bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious wild‐type and D79N α2A‐adrenoceptor transgenic mice
Authors: Zhu Q‐M , Lesnick J D , Jasper J R , MacLennan S J , Dillon M P , Eglen R M , Blue D R 
Published: January 2005

We investigated the cardiovascular effects of rilmenidine, moxonidine and clonidine in conscious wild‐type and D79N α2A‐adrenoceptor mice. The in vitro pharmacology of these agonists was determined at recombinant (human) α2‐adrenoceptors and at endogenous (dog) α2A‐adrenoceptors.
In wild‐type mice, rilmenidine, moxonidine (100, 300 and 1000 μg kg−1, i.v.) and clonidine (30, 100 and 300 μg kg−1, i.v.) dose‐dependently decreased blood pressure and heart rate.
In D79N α2A‐adrenoceptor mice, responses to rilmenidine and moxonidine did not differ from vehicle control. Clonidine‐induced hypotension was absent, but dose‐dependent hypertension and bradycardia were observed.
In wild‐type mice, responses to moxonidine (1 mg kg−1, i.v.) were antagonized by the non‐selective, non‐imidazoline α2‐adrenoceptor antagonist, RS‐79948‐197 (1 mg kg−1, i.v.).
Affinity estimates (pKi) at human α2A‐, α2B‐ and α2C‐adrenoceptors, respectively, were: rilmenidine (5.80, 5.76 and 5.33), moxonidine (5.37, <5 and <5) and clonidine (7.21, 7.16 and 6.87). In a [35S]‐GTPγS incorporation assay, moxonidine and clonidine were α2A‐adrenoceptor agonists (pEC50/intrinsic activity relative to noradrenaline): moxonidine (5.74/0.85) and clonidine (7.57/0.32).
In dog saphenous vein, concentration‐dependent contractions were observed (pEC50/intrinsic activity relative to noradrenaline): rilmenidine (5.83/0.70), moxonidine (6.48/0.98) and clonidine (7.22/0.83). Agonist‐independent affinities were obtained with RS‐79948‐197.
Thus, expression of α2A‐adrenoceptors is a prerequisite for the cardiovascular effects of moxonidine and rilmenidine in conscious mice. There was no evidence of I1‐imidazoline receptor‐mediated effects. The ability of these compounds to act as α2A‐adrenoceptor agonists in vitro supports this conclusion.

British Journal of Pharmacology (1999) 126, 1522–1530; doi:10.1038/sj.bjp.0702429
Bradykinin‐induced phosphoinositide hydrolysis and Ca2+ mobilization in canine cultured tracheal epithelial cells
Authors: Luo Shue‐Fen , Pan Shiow‐Lin , Wu Wen‐Bin , Wang Chuan‐Chwan , Chiu Chi‐Tso , Tsai Yih‐Jeng , Yang Chuen‐Mao 
Published: January 2005

Experiments were designed to differentiate the mechanisms and subtype of kinin receptors mediating the changes in intracellular Ca2+ concentration ([Ca2+]i) induced by bradykinin (BK) in canine cultured tracheal epithelial cells (TECs).
BK and Lys‐BK caused an initial transient peak of [Ca2+]i in a concentration‐dependent manner, with half‐maximal stimulation (pEC50) obtained at 7.70 and 7.23, respectively.
Kinin B2 antagonists Hoe 140 (10 nM) and [D‐Arg0, Hyp3, Thi5,8, D‐Phe7]‐BK (1 μM) had high affinity in antagonizing BK‐induced Ca2+ response with pKB values of 8.90 and 6.99, respectively.
Pretreatment of TECs with pertussis toxin (100 ng ml−1) or cholera toxin (10 μg ml−1) for 24 h did not affect the BK‐induced IP accumulation and [Ca2+]i changes in TECs.
Removal of Ca2+ by the addition of EGTA or application of Ca2+‐channel blockers, verapamil, diltiazem, and Ni2+, inhibited the BK‐induced IP accumulation and Ca2+ mobilization, indicating that Ca2+ influx was required for the BK‐induced responses.
Addition of thapsigargin (TG), which is known to deplete intracellular Ca2+ stores, transiently increased [Ca2+]i in Ca2+‐free buffer and subsequently induced Ca2+ influx when Ca2+ was re‐added to this buffer. Pretreatment of TECs with TG completely abolished BK‐induced initial transient [Ca2+]i, but had slight effect on BK‐induced Ca2+ influx.
Pretreatment of TECs with SKF96365 and U73122 inhibited the BK‐induced Ca2+ influx and Ca2+ release, consistent with the inhibition of receptor‐gated Ca2+ ‐channels and phospholipase C in TECs, respectively.
These results demonstrate that BK directly stimulates kinin B2 receptors and subsequently phospholipase C‐mediated IP accumulation and Ca2+ mobilization via a pertussis toxin‐insensitive G protein in canine TECs. These results also suggest that BK‐induced Ca2+ influx into the cells is not due to depletion of these Ca2+ stores, as prior depletion of these pools by TG has no effect on the BK‐induced Ca2+ influx that is dependent on extracellular Ca2+ in TECs.

