318 results match your criteria Receptors and Channels[Journal]


Human gastric tissues simultaneously express the classical and alternative splicing cholecystokinin-B/gastrin receptors.

Receptors Channels 2004 ;10(5-6):185-8

Department of Biochemistry and Molecular Biology, School of Basic Medical Science, Sichuan University, Chengdu, China.

To explore whether cholecystokinin-B/gastrin receptor (CCKBRwt) gene and its alternative splicing variant preserving intron 4 (CCKBRi4sv) are expressed in human gastric carcinoma cell line and tissue, we detect mRNA expression of CCKBRwt and CCKBRi4sv in 30 gastric carcinoma and their corresponding normal tissues, 10 gastritis, and 2 autopsied normal stomach specimens as well as in a gastric carcinoma cell line SGC-7901 cells by RT-PCR and sequencing. The results revealed that human normal, inflammatory, and malignant gastric tissues simultaneously expressed the classical and alternative splicing cholecystokinin-B/gastrin receptor genes. The alternative splicing variant contains the intron 4 of cholecystokinin-B/gastrin receptor gene. Read More

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August 2005
11 Reads

Regulation of receptor-coupling to (multiple) G proteins. A challenge for basic research and drug discovery.

Authors:
Jyrki P Kukkonen

Receptors Channels 2004 ;10(5-6):167-83

Department of Neuroscience, Physiology, Uppsala University, Uppsala, Sweden.

G protein-coupled receptors induce intracellular signals via interaction of with cytosolic/peripheral membrane proteins, mainly G proteins. There has been much debate about the mode of interaction between the receptors, G proteins and effectors, their mobility and the ways of determining the specificity of interaction. Additional complexity has been added to system upon the discovery of i) coupling of single receptors to several G proteins and ii) active direction of this by different ligands (stimulus trafficking). Read More

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August 2005
2 Reads

High efficiency activation of L-type Ca2+ current by 5-HT in human atrial myocytes.

Receptors Channels 2004 ;10(5-6):159-65

CNRS UMR 6542, Faculté des Sciences, Université de Tours, France.

In human atrial myocytes, serotonin rather than sympathetic, stimulation is more frequently associated with atrial fibrillation. So does the arrhythmogenic effect of serotonin result from the mechanism of action of the receptor or the context of its action upon cardiac myocytes? The capacity of agonists to produce cAMP followed the sequence 5-HT < Iso < Forskolin to increase ICaL with 5-HT = Iso = Forskolin. The simultaneous application of threshold concentrations of 5-HT and Iso maximally increased ICaL. Read More

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August 2005
5 Reads

Effects of losartan on blood pressure, oxidative stress, and nitrate/nitrite levels in the nitric oxide deficient hypertensive rats.

Receptors Channels 2004 ;10(5-6):147-57

Department of Pharmacology, College of Pharmacy, King Saud University, Kingdom of Saudi Arabia.

Losartan, an angiotensin II type-1 receptor (AT1) antagonist, was used to investigate whether it can offer protection against the sustained hypertension, cardiac hypertrophy, and renal damage induced by chronic inhibition of nitric oxide (NO) by Nomega-nitro-L-arginine methyl ester (L-NAME). We studied the involvement of both NO metabolism and oxidative stress in L-NAME-induced hypertension, and how AT1 receptor antagonism may interact. Male Wistar albino rats were subjected to NO synthesis inhibition by the use of L-NAME (60 mg/kg/day), and the effects of losartan (10 mg/kg/day) in drinking water for six weeks were observed. Read More

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August 2005
12 Reads

Modification by L-NAME of codeine induced analgesia: possible role of nitric oxide.

Receptors Channels 2004 ;10(5-6):139-45

Department of Pharmacology, College of Pharmacy, King Saud University, Kingdom of Saudi Arabia.

Objectives were to investigate the effect of nonselective nitric oxide synthase (NOS) inhibitor, L-NAME on codeine-induced analgesia and to see the role of NO in its antinociceptive effect. Also, to see if L-NAME can potentiate the antinociceptive response of sub-effective dose of codeine and to explore if opioid receptors have some role to play in L-NAME effects. Mice were injected with selected doses of codeine or other selected agents intraperitoneally and the latency to hot plate was recorded at zero, 15, 30, and 60 min of the treatments. Read More

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August 2005
4 Reads

Inactivation-deficient human skeletal muscle Na+ channels (hNav1.4-L443C/A444W) in stably transfected HEK-293 cells.

