bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogeneity of α2‐adrenoceptors in human and rat myometrium and differential expression during pregnancy
Authors: Bouet‐Alard Rachel , Mhaouty‐Kodja Sakina , Limon‐Boulez Isabelle , Coudouel Noelline , Maltier Jean Paul , Legrand Chantal 
Published: January 2005

The aim of this study was first, to characterize α2‐adrenoceptor subtypes in human and rat pregnant myometrium and second, to investigate the possibility of a differential expression of the putative subtypes according to the stage of pregnancy.
In both species, specific [3H]‐rauwolscine binding was inhibited by five different compounds with an order of affinity characteristic of the one described for α2‐adrenoceptors (yohimbineclonidine>noradrenaline>phenylephrine>propranolol). Binding affinities (pKi) for the compounds tested were, in human and rat, respectively: 7.63 and 8.93 for yohimbine, 6.91 and 8.71 for clonidine, 6.23 and 6.09 for noradrenaline, 5.37 and 5.73 for phenylephrine, 4.64 and 4.72 for propranolol.
By use of non‐linear iterative curve fitting procedures and by fitting the data to a two‐site model, analysis of [3H]‐rauwolscine inhibition binding curves performed in the presence of oxymetazoline (α2A‐selective), ARC239, prazosin or chlorpromazine (α2B‐ and α2C‐selective) indicated that pregnant human and rat myometrium contain at least two pharmacologically distinct α2‐adrenoceptor subtypes (α2A, α2B and/or α2C). RNA blot analysis with probes specific for each cloned human and rat α2‐adrenoceptor subtype demonstrated that α2A‐ and α2B‐subtypes were present in both species but α2C seems to be expressed only in human tissues.
In the pregnant rat myometrium, subtype selective compounds competition curves revealed a predominant expression of α2A‐adrenoceptors at mid‐pregnancy whereas, at term, α2A‐ and α2B‐subtypes density reached approximately the same level (α2A : α2B ratio=73 : 27 at mid‐pregnancy and=43 : 57 at term). In addition, quantification of α2A‐ and α2B‐transcripts by densitometry, following data normalization with an oligo(dT)12–18 probe, showed a pattern of expression comparable to the one characterized by pharmacological studies.
In conclusion, these data demonstrate heterogeneity of α2‐adrenoceptors in pregnant human and rat myometria and an alteration of the α2A‐/α2B‐subtypes expression pattern during rat pregnancy. Such observations lead us to suggest a multiple role for α2‐adrenoceptors in regulating specific functions of myometrium throughout the time course of pregnancy.
Prolonged effect of a novel S‐nitrosated glyco‐amino acid in endothelium‐denuded rat femoral arteries: potential as a slow release nitric oxide donor drug
Authors: Megson I. L. , Greig I. R. , Gray G. A. , Webb D. J. , Butler A. R. 
Published: January 2005

