg kg−1) or KB‐R7943 (1 and 3 mg kg−1), but both K+ channel and Na+‐Ca2+ exchange blockers partially attenuated hyperinflation‐induced SAR inhibition.
These results suggest that hyperinflation‐induced SAR inhibition in the presence of flecainide (9 mg kg−1) involves the activation of several K+ conductance pathways.

British Journal of Pharmacology (2001) 134, 682–690; doi:10.1038/sj.bjp.0704277
The new compound, LASSBio 294, increases the contractility of intact and saponin‐skinned cardiac muscle from Wistar rats
Authors: Sudo R T , Zapata‐Sudo G , Barreiro E J 
Published: January 2005

A new compound designated as LASSBio 294 (L‐294), 3,4‐methylenedioxybenzoyl‐2‐thienylhydrazone, was synthesized as an alternative therapeutic for cardiac dysfunction.
L‐294 increased in a dose‐dependent manner the spontaneous contractions of isolated hearts from Wistar rats with maximal effect (128.0±0.7% of control) observed at 25 μM.
The positive inotropic effect of L‐294 was also observed in electrically stimulated cardiac tissues from Wistar rats. The maximal increment of twitches, at 200 μM, was 163.1±18.4% for atrial, 153.5±28.5% for papillary and 201.5±18.5% for ventricular muscles.
In saponin skinned ventricular cells: (a) L‐294 present in the period of sarcoplasmic reticulum (SR) loading with Ca2+ shifted the dose and caffeine‐induced contracture curve; (b) L‐294 (100 μM) increased 40% the Ca2+ uptake into SR; (c) L‐294 did not significantly alter the sensitivity of contractile proteins to Ca2+ in SR‐disrupted skinned ventricular cells.
Retrograde perfusion of the isolated heart from Wistar rats with L‐294 (100 μM) did not cause any significant change in rhythm, heart rate (control, 220±14.7 b.p.m.; 246±24.6 b.p.m. for L‐294), PR interval (control, 66.0±2.4 ms; 64.0±2.3 ms for L‐294) or QRS duration (control, 28.8±3.4 ms; 32.0±2.0 ms for L‐294).
These results suggest a novel mechanism for a positive cardioinotropic effect through an interaction with the Ca2+ uptake/release process of the SR. The effect of L‐294 could be explained by a pronounced increased accumulation of Ca2+ into the SR.

British Journal of Pharmacology (2001) 134, 603–613; doi:10.1038/sj.bjp.0704291
Modulation of serotonergic neurotransmission by short‐ and long‐term treatments with sigma ligands
Authors: Bermack J E , Debonnel G 
Published: January 2005

Sigma receptors were first described in 1976 as opiate receptors but were later determined to be a distinct class of receptors with two subtypes, sigma1 and sigma2. Although the endogenous ligand is yet to be elucidated, the sigma1 receptor has recently been cloned.
Behavioural models used to test potential antidepressants have shown sigma ligands to produce antidepressant effects but their mechanism of action is unknown.
The goal of the present study was to assess the effects of various sigma1 ligands on the firing activity of serotonin (5‐HT) neurons of the dorsal raphe nucleus (DRN) using extracellular in vivo recordings in anaesthetized rats.
The sigma1 ligands (+)‐pentazocine and 4‐(N‐benzylpiperidin‐4‐yl)‐4‐iodobenzamide (4‐IBP) (2 mg kg−1 day−1) increased markedly 5‐HT firing activity after 2 days of treatment and maintained the same increased firing rate after long‐term (21 days) treatments. Furthermore, the increased firing rate produced by 2 and 21 day treatments with (+)‐pentazocine was prevented by the co‐administration of N,N‐dipropyl‐2‐(4‐methoxy‐3‐(2‐phenylethoxy)phenyl)‐thylamine (NE‐100) (10 mg kg−1 day−1) a selective sigma1 antagonist, confirming the sigma1 receptor's modulation of these effects. In contrast, the sigma1 ligands (+)‐N‐cyclopropylmethyl‐N‐methyl‐1,4‐diphenyl‐1‐1‐ethyl‐but‐3‐en‐1‐ylamine hydrochloride (JO‐1784) and 2‐(4‐morpholinoethyl 1‐phenyl‐cyclohexane‐1‐carboxylate hydrochloride (PRE‐084) had no effect.
Following a 21‐day treatment with (+)‐pentazocine there was a marked reduction in the number of neurons found per track. This decrease was not seen after chronic treatment with 4‐IBP and may represent a depolarization block.
These results suggest a modulation of serotonergic neurotransmission by some sigma receptors and provide a potential mechanism for the ‘antidepressant effects’ reported and provide evidence toward sigma1 ligands as potential antidepressants with a rapid onset of action.