Receptors Channels 2004 ;10(3-4):131-8

Department of Biology, State University of New York at Albany, Albany, NY, USA.

After transient transfection of an hNav1.4-L443C/A444W mutant clone, HEK-293 cells exhibited large inactivation-deficient Na+currents. We subsequently established a stable cell line expressing robust inactivation-deficient Na+currents. Read More

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http://dx.doi.org/10.1080/10606820490514914DOI Listing
March 2005
4 Reads

Polyclonal antibody effects on the human cardiac 5-HT4(e) receptors depend upon the expression system.

Receptors Channels 2004 ;10(3-4):125-9

UMR CNRS 6542, Physiologie des Cellules Cardiaques et Vasculaires, Faculté des Sciences et Techniques, Université de, Tours, France.

The initial objective of this work was to examine the effects of an antibody (Anti-G21V) directed against the second extracellular loop of human heart 5-HT4 receptors expressed in Chinese hamster ovary (CHO) cells. The antibody anti-G21V had no effect upon either basal cAMP-or 5-HT-evoked increases in cAMP in CHO cells, whereas it had shown an agonist-like effect in COS-7 cells. Analysis of agonist fractions of h5-HT4(e) receptors in CHO and COS-7 cells revealed that equilibrium constant could underlie the different responses of the receptor toward the anti-G21V antibody. Read More

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http://dx.doi.org/10.1080/10606820490514950DOI Listing
March 2005
11 Reads

Heterologous expression of G protein-coupled receptors in U-2 OS osteosarcoma cells.

Receptors Channels 2004 ;10(3-4):117-24

Gene Expression & Protein Biochemistry, Discovery Research Biology, GlaxoSmithKline, King of Prussia, Pennsylvania, USA.

Recombinant baculoviruses, in which the insect cell-specific polyhedrin promoter has been replaced with a mammalian cell-active expression cassette (BacMam viruses), are efficient gene delivery vehicles for many mammalian cell types. BacMam viruses have been generated for expression of G protein-coupled receptors (GPCRs) and used to establish Ca2+mobilization assays in HEK-293 human embryonic kidney cells and U-2 OS human osteosarcoma cells. U-2 OS cells are highly susceptible to BacMam-based gene delivery and lack many of the endogenous receptors present on HEK-293 and other mammalian cell lines typically used for heterologous expression of GPCRs. Read More

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http://dx.doi.org/10.1080/10606820490515012DOI Listing
March 2005
24 Reads

Bulk is a determinant of oxymetazoline affinity for the alpha1A-adrenergic receptor.

Receptors Channels 2004 ;10(3-4):109-16

Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.

The alpha1A-adrenergic receptor (AR) has a higher affinity for several agonists and antagonists compared to alpha1B or alpha1D ARs. Mutagenesis studies were used to determine residues potentially responsible for this subtype selectivity. Oxymetazoline has a 50-fold lower affinity for alpha1D ARs compared to alpha1A ARs and also displayed a significant loss of affinity for an alpha1A Leu-290 to Phe mutant. Read More

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http://dx.doi.org/10.1080/10606820490514923DOI Listing
March 2005
2 Reads

BacMam recombinant baculoviruses in G protein-coupled receptor drug discovery.

Receptors Channels 2004 ;10(3-4):99-107

Gene Expression & Protein Biochemisty, Discovery Research Biology, GlaxoSmithKline, King of Prussia, PA 19406-0939, USA.

With completion of the sequencing of the human and mouse genomes, the primary sequences of close to 400 non-olfactory G protein-coupled receptors (GPCRs) have been determined. There are intensive efforts within the pharmaceutical industry to discover and develop new therapeutic agents acting via GPCRs. In addition, there is a concerted effort to identify potential new drug targets from the remaining 150+orphan GPCRs through the identification of their ligands. Read More

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http://dx.doi.org/10.1080/10606820490514969DOI Listing
March 2005
10 Reads

Proteinous amino acids in hearts' muscle cytosol of rats pretreated with digoxin, caffeine or isoproterenol.

