bluuebunny/crossref_metadata_2025_split huggingface dataset:
The protective action of chlormethiazole against ischaemia‐induced neurodegeneration in gerbils when infused at doses having little sedative or anticonvulsant activity
Authors: Cross A.J. , Jones J.A. , Snares M. , Jostell K.‐G. , Bredberg U. , Green A.R. 
Published: July 2012

The effect of chlormethiazole administration on delayed neuronal death in gerbil hippocampus following transient global ischaemia has been examined. Chlormethiazole was administered either intraperitoneally or by intravenous infusion with either the dose or the time of infusion varied.
Chlormethiazole (600 μmol kg−1, i.p.) given 60 min after ischaemia produced substantial (>60%) neuroprotection when damage was assessed 5, 14 or 21 days later, indicating the drug does not merely delay cell death.
Infusion protocols were developed which would result in sustained and defined plasma concentrations. Chlormethiazole (930 μmol kg−1) was then infused intravenously for 30min, 76.5 min or HOmin in ways resulting in sustained plasma concentrations of 200, 100 and 50 nmol ml−1 respectively. When treatment was initiated 30 min after the ischaemic episode all protocols provided effective neuroprotection. There was a dose‐dependent decline in protection when plasma chlormethiazole concentrations of 50, 30 and 10 nmol ml−1 were sustained for 110 min with no protection observed at 10 nmol ml−1.
In contrast, when a plasma concentration of 10 nmol ml−1 was sustained by infusion for 24 h, almost total neuroprotection against the ischaemic damage was achieved. This plasma concentration produced no sedative or anticonvulsant activity.
These data suggest that neuroprotection depends on both dose and duration of chlormethiazole administration and that excellent neuroprotection is possible in the absence of the sedative and anticonvulsant effects of the drug.
Inhibition of rabbit aortic smooth muscle cell proliferation by selective inhibitors of protein kinase C
Authors: Newby Andrew C. , Lim Karene , Evans Marilyn A. , Brindle Nicholas P.J. , Booth Robert F.G. 
Published: July 2012

We studied the effect of two structurally‐related, selective inhibitors of protein kinase C, Ro 31–8220 and Ro 31–7549, on the reinitiation of proliferation in quiescent first passage rabbit aortic smooth muscle cells in response to (a) the direct activator of protein kinase C, phorbol dibutyrate (PDBu), (b) platelet‐derived growth factor (PDGF), (c) a combination of PDGF and 5‐hydroxytryptamine (5‐HT) or (d) serum.
Ro 31–8220 and Ro 31–7549 concentration‐dependently inhibited prliferation in response to each mitogen. The inhibitory potency (IC50) of Ro 31–8220 and Ro 31–7549, respectively, was similar against proliferation induced by PDBu (0.55 and 1.1 μm), PDGF (0.6 and 0.9 μm), PDGF and 5‐HT (0.68 and 1.1 μm), although slightly less against serum (1.7 and 5 μm). The effects of the protein kinase C inhibitors on proliferation could not be ascribed to cytotoxicity. Neither Ro 31–8220 nor Ro 31–7549 (0.3‐3 μm) inhibited PDGF receptor tyrosine phosphorylation.
The results show that Ro 31–8220 and Ro 31–7549 are potent inhibitors of smooth muscle cell proliferation in response to a direct activator of protein kinase C, the defined growth factors, PDGF and 5‐HT, and the complex mixture of mitogens in serum. Protein kinase C activation thus appears to be an important growth transducing mechanism for each of these agents.
Pharmacological analysis of the interaction between purinoceptor agonists and antagonists in the guinea‐pig taenia caecum
Authors: Prentice D.J. , Shankley N.P. , Black J.W. 
Published: July 2012

