bluuebunny/crossref_metadata_2025_split huggingface dataset:
A role of protein kinase Cμ in signalling from the human adenosine A1 receptor to the nucleus
Authors: Hill Kathryn J , Webber Anne C , Hill Stephen J 
Published: June 2003

Stimulation of adenosine A1 receptors produced a stimulation of c‐fos promoter‐regulated gene transcription in Chinese hamster ovary (CHO)‐A1 cells expressing the human A1 receptor. Gene transcription was monitored using a luciferase‐based reporter gene (pGL3).
This response to the A1 receptor agonist N6‐cyclopentyladenosine (CPA) was sensitive to inhibition by pertussis toxin, the MEK‐1 inhibitor PD 98059 and by the phosphatidylinositol‐3‐kinase inhibitors wortmannin and LY 294002. The response was also completely abolished by the protein kinase C (PKC) inhibitor Ro‐31‐8220.
Several isoforms of PKC can be detected in CHO‐A1 cells (α, δ, ɛ, μ, ι, ζ), but only PKCα, PKCδ and PKC were downregulated by prolonged treatment with phorbol ester. The c‐fos‐regulated luciferase response to A1 agonists was not, however, inhibited by 24 h pretreatment with the phorbol esters phorbol 12,13‐dibutyrate (PDBu). This observation, together with the fact that a significant attenuation (40%) of the c‐fos‐luciferase response to PDBu and A1 agonist was produced by low concentrations of the PKC inhibitor Gö 6976 suggests a role for PKCμ.
Stimulation of CHO‐A1 cells with CPA stimulated the activation of endogenous PKCμ as measured by autophosphorylation. This was rapid, occurred within 1–2 min, but returned to basal levels after 30 min. Furthermore, transient expression of a constitutively active form of PKCμ resulted in a significant increase in c‐fos‐regulated gene expression.
Taken together, these data suggest that PKCμ plays an important role in the ability of the adenosine A1 receptor to signal to the nucleus.

British Journal of Pharmacology (2003) 139, 721–732. doi:10.1038/sj.bjp.0705294
Selective activation by photodynamic action of cholecystokinin receptor in the freshly isolated rat pancreatic acini
Authors: An Yu Ping , Xiao Rui , Cui Hong , Cui Zong Jie 
Published: June 2003

Sulphonated aluminium phthalocyanine (SALPC) photodynamic action induces amylase secretion and permanent calcium oscillation in rat pancreatic acinar cells, because of the activation of phospholipase C or signalling proteins upstream. The aim of the present study was to investigate the involvement of muscarinic acetylcholine and cholecystokinin (CCK) receptors.
Muscarinic receptor antagonist atropine (10 μM) blocked amylase secretion induced by bethanechol (100 μM), and CCK1 receptor antagonist (S)‐N‐[1‐(2‐fluorophenyl)‐3,4,6,7‐tetrahydor‐4‐oxo‐pyrrolo‐[3,2,1‐jk][1,4] benzodiazepine‐3yl]‐1H‐indole‐2‐carboxamide (FK480) (1 μM) blocked amylase secretion induced by CCK (100 pM).
Amylase secretion induced by SALPC photodynamic action was not inhibited when atropine and FK480 were present during photodynamic action. However, addition of FK480 1 μM after initiation of photodynamic action inhibited photodynamic amylase secretion. Bethanechol (10, 100 μM) added after photodynamic action resulted in a full secretory response.
Atropine (10 nM) abolished calcium oscillation induced by bethanechol (5 μM), and FK480 (10 nM) blocked calcium oscillation induced by CCK (10 pM).
Atropine up to 10 μM was without effect on Ca2+ oscillation triggered by photodynamic action, but these oscillations were abolished by FK480 (10 nM). FK480 (10 nM) had no effect on calcium oscillations induced by bethanechol (5 μM). Bethanechol 5 μM, added after FK480 blockade of photodynamic calcium oscillation, still triggered regular calcium oscillation.
It is concluded that SALPC photodynamic action selectively and permanently activates CCK receptor in rat pancreatic acini. Such permanent and selective modulation of signalling proteins has important implications for the treatment of pancreatitis, prion diseases, and neurodegenerative disorders.