Receptors Channels 2004 ;10(2):91-7

Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland.

Levels of the 19 proteinous amino acids and total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been exposed to the cardioactive drugs digoxin, caffeine, and isoproterenol, each having different mechanisms of action. We demonstrated that, in the atrial and ventricular cardiac muscle cytosol of control (untreated) rats, arginine, glutamine, and cysteine existed in their highest levels: 35. Read More

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http://dx.doi.org/10.1080/10606820490464352DOI Listing
January 2005
11 Reads

Proteinous amino acids in muscle cytosol of rats' heart, after their treatment with propranolol, pentylenetetrazol or reserpine.

Receptors Channels 2004 ;10(2):83-90

Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland.

Tissue levels of nineteen amino acids and total free amino acids, were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular muscle cardiomyocytes. The tissues were assayed after the rats had been administered IP with the three cardioactive drugs, exerting a significant effect on their heart action: propranolol, pentylenetetrazol and reserpine. It was demonstrated that while in the atrial and ventricular cardiac muscle cytosols of control rats, arginine, glutamine and cysteine were detected in high levels (35. Read More

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http://dx.doi.org/10.1080/10606820490464343DOI Listing
January 2005
9 Reads

Interactions of "ultra-low" doses of naltrexone and morphine in mature and young male and female rats.

Receptors Channels 2004 ;10(2):73-81

Department of Anesthesiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0293, USA.

Sex and age influence morphine analgesia in humans and animals. Mature rats show greater morphine analgesia in males than in females. Ultra-low doses of naltrexone enhance morphine analgesia. Read More

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http://dx.doi.org/10.1080/10606820490464334DOI Listing
January 2005
3 Reads

Evaluation of pyridine-3-carboxylic acid as a drug carrier by utilizing multivariate methods, structure property correlations, and pattern recognition techniques.

Receptors Channels 2004 ;10(2):61-71

University of Nebraska, Durham Science Center, Chemistry Department, Medicinal Chemistry Laboratory, Omaha, Nebraska 68182, USA.

Multivariate methods and molecular properties are utilized to show similarity of pyridine-3-carboxylic acid (nicotinic acid) to seven drugs that penetrate the central nervous system. Multivariate methods applied include cluster analysis, discriminant analysis, correspondence analysis, self organizing tree algorithm (SOTA) analysis, factor analysis, and principal component analysis. Numerical values of properties for nicotinic acid showed very high correlation with the values from dihydropyridine, barbital, metharbital, phenobarbital, methohexital, 4-aminohex-5-enoic acid, and (4-chlorophenyl)(5-fluoro-2-hydroxyphenyl)methanone. Read More

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http://dx.doi.org/10.1080/10606820490464325DOI Listing
January 2005
3 Reads

G-protein coupled receptors as allosteric machines.

Authors:
Terry Kenakin

Receptors Channels 2004 ;10(2):51-60

Molecular Discovery, GlaxoSmithKline Research and Development, 5 Moore Drive, RTP 27709, USA.

Allosterism, whereby small molecule ligands produce global changes in the conformations of receptors, is a powerful mechanism for drug effect. This is illustrated by the recent data describing CCR5 antagonists as blockers of HIV infection. Allosteric effects are described in terms of a change in the tertiary conformation of the receptor. Read More

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http://dx.doi.org/10.1080/10606820490464316DOI Listing
January 2005
7 Reads

Production of the human D2S receptor in the methylotrophic yeast P. pastoris.

Receptors Channels 2004 ;10(1):37-50

Max-Planck-Institut für Biophysik, Abt. Molekulare Membranbiologie, Frankfurt, Germany.

In order to evaluate the methylotrophic yeast Pichia pastoris as means for high-yield production of homogenous D(2S) receptor protein, we have expressed the unmodified D(2S) receptor and various D(2S) receptor fusion constructs under the transcriptional control of the highly inducible promotor of the P. pastoris alcoholoxidase 1 gene in strain SMD1163. Fusion of the D(2S) receptor gene to the alpha-factor preprosequence proved to be essential for receptor production. Read More

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October 2004
3 Reads

Comparison of modulation of Kv1.3 channel by two receptor tyrosine kinases in olfactory bulb neurons of rodents.