The vasodilator properties of a novel S‐nitrosated glyco‐amino acid (RIG200) were investigated in isolated rat femoral arteries and compared with those of the parent S‐nitrosothiol compound, S‐nitroso‐N‐acetylpenicillamine (SNAP).
Spectrophotometric analysis revealed that 2.5 mm solutions of RIG200 decomposed more slowly (half‐life (t1/2)=216.2±26.7 min) than SNAP (t1/2=37.2±13.8 min) in Krebs buffer at 24°C. Furthermore, the rate of decomposition of SNAP, but not of RIG200, was significantly reduced by the Cu(I) chelator, neocuproine. We concluded that the relative stability of RIG200 is due, at least in part, to its resistance to trace Cu(I)‐catalyzed decomposition. Nitric oxide (NO) generation from SNAP and RIG200 was confirmed by use of an NO electrode.
Experiments to investigate the vasodilator effects of RIG200 were carried out on isolated femoral arteries taken from adult male Wistar rats (400–550 g). Lengths of artery (7–8 mm long) were cannulated, dissected free and perfused at constant flow rate (0.6 ml min−1) with Krebs buffer. Vessels were precontracted with phenylephrine (10.2±0.3 μm) and developed pressures of 91.8 ± 4 mmHg, detected upstream by a differential pressure transducer.
Concentration‐dependent vasodilator responses to bolus injections of SNAP or RIG200 (10 μl; 10−8–10−3 m) made into the perfusate of endothelium‐intact vessels were transient, recovering the pre‐injection pressure in <20 min.
Responses to equivalent bolus injections of SNAP in endothelium‐denuded vessels were also transient but those in response to concentrations of RIG200 >10−5 m were sustained. Responses to 10−3 m RIG200 were sustained for periods >4 h. Sustained vasodilatation was reversed by the NO scavenger, ferrohaemoglobin (10 μm) but was unaffected by the NO synthase inhibitor, Nω‐nitro‐L‐arginine methyl ester (200 μm), indicating involvement of NO from a source other than NO synthase.
We suggest that a possible explanation for the prolonged effect of RIG200 is retention of the compound by the vascular wall, facilitated by endothelial denudation. Slow decomposition of RIG200 in situ would release sufficient NO to maintain a ‘vasodilator tone’ which persists for more than 4 h. Selective retention by damaged vessels could have important therapeutic implications with regard to targeted delivery of NO, restoring protection to areas deprived of endogenous NO, whilst avoiding unwanted hypotension.
Involvement of 5‐hydroxytryptamine7 receptors in inhibition of porcine myometrial contractility by 5‐hydroxytryptamine
Authors: Kitazawa Takio , Kubo Osamu , Satoh Masami , Taneike Tetsuro 
Published: January 2005

5‐Hydroxytryptamine (5‐HT; 1 nM–100 μM) concentration‐dependently inhibited the amplitude and frequency of spontaneous contractions in longitudinal and circular muscles of the porcine myometrium. The circular muscle (EC50; 68–84 nM) was more sensitive than the longitudinal muscle (EC50; 1.3–1.44 μM) to 5‐HT. To characterize the 5‐HT receptor subtype responsible for inhibition of myometrial contractility, the effects of 5‐HT receptor agonists on spontaneous contractions and of 5‐HT receptor antagonists on inhibition by 5‐HT were examined in circular muscle preparations.
Pretreatment with tetrodotoxin (1 μM), propranolol (1 μM), atropine (1 μM), guanethidine (10 μM) or L‐NAME (100 μM) failed to change the inhibition by 5‐HT, indicating that the inhibition was due to a direct action of 5‐HT on the smooth muscle cells.
5‐CT, 5‐MeOT and 8‐OH‐DPAT mimicked the inhibitory response of 5‐HT, and the rank order of the potency was 5‐CT>5‐HT>5‐MeOT>8‐OH‐DPAT. On the other hand, oxymethazoline, α‐methyl‐5‐HT, 2‐methyl‐5‐HT, cisapride, BIMU‐1, BIMU‐8, ergotamine and dihydroergotamine had almost no effect on spontaneous contractions, even at 10–100 μM.
Inhibition by 5‐HT was not decreased by either pindolol (1 μM), ketanserin (1 μM), tropisetron (10 μM), MDL72222 (1 μM) or GR113808 (10 μM), but was antagonized by the following compounds in a competitive manner (with pA2 values in parentheses): methiothepin (8.05), methysergide (7.92), metergoline (7.4), mianserin (7.08), clozapine (7.06) and spiperone (6.86).
Ro 20‐1724 (20 μM) and rolipram (10 μM) significantly enhanced the inhibitory response of 5‐HT, but neither zaprinast (10 μM) nor dipyridamole (10 μM) altered the response of 5‐HT.
5‐HT (1 nM–1 μM) caused a concentration‐dependent accumulation of intracellular cyclic AMP in the circular muscle.
From the present results, the 5‐HT receptor, which is functionally correlated with the 5‐HT7 receptor, mediates the inhibitory effect of 5‐HT on porcine myometrial contractility. This inhibitory response is probably due to an increase in intracellular cyclic AMP through the activation of adenylate cyclase that is positively coupled to 5‐HT7 receptors.