British Journal of Pharmacology (2003) 139, 872–880. doi:10.1038/sj.bjp.0705295
Role of PAF receptors during intestinal ischemia and reperfusion injury. A comparative study between PAF receptor‐deficient mice and PAF receptor antagonist treatment
Authors: Souza Danielle G , Pinho Vanessa , Soares Adriana C , Shimizu Takao , Ishii Satoshi , Teixeira Mauro M 
Published: June 2003

The reperfusion of ischemic tissues may be associated with local and systemic inflammation that prevents the full benefit of blood flow restoration. The present study aimed to confirm a role for platelet‐activating factor receptor(s) (PAFR) during ischemia and reperfusion injury by using genetically modified mice deficient in the PAFR (PAFR−/− mice) and to evaluate comparatively the effectiveness of pharmacological treatment using the PAFR antagonist UK‐74,505 (modipafant).
The reperfusion of the ischemic superior mesenteric artery (SMA) induced marked local (intestine) and remote (lungs) tissue injury, as assessed by the increase in vascular permeability, neutrophil influx and intestinal hemorrhage and in the production of TNF‐α. There was also a systemic inflammatory response, as shown by the increase in serum TNF‐α concentrations and marked reperfusion‐associated lethality.
After reperfusion of the ischemic SMA, PAFR−/− mice had little tissue or systemic inflammation and lethality was delayed, but not prevented, in these mice. Interestingly, the reperfusion‐associated increases in tissue concentrations of IL‐10 were significantly greater in PAFR−/− than wild‐type mice.
Pretreatment with PAFR antagonist UK‐74,505 (1 mg kg−1) markedly prevented tissue injury, as assessed by the increase in vascular permeability, neutrophil accumulation, hemorrhage and TNF‐α concentrations in the intestine and lungs. In contrast, UK‐74,505 failed to affect reperfusion‐associated lethality and increases in serum TNF‐α when used at 1 mg kg−1.
Reperfusion‐associated lethality and increase in serum TNF‐α were only affected when a supra‐maximal dose of the antagonist was used (10 mg kg−1). At this dose, UK‐74,505 also induced a marked enhancement of reperfusion‐associated increases in tissue concentrations of IL‐10. However, at the same dose, UK‐74,505 failed to prevent reperfusion‐associated lethality in PAFR−/− mice any further.
The present studies using genetically modified animals and a receptor antagonist firmly establish a role of PAFR activation for the local, remote and systemic inflammatory injury and lethality which follows reperfusion of the ischemic SMA in mice. Moreover, it is suggested that high doses of PAFR antagonists need to be used if the real efficacy of these compounds is to be tested clinically.

British Journal of Pharmacology (2003) 139, 733–740. doi:10.1038/sj.bjp.0705296
Actions of tramadol on micturition in awake, freely moving rats
Authors: Pandita Raj Kumar , Pehrson Rikard , Christoph Thomas , Friderichs Elmar , Andersson Karl‐Erik 
Published: June 2003

(±)‐Tramadol, a widely used analgesic, is a racemate stimulating opioid receptors and inhibiting reuptake of noradrenaline and serotonin, that is, pharmacological principles previously shown to influence rat micturition.
We studied both (±)‐tramadol and its enantiomers in conscious Sprague–Dawley rats undergoing continuous cystometry. The effects of these agents were compared to those of morphine (μ‐opioid receptor agonist) and tested after pretreatment with naloxone (μ‐opioid receptor antagonist). Cystometries were evaluated before and after intravenous (i.v.), intraperitoneal (i.p.) and intrathecal (i.t.) drug administrations.
The most conspicuous effects of i.v. (±)‐tramadol (0.1–10 mg kg−1) was an increase in threshold pressure and an increase in micturition volume.
These effects were mimicked by (+)‐tramadol (0.1–5 mg kg−1 i.v.), whereas (−)‐tramadol (5 mg kg−1 i.v.) did not influence threshold pressure and micturition volume.
The effects of (±)‐tramadol 5 mg kg−1 on micturition volume were blocked by pretreatment with naloxone 0.3 mg kg−1. Morphine (0.3–10 mg kg−1 i.p.) increased threshold pressure but did not significantly increase micturition volume in doses not resulting in overflow incontinence.
(±)‐Tramadol 10 mg kg−1 increased urine production, an effect blocked by desmopressin 25 ng kg−1.
(±)‐Tramadol effectively inhibits micturition in conscious rats by stimulating μ‐opioid receptors. A synergy between opioid receptor stimulation and monoamine reuptake inhibition may contribute to the micturition effects.

