bluuebunny/crossref_metadata_2025_split huggingface dataset:
Apparent species differences in the kinetic properties of P2X7 receptors
Authors: Hibell A D , Kidd E J , Chessell I P , Humphrey P P A , Michel A D 
Published: January 2005

Apparent species differences in the responses of recombinant P2X7 receptors to repeated application of 2′‐ and 3′‐O‐(4‐benzoylbenzoyl)‐ATP (BzATP) have been investigated.
Repeated application of 100 μM BzATP resulted in a progressive increase in current magnitude (current growth) at mouse and human, but not rat P2X7 receptors.
Current growth was thought to reflect progressive dilation of the P2X7 ion‐channel to a pore permeable to large molecules (MW<900), suggesting that channel dilation was not occurring at the rat P2X7 receptor. However, 100 μM BzATP produced a rapid influx of YO‐PRO‐1 (MW375) in cells expressing rat or human P2X7 receptors.
There were, however, species differences in agonist potency such that 100 μM BzATP was a supra‐maximal concentration at rat, but not human or mouse, P2X7 receptors. Importantly, when sub‐maximal concentrations of BzATP or ATP were examined, current growth occurred at rat P2X7 receptors.
The rate of current growth and YO‐PRO‐1 accumulation increased with agonist concentration and appeared more rapid at rat and human, than at mouse P2X7 receptors.
The potency of BzATP and ATP was 1.5–10 fold lower in naïve cells than in cells repeatedly exposed to ATP.
This study demonstrates that current growth occurs at mouse, rat and human P2X7 receptors but only when using sub‐maximal concentrations of agonist. Previously, current growth was thought to reflect the progressive increase in pore diameter of the P2X7 receptor ion channel, however, the results of this study suggest a progressive increase in agonist potency may also contribute.

British Journal of Pharmacology (2000) 130, 167–173; doi:10.1038/sj.bjp.0703302
Identification of the adenylyl cyclase‐activating 5‐hydroxytryptamine receptor subtypes expressed in the rat submandibular gland
Authors: Bourdon D M , Camden J M , Landon L A , Levy F O , Turner J T 
Published: January 2005

Serotonin (5‐hydroxytryptamine, 5‐HT) has been shown to increase cyclic AMP production in dispersed cell aggregates from the major salivary glands of the rat. The goal of the present study was to identify the 5‐HT receptor subtypes that mediate these effects in rat submandibular glands (SMG).
Among the 5‐HT receptor subtypes identified in the rat, 5‐HT4(a,b), 5‐HT6 and 5‐HT7(a,b,c) activate adenylyl cyclase (AC). We used subtype specific primers to screen rat SMG by reverse transcription‐PCR. Results indicate the presence of mRNA for 5‐HT4(b) and 5‐HT7(a) but not for 5‐HT4(a), 5‐HT6 and 5‐HT7(b,c).
In dispersed SMG cells, 5‐carboxyamidotryptamine (5‐CT), a 5‐HT7 receptor agonist, stimulated cyclic AMP synthesis with higher potency (EC50=27±5 nM) but lower efficacy than 5‐HT, suggesting a 5‐HT7 component and an additional component in the response to 5‐HT. The 5‐HT7 contribution was further supported by antagonism of the 5‐CT effect by metergoline, a 5‐HT7 antagonist, which exhibited an affinity (Ki=50 nM) similar to that obtained at the cloned 5‐HT7 receptor.
In the presence of a maximally effective concentration of 5‐CT, 5‐HT produced an additional increase in cyclic AMP production that was inhibited by the 5‐HT4 receptor antagonist, GR113808, suggesting that the second component of cyclic AMP production is mediated by 5‐HT4 receptors.
These findings indicate the presence in rat SMG of both 5‐HT4(b) and 5‐HT7(a) receptors positively coupled to AC.