British Journal of Pharmacology (1999) 126, 1341–1350; doi:10.1038/sj.bjp.0702431
Conformational restraints revealing bioactive β‐bend structures for hα CGRP8–37 at the CGRP2 receptor of the rat prostatic vas deferens
Authors: Wisskirchen F M , Doyle P M , Gough S L , Harris C J , Marshall I 
Published: January 2005

The main aim of this study was to identify putative β‐bends and the role of the N‐ and C‐terminus in the CGRP receptor antagonist hα CGRP8–37, which was measured against hα CGRP inhibition of twitch responses in the rat prostatic vas deferens.
With a bend‐biasing residue (proline) at position 16 in hα CGRP8–37 (10−5 M) an inactive compound was produced, while alanine at the same position retained antagonist activity (apparent pKB 5.6±0.1 at 10−5 M). Proline at position 19 within hα CGRP8–37 (10−5 M) was an antagonist (apparent pKB 5.8±0.1).
Incorporation of a bend‐forcing structure (beta‐turn dipeptide or BTD) at either positions 19,20 or 33,34 in hα CGRP8–37 (10−5 M) antagonized hα CGRP responses (apparent pKB 6.0±0.1 and 6.1±0.1, respectively). Replacement by BTD at both positions 19,20 and 33,34 within hα CGRP8–37 competitively antagonized responses to hα CGRP (pA2 6.2; Schild plot slope 1.0±0.1).
Hα CGRP8–37 analogues (10−5 M), substituted at the N‐terminus by either glycine8, or des‐NH2 valine8 or proline8 were all antagonists against hα CGRP (apparent pKB 6.1±0.1, 6.5±0.1 and 6.1±0.1, respectively), while hα CGRP8–37 (10−5 M) substituted in three places by proline8 and glutamic acid10,14 was inactive.
Replacement of the C‐terminus by alanine amide37 in hα CGRP8–37 (10−5 M) failed to antagonize hα CGRP responses.
Peptidase inhibitors did not alter either the agonist potency of hα CGRP or the antagonist affinities of hα CGRP8–37 BTD19,20 and 33,34 and hα CGRP8–37 Gly8 (against hα CGRP responses).
In conclusion, two β‐bends at positions 18–21 and 32–35 are compatible with high affinity by BTD and is the first approach of modelling the bioactive structure of hα CGRP8–37. Further, the N‐terminus of hα CGRP8–37 is not essential for antagonism, while the C‐terminus interacts directly with CGRP receptor binding sites of the rat vas deferens.