British Journal of Pharmacology (2003) 139, 741–748. doi:10.1038/sj.bjp.0705297
Functional consequences of neuropeptide Y Y2 receptor knockout and Y2 antagonism in mouse and human colonic tissues
Authors: Hyland Niall P , Sjöberg Frida , Tough Iain R , Herzog Herbert , Cox Helen M 
Published: June 2003

Neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP) differentially activate three Y receptors (Y1, Y2 and Y4) in mouse and human isolated colon.
The aim of this study was to characterise Y2 receptor‐mediated responses in colon mucosa and longitudinal smooth muscle preparations from wild type (Y2+/+) and knockout (Y2−/−) mice and to compare the former with human mucosal Y agonist responses. Inhibition of mucosal short‐circuit current and increases in muscle tone were monitored in colonic tissues from Y2+/+ and Y2−/− mice±Y1 ((R)‐N‐[[4‐(aminocarbonylaminomethyl)phenyl)methyl]‐N2‐(diphenylacetyl)‐argininamide‐trifluoroacetate (BIBO3304) or Y2 (S)‐N2‐[[1‐[2‐[4‐[(R,S)‐5,11‐dihydro‐6(6H)‐oxodibenz[b,e]azepin‐11‐yl]‐1‐piperazinyl]‐2‐oxoethyl]cyclopentyl]acetyl]‐N‐[2‐[1,2‐dihydro‐3,5(4H)‐dioxo‐1,2‐diphenyl‐3H‐1,2,4‐triazol‐4‐yl]ethyl]‐argininamide (BIIE0246) antagonists.
Predictably, Y2−/− tissues were insensitive to Y2‐preferred agonist PYY(3‐36) (100 nM), but unexpectedly Y4‐preferred PP responses were right‐shifted probably as a consequence of elevated circulating PP levels, particularly in male Y2−/− mice (Sainsbury et al., 2002).
BIBO3304 and BIIE0246 elevated mucosal ion transport, indicating blockade of inhibitory mucosal tone in Y2+/+ tissue. While BIBO3304 effects were unchanged, those to BIIE0246 were absent in Y2−/− mucosae. Neither antagonist altered muscle tone; however, BIIE0246 blocked NPY and PYY(3‐36) increases in Y2+/+ basal tone. BIBO3304 abolished residual Y1‐mediated NPY responses in Y2−/− smooth muscle.
Tetrodotoxin significantly reduced BIIE0246 and PYY(3‐36) effects in Y2+/+ mouse and human mucosae, but had no effect upon Y‐agonist contractile responses, indicating that Y2 receptors are located on submucosal, but not myenteric neurones.
Tonic activation of submucosal Y2 receptors by endogenous NPY, PYY or PYY(3‐36) could indirectly reduce mucosal ion transport in murine and human colon, while direct activation of Y2 receptors on longitudinal muscle results in contraction.

British Journal of Pharmacology (2003) 139, 863–871. doi:10.1038/sj.bjp.0705298
Neuromuscular effects of candoxin, a novel toxin from the venom of the Malayan krait (Bungarus candidus)
Authors: Nirthanan S , Charpantier E , Gopalakrishnakone P , Gwee M C E , Khoo H E , Cheah L S , Kini R M , Bertrand D 
Published: June 2003