British Journal of Pharmacology (2001) 134, 691–699; doi:10.1038/sj.bjp.0704294
Nitric oxide regulates human eosinophil adhesion mechanisms in vitro by changing integrin expression and activity on the eosinophil cell surface
Authors: Conran N , Ferreira H H A , Lorand‐Metze I , Thomazzi S M , Antunes E , De Nucci G 
Published: January 2005

The nitric oxide synthase (NOS) inhibitor, Nω‐nitro‐L‐arginine methyl ester (L‐NAME), inhibits both rat and human eosinophil chemotaxis in vitro. Here, the role of nitric oxide (NO) in human eosinophil cell surface integrin expression and function was investigated.
Human peripheral blood eosinophils were treated with L‐NAME (0.01 – 1.0 mM) and their adhesion to human fibronectin and serum observed. Adhesion of cells to fibronectin and serum increased by 24.0±4.6 and 43.8±4.7%, respectively, when eosinophils were treated with 1.0 mM L‐NAME. Increased adhesion by L‐NAME could be abolished when cells were co‐incubated with VLA‐4‐ and Mac‐1‐specific monoclonal antibodies (mAbs).
The NO donor, sodium nitroprusside (2.5 mM), significantly inhibited eosinophil adhesion to fibronectin and serum by 34.3±4.5 and 45.2±5.6%, respectively. This inhibition was accompanied by a 4 fold increase in the levels of intracellular cyclic GMP.
Flow cytometrical analysis demonstrated that L‐NAME induced an increased expression of CD11b (Mac‐1) on the eosinophil cell surface of 36.3±7.4%. L‐NAME had no effect upon CD49d (VLA‐4) expression.
Treatment of human eosinophils, in vitro, with H‐[1,2,4] oxadiazolo quinoxalin‐1‐one (ODQ) (0.1 mM), an inhibitor of soluble guanylate cyclase, also significantly increased eosinophil adhesion to fibronectin and serum by 73.5±17.9 and 91.7±12.9%, respectively. This increase in adhesion could also be inhibited by co‐incubation with the Mac‐1 and VLA‐4‐specific mAbs.
In conclusion, results indicate that NO, via a cyclic GMP‐dependent mechanism, inhibits the adhesion of human eosinophils to the extracellular matrix (ECM). This inhibition is accompanied by a decrease in the expression and function of the eosinophil's adhesion molecules, in particular, the expression of the Mac‐1 integrin and the function of the VLA‐4 integrin.

British Journal of Pharmacology (2001) 134, 632–638; doi:10.1038/sj.bjp.0704295
Despite substantial degradation, 2‐arachidonoylglycerol is a potent full efficacy agonist mediating CB1 receptor‐dependent G‐protein activation in rat cerebellar membranes
Authors: Savinainen Juha R , Järvinen Tomi , Laine Krista , Laitinen Jarmo T 
Published: January 2005

Two endocannabinoids, arachidonoyl ethanolamide (AEA) and 2‐arachidonoylglycerol (2‐AG) bind and activate G‐protein‐coupled cannabinoid receptors, but limited data exist on their relative ability to activate G‐proteins.
Here we assess agonist potency and efficacy of various cannabinoids, including 2‐AG, HU‐310 (2‐arachidonoyl glyceryl ether, a third putative endocannabinoid), HU‐313 (another ether analogue of 2‐AG), AEA, R‐methanandamide (an enzymatically stable analogue of AEA), and CP‐55,940 at rat brain CB1 receptors using agonist‐stimulated [35S]‐GTPγS binding to cerebellar membranes and whole brain sections. Degradation of endocannabinoids under experimental conditions was monitored by HPLC.
To enhance efficacy differences, agonist dose‐response curves were generated using increasing GDP concentrations. At 10−6 M GDP, all compounds, except HU‐313, produced full agonists responses ∼2.5 fold over basal. The superior efficacy of 2‐AG over all other compounds became evident by increasing GDP (10−5 and 10−4 M).
In membrane incubations, 2‐AG was degraded by 85% whereas AEA and HU‐310 were stable. Pretreatment of membranes with phenylmethylsulphonyl fluoride inhibited 2‐AG degradation, resulting in 2 fold increase in agonist potency. Such pretreatment had no effect on AEA potency.
Responses in brain sections were otherwise consistent with membrane binding data, but 2‐AG evoked only a weak signal in brain sections, apparently due to more extensive degradation.
These data establish that even under conditions of substantial degradation, 2‐AG is a full efficacy agonist, clearly more potent than AEA, in mediating CB1 receptor‐dependent G‐protein activity in native membranes.