British Journal of Pharmacology (1998) 123, 173–182; doi:10.1038/sj.bjp.0701583
Characterization of [125I]‐PD164333, an ETA selective non‐peptide radiolabelled antagonist, in normal and diseased human tissues
Authors: Davenport Anthony P , Kuc Rhoda E , Ashby Michael J , Patt William C , Doherty Annette M 
Published: January 2005

We have synthesized a new low molecular weight, non‐peptide radioligand, [125I]‐PD164333, an analogue of the orally active butenolide antagonists of the endothelin ETA receptor.
Analysis of saturation binding assays demonstrated that [125I]‐PD164333 bound with high affinity to a single population of receptors (n3 individuals ±s.e.mean) in human aorta (KD=0.26±0.08 nM; Bmax=8.8±3.95 fmol mg‐1 protein), left ventricle from the heart (KD=0.16±0.02 nM; Bmax=34.2± 3.02 fmol mg‐1 protein) and kidney (KD=1.24±0.16 nM; Bmax=125.3±35.07 fmol mg‐1 protein). In each case Hill slopes were close to unity.
In kinetic experiments, the binding of [125I]‐PD164333 to ETA receptors in sections of heart was time‐dependent and rapid at 23°C. The data were fitted to a one site model, with an association rate constant (K1 of 2.66±0.213×108 M‐1 min‐1, and a half‐time for association of 11 min. The binding was reversible at 23°C: analysis of the data indicated [125I]‐PD164333 dissociated from a single site, with a dissociation rate constant of 0.0031±0.0004 min‐1, a half‐time for dissociation of 216 min and a KD calculated from these kinetic data of 0.01 nM.
Unlabelled PD164333 inhibited the binding of [125I]‐ET‐1 to left ventricle (which expresses both subtypes) in a biphasic manner with a KDETA of 0.99±0.32 nM and KDETB of 2.41±0.22 μM, giving a selectivity of 2500 fold. ETA‐selective ligands competed monophasically for [125I]‐PD164333 binding in left ventricle, a one site fit was preferred to a two site model giving similar nanomolar affinities: BQ123, KD=3.93 ±0.18 nM; FR139317 KD=3.53±0.69 nM. In contrast, the ETB selective agonists, BQ3020 and sarafotoxin S6c (1 μM) did not inhibit binding.
In human isolated saphenous vein, unlabelled PD164333 was a functional antagonist, producing parallel rightward shifts of the endothelin‐1 (ET‐1) concentration‐response curve (pA2=8.84) and a slope of unity.
In the human brain, autoradiography revealed high levels of [125I]‐PD164333 binding to the pial arteries of the cerebral cortex and to the numerous smaller intercerebral vessels penetrating the underlying grey and white matter. Conduit and resistance vessels contributing to the control of blood pressure from the heart, kidney, lungs and adrenal also displayed high densities of binding. In diseased vessels, binding of [125I]‐PD164333 was confined to the medial layer of both coronary arteries with advanced atherosclerotic lesions or occluded saphenous vein grafts. In contrast, little or no binding was detected in the proliferated smooth muscle of the intimal layer or occluded lesion.
These results show [125I]‐PD164333 is a specific, high affinity, reversible non‐peptide radioligand for human ETA receptors, which will facilitate the further characterization of this subtype, in vitro and in vivo.

British Journal of Pharmacology (1998) 123, 223–230; doi:10.1038/sj.bjp.0701597
Studies on the effects of anandamide in rat hepatic artery
Authors: Zygmunt Peter M. , Högestätt Edward D. , Waldeck Kristian , Edwards Gillian , Kirkup Anthony J. , Weston Arthur H. 
Published: January 2005