In the absence of adenosine uptake inhibition, adenosine produced a concentration‐dependent (threshold 30 μm) relaxation of the 5‐methylfurmethide pre‐contracted guinea‐pig taenia caecum. The relaxation was not blocked by 8‐phenyltheophylline (8‐PT, 3 μm) or 1,3‐dipropyl, 8‐cyclopentylxanthine (DPCPX, 30 μm).
In the presence of the adenosine uptake inhibitor, dipyridamole (Dip, 3μm), a biphasic adenosine concentration‐effect curve was obtained (threshold 0.3 μm). The time course of the responses to adenosine in the absence of Dip was similar to that of the second phase responses in the presence of Dip and occurred over the same adenosine concentration‐range. 5′‐(N‐ethyl) carboxamido‐adenosine (NECA) concentration‐effect curves (in the absence of Dip) were also biphasic. Only the first phases of the concentration‐effect curves obtained with NECA and adenosine (plus Dip) were inhibited by 8‐PT. The pA2 values for 8‐PT of 6.7 and 7.0 versus adenosine and NECA, respectively, were consistent with actions at P1‐purinoceptors. There was a trend towards an increase in the upper asymptote of the first phase of the NECA curve in the presence of increasing concentrations of 8‐PT. The A1‐purinoceptor selective antagonist, DPCPX, also blocked only the first phase of the NECA concentration‐effect curve and produced a significant increase in the upper asymptote. The pA2 value (6.8) obtained was consistent with activation of A2‐subtype P1purinoceptors by the low concentrations of NECA.
There was no correlation between A1‐purinoceptor affinity and the propensity to cause the increase in the upper asymptote of the first phase of the NECA concentration‐effect curves amongst a series of 9‐methyl adenine analogues, suggesting that the amplification was not due to inhibition of an underlying A1purinoceptor‐mediated contractile response.
DPCPX (10 μm) produced a significant increase in the upper asymptote of the NECA concentration‐effect curve, but had no effect on isoprenaline curves whereas the phosphodiesterase inhibitor Ro 20–1724 (30 μm) produced a significant increase in the upper asymptote of both NECA and isoprenaline concentration‐effect curves. Therefore the amplification of the first phase responses by DPCPX did not appear to be due to phosphodiesterase inhibition.
It was not possible to conclude whether second phase responses to adenosine and NECA were mediated by intracellular or extracellular sites of action. However, if intracellular sites of action were involved then adenosine did not apparently gain access by the Dip‐sensitive uptake system.
Contractile actions of thrombin receptor‐derived polypeptides in human umbilical and placental vasculature: evidence for distinct receptor systems
Authors: Tay‐Uyboco Jean , Poon Man‐Chiu , Ahmad Sultan , Hollenberg Morley D. 
Published: July 2012

We studied the structure‐activity profiles of four thrombin receptor‐derived polypeptides (TRPs) (P5, SFLLR; P5‐NH2, SFLLR‐NH2; P7, SFLLRNP; P7‐NH2, SFLLRN) in contractile human placental artery (PA), umbilical artery (UA) and umbilical vein (UV) preparations and in a human platelet aggregation assay.
The contractile actions of the TRPs in the two arterial preparations were endothelium‐independent, whereas in the UV tissue a contractile response was observed only in an endothelium‐denuded preparation; no endothelium‐mediated relaxation responses were observed in any of the vascular preparations.
In the three vascular preparations, the contractile responses required extracellular calcium and were attenuated by the tyrosine kinase inhibitor, genistein.
The relative contractile orders of potencies of the TRPs in the three vascular preparations were distinct from each other (PA: P7‐NH2>P7>P5‐NH2>P5; UA: P7‐NH2≥P5‐P72‐∼P7> >P5; UV: P5‐NH2 > > P7‐NH2 = P7 > > P5) and these were in turn distinct from the potency order observed in the platelet aggregation assay (P5‐NH2≥P7‐NH2>P7> >P5).
Despite the markedly dissimilar TRP potency orders in the placental artery and umbilical vein preparations, the cDNA sequences for the thrombin receptor obtained by polymerase chain reaction cloning of cDNA from the two tissue sources were identical.
We conclude that the four tissues studied possess functionally distinct thrombin receptor systems that interact in a distinct way with agonist peptides. In view of the identity of the thrombin receptor cDNA in the two tissues displaying the most dissimilar structure‐activity profiles, we suggest that in different tissues, differences in post‐translational receptor processing or differences in receptor‐effector coupling interactions may result in unique thrombin receptor systems that can display distinct structure‐activity profiles.
The pharmacology and distribution of human 5‐hydroxytryptamine2B (5‐HT2b) receptor gene products: comparison with 5‐HT2a and 5‐HT2c receptors
Authors: Bonhaus Douglas W. , Bach Chinh , DeSouza Andrea , Salazar F.H. Rick , Matsuoka Barbara D. , Zuppan Patricia , Chan Hardy W. , Eglen Richard M. 
Published: July 2012