Candoxin (MW 7334.6), a novel toxin isolated from the venom of the Malayan krait Bungarus candidus, belongs to the poorly characterized subfamily of nonconventional three‐finger toxins present in Elapid venoms. The current study details the pharmacological effects of candoxin at the neuromuscular junction.
Candoxin produces a novel pattern of neuromuscular blockade in isolated nerve‐muscle preparations and the tibialis anterior muscle of anaesthetized rats. In contrast to the virtually irreversible postsynaptic neuromuscular blockade produced by curaremimetic α‐neurotoxins, the neuromuscular blockade produced by candoxin was rapidly and completely reversed by washing or by the addition of the anticholinesterase neostigmine.
Candoxin also produced significant train‐of‐four fade during the onset of and recovery from neuromuscular blockade, both, in vitro and in vivo. The fade phenomenon has been attributed to a blockade of putative presynaptic nicotinic acetylcholine receptors (nAChRs) that mediate a positive feedback mechanism and maintain adequate transmitter release during rapid repetitive stimulation. In this respect, candoxin closely resembles the neuromuscular blocking effects of d‐tubocurarine, and differs markedly from curaremimetic α‐neurotoxins that produce little or no fade.
Electrophysiological experiments confirmed that candoxin produced a readily reversible blockade (IC50∼10 nM) of oocyte‐expressed muscle (αβγδ) nAChRs. Like α‐conotoxin MI, well known for its preferential binding to the α/δ interface of the muscle (αβγδ) nAChR, candoxin also demonstrated a biphasic concentration–response inhibition curve with a high‐ (IC50∼2.2 nM) and a low‐ (IC50∼98 nM) affinity component, suggesting that it may exhibit differential affinities for the two binding sites on the muscle (αβγδ) receptor. In contrast, curaremimetic α‐neurotoxins have been reported to antagonize both binding sites with equal affinity.

British Journal of Pharmacology (2003) 139, 832–844. doi:10.1038/sj.bjp.0705299
NADH supplementation decreases pinacidil‐primed IK(ATP) in ventricular cardiomyocytes by increasing intracellular ATP
Authors: Pelzmann Brigitte , Hallström Seth , Schaffer Peter , Lang Petra , Nadlinger Karl , Birkmayer George D , Vrecko Karoline , Reibnegger Gilbert , Koidl Bernd 
Published: June 2003

The aim of this study was to investigate the effect of nicotinamide‐adenine dinucleotide (NADH) supplementation on the metabolic condition of isolated guinea‐pig ventricular cardiomyocytes. The pinacidil‐primed ATP‐dependent potassium current IK(ATP) was used as an indicator of subsarcolemmal ATP concentration and intracellular adenine nucleotide contents were measured.
Membrane currents were studied using the patch‐clamp technique in the whole‐cell recording mode at 36–37°C. Adenine nucleotides were determined by HPLC.
Under physiological conditions (4.3 mM ATP in the pipette solution, ATPi) IK(ATP) did not contribute to basal electrical activity.
The ATP‐dependent potassium (K(ATP)) channel opener pinacidil activated IK(ATP) dependent on [ATP]i showing a significantly more pronounced activation at lower (1 mM) [ATP]i.
Supplementation of cardiomyocytes with 300 μg ml−1 NADH (4–6 h) resulted in a significantly reduced IK(ATP) activation by pinacidil compared to control cells. The current density was 13.8±3.78 (n=6) versus 28.9±3.38 pA pF−1 (n=19; P<0.05).
Equimolar amounts of the related compounds nicotinamide and NAD+ did not achieve a similar effect like NADH.
Measurement of adenine nucleotides by HPLC revealed a significant increase in intracellular ATP (NADH supplementation: 45.6±1.88 nmol mg−1 protein versus control: 35.4±2.57 nmol mg−1 protein, P<0.000005).
These data show that supplementation of guinea‐pig ventricular cardiomyocytes with NADH results in a decreased activation of IK(ATP) by pinacidil compared to control myocytes, indicating a higher subsarcolemmal ATP concentration.
Analysis of intracellular adenine nucleotides by HPLC confirmed the significant increase in ATP.

British Journal of Pharmacology (2003) 139, 749–754. doi:10.1038/sj.bjp.0705300
Anticonvulsant activity, teratogenicity and pharmacokinetics of novel valproyltaurinamide derivatives in mice
Authors: Isoherranen Nina , Yagen Boris , Spiegelstein Ofer , Finnell Richard H , Merriweather Michelle , Woodhead Jose H , Wlodarczyk Bogdan , White H Steve , Bialer Meir 
Published: June 2003