Receptors Channels 2004 ;10(1):25-36

Department of Biological Science, Program in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.

Activation of the receptor tyrosine kinase (RTK), insulin (IRK) or neurotrophin B (TrkB), was characterized and compared in olfactory bulb neuron (OBN) cultures from Sprague Dawley rats and sv129 B6 mice. Current suppression attributed to modulation of the delayed rectifier, Kv1.3, a voltage-gated potassium (Kv) channel of the Shaker family, was observed following acute application of the growth factors, insulin or brain-derived neurotrophic factor (BDNF), to mitral cells of either rodent model. Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3082840PMC
October 2004
3 Reads

Comparison of the pharmacological properties of rat Na(V)1.8 with rat Na(V)1.2a and human Na(V)1.5 voltage-gated sodium channel subtypes using a membrane potential sensitive dye and FLIPR.

Receptors Channels 2004 ;10(1):11-23

Theravance Inc., 901 Gateway Boulevard, South San Francisco, CA 94080, USA.

A novel, membrane potential sensitive dye and a fluorescence imaging plate reader (FLIPR) have been used to characterize the pharmacological properties of rat Na(v)1.8 voltage-gated sodium channels (VGSC) in parallel with rat Na(v)1.2a and human Na(v)1. Read More

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October 2004
15 Reads

Desensitization of muscarinic receptors.

Receptors Channels 2004 ;10(1):1-10

Heymans Institute for Pharmacology, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium.

When Chinese hamster ovary cells transfected with the gene for M(3)-muscarinic receptors were stimulated with carbachol continuously for 30 min, the response at the end of the stimulation period was about 20% of the early response (2-3 min after the start of the stimulation). Long-term treatment of the cells with phorbol ester abolished the response completely while desensitization was significantly reduced upon pre-treatment of the cells with GF109203X, antisense oligonucleotide against the alpha-isoform of protein kinase C and wortmannin. We conclude that in the Chinese hamster ovary expression system, desensitization of M(3)-muscarinic receptors is dependent on a fast feedback loop including the alpha-isoform of protein kinase C. Read More

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October 2004
3 Reads

Biophysical properties of Kv3.1 channels in SH-SY5Y human neuroblastoma cells.

Receptors Channels 2003 ;9(6):387-96

Universitätsklinik für Anästhesiologie, University of Hamburg, Martinistrasse 52, 20251 Hamburg, FRG.

Biophysical properties of delayed rectifier K channels in the human neuroblastoma SH-SY5Y were established using patch clamp recordings. The whole cell K+ conductance activated at membrane potentials positive to -20 mV. The midpoint of current activation was 9. Read More

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July 2004
4 Reads

Melatonin for the treatment of disorders in circadian rhythm and sleep: could it form a basis for medication?

Authors:
Isaac Nir

Receptors Channels 2003 ;9(6):379-85

Department of Pharmacology, Faculty of Medicine, The Hebrew University-Hadassah Medical School,PO Box 12065, Ein-Kerem, Jerusalem 91120, Israel.

The various aspects of the existing knowledge on the physiological role of melatonin and its mode of action in circadian rhythms and sleep are presented. Furthermore, the possibility of its clinical application in maintenance of sleep under regular and environmental changes is discussed. Read More

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July 2004
11 Reads

Phylogenomic analysis and evolution of the potassium channel gene family.

Receptors Channels 2003 ;9(6):363-77

School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.

Potassium channels govern the permeability of cells to potassium ions, thereby controlling the membrane potential. In metazoa, potassium channels are encoded by a large, diverse gene family. Previous analyses of this gene family have focused on its diversity in mammals. Read More

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July 2004
3 Reads

Stoichiometry of recombinant heteromeric glycine receptors revealed by a pore-lining region point mutation.

Receptors Channels 2003 ;9(6):353-61

The School of Pharmacy, London, United Kingdom.

Heteromeric glycine receptors mediate synaptic inhibition in the caudal areas of the adult mammalian central nervous system (CNS). These channels resemble other receptors in the nicotinic superfamily in that they are pentamers, but may differ in that they contain alpha and beta subunits in a 3:2 rather than a 2:3 ratio. Evidence in favor of a 3alpha:2beta stoichiometry of heteromeric glycine receptors comes from biochemical data and from the expression of chimeric subunits. Read More

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July 2004
9 Reads

The urea transporter (UT) family: bioinformatic analyses leading to structural, functional, and evolutionary predictions.