The effects of anandamide on K+ currents and membrane potential have been examined in freshly‐isolated smooth muscle cells from rat hepatic artery and the results compared with the effects of this arachidonic acid derivative on tension and membrane potential changes in segments of whole artery.
In the presence of 0.3 mm l‐NOARG and 10 μm indomethacin, anandamide (0.1–100 μm) and endothelium‐derived hyperpolarizing factor (EDHF; liberated by acetylcholine, 0.01–10 μm) each relaxed endothelium‐intact segments of hepatic artery precontracted with phenylephrine. These effects of anandamide, but not those of EDHF, were antagonized by the cannabinoid receptor antagonist, SR141716A (3 μm).
The relaxant effects of anandamide were unaffected by a toxin combination (apamin plus charybdotoxin, each 0.3 μm) which abolishes EDHF relaxations and were essentially unchanged in endothelium‐denuded arteries. The relaxant effects of anandamide in endothelium‐intact arteries were significantly reduced in a physiological salt solution containing 30 mm KCl and abolished when the K+ concentration was raised to 60 mm.
Anandamide (10 μm), acetylcholine (1 μm, via release of EDHF) and levcromakalim (10 μm) each markedly hyperpolarized the membrane potential of the smooth muscle cells of endothelium‐intact arteries. However, when the endothelium was removed, the hyperpolarizing effects of both anandamide (10 μm) and acetylcholine were essentially abolished whereas those of levcromakalim (10 μm) were unaffected.
Under voltage‐clamp conditions, anandamide (10 μm) abolished spontaneous transient outward currents (STOCs) in freshly‐isolated single hepatic artery cells held at 0 mV but had no effect on the holding current at this potential. In current‐clamp mode, the spontaneous hyperpolarizing potentials which corresponded to the STOCs were abolished with no significant change in basal membrane potential.
Anandamide (10 μm) abolished the iberiotoxin‐sensitive K+ current (IBK(Ca)) produced by caffeine and the corresponding hyperpolarizations generated by this xanthine derivative in current‐clamp mode. In contrast, anandamide had no effect on IBK(Ca) generated on exposure to NS1619 (30 μm).
It was concluded that anandamide is not EDHF in the rat hepatic artery. Anandamide‐induced hyperpolarization is exerted indirectly and requires the presence of the endothelium. Anandamide also acts on the smooth muscle cells to inhibit processes which require functional intracellular calcium stores. This direct action seems more important than membrane hyperpolarization in relaxing phenylephrine‐contracted vessels.
Investigation of the effects of platelet‐activating factor (PAF) on ion transport and prostaglandin synthesis in human colonic mucosa in vitro
Authors: Borman R A , Jewell R , Hillier K 
Published: January 2005

We have investigated the effects of platelet‐activating factor (PAF), an endogenous mediator of inflammation, on ion transport and prostaglandin synthesis in the human isolated colon.
Application of PAF to the serosal surface of human colonic mucosa induced a marked, concentration‐dependent increase in ion transport. Mucosal application was without effect.
The secretory response to PAF was significantly inhibited by prior application of a specific PAF receptor antagonist WEB 2170, indicating that the response is dependent on PAF receptor activation.
The response to PAF was attenuated by prior application of indomethacin or piroxicam, implicating products of the cyclo‐oxygenase pathway in the response.
The response to PAF was attenuated by the loop diuretic bumetanide, indicating an involvement of chloride ion secretion in the response.
Addition of PAF to the serosal surface induced a significant increase in serosal prostaglandin E2 (PGE2), but not 6‐oxo‐PGF1α release. There was no effect on mucosal application of PAF.
In summary, we have shown that PAF is a potent secretagogue in isolated preparations of human colon and that the response is dependent on a specific PAF receptor, cyclo‐oxygenase products and bumetanide‐sensitive chloride ion transport.