The purpose of this study was to synthesize novel valproyltaurine (VTA) derivatives including valproyltaurinamide (VTD), N‐methyl‐valproyltaurinamide (M‐VTD), N,N‐dimethyl‐valproyltaurinamide (DM‐VTD) and N‐isopropyl‐valproyltaurinamide (I‐VTD) and evaluate their structure–pharmacokinetic–pharmacodynamic relationships with respect to anticonvulsant activity and teratogenic potential. However, their hepatotoxic potential could not be evaluated. The metabolism and pharmacokinetics of these derivatives in mice were also studied.
VTA lacked anticonvulsant activity, but VTD, DM‐VTD and I‐VTD possessed anticonvulsant activity in the Frings audiogenic seizure susceptible mice (ED50 values of 52, 134 and 126 mg kg−1, respectively).
VTA did not have any adverse effect on the reproductive outcome in the Swiss Vancouver/Fnn mice following a single i.p. injection of 600 mg kg−1 on gestational day (GD) 8.5. VTD (600 mg kg−1 at GD 8.5) produced an increase in embryolethality, but unlike valproic acid, it did not induce congenital malformations. DM‐VTD and I‐VTD (600 mg kg−1 at GD 8.5) produced a significant increase in the incidence of gross malformations. The incidence of birth defects increased when the length of the alkyl substituent or the degree of N‐alkylation increased.
In mice, N‐alkylated VTDs underwent metabolic N‐dealkylation to VTD. DM‐VTD was first biotransformed to M‐VTD and subsequently to VTD. I‐VTD's fraction metabolized to VTD was 29%. The observed metabolic pathways suggest that active metabolites may contribute to the anticonvulsant activity of the N‐alkylated VTDs and reactive intermediates may be formed during their metabolism. In mice, VTD had five to 10 times lower clearance (CL), and three times longer half‐life than I‐VTD and DM‐VTD, making it a more attractive compound than DM‐VTD and I‐VTD for further development. VTD's extent of brain penetration was only half that observed for the N‐alkylated taurinamides suggesting that it has a higher intrinsic activity that DM‐VTD and I‐VTD.
In conclusion, from this series of compounds, although VTD caused embryolethality, this compound emerged as the most promising new antiepileptic drug, having a preclinical spectrum characterized by the highest anticonvulsant potential, lowest potential for teratogenicity and favorable pharmacokinetics.

British Journal of Pharmacology (2003) 139, 755–764. doi:10.1038/sj.bjp.0705301
Intracarotid administration of short‐chain alkylglycerols for increased delivery of methotrexate to the rat brain
Authors: Erdlenbruch Bernhard , Schinkhof Claudia , Kugler Wilfried , Heinemann Dagmar E H , Herms Jochen , Eibl Hansjörg , Lakomek Max 
Published: June 2003

The intracarotid administration of alkylglycerols has been reported previously by us to be a novel strategy for increased delivery of various chemotherapeutic drugs to the normal brain and brain tumors in rats.
Effectiveness and structure–activity relations of the most promising pentyl‐ and hexylglycerol derivatives have been elucidated in vivo by analyzing the transfer of methotrexate (MTX) across the blood–brain barrier (BBB) in normal rats. The effects were compared with BBB disruption using hypertonic mannitol or intracarotid infusion of bradykinin. Furthermore, toxicity of the alkylglycerols has been studied in long‐term experiments.
Apart from 1‐O‐pentyldiglycerol, all alkylglycerols induced a concentration‐dependent increase in MTX delivery to the brain varying from 1.1 to more than 300‐fold compared to intra‐arterial MTX alone. Enhanced barrier permeability rapidly approached baseline values within 5 and 120 min at the latest. Chemical structure, concentration, time schedule of injections and combination of different alkylglycerols were identified as instruments suited to regulate the MTX accumulation within a wide range. Mannitol 1.4 M resulted in very high MTX levels in the brain as observed using the highest concentrations of alkylglycerols. Intracarotid infusion of bradykinin had only a minor effect on the BBB. Using 1‐O‐pentylglycerol or 2‐O‐hexyldiglycerol, both cell culture experiments and long‐term in vivo analyses including clinical, laboratory and histopathological evaluations revealed no signs of toxicity.
In summary, intracarotid short‐chain alkylglycerols constitute a very effective and low toxic strategy for transient opening of the BBB to overcome the limited access of cytotoxic drugs to the brain.