Receptors Channels 2003 ;9(6):345-52

Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA.

We have identified all currently sequenced members of the urea transporter (UT) family (TC #1.A.28). Read More

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July 2004
4 Reads

Biogenic amines in striatum of rats that had been treated with ethanol, and their brains later stored in different temperatures.

Receptors Channels 2003 ;9(5):339-42

Department of Pharmacology, Medical University of Silesia, Poland.

The purpose of this study was to investigate how ethanol pretreatment and storage temperatures of brain striatum affect levels of biogenic amines in this tissue. Adult Wistar male rats were injected with 25% ethanol (5.0 g/kg i. Read More

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June 2004
11 Reads

Effects of (+/-)-idazoxan alone and in combination with L-DOPA methyl ester in MPTP-induced hemiparkinsonian monkeys.

Receptors Channels 2003 ;9(5):335-8

Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109-0632, USA.

The effects of a combination of the alpha2-adrenergic receptor antagonist (+/-)-idazoxan with L-DOPA methyl ester were examined in three of four female adult monkeys (Macaca nemestrina) rendered hemiparkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). (+/-)-Idazoxan (0.16, 0. Read More

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June 2004
3 Reads

Combined effects of Cordyceps sinensis and methotrexate on hematogenic lung metastasis in mice.

Receptors Channels 2003 ;9(5):329-34

Department of Pharmacology, Faculty of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.

We investigated antitumor effects of water extracts of Cordyceps sinensis (WECS). WECS (100 microg/ml) induced apoptosis of B16 melanoma cells after 48 h exposure in vitro as determined by both the TUNEL (TdT-mediated dUTP-biotin nick end labeling) method and the detection of a DNA ladder. In vivo, combined treatment with WECS and methotrexate (MTX) in mice intravenously inoculated with B16 melanoma cells was conducted. Read More

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June 2004
46 Reads

The effects of flumazenil on the antinociceptive actions of morphine in rats.

Receptors Channels 2003 ;9(5):325-8

Department of Anesthesiology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536-0296, USA.

The 8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H-imidazol[1,5-a][1,4]benzodiazepine-3-carboxylic acid ethyl ester (Flumazenil)-morphine interaction on analgesia (acute pain model, tail-flick test) was tested after intraperitoneal (IP) and intrathecal (IT) routes of administration in female rats. Analgesia was enhanced by the concurrent administration of Flumazenil with morphine (IP), in a dose-related way. Flumazenil alone (IP) did not produce analgesia. Read More

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June 2004
3 Reads

Properties of Arg389-beta1-adrenoceptor-Gsalpha fusion proteins: comparison with Gly389-beta1-adrenoceptor-Gsalpha fusion proteins.

Receptors Channels 2003 ;9(5):315-23

Department of Pharmacology and Toxicology, The University of Kansas, Lawrence, Kansas 66045-7582, USA.

The human beta1-adrenoceptor (beta1AR) exists in several isoforms and activates adenylyl cyclase (AC) via Gs-proteins. The Arg389-isoform of the beta1AR (beta1AR-R389) expressed in CHW cells is much more efficient than the Gly389 isoform of the beta1AR (beta1AR-G389) at stabilizing the ternary complex and activating AC (Mason et al. 1999). Read More

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June 2004
3 Reads

A bifunctional alkylating nitrogen mustard agent that utilizes barbituric acid as carrier drug with the potential for crossing the brain-blood barrier.

Receptors Channels 2003 ;9(5):309-13

University of Nebraska, College of Arts & Sciences, Chemistry Department, Durham Science Center, Omaha, Nebraska 68182, USA.

Barbituric acid is the parent compound of a large family of hypnotic barbiturates. A nitrogen mustard (N-mustard) group (-CH2CH2N[CH2CH2Cl]2) was placed onto the two nitrogen atoms at positions 1 and 3 of the pyrimidine ring. This N-mustard agent is a solid at 25 degrees C, stable at -10 degrees C for >10 weeks, and soluble in aqueous solvent at 37 degrees C and 25 degrees C. Read More

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June 2004
9 Reads

Proteinous amino acids in muscle cytosol of rats' heart after exercise and hypoxia.