British Journal of Pharmacology (1998) 123, 231–236; doi:10.1038/sj.bjp.0701602
Endothelium‐dependent sensory NANC vasodilatation: involvement of ATP, CGRP and a possible NO store
Authors: Kakuyama Masahiro , Vallance Patrick , Ahluwalia Amrita 
Published: January 2005

Non‐adrenergic non‐cholinergic (NANC) vasodilator nerves regulate tone in certain vascular beds. We have investigated the mechanisms of the NANC dilator response in the isolated small mesenteric artery of the rabbit by use of the tension myograph.
Small second or third order (150–300 μm in diameter) arteries of the rabbit mesenteric bed were mounted in a Mulvany tension myograph. Responses to electrical field stimulation (EFS) and exogenous vasodilators were investigated.
EFS (0.5–16 Hz, 10 V, 0.3 ms for 5 s), in the presence of guanethidine (5 μM) and atropine (1 μM) produced frequency‐dependent relaxation of small arteries. Pretreatment with tetrodotoxin (1 μM) abolished the relaxation and desensitization with capsaicin (10 μM) strongly inhibited the relaxation.
Pretreatment with a P2Y‐purinoceptor antagonist, basilen blue (3 μM) or a human calcitonin gene‐related peptide (hCGRP) receptor antagonist, hCGRP8–37 (1 μM) suppressed the NANC relaxation by approximately 40–60 % in each case and combined pretreatment almost abolished the relaxation.
The EFS‐induced relaxation was suppressed by endothelium‐removal, pretreatment with the soluble guanylyl cyclase inhibitor ODQ (1 μM) and the NO scavenger oxyhaemoglobin (OxyHb; 20 μM) but not by NO synthase inhibitors NG‐nitro‐L‐arginine methyl ester (L‐NAME; 300 μM) or NG‐nitro‐L‐arginine (L‐NOARG; 300 μM). Combined pretreatment with ODQ and CGRP8–37 almost abolished the relaxation.
A P2Y‐purinoceptor agonist, 2‐methylthio ATP, produced endothelium‐dependent relaxation which was inhibited by L‐NAME and ODQ (1 μM), whilst hCGRP produced endothelium‐independent and ODQ‐insensitive relaxation.
Ultraviolet light (320 nm, 5 shots over 20 s) produced relaxation that was blocked by both OxyHb and ODQ but not by NG‐monomethyl‐L‐arginine (L‐NMMA, 300 μM).
The present study suggests that EFS‐induced NANC relaxation of the mesenteric small artery of the rabbit is mediated mainly by capsaicin‐sensitive sensory C‐fibres and that both ATP and CGRP are involved. The action of ATP released by EFS appears to be endothelium‐dependent and involve activation of soluble guanylyl cyclase, but is resistant to inhibitors of NO synthase. The response to CGRP is endothelium‐independent. These results show that ATP and CGRP account fully for the NANC relaxation of this vessel type and that the endothelium is involved in NANC‐induced relaxation. The endothelium‐dependent part of the response is consistent with the release of NO, either from NO synthase, incompletely inhibited by the NO synthase inhibitors, or by some preformed stores.

British Journal of Pharmacology (1998) 123, 310–316; doi:10.1038/sj.bjp.0701610
Effect of dietary phenolic compounds on apoptosis of human cultured endothelial cells induced by oxidized LDL
Authors: Vieira Otilia , Escargueil‐Blanc Isabelle , Meilhac Olivier , Basile Jean‐Pierre , Laranjinha Joao , Almeida Leonor , Salvayre Robert , Nègre‐Salvayre Anne 
Published: January 2005