Full length clones of the human 5‐HT2B receptor were isolated from human liver, kidney and pancreas. The cloned human 5‐HT2B receptors had a high degree of homology (∼80%) with the rat and mouse 5‐HT2B receptors.
PCR amplification was used to determine the tissue distribution of human 5‐HT2B receptor mRNA. mRNA encoding the 5‐HT2B receptor was expressed with greatest abundance in human liver and kidney. Lower levels of expression were detected in cerebral cortex, whole brain, pancreas and spleen. Expression was not detected in heart.
Northern blot analysis confirmed the presence of 5‐HT2B receptor mRNA (a 2.4 kB sized band) in pancreas, liver and kidney. An additional 3.2 kB sized band of hybridization was detected in liver and kidney. This raises the possibility of a splice variant of the receptor or the presence of an additional homologous receptor.
The human 5‐HT2B receptor was expressed in Cos‐7 cells and its ligand binding characteristics were compared to similarly expressed human 5‐HT2A and 5‐HT2C receptors. The ligand specificity of the human 5‐HT2B receptor (5‐HT > ritanserin > SB 204741 > spiperone) was distinct from that of the human 5‐HT2A (ritanserin > spiperone > 5‐HT > SB 204741) and 5‐HT2C (ritanserin > 5‐HT > spiperone = SB 204741) receptors. On the basis of a higher affinity for ketanserin and a lower affinity for yohimbine the human 5‐HT2B receptor also appeared to differ from the rat 5‐HT2B receptor.
These findings confirm the sequence of the human 5‐HT2B receptor and they demonstrate that the receptor has a widespread tissue distribution. In addition, these data suggest that there are differences in ligand affinities between different species homologues of the receptor. Finally, the finding of two distinct bands on the Northern blots of liver and kidney raises the possibility of splice variants or subtypes of 5‐HT2B receptors, within these tissues.
Elevation of plasma noradrenaline levels in urethane‐anaesthetized rats by activation of central prostanoid EP3 receptors
Authors: Yokotani Kunihiko , Nishihara Makoto , Murakami Yoshinori , Hasegawa Takashi , Okuma Yasunobu , Osumi Yoshitsugu 
Published: July 2012

We studied the effects of intracerebroventricular (i.c.v.) administration of prostaglandin E2 (PGE2) and its receptor subtype ligands on plasma levels of catecholamines in urethane‐anaesthetized rats.
Administration of PGE2 (0.15, 0.3 and 1.5 nmol per animal, i.c.v.) dose‐dependently elevated plasma levels of noradrenaline (NA), while the levels of adrenaline were not affected.
Administration of sulprostone (EP3/EP1 agonist) and misoprostol (EP3/EP2 agonist) effectively elevated plasma NA levels in a dose‐dependent manner (0.1, 0.3, and 1.0 nmol per animal). Butaprost (EP2 agonist) (0.3, 1.0 and 3.0 nmol per animal) was without effect. 17‐Phenyl‐ω‐trinor PGE2 (EP1/EP3 agonist) effectively elevated plasma NA levels only at its highest dose (1.0 nmol per animal), but this elevation was not attenuated by pretreatment with SC‐19220 (selective EP1 antagonist) (20 nmol per animal, i.c.v.).
The potency of these test agents in elevating plasma levels of NA was as follows; misoprostol > sulprostone > PGE2> > 17‐phenyl‐ω‐trinor PGE2 > > > butaprost. These results suggest that activation of central prostanoid EP3‐receptors induces central sympathetic outflow in rats.
Cytokine‐mediated inflammatory hyperalgesia limited by interleukin‐10
Authors: Poole S. , Cunha F.Q. , Selkirk S. , Lorenzetti B.B. , Ferreira S.H. 
Published: July 2012