British Journal of Pharmacology (1999) 126, 1163–1170; doi:10.1038/sj.bjp.0702432
4‐trifluoromethyl derivatives of salicylate, triflusal and its main metabolite 2‐hydroxy‐4‐trifluoromethylbenzoic acid, are potent inhibitors of nuclear factor κB activation
Authors: Bayón Yolanda , Alonso Andrés , Crespo Mariano Sánchez 
Published: January 2005

The effect of two derivatives of salicylate, 2‐hydroxy‐4‐trifluoromethylbenzoic acid (HTB) and 2‐acetoxy‐4‐trifluoromethylbenzoic acid (triflusal), on the activation of NF‐κB elicited by tumour necrosis factor‐α (TNF‐α) on human umbilical vein endothelial cells (HUVEC) was tested.
The expression of the mRNA of vascular cell adhesion molecule‐1 (VCAM‐1) was studied as an example of a gene the expression of which is regulated by NF‐κB. To extend these findings to other systems, the induction of nitric oxide synthase in rat adherent peritoneal macrophages was studied.
Both HTB and triflusal were more potent than aspirin or salicylate as inhibitors of the nuclear translocation of NF‐κB. The calculation of the IC50 values showed ∼amp;2 mM for HTB, 4 mM for aspirin and >4 mM for salicylate.
Comparison of the potency of these compounds on VCAM‐1 mRNA expression showed complete inhibition by both triflusal and HTB at a concentration of 4 mM whereas aspirin and salicylate produced only 36–43% inhibition at the same concentration.
Inhibition of NF‐κB activation was also observed in rat peritoneal macrophages stimulated via their receptors for the Fc portion of the antibody molecule with IgG/ovalbumin immune complexes. This was accompanied by a dose‐dependent inhibition of nitrite production by the L‐arginine pathway via iNOS. IC50 values for this effect were 1.13±0.12 mM (triflusal), 1.84±0.34 (HTB), 6.08±1.53 mM (aspirin) and 9.16±1.9 mM (salicylate).
These data indicate that the incorporation of a 4‐trifluoromethyl group to the salicylate molecule strongly enhances its inhibitory effect on NF‐κB activation, VCAM‐1 mRNA expression and iNOS induction, irrespective of the presence of the acetyl moiety involved in the inhibition of cyclo‐oxygenase.

British Journal of Pharmacology (1999) 126, 1359–1366; doi:10.1038/sj.bjp.0702441
Effect of α‐trinositol on interstitial fluid pressure, oedema generation and albumin extravasation in experimental frostbite in the rat
Authors: Berg A , Aas P , Gustafsson T , Reed R K 
Published: January 2005

The anti‐inflammatory effect of α‐trinositol (D‐myo‐inositol‐1,2,6‐trisphosphate) on oedema formation, microvascular protein leakage and interstitial fluid pressure (Pif) in rat skin after frostbite injury, was investigated. α‐Trinositol (40 mg kg body weight−1) was administered intravenously as a bolus both before and/or in the interval between freezing and thawing of the tissue.
Pif was measured in rat paw skin with micropipettes connected to a servo‐controlled counterpressure system. Oedema formation was estimated by measuring the increase in total tissue water content (wet weight minus dry weight divided by dry weight). Albumin extravasation (i.e., the difference between the plasma equivalent space for 125I‐ and 131I‐human serum albumin (HSA) circulating for different time intervals) was used to estimate the microvascular leakage.
Compared to untreated animals, α‐trinositol given pre‐ and/or post‐freeze reduced total tissue water and albumin extravasation as well as the fall in Pif in injured tissue significantly (P<0.05). α‐Trinositol given only post‐freeze reduced total tissue water and albumin extravasation from 4.46±0.93 and 2.37±1.12 to 2.51±0.29 and 0.36±0.18 ml g dry weight−1, respectively (P<0.05).
Pif fell from −0.8±0.2 mmHg pre‐freeze to −3.4±1.0 mmHg (P<0.05) at 20 min after tissue injury (circulatory arrest) and was attenuated by treatment with α‐trinositol.
We conclude that α‐trinositol exerts its anti‐oedematous effect by acting on the extracellular matrix, attenuating the lowering of Pif as well as on the microvascular wall, thereby decreasing the protein extravasation.