Receptors Channels 2003 ;9(5):301-7

Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland.

Levels of 19 proteinous amino acids and of total free amino acids were assayed by gas-liquid chromatography in cytosols of rat atrial and ventricular heart muscle cardiomyocytes. These amino acids were assayed after the rats had been exposed to either exercise (swimming) or hypoxia (hypobaric pressure of 686 hectoPascals). Out of the total free amino acids levels of arginine, glutamine and cysteine in atrial and ventricular cardiac muscle cytosols of control rats were the highest of all amino acids assayed. Read More

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June 2004
5 Reads

Stable expression and characterization of human PN1 and PN3 sodium channels.

Receptors Channels 2003 ;9(5):291-9

Department of Molecular and Cellular Biology, Nippon Boehringer Ingelheim Co., Ltd., Kawanishi Pharma Research Institute, Yato, Kawanishi, Japan.

Nociceptive transduction in inflammatory and neuropathic pain involves peripherally expressed voltage-gated sodium channels, such as tetrodotoxin (TTX)-sensitive PN1 and TTX-resistant PN3. We generated recombinant cell lines stably expressing the human PN1 and PN3 sodium channels in Chinese hamster ovary (CHO) cells using inducible expression vectors. The PN1 and PN3 cDNAs were isolated from human adrenal gland and heart poly(A)+ RNAs, respectively. Read More

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June 2004
5 Reads

Application of the Cytosensor microphysiometer to drug discovery.

Receptors Channels 2003 ;9(2):125-31

Nobex Corporation, 617 Davis Drive, Durham, NC 27713, USA.

The Cytosensor microphysiometer uses silicon chip technology to correlate changes in extracellular acidification rates with quantitative changes in cellular metabolism in response to ligand binding to surface receptors. This functional measure of physiology makes the Cytosensor a valuable tool in drug discovery research by allowing application of the instrument to screening of prospective pharmacologically active agents, characterizations of dose responses and structure-activity relationships, and investigation of mechanisms of action. Read More

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December 2003
4 Reads

Development of a high-throughput viral-free assay for the measurement of CCR5-mediated HIV/cell fusion.

Receptors Channels 2003 ;9(2):117-23

GlaxoSmithKline Research and Development, 5 Moore Drive, Research Triangle Park, North Carolina 27709, USA.

M-tropic HIV strains gain access to their host cell via interaction of the viral envelope protein gp120 with the CCR5 coreceptor and CD4 located on the host cell. Inhibition of this event has been shown to reduce viral fusion and entry into cells in vitro. In the present study we describe the development of a novel cell/cell fusion assay that both mimics the viral/cell fusion process and allows quantification of this event. Read More

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December 2003
7 Reads

Unaltered agonist potency upon inducible 5-HT7(a) but not 5-HT4(b) receptor expression indicates agonist-independent association of 5-HT7(a) receptor and Gs.

Receptors Channels 2003 ;9(2):107-16

MSD Cardiovascular Research Center, Institute for Surgical Research, Department of Pharmacology, University of Oslo, Rikshospitalet University Hospital, Oslo, Norway.

We compared adenylyl cyclase (AC) activation by the G protein-coupled human serotonin (5-HT) receptors 5-HT4(b) and 5-HT7(a) using an ecdysone-inducible expression system, which allowed for reproducible expression of increasing receptor densities in clonal HEK293 (EcR293) cell lines. Low constitutive expression of receptors (2-70 fmol/mg protein) was observed and could be titrated up to 50-200-fold (approximately 400-7000 fmol/mg protein) by the ecdysone analogue ponasterone A. Although 5-HT-stimulated AC activity increased with receptor density, interclonal variation precluded comparisons of coupling efficiency. Read More

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December 2003
5 Reads

Putative dynamics of vasopressin in its V1a receptor binding site.

Receptors Channels 2003 ;9(2):93-106

Institute of Pharmacy, Department of Pharmaceutical Chemistry, University of Innsbruck, Innrain 52, A-6020, Innsbruck, Austria.