The effect of interleukin‐10 (IL‐10) upon the hyperalgesic activities in rats of bradykinin, tumor necrosis factor α (TNFα), interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6), interleukin‐8 (IL‐8), prostaglandin E2 (PGE2) and carrageenin were investigated in a model of mechanical hyperalgesia.
Hyperalgesic responses to bradykinin (1 μg) were inhibited in a dose‐dependent manner by prior treatment with IL‐10 (1–100 ng).
Hyperalgesic responses to TNFα (2.5 pg), IL‐1β (0.5 pg) and IL‐6 (1.0 ng) but not to IL‐8 (0.1 ng) and PGE2 (50 ng and 100 ng) were inhibited by prior treatment with IL‐10 (10 ng).
Hyperalgesic responses to carrageenin (100 μg) were inhibited by IL‐10 (10 ng) when this cytokine was injected before but not after the carrageenin.
A monoclonal antibody to mouse IL‐10 potentiated the hyperalgesic responses to carrageenin (10 μg) and TNFα (0.025 pg) but not that to IL‐8 (0.01 ng).
In in vitro experiments in human peripheral blood mononuclear cells (MNCs), IL‐10 (0.25‐4.0 ng ml−1) inhibited in a dose‐dependent manner PGE2 production by MNCs stimulated with IL‐1β (1–64 ng ml−1) or endotoxin (lipopolysaccharide, LPS, 1 iu=143 pg ml−1) but evoked only small increases in IL‐Ira production.
These data suggest that IL‐10 limits the inflammatory hyperalgesia evoked by carrageenin and bradykinin by two mechanisms: inhibition of cytokine production and inhibition of IL‐1β evoked PGE2 production. Our data suggest that the latter effect is not mediated via IL‐10 induced IL‐Ira and may result from suppression by IL‐10 of prostaglandin H synthase‐2 (COX‐2).
Gi proteins and the response to 5‐hydroxytryptamine in porcine cultured endothelial cells with impaired release of EDRF
Authors: Day Nancy S. , Ge Tong , Codina Juan , Birnbaumer Lutz , Vanhoutte Paul M. , Boulanger Chantal M. 
Published: July 2012

The receptor‐mediated release of endothelium‐derived relaxing factor(s) (EDRF) requires the presence of different functional G proteins in endothelial cells. Release of EDRF in response to 5‐hydroxytryptamine (5‐HT), which involves activation of pertussis toxin‐sensitive Gi proteins, is impaired in both regenerated endothelium of the coronary artery following balloon catheterization and in porcine cultured endothelial cells. This study used porcine cultered endothelial cells as a model of regenerated endothelium to determine if the abnormal release of EDRF in response to 5‐HT may be associated with the loss of functional pertussis toxin‐sensitive Gi proteins.
Binding studies on porcine cultured endothelial cells demonstrated specific binding sites for [3H]‐5‐HT. Scatchard analyses revealed a single binding site for [3H]‐5‐HT with Kd of 7.2 ±3.5 nM and maximal binding Bmax) of 121.4±51.3 fmol mg−1 protein. Binding of [3H]‐5‐HT was displaced by methiothepin (5‐HT1 and 5‐HT2 antagonist; Ki = 62 ±1.2 nM), but not by ketanserin (preferential 5‐HT2 antagonist).
Giα protein was expressed in cultured but not in native endothelial cells. Giα2 and Giα3 proteins were expressed to significant levels in porcine native and cultured endothelial cells, as detected by Northern and Western blot analysis.
In membranes from cultured endothelial cells, two bands of 40 and 41 kDa, which corresponded to the Giα2 and the combination of Giα3‐Giα1 proteins, respectively, were ADP‐ribosylated by pertussis toxin. The labelling intensity was Gia2>Giα3‐Giαl and the amount of ADP‐ribosylation was not different between porcine native and cultured endothelial cells. Stimulation of the cultured cells with 5‐HT (3 × 10−6 m; 4 min) decreased significantly further ADP‐ribosylation of Gia2 by pertussis toxin, but not that of Giα3 and/or Giαl.
The present results suggest that porcine endothelial cell culture may lead to the abnormal expression of Giαl protein and that the dysfunctional release of EDRF from cultured porcine endothelial cells in response to 5‐HT is not associated with the loss of Giα proteins or the absence of 5‐HT binding sites.
Endothelial function in spontaneously hypertensive rats: influence of quinapril treatment
Authors: Kähönen Mika , Mäkynen Heikki , Wu Xiumin , Arvola Pertti , Pörsti Ilkka 
Published: July 2012