British Journal of Pharmacology (1999) 126, 1367–1374; doi:10.1038/sj.bjp.0702442
Thermogenic effects of sibutramine and its metabolites
Authors: Connoley Ian P , Liu Yong‐Ling , Frost Ian , Reckless Ian P , Heal David J , Stock Michael J 
Published: January 2005

The thermogenic activity of the serotonin and noradrenaline reuptake inhibitor sibutramine (BTS 54524; Reductil) was investigated by measuring oxygen consumption (VO2) in rats treated with sibutramine or its two pharmacologically‐active metabolites.
Sibutramine caused a dose‐dependent rise in VO2, with a dose of 10 mg kg−1 of sibutramine or its metabolites producing increases of up to 30% that were sustained for at least 6 h, and accompanied by significant increases (0.5–1.0°C) in body temperature.
Based on the accumulation in vivo of radiolabelled 2‐deoxy‐[3H]‐glucose, sibutramine had little or no effect on glucose utilization in most tissues, but caused an 18 fold increase in brown adipose tissue (BAT).
Combined high, non‐selective doses (20 mg kg−1) of the β‐adrenoceptor antagonists, atenolol and ICI 118551, inhibited completely the VO2 response to sibutramine, but the response was unaffected by low, β1‐adrenoceptor‐selective (atenolol) or β2‐adrenoceptor‐selective (ICI 118551) doses (1 mg kg−1).
The ganglionic blocking agent, chlorisondamine (15 mg kg−1), inhibited completely the VO2 response to the metabolites of sibutramine, but had no effect on the thermogenic response to the β3‐adrenoceptor‐selective agonist BRL 35135.
Similar thermogenic responses were produced by simultaneous injection of nisoxetine and fluoxetine at doses (30 mg kg−1) that had no effect on VO2 when injected individually.
It is concluded that stimulation of thermogenesis by sibutramine requires central reuptake inhibition of both serotonin and noradrenaline, resulting in increased efferent sympathetic activation of BAT thermogenesis via β3‐adrenoceptor, and that this contributes to the compound's activity as an anti‐obesity agent.

British Journal of Pharmacology (1999) 126, 1487–1495; doi:10.1038/sj.bjp.0702446
Analysis of the behaviour of selected CCKB/gastrin receptor antagonists in radioligand binding assays performed in mouse and rat cerebral cortex
Authors: Harper E A , Griffin E P , Shankley N P , Black J W 
Published: January 2005

The previously described complex behaviour of the CCKB/gastrin receptor antagonist, L‐365,260, in radioligand binding assays could be explained by a variable population of two binding sites. We have investigated whether other CCKB/gastrin receptor ligands (PD134,308, PD140,376, YM022 and JB93182) can distinguish between these sites.
In the mouse cortex assay, Hill slopes were not different from unity and the ligand pKI values did not differ when either [125I]‐BH‐CCK‐8S or [3H]‐PD140,376 was used as label as expected for a single site (G2).
In the rat cortex, where previous analysis of replicate (n=48) L‐365,260 data indicated the presence of two CCKB/gastrin sites (G1 and G2), the competition data for PD134,308, PD140,376, YM022 and JB93182 could be explained by a homogeneous population of CCKB/gastrin sites because the Hill slope estimates were not significantly different from unity. However, the estimated affinity values for JB93182 and YM022 were significantly higher and that for PD134,308 was significantly lower than those obtained in the mouse cortex when the same radioligand was used. In view of our previous data obtained with L‐365,260, the rat cortex data were also interpreted using a two‐site model. In this analysis, SR27897 expressed ∼9 fold, PD134,308 ∼13 fold and PD140,376 ∼11 fold selectivity for the G2 site. In contrast, JB93182 expressed ∼23 fold and YM022 ∼4 fold selectivity for the G1 site. If the two‐site interpretation of the data is valid then, because of its reverse selectivity to L‐365,260, JB93182 has been identified as a compound which if radiolabelled could provide a test of this receptor subdivision.