Oxidized low density lipoproteins (LDL) are toxic to cultured endothelial cells. Mildly oxidized LDL, characterized by relatively low levels of TBARS and only minor modifications of apoB, were obtained by using 2 experimental model systems of oxidation, namely oxidation by u.v. radiation or ferrylmyoglobin (a two electron oxidation product from the reaction of metmyoglobin with H2O2).
Toxic concentrations of mildly oxidized LDL induce apoptosis (programmed cell death) of cultured endothelial cells, as shown by typical morphological features, by the in situ TUNEL procedure and by DNA fragmentation revealed on gel electrophoresis. This apoptosis is calcium‐dependent and subsequent to the intense and sustained cytosolic [Ca2+]i peak elicited by oxidized LDL.
Five naturally occurring phenolic compounds present in food and beverages were able to prevent, in a concentration‐dependent manner, the apoptosis of endothelial cells induced by oxidized LDL. Among the compounds tested, caffeic acid was the most effective. Under the conditions used, the protective effect of caffeic acid (IC50 8.3±2.1 μmol  l−1) in the prevention of apoptosis induced by oxidized LDL was significantly higher than that of the other compounds tested (IC50s were 12.4±3.2, 14.1±4.1, 20.4±4.4 and 72.6±9.2 μmol  l−1 for ferulic, protocatechuic, ellagic and p‐coumaric acids, respectively).
The anti‐apoptotic effect of caffeic acid results from the addition of two effects, (i) the antioxidant effect which prevents LDL oxidation and subsequent toxicity (‘indirect’ protective effect); (ii) a ‘direct’ cytoprotective effect, acting at the cellular level.
Effective concentrations of caffeic acid acted at the cellular level by blocking the intense and sustained cytosolic [Ca2+]i rise elicited by oxidized LDL.
In conclusion, phenolic acids (caffeic and ferulic acids being the most potent of the compounds tested under the conditions used) exhibit a potent cytoprotective effect of cultured endothelial cells against oxidized LDL. In addition to antioxidant effect delaying LDL oxidation, caffeic acid acts as a cytoprotective agent, probably by blocking the intracellular signalling triggered by oxidized LDL and culminating in the sustained calcium rise which is involved in oxidized LDL‐induced apoptosis.

British Journal of Pharmacology (1998) 123, 565–573; doi:10.1038/sj.bjp.0701624
Pharmacological characterization of the cysteinyl‐leukotriene antagonists CGP 45715A (iralukast) and CGP 57698 in human airways in vitro
Authors: Capra Valérie , Bolla Manlio , Angelo Belloni Pier , Mezzetti Maurizio , Carlo Folco G. , Nicosia Simonetta , Enrico Rovati G. 
Published: January 2005

Cysteinyl‐leukotrienes (cysteinyl‐LTs) are important mediators in the pathogenesis of asthma. They cause bronchoconstriction, mucus hypersecretion, increase in microvascular permeability, plasma extravasation and eosinophil recruitment.
We investigated the pharmacological profile of the cysteinyl‐LT antagonists CGP 45715A (iralukast), a structural analogue of LTD4 and CGP 57698, a quinoline type antagonist, in human airways in vitro, by performing binding studies on human lung parenchyma membranes and functional studies on human isolated bronchial strips.
Competition curves vs [3H]‐LTD4 on human lung parenchyma membranes demonstrated that: (a) both antagonists were able to compete for the two sites labelled by [3H]‐LTD4; (b) as in all the G‐protein coupled receptors, iralukast and CGP 57698 did not discriminate between the high and the low affinity states of the CysLT receptor labelled by LTD4 (Ki1=Ki2=16.6 nM±36% CV and Ki1= Ki2=5.7 nM±19% CV, respectively); (c) iralukast, but not CGP 57698, displayed a slow binding kinetic, because preincubation (15 min) increased its antagonist potency.
In functional studies: (a) iralukast and CGP 57698 antagonized LTD4‐induced contraction of human bronchi, with pA2 values of 7.77±4.3% CV and 8.51±1.6% CV, respectively, and slopes not significantly different from unity; (b) the maximal LTD4 response in the presence of CGP 57698 was actually increased, thus clearly deviating from apparent simple competition.
Both antagonists significantly inhibited antigen‐induced contraction of human isolated bronchial strips in a concentration‐dependent manner, lowering the upper plateau of the anti‐IgE curves.
In conclusion, the results of the present in vitro investigation indicate that iralukast and CGP 57698 are potent antagonists of LTD4 in human airways, with affinities in the nanomolar range, similar to those obtained for ICI 204,219 and ONO 1078, two of the most clinically advanced CysLT receptor antagonists. Thus, these compounds might be useful drugs for the therapy of asthma and other allergic diseases.

British Journal of Pharmacology (1998) 123, 590–598; doi:10.1038/sj.bjp.0701636