Angiotensin converting enzyme (ACE) inhibition has been shown to restore the impaired endothelial function in hypertension, but the mediators underlying the promoted endothelium‐dependent dilatation have not been fully characterized. Therefore, we investigated the effects of 10‐week‐long quinapril therapy (10 mg kg−1 day−1) on responses of mesenteric arterial rings in vitro from spontaneously hypertensive rats (SHR) and normotensive Wistar‐Kyoto (WKY) rats.
Endothelium‐dependent relaxations of noradrenaline (NA)‐precontracted rings to acetylcholine (ACh) and adenosine 5′‐diphosphate (ADP) were similar in WKY rats and quinapril‐treated SHR and more pronounced than in untreated SHR. The nitric oxide (NO) synthase inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME) attenuated the relaxations in both WKY groups and quinapril‐treated SHR, and completely inhibited them in untreated SHR. When endothelium‐dependent hyperpolarization was prevented by precontraction of the preparations with potassium chloride (KC1), no differences were found in relaxations to ACh and ADP between the study groups. In addition, in NA‐precontracted rings the L‐NAME‐ and indomethacin‐resistant relaxations to ACh were partially prevented by apamin, an inhibitor of calcium‐activated potassium channels.
Interestingly, in quinapril‐treated SHR but not in the other groups, exogenous bradykinin potentiated the relaxations to ACh in both NA‐ and KCl‐precontracted arterial rings.
Contractile sensitivity of endothelium‐intact rings to NA was reduced in SHR by quinapril, and was more effectively increased by L‐NAME in quinapril‐treated than untreated SHR.
In conclusion, since the relaxations to ACh and ADP in quinapril‐treated SHR were augmented in the absence and presence of NO synthesis inhibition but not under conditions which prevented hyperpolarization, enhanced endothelium‐dependent relaxation after long‐term ACE inhibition can be attributed to increased endothelium‐dependent hyperpolarization. However, the potentiation of the response to ACh by exogenous bradykinin in quinapril‐treated SHR, as well as the increased attenuating effect of the endothelium on NA‐induced contractions in these animals appear to result from enhanced endothelium‐derived NO release.
Absence of a losartan interaction with renal lithium excretion in the rat
Authors: Barthelmebs Mariette , Alt‐Tebacher Martine , Madonna Olivier , Grima Michèle , Imbs Jean‐Louis 
Published: July 2012

The interaction of losartan, a non‐peptide specific AT1 receptor antagonist with the renal handling of lithium was analysed in conscious normotensive Wistar rats and compared with the known increase in renal tubular lithium reabsorption induced by the non‐steroidal anti‐inflammatory drug, indomethacin.
The rats were treated for five days with losartan (10 mg kg−1 day−1, orally), indomethacin (2.5 mg kg−1 day−1, intramuscularly) or their solvents. Lithium chloride (16.7 mg kg−1, i.p.) was given as a single dose on the fifth day; renal functions were then measured.
Indomethacin, in the absence of any effect on creatinine clearance, increased renal fractional lithium reabsorption and led to an increase in plasma lithium levels.
Losartan did not modify renal lithium handling and its plasma level. No change was observed in renal lithium clearance, the quantity of filtered lithium or the fractional reabsorption of the metal. As expected, losartan had no effect on systolic blood pressure in normotensive rats.
In conclusion, our results indicate that losartan, when given orally in the rat at a dose of 10 mg kg−1 day−1 over five days, does not modify renal lithium handling. They suggest that blockade of the angiotensin II receptors does not interfere with renal lithium reabsorption, which occurs mainly at a proximal tubular site.
Pituitary adenylate cyclase‐activating polypeptide, helospectin, and vasoactive intestinal polypeptide in human corpus cavernosum
Authors: Hedlund P. , Alm P. , Ekström P. , Fahrenkrug J. , Hannibal J. , Hedlund H. , Larsson B. , Andersson K.‐E. 
Published: July 2012