British Journal of Pharmacology (1999) 126, 1496–1503; doi:10.1038/sj.bjp.0702448
Cellular disposition of sulphamethoxazole and its metabolites: implications for hypersensitivity
Authors: Naisbitt Dean J , Hough Sally J , Gill Helen J , Pirmohamed Munir , Kitteringham Neil R , Park B Kevin 
Published: January 2005

Bioactivation of sulphamethoxazole (SMX) to chemically‐reactive metabolites and subsequent protein conjugation is thought to be involved in SMX hypersensitivity. We have therefore examined the cellular metabolism, disposition and conjugation of SMX and its metabolites in vitro.
Flow cytometry revealed binding of N‐hydroxy (SMX‐NHOH) and nitroso (SMX‐NO) metabolites of SMX, but not of SMX itself, to the surface of viable white blood cells. Cellular haptenation by SMX‐NO was reduced by exogenous glutathione (GSH).
SMX‐NHOH and SMX‐NO were rapidly reduced back to the parent compound by cysteine (CYS), GSH, human peripheral blood cells and plasma, suggesting that this is an important and ubiquitous bioinactivation mechanism.
Fluorescence HPLC showed that SMX‐NHOH and SMX‐NO depleted CYS and GSH in buffer, and to a lesser extent, in cells and plasma.
Neutrophil apoptosis and inhibition of neutrophil function were induced at lower concentrations of SMX‐NHOH and SMX‐NO than those inducing loss of membrane viability, with SMX having no effect. Lymphocytes were significantly (P<0.05) more sensitive to the direct cytotoxic effects of SMX‐NO than neutrophils.
Partitioning of SMX‐NHOH into red blood cells was significantly (P<0.05) lower than with the hydroxylamine of dapsone.
Our results suggest that the balance between oxidation of SMX to its toxic metabolites and their reduction is an important protective cellular mechanism. If an imbalance exists, haptenation of the toxic metabolites to bodily proteins including the surface of viable cells can occur, and may result in drug hypersensitivity.

British Journal of Pharmacology (1999) 126, 1393–1407; doi:10.1038/sj.bjp.0702453
Role of Na+/Ca2+ exchange in endothelin‐1‐induced increases in Ca2+ transient and contractility in rabbit ventricular myocytes: pharmacological analysis with KB‐R7943
Authors: Yang Huang‐Tian , Sakurai Kiyoharu , Sugawara Hiromi , Watanabe Tomoo , Norota Ikuo , Endoh Masao 
Published: January 2005

The effects of endothelin‐1 (ET‐1) on intracellular Ca2+ ion level and cell contraction were simultaneously investigated in rabbit ventricular cardiac myocytes loaded with indo‐1/AM. The role of Na+/Ca2+ exchange in ET‐1‐induced positive inotropic effect (PIE) was examined by using KB‐R7943 (2‐[2‐[4‐(4‐nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulphonate), a selective inhibitor of reverse mode Na+/Ca2+ exchange.
ET‐1 at 0.3 pM–1 nM increased cell contraction and Ca2+ transient (CaT) with EC50 values of 2.9 pM and 1.2 pM, respectively, and the increase in amplitude of CaT was much smaller relative to the PIE: ET‐1 at 1 nM increased peak cell shortening by 237%, while it increased peak CaT by 167%. For a given level of PIE, ET‐1‐induced increase in CaT was much smaller than that induced by elevation of [Ca2+]o and by isoprenaline. Therefore, ET‐1 shifted the relationship between peak CaT and cell shortening to the left relative to the relationship for increase in [Ca2+]o, an indication that ET‐1 increased myofibrillar Ca2+ sensitivity.
KB‐R7943 at 0.1 μM and higher inhibited contraction and CaT induced by 0.1 nM ET‐1 and at 0.3 μM it abolished the increase in CaT while inhibiting the PIE by 48.1%. Over concentration range of 0.1–0.3 μM, KB‐R7943 neither inhibited baseline contraction and CaT nor the isoprenaline‐induced response, although at 1 μM and higher it had a significant inhibitory action on these responses.
These results indicate that in rabbit ventricular myocytes both increases in CaT and myofibrillar Ca2+ sensitivity contribute to the ET‐induced PIE, and the activation of reverse mode Na+/Ca2+ exchange may play a crucial role in increase in CaT induced by ET‐1 in rabbit ventricular cardiac myocytes.