British Journal of Pharmacology (2000) 130, 104–108; doi:10.1038/sj.bjp.0703303
Involvement of the cyclic AMP system in the switch from tolerance into supersensitivity to the antinociceptive effect of the opioid sufentanil
Authors: Hurlé María A , Goirigolzarri Isabel , Valdizán Elsa M 
Published: January 2005

We have previously demonstrated that chronic and simultaneous treatment of rats with the μ‐opioid receptor agonist sufentanil and the Ca2+ channel blocker nimodipine, not only prevented tolerance development, but the animals became supersensitive to the antinociceptive effect of the opioid. The focus of the present work was to determine the possible involvement of cross interactions between the adenylyl cyclase pathway and L‐type voltage‐sensitive Ca2+‐channels, in modulating the switch from opioid tolerance into supersensitivity.
The modulatory effect of sufentanil on adenylyl cyclase activity was determined by measuring cyclic AMP production in slices from the cortex of rats rendered tolerant or supersensitive to the antinociceptive effect of the opioid. Tolerance was induced by chronic infusion of sufentanil, at a rate of 2 μg h−1, for 7 days. Supersensitivity was induced by concurrent infusion of sufentanil (2 μg h−1) and nimodipine (1 μg h−1) for 7 days. Antinociception was evaluated by the tail‐flick test.
Tolerance to the analgesic effect of sufentanil was associated with a significant reduction in the response of adenylyl cyclase to forskolin. Furthermore, the effect of the opioid on forskolin‐induced cyclic AMP accumulation was abolished. On the other hand, supersensitivity to the analgesic effect of the opioid was associated with an increase in both, the adenylyl cyclase response to forskolin, and the opioid inhibition of cyclic AMP production.
We suggest that sustained L‐type Ca2+ channel blockade may result in changes in the adenylyl cyclase effector system triggered by μ‐opioid receptor activation, leading to the switch from opioid tolerance into supersensitivity.

British Journal of Pharmacology (2000) 130, 174–180; doi:10.1038/sj.bjp.0703304
Inhibition of pulmonary eosinophilia and airway hyperresponsiveness in allergic mice by rolipram: involvement of endogenously released corticosterone and catecholamines
Authors: Kung T T , Crawley Y , Luo B , Young S , Kreutner W , Chapman R W 
Published: January 2005

This study investigates the role of adrenal‐derived catecholamines and corticosterone on the inhibition by rolipram, a phosphodiesterase (PDE)‐4 inhibitor, of pulmonary eosinophilia and airway hyperresponsiveness (AHR) in allergic mice.
The following experimental groups were studied in mice sensitized and challenged with ovalbumin (OVA): normal, adrenalectomized, propranolol (β‐adrenoceptor antagonist) and metyrapone (corticosterone synthesis inhibitor) treated. These interventions were studied both in the absence and in the presence of rolipram. Eosinophil numbers in the bronchoalveolar lavage (BAL) and AHR to methacholine were measured 24 h after OVA challenge.
Treatment of sensitized mice with rolipram (0.3–10 mg kg−1, p.o.), inhibited pulmonary eosinophilia and the AHR to methacholine in OVA‐challenged mice.
Adrenalectomy increased the number of eosinophils in the BAL of OVA‐challenged mice but had no effect on AHR to methacholine. Adrenalectomy attenuated both the rolipram‐induced inhibition of BAL eosinophilia and AHR to methacholine in OVA challenged mice. Propranolol (10 mg kg−1, p.o.) had no effect on the inhibition of eosinophilia by rolipram but attenuated the inhibition of AHR to methacholine in OVA challenged mice. On the other hand, metyrapone (10 mg kg−1, p.o.) attenuated the inhibition of eosinophilia by rolipram but had no effect on the inhibition of AHR to methacholine in OVA challenged mice. Metyrapone‐treatment alone increased the number of eosinophils in the BAL of OVA‐challenged mice.
These results identify an important role for adrenal‐derived catecholamines and corticosterone on the inhibition of pulmonary eosinophilia and AHR by rolipram in allergic mice.