The molecular architecture of the GPCRs, including the dynamic set of interactions between the receptor and the ligand, is one of the key structural questions of biophysical approaches. In the present study, molecular dynamics (MD) simulations were performed on the well-validated molecular model of the vasopressin V1a receptor applying different parameters (i.e. Read More

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December 2003
7 Reads

Disulfide bond structure and accessibility of cysteines in the ectodomain of the cholecystokinin receptor: specific mono-reactive receptor constructs examine charge-sensitivity of loop regions.

Receptors Channels 2003 ;9(2):83-91

Department of Molecular Pharmacology and Experimental Therapeutics, Cancer Center, Mayo Clinic Scottsdale, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA.

Cysteine residues play a unique role in structural analysis. We examined endogenous cysteine residues in the cholecystokinin receptor to determine participation in disulfide bonds and accessibility to methanethiosulfonate (MTS) reagents. Bonds linking Cys114 to Cys196 and Cys18 to Cys29 were demonstrated, with the first functionally important and the amino-terminal bond having no apparent function. Read More

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December 2003
3 Reads

Immunocytochemical study of alpha 1 and beta 2/3 subunits of GABAA receptors in freehand isolated vestibular Deiters' neurons.

Receptors Channels 2003 ;9(2):77-81

Istituto di Bioimmagini e Fisiologia Molecolare, C.N.R. Via De Toni 5, 16132 Genova, Italy.

Vestibular Deiters' neurons have been isolated from bovine brain by the Hydén's freehand dissection technique and challenged with monoclonal antibodies directed toward the alpha 1 and beta 2/3 subunits of the GABAA receptors. Subsequent challenge with fluorescent secondary antibodies and confocal microscopy allowed the study of the cellular distribution of such subunits. In Deiters' neurons the beta 2/3 subunit displayed a clear presence all along the cell body profile and the initial parts of the dendrites. Read More

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December 2003
3 Reads

Characterization of adenosine A1 receptors in human proximal tubule epithelial (HK-2) cells.

Receptors Channels 2003 ;9(2):67-75

Department of Drug Discovery, Johnson and Johnson Pharmaceutical Research and Development, L.L.C, 1000 Rt. 202, Raritan, NJ 08869, USA.

Background: Adenosine A1 receptors (A1ARs) modulate various aspects of renal functions, such as hormone release, hemodynamics and tubular absorption. Here we set up to demonstrate the expression of A1ARs in an immortalized cell line (HK-2) derived from normal adult human proximal tubule. We also examined the mechanism whereby A1ARs signal in HK-2 cells and their potential role in renal physiology such as sodium-dependent phosphate transport. Read More

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December 2003
3 Reads

M1-M5 muscarinic receptor knockout mice as novel tools to study the physiological roles of the muscarinic cholinergic system.

Receptors Channels 2003 ;9(4):279-90

Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.

A large body of evidence indicates that muscarinic acetylcholine receptors (mAChRs) play critical roles in regulating the activity of many important functions of the central and peripheral nervous systems. However, identification of the physiological and pathophysiological roles of the individual mAChR subtypes (M(1)-M(5)) has proven a difficult task, primarily due to the lack of ligands endowed with a high degree of receptor subtype selectivity and the fact that most tissues and organs express multiple mAChRs. To circumvent these difficulties, we used gene targeting technology to generate mutant mouse lines containing inactivating mutations of the M(1)-M(5) mAChR genes. Read More

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April 2004
5 Reads

Pharmacological analysis of the contractile role of M2 and M3 muscarinic receptors in smooth muscle.

Receptors Channels 2003 ;9(4):261-77

Department of Pharmacology, College of Medicine, University of California, Irvine, Irvine, California 92697-4625, USA.

Muscarinic receptors expressed on smooth muscle cells are primarily of the M(2) and M(3) subtypes. The M(3) subtype triggers contraction through an interaction with G(q) proteins to stimulate phosphoinositide hydrolysis and mobilize Ca(2+). In contrast, activation of M(2) receptors modulates contraction by preventing relaxation or by potentiating M(3) receptor-mediated contractions, which enhances heterologous desensitization. Read More

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April 2004
3 Reads

Cellular signaling mechanisms for muscarinic acetylcholine receptors.

Receptors Channels 2003 ;9(4):241-60

Department of Pharmacology, The University of Melbourne, Victoria, Australia.

Signaling pathways for muscarinic acetylcholine receptors (mAChRs) include several