British Journal of Pharmacology (1999) 126, 1785–1795; doi:10.1038/sj.bjp.0702454
Substrates of multidrug resistance‐associated proteins block the cystic fibrosis transmembrane conductance regulator chloride channel
Authors: Linsdell Paul , Hanrahan John W 
Published: January 2005

The effects of physiological substrates of multidrug resistance‐associated proteins (MRPs) on cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel currents were examined using patch clamp recording from CFTR‐transfected mammalian cell lines.
Two MRP substrates, taurolithocholate‐3‐sulphate (TLCS) and β‐estradiol 17‐(β‐D‐glucuronide) (E217βG) caused a voltage‐dependent block of macroscopic CFTR Cl− currents when applied to the intracellular face of excised membrane patches, with mean apparent dissociation constants (KDs) of 96±10 and 563±103 μM (at 0 mV) respectively. The unconjugated bile salts taurocholate and cholate were also effective CFTR channel blockers under these conditions, with KDs of 453±44 and 3760±710 μM (at 0 mV) respectively.
Reducing the extracellular Cl− concentration from 154 to 20 mM decreased the KD for block intracellular TLCS to 54±1 μM, and also significantly reduced the voltage dependence of block, by suggesting that TLCS blocks Cl− permeation through CFTR by binding within the channel pore.
Intracellular TLCS reduced the apparent amplitude of CFTR single channel currents, suggesting that the duration of block is very fast compared to the gating of the channel.
The apparent affinity of block by TLCs is comparable to that of other well‐known CFTR channel blockers, suggesting that MRP substrates may comprise a novel class of probes of the CFTR channel pore.
These results also suggest that the related proteins CFTR and MRP may share a structurally similar anion binding site at the cytoplasmic face of the membrane.

British Journal of Pharmacology (1999) 126, 1471–1477; doi:10.1038/sj.bjp.0702458
GABAB receptor isoforms GBR1a and GBR1b, appear to be associated with pre‐ and post‐synaptic elements respectively in rat and human cerebellum
Authors: Billinton Andrew , Upton Neil , Bowery Norman G 
Published: January 2005

Metabotropic γ‐aminobutyric acid (GABA) receptors, GABAB, are coupled through G‐proteins to K+ and Ca2+ channels in neuronal membranes. Cloning of the GABAB receptor has not uncovered receptor subtypes, but demonstrated two isoforms, designated GBR1a and GBR1b, which differ in their N terminal regions. In the rodent cerebellum GABAB receptors are localized to a greater extent in the molecular layer, and are reported to exist on granule cell parallel fibre terminals and Purkinje cell (PC) dendrites, which may represent pre‐ and post‐synaptic receptors.
The objective of this study was to localize the mRNA splice variants, GBR1a and GBR1b for GABAB receptors in rat cerebellum, for comparison with the localization in human cerebellum using in situ hybridization.
Receptor autoradiography was performed utilizing [3H]‐CGP62349 to localize GABAB receptors in rat and human cerebellum. Radioactively labelled oligonucleotide probes were used to localize GBR1a and GBR1b, and by dipping slides in photographic emulsion, silver grain images were obtained for quantification at the cellular level.
Binding of 0.5 nM [3H]‐CGP62349 demonstrated significantly higher binding to GABAB receptors in the molecular layer than the granule cell (GC) layer of rat cerebellum (molecular layer binding 200±11% of GC layer; P<0.0001). GBR1a mRNA expression was found to be predominantly in the GC layer (PC layer grains 6±6% of GC layer grains; P<0.05), and GBR1b expression predominantly in PCs (PC layer grains 818±14% of GC layer grains; P<0.0001).
The differential distribution of GBR1a and GBR1b mRNA splice variants for GABAB receptors suggests a possible association of GBR1a and GBR1b with pre‐ and post‐synaptic elements respectively.

British Journal of Pharmacology (1999) 126, 1387–1392; doi:10.1038/sj.bjp.0702460