British Journal of Pharmacology (2000) 130, 457–463; doi:10.1038/sj.bjp.0703308
Pharmacological evaluation of the role of cyclooxygenase isoenzymes on the micturition reflex following experimental cystitis in rats
Authors: Lecci Alessandro , Birder Lori A , Meini Stefania , Catalioto Rose‐Marie , Tramontana Manuela , Giuliani Sandro , Criscuoli Marco , Maggi Carlo A 
Published: January 2005

Prostanoids, generated from cyclooxygenase (COX) isoenzymes, play a role in the physiological function of the lower urinary tract and are important mediators of inflammatory hyperalgesia. The present work evaluates the effects of the COX‐1/COX‐2 inhibitor dexketoprofen as well as of a selective COX‐2 inhibitor, NS‐398, on urodynamic function following endotoxin (LPS) or cyclophosphamide (CYP)‐induced inflammation of the urinary bladder.
The application of arachidonic acid (330 μg rat−1) onto the serosal surface of the urinary bladder in control rats elicited bladder contractions which could be blocked in a dose‐dependent manner by dexketoprofen (0.1–3 mg kg−1, i.v.) but not by NS‐398 (0.2–6 mg kg−1, i.v.).
Dexketoprofen (3 mg kg−1, i.v.) decreased the micturition frequency and increased the pressure threshold for triggering the micturition either when administered within 15 min or 3 h following surgery in control animals. NS‐398 (6 mg kg−1, i.v.) decreased the micturition frequency and increased the pressure threshold when administered 3 h but not 15 min following surgery.
Administration of LPS (2 mg kg−1, i.v., 90–120 min) increased both the micturition frequency and the pressure threshold for triggering the micturition reflex. Changes in urodynamic parameters induced by LPS were prevented by doses of either dexketoprofen (1 mg kg−1, i.v.) or NS‐398 (2 mg kg−1, i.v.) which were ineffective in control animals.
Pretreatment with CYP (150 mg kg−1, i.p., 48 h) increased the micturition frequency, pressure threshold, and the minimal intravesical pressure but decreased the mean amplitude of micturition contractions. In CYP‐treated rats, dexketoprofen (1 mg kg−1, i.v.) or NS‐398 (2 mg kg−1, i.v.) blocked the CYP‐induced urodynamic changes with exception of the micturition contraction amplitude.
These results indicate that COX‐1 may be involved in modulating the threshold for activating the micturition reflex in the normal rats and also demonstrates that inhibition of COX‐2 prevents or reverses the urodynamic changes associated with bladder inflammation induced either by surgery, LPS or CYP treatments.

British Journal of Pharmacology (2000) 130, 331–338; doi:10.1038/sj.bjp.0703309
CGRP2 receptor in the internal anal sphincter of the rat: implications for CGRP receptor classification
Authors: Wisskirchen F M , Marshall I 
Published: January 2005

The CGRP receptor mediating relaxation of the rat internal anal sphincter (IAS) has been characterized using CGRP analogues, homologues, the antagonist CGRP8–37 and its analogues.
In isolated IAS strips, the spontaneously developed tone was concentration‐dependently relaxed by hα CGRP, hβ CGRP and rat β CGRP (pEC50 8.1±0.2, 8.3±0.1 and 8.4±0.2, respectively; 100% maximum response). Vasoactive intestinal polypeptide (VIP) was around 7 fold more potent than hα CGRP (pEC50 9.0±0.1; 100% maximum relaxation). [Cys(ACM2.7)] hα CGRP and salmon calcitonin were inactive (up to 10−5 M).
Hα CGRP8–37 (10−5 M) antagonized responses to hα CGRP (apparent pKB 5.7±0.3) and rat β CGRP (apparent pKB 5.8±0.2), but not to VIP. Hβ CGRP8–37 (10−5 M) was an antagonist against hα CGRP (apparent pKB 6.1±0.1). Hα CGRP8–37 analogues (10−5 M), with substitutions at the N‐terminus by either glycine8 or des‐NH2 valine8 or proline8, antagonized hα CGRP responses with similar affinities (apparent pKB 5.8±0.1, 5.8±0.1 and 5.5±0.1, respectively).
Peptidase inhibitors (amastatin, bestatin, captopril, phosphoramidon and thiorphan, 10−6 M each) did not increase the agonist potency of either hα CGRP or [Cys(ACM2,7)] hα CGRP, or the antagonist affinity of hα CGRP8–37 against hα CGRP or rat β CGRP.
These data demonstrate for the first time a CGRP receptor in the rat IAS for which hα CGRP 8–37 and its analogues have an affinity that is consistent with a CGRP2 receptor. However, there is a marked species difference as the antagonist has a 100 fold lower affinity in the rat than in the same tissue of the opossum (Chakder & Rattan, 1991).