British Journal of Pharmacology (2003) 139, 685–694. doi:10.1038/sj.bjp.0705302
Prevention of cultured rat stellate cell transformation and endothelin‐B receptor upregulation by retinoic acid
Authors: Chi Xuedong , Anselmi Kristin , Watkins Simon , Gandhi Chandrashekhar R 
Published: June 2003

Physiologically, perisinusoidal hepatic stellate cells (HSC) are quiescent and store retinoids. During liver injury and in cell culture, HSC transform into proliferating myofibroblast‐like cells that express α‐smooth muscle actin (α‐sma) and produce excessive amounts of extracellular matrix. During transformation (also known as activation), HSC are depleted of the retinoid stores, and their expression of the endothelin‐1 (ET‐1) system is increased. ET‐1 causes contraction of transformed HSC and is implicated in their proliferation and fibrogenic activity. In order to understand the association between retinoids, ET‐1 and the activation of HSC, we investigated the effect of 13‐cis‐retinoic acid on the transformation of cultured HSC and the expression of ET‐1 system.
HSC derived from normal rat liver were maintained for 10–12 days in a medium supplemented with 5% serum and containing 2.5 μM retinoic acid without or with 50 nM ET‐1 (ETA+ETB agonist) or sarafotoxin S6c (ETB agonist). In another set of experiments, cells treated for 10–12 days with vehicle (ethanol) or retinoic acid were challenged with ET‐1 or sarafotoxin S6c, and various determinations were made at 24 h.
Retinoic acid inhibited transformation and proliferation of HSC as assessed by morphological characteristics, expression of α‐sma, bromodeoxyuridine incorporation and cell count. Retinoic acid also prevented upregulation of ETB receptors without affecting ET‐1 or ETA expression. Total protein synthesis ([3H]leucine incorporation), collagen α types I mRNA expression and collagen synthesis ([3H]proline incorporation) were lower in retinoic acid‐treated cells. Although ET‐1‐treated cells were morphologically similar to the control cells, their expression of α‐smooth muscle actin was significantly inhibited. The presence of retinoic acid in the medium during treatment with ET‐1 caused further reduction in the expression of α‐smooth muscle actin. ET‐1 and sarafotoxin S6c stimulated total protein synthesis in vehicle‐ and retinoic acid‐treated cells, but collagen synthesis only in the latter.
These results showing prevention of HSC activation and negative regulation of ETB receptor expression in them by retinoic acid may have important pathophysiologic implications.

British Journal of Pharmacology (2003) 139, 765–774. doi:10.1038/sj.bjp.0705303
Upregulation of cytochromes P450 2B in rat liver by orphenadrine
Authors: Murray Michael , Fiala‐Beer Eva , Sutton Dylan 
Published: June 2003

The alkylamine drug orphenadrine (ORPH) is an inducer and inhibitor of the microsomal cytochrome P450 (CYP) system in mammals. This study evaluated the selectivity of CYP induction by ORPH in rat liver.
Immunoblot analysis indicated that ORPH was a selective inducer of the phenobarbitone (PB)‐inducible CYP2B in rat liver. CYP2B protein was increased to ∼14‐fold of levels in untreated rat liver. By comparison PB increased CYP2B expression 40‐fold. Corresponding increases in the activity of CYP2B‐dependent androstenedione 16β‐hydroxylation were measured in microsomes from ORPH and PB‐induced rats.
Northern analysis indicated that CYP2B1/2 mRNA was increased in ORPH‐induced rat liver. Consistent with this finding, ORPH was found to activate a PB‐responsive enhancer module in constitutive androstane receptor (CAR)‐transfected Hep G2 cells.
Other alkylamines like troleandomycin impair CYP turnover. We tested whether ORPH induction of CYP2B may include a post‐translational component. In PB‐pretreated animals ORPH administration delayed the loss of CYP2B after PB withdrawal, but no evidence for altered turnover was found.
These studies establish ORPH as a selective inducer of CYP2B in rat liver. Induction appears to be mediated pretranslationally by CAR activation of CYP2B gene transcription. Post‐translational stabilisation by an ORPH metabolite does not elicit induction. Induction of CYP2B may influence pharmacokinetic interactions involving ORPH.

British Journal of Pharmacology (2003) 139, 787–796. doi:10.1038/sj.bjp.0705305