British Journal of Pharmacology (2001) 134, 664–672; doi:10.1038/sj.bjp.0704297
Mechanisms of hydralazine induced vasodilation in rabbit aorta and pulmonary artery
Authors: Ellershaw D C , Gurney A M 
Published: January 2005

The directly acting vasodilator hydralazine has been proposed to act at an intracellular site in vascular smooth muscle to inhibit Ca2+ release.
This study investigated the mechanism of action of hydralazine on rabbit aorta and pulmonary artery by comparing its effects on the tension generated by intact and β‐escin permeabilized vessels and on the cytoplasmic Ca2+ concentration, membrane potential and K+ currents of isolated vascular smooth muscle cells.
Hydralazine relaxed pulmonary artery and aorta with similar potency. It was equally effective at inhibiting phasic and tonic contractions evoked by phenylephrine in intact vessels and contractions evoked by inositol 1,4,5 trisphosphate (IP3) in permeabilized vessels.
Hydralazine inhibited the contraction of permeabilized vessels and the increase in smooth muscle cell Ca2+ concentration evoked by caffeine with similar concentration dependence, but with lower potency than its effect on IP3 contractions.
Hydralazine had no effect on the relationship between Ca2+ concentration and force generation in permeabilized vessels, but it slowed the rate at which maximal force was developed before, but not after, destroying sarcoplasmic reticulum function with the calcium ionophore, ionomycin.
Hydralazine had no effect on membrane potential or the amplitudes of K+ currents recorded from isolated smooth muscle cells over the concentration range causing relaxation of intact vessels.
The results suggest that the main action of hydralazine is to inhibit the IP3‐induced release of Ca2+ from the sarcoplasmic reticulum in vascular smooth muscle cells.

British Journal of Pharmacology (2001) 134, 621–631; doi:10.1038/sj.bjp.0704302
Systemic ETA receptor antagonism with BQ‐123 blocks ET‐1 induced forearm vasoconstriction and decreases peripheral vascular resistance in healthy men
Authors: Spratt James C S , Goddard Jane , Patel Neil , Strachan Fiona E , Rankin Andrew J , Webb David J 
Published: January 2005

The effect on systemic haemodynamics of BQ‐123, a selective endothelin A (ETA) receptor antagonist, was investigated in healthy men by giving, on separate occasions, ascending intravenous doses of 100, 300, 1000 and 3000 nmol min−1 BQ‐123, each for 15 min, in a randomized, placebo‐controlled, double‐blind study. The response of forearm blood flow to brachial artery infusion of endothelin‐1 (ET‐1; 5 pmol min−1 for 90 min) was also studied using bilateral forearm plethysmography, after systemic pre‐treatment, on separate occasions, with one of two doses of BQ‐123 (300 and 1000 nmol min−1 for 15 min) or placebo.
Systemic BQ‐123 dose‐dependently decreased systemic vascular resistance (P<0.01 for all doses vs placebo) and mean arterial pressure (P<0.05 for 300 nmol min−1 and P<0.01 for 1000 and 3000 nmol min−1) during the 60 min following infusion. There were concurrent increases in heart rate and cardiac index. BQ‐123, when infused systemically for 15 min, appeared to reach a maximum effect at 1000 nmol min−1.
Intra‐brachial ET‐1 infusion, after pre‐treatment with placebo, caused a slow onset progressive forearm vasoconstriction without systemic effects. This vasoconstriction was attenuated by pre‐treatment with BQ‐123 at 300 nmol min−1 and abolished by BQ‐123 at 1000 nmol min−1 (P<0.01 vs placebo).
These effects occurred at concentrations of BQ‐123 in the plasma (510±64 nmol l−1) that were ETA receptor selective, and were not accompanied by an increase in plasma ET‐1 that would have indicated ETB receptor blockade.
We conclude that ETA‐mediated vascular tone contributes to the maintenance of basal systemic vascular resistance and blood pressure in healthy men.

British Journal of Pharmacology (2001) 134, 648–654; doi:10.1038/sj.bjp.0704304