British Journal of Pharmacology (2000) 130, 464–470; doi:10.1038/sj.bjp.0703315
Pharmacological characterization of neurogenic responses of the sheep isolated internal anal sphincter
Authors: Mundey M K , Jonas M , Worthley T , Scholefield J H , Wilson V G 
Published: January 2005

The aim of the study was to establish the nature of the neurogenic responses of the sheep isolated anal sphincter.
Isolated strips of sheep internal anal sphincter develop intrinsic contractile tone following the application of stretch tension. On transmural stimulation (1–20 Hz, 10 V pulse strength, 0.5 ms pulse width, 1 s every 180 s) transient relaxations were observed.
The amplitude of the relaxations were frequency‐dependent reaching a maximal response at 10–20 Hz and were inhibited by tetrodotoxin (0.3 μM). Neither atropine (0.3 μM) nor phentolamine (1 μM) affected control responses.
The nitric oxide synthase inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME, 100 μM) and the selective inhibitor of soluble guanylyl cyclase ODQ, (1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one) (1 μM) completely inhibited the neurogenic relaxations and uncovered contractions that were abolished by 1 μM phentolamine and 0.1 μM prazosin. The effect of L‐NAME, but not that of ODQ, was partially reversed by the addition of L‐arginine (1 mM).
Sodium nitroprusside (10 nM–10 μM) caused concentration‐dependent inhibition of myogenic tone and this effect was significantly reduced by ODQ. Calcium‐free Krebs‐Henseleit solution also reduced myogenic tone by 85%.
Transmural electrical stimulation of the sheep isolated internal anal sphincter causes a transient relaxation of myogenic tone that appears to involve nitric oxide from non‐adrenergic, non‐cholinergic nerves and, to a lesser degree, noradrenaline from sympathetic nerves. The characteristics of the preparation compares well with that of human tissue and may prove to be a suitable animal based model for further studies.

British Journal of Pharmacology (2000) 130, 489–494; doi:10.1038/sj.bjp.0703322
Cyclo‐oxygenase‐2 enhances basic fibroblast growth factor‐induced angiogenesis through induction of vascular endothelial growth factor in rat sponge implants
Authors: Majima Masataka , Hayashi Izumi , Muramatsu Michiko , Katada Jun , Yamashina Shohei , Katori Makoto 
Published: January 2005

Angiogenesis is reportedly enhanced by prostaglandins (PGs). In the present study, we investigated whether or not cyclo‐oxygenase (COX)‐2 mediated angiogenesis in chronic and proliferate granuloma.
In rat sponge implants, angiogenesis was gradually developed over a 14‐day experimental period as granuloma formed. This angiogenesis was enhanced by topical injections of human recombinant basic fibroblast growth factor (bFGF).
In sponge granuloma, mRNA of COX‐1 was constitutively expressed, whereas that of COX‐2 was increased with neovascularization in parallel with that of vascular endothelial growth factor (VEGF).
Topical injections of bFGF increased the expression of COX‐2 mRNA. bFGF‐stimulated angiogenesis was inhibited by indomethacin or selective COX‐2 inhibitors, NS‐398, nimesulide, and JTE‐522.
The levels of PGE2 and 6‐keto‐PGF1α in the sponge granuloma were increased with bFGF 13 fold and 9 fold, respectively, and these levels were markedly reduced by NS‐398.
The expression of VEGF mRNA in the granuloma was also enhanced by bFGF, and was reduced by NS‐398.
Topical injections of PGE2 and beraprost sodium, a PGI2 analogue, increased the expression of VEGF mRNA, with angiogenesis enhancement.
The enhanced angiogenesis by bFGF was significantly inhibited by topical injections of VEGF anti‐sense oligonucleotide.
These results suggested that COX‐2 may enhance bFGF‐induced neovascularization in sponge granuloma by PG‐mediated expression of VEGF, and that a COX‐2 inhibitor would facilitate the management of conditions involving angiogenesis.

British Journal of Pharmacology (2000) 130, 641–649; doi:10.1038/sj.bjp.0703327
Selective inhibitory effects of niflumic acid on 5‐HT‐induced contraction of the rat isolated stomach fundus
Authors: Scarparo H C , Santos G C M , Leal‐Cardoso J H , Criddle D N 
Published: January 2005

The effects of niflumic acid (NFA), an inhibitor of calcium‐activated chloride currents ICl(Ca), were compared with the actions of the voltage‐dependent calcium channel (VDCC) blocker nifedipine on 5‐hydroxtryptamine (5‐HT)‐ and acetylcholine (ACh)‐induced contractions of the rat isolated fundus.
NFA (1–30 μM) elicited a concentration‐dependent inhibition of contractions induced by 5‐HT (10 μM) with a reduction to 15.5±6.0% of the control value at 30 μM. 1 μM nifedipine reduced 5‐HT‐induced contraction to 15.2±4.9% of the control, an effect not greater in the additional presence of 30 μM NFA.
In contrast, the contractile response to ACh (10 μM) was not inhibited by NFA in concentrations 100 μM, although this response was partly inhibited by nifedipine (1 μM) to 67.6±11.8% of the control value.
NFA (1–30 μM) did not affect contraction induced by either 20 mM or 60 mM KCl, suggesting that this drug was not acting via blockade of VDCCs or activation of potassium channels. In contrast, 3,5‐dichlorophenylamine‐2‐carboxylic acid and 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid were less selective in their inhibitory effects, inducing reductions of 60 mM KCl‐induced contraction at concentrations 10 μM.
Our results show that NFA can exert selective inhibitory effects on the chloride‐dependent 5‐HT‐induced contractions of the rat fundus. The data support the hypothesis that activation of Cl(Ca) channels leading to calcium entry via VDCCs is a mechanism utilized by 5‐HT, but not by ACh, to elicit contraction of the rat fundus.

British Journal of Pharmacology (2000) 130, 678–684; doi:10.1038/sj.bjp.0703331
Caspase inhibition and limitation of myocardial infarct size: protection against lethal reperfusion injury
Authors: Mocanu M M , Baxter G F , Yellon D M 
Published: January 2005

Ischaemia‐reperfusion injury causes cell death by both necrosis and apoptosis. Caspase activation is a major event in apoptosis. We therefore examined the effect of caspase inhibitors during reperfusion upon myocardial infarction. Rat isolated hearts were subjected to 35 min coronary occlusion and 120 min reperfusion. Treatment groups were perfused with caspase inhibitors during early reperfusion. We assessed a non‐selective caspase inhibitor (Z‐VAD·fmk, 0.1 μM), a caspase‐8 inhibitor (Z‐IETD·fmk, 0.07 μM), a caspase‐9 inhibitor (Z‐LEHD·fmk, 0.07 μM) and a caspase‐3 inhibitor (Ac‐DEVD·cmk, 0.07 μM). All caspase inhibitors limited infarct size (infarct‐risk ratio per cent: control 38.5±2.6; Z‐VAD·fmk 24.6±3.4; Z‐LEHD·fmk 19.3±2.4; Z‐IETD·fmk 23.0±5.4; Ac‐DEVD·cmk 27.8±3.3; P<0.05 when compared with control value, 1‐way ANOVA). We conclude that caspase inhibition during early reperfusion protects myocardium against lethal reperfusion injury.British Journal of Pharmacology (2000) 130, 197–200; doi:10.1038/sj.bjp.0703336
Thermodynamically distinct high and low affinity states of the A1 adenosine receptor induced by G protein coupling and guanine nucleotide ligation states of G proteins
Authors: Lorenzen Anna , Guerra Laura , Campi Franca , Lang Heidrun , Schwabe Ulrich , Borea Pier Andrea 
Published: January 2005

The influence of the receptor‐G protein coupling state and the guanine nucleotide ligation state of the G protein on the binding mechanism of A1 adenosine receptor ligands has been investigated in [3H]‐1,3‐dipropyl‐8‐cyclopentylxanthine ([3H]‐DPCPX) binding studies in rat brain membranes. Thermodynamic parameters of binding of A1 adenosine receptor ligands of different intrinsic activities were determined in the absence or presence of GDP and compared to the binding mechanism after receptor‐G protein uncoupling.
In agreement with previous studies, it was found that xanthine and non‐xanthine antagonists showed an enthalpy‐ or enthalpy‐ and entropy‐driven binding mechanism under all conditions.
In contrast to antagonists, the binding mechanism of agonists was strongly affected by the G protein coupling state or the absence or presence of guanine nucleotides. Binding of full and partial agonists to the high‐affinity state of the A1 receptor was entropy‐driven in the absence of GDP, and a good correlation between intrinsic activities and the contribution of entropy was observed. In the absence of GDP, binding of full and partial agonists and antagonists to the high affinity state of the receptor was thermodynamically discriminated. In contrast, no such discrimination was found in the presence of GDP.
The binding mechanism of agonists to the low‐affinity state of the receptor was identical to that of antagonists only after uncoupling of the receptor from G proteins by pretreatment with N‐ethylmaleimide or guanosine‐5′‐(γ‐thio)‐triphosphate (GTPγS).
These results indicate the existence of two thermodynamically distinct high‐ and low‐affinity states of the A1 adenosine receptor.

British Journal of Pharmacology (2000) 130, 595–604; doi:10.1038/sj.bjp.0703339
Further evidence that 5‐HT‐induced relaxation of pig pulmonary artery is mediated by endothelial 5‐HT2B receptors
Authors: Glusa E , Pertz H H 
Published: January 2005

The endothelial 5‐HT receptor mediating relaxation of pig pulmonary artery has been characterized using the selective 5‐HT2B receptor agonist BW 723C86 and a variety of structurally diverse 5‐HT receptor antagonists.
If arterial rings with intact endothelium were precontracted with prostaglandin F2α (3 μM), BW 723C86 caused concentration‐dependent relaxation with a pEC50=8.21±0.03 and Emax=89±4% relative to 5‐HT. The relaxant responses to BW 723C86 were inhibited by the 5‐HT2B receptor antagonist SB 204741, the 5‐HT2B/2C receptor antagonist SB 206553 and the antimigraine drug pizotifen, yielding pA2 values of 6.68, 7.20 and 8.32, respectively. The pA2 values against BW 723C86 were similar to those determined against 5‐HT.
The relaxant effect of 5‐HT was antagonized by a variety of 22 compounds of diverse chemical structures. Based on the calculated mean pA2 values the order of the most potent antagonists was ritanserin (9.38) > methysergide (8.86) > pizotifen (8.47) methiothepin (8.32) > LY 53857 (7.84) amoxapine (7.80) loxapine (7.73) metergoline (7.64) mianserin (7.51) rauwolscine (7.39). Compounds with weak blocking potency were yohimbine (6.37), spiperone (5.88) and ketanserin (5.85). Correlation analysis between the affinities of the antagonists in pig pulmonary artery and those from radioligand binding studies at human and rat 5‐HT2B receptors showed a highly significant correlation (r=0.95 and 0.84, P<0.002 and <0.005). Correlation with 5‐HT2C receptors was much lower (r=0.57, P=0.035), and no correlations were obtained with 5‐ht6 and 5‐HT7 receptors.
It is concluded that the 5‐HT receptor mediating endothelium‐dependent relaxation of pig pulmonary artery is of the 5‐HT2B subtype.

British Journal of Pharmacology (2000) 130, 692–698; doi:10.1038/sj.bjp.0703341