The distribution and effects of pituitary adenylate cyclase‐activating polypeptide (PACAP‐27 and −38), helospectin (Hel‐l and Hel‐2), and vasoactive intestinal polypeptide (VIP), were investigated in isolated preparations of human corpus cavernosum (CC).
Immunohistochemistry revealed coinciding profiles of nerve structures that showed immunoreactivities for VIP and PACAP, and VIP and Hel. Confocal microscopy showed the co‐existence of VIP‐ and PACAP‐immunoreactivities, and VIP‐ and Hel‐immunoreactivities in most (90%) varicose nerve structures.
As determined by radioimmunoassay, the amounts of VIP, PACAP‐27, and PACAP‐38 in the preparations were 61.7 ±11.6, 0.1 ±0.05, and 3.7±0.5 pmol g−1 wet weight of tissue (pmol g−1 wet wt.), respectively. In tissue from patients with diabetes, the content of VIP was lower (13.7 ±0.5 pmol g−1 wet wt.), whereas that of PACAP (−27 and −38) was unchanged.
Cyclic nucleotide levels were determined in preparations exposed to PACAP‐27, PACAP‐38, Hel‐1, Hel‐2, and VIP. All the peptides, but Hel‐2, significantly increased the concentrations of cyclic AMP, whereas the levels of cyclic GMP were unchanged.
The peptides concentration‐dependently relaxed noradrenaline‐contracted preparations. The order of potency was VIP>PACAP 27>Hel‐1>Hel‐2>PACAP‐38.
Hel‐1, VIP and PACAP‐27 effectively counteracted electrically induced contractions. At 10−6 m, the highest peptide concentration used, the inhibitory effects obtained reached 96±3%, 87±6%, and 80±3%, respectively. 7 The results suggest that PACAP and Hel‐1 are co‐localized with VIP in nerve structures within the human cavernous tissue, and that the peptides are effective relaxants of CC preparations in vitro. The role of the investigated peptides for penile erection remains to be established.
Failure of the putative neuropeptide Y antagonists, benextramine and PYX‐2, to inhibit Y2 receptors in rat isolated prostatic vas deferens
Authors: Palea S. , Corsi M. , Rimland J.M. , Trist D.G. , Ratti E. 
Published: July 2012

The pharmacological activity of neuropeptide Y (NPY) and some analogues in inhibiting the twitch contractions induced by electrical stimulation (single pulses at 25 V, 0.15 Hz, 1 ms) in the prostatic portion of the rat isolated vas deferens was investigated. The rank order of agonist potency was: PYY > NPY2–36 > NPY >> NPY13–36 >> NPY>8–36 >>> [Leu31, Pro34]NPY = hPP, which is consistent with the activation of a Y2 receptor.
The putative Y1 and Y2 antagonist, benextramine (BXT), incubated at 100 μm for 10 or 60 min, was ineffective against PYY‐induced inhibition of the twitch response, suggesting that the prejunctional Y2 receptor in this tissue is different from the postjunctional one reported in the literature to be sensitive to BXT blockade.
The putative NPY antagonist, PYX‐2, incubated at 1 μm for 20 min, was completely ineffective in antagonizing PYY‐induced inhibition of twitches.
The twitch response was totally inhibited by suramin (100 μm) but was little affected by prazosin (1 μm). Futhermore, NPY was without effect on the dose‐response curve to ATP in resting conditions. Taken together, these results suggest that in our paradigm, NPY inhibits the release of a purinergic neurotransmitter which mediates contraction of the prostatic portion of the rat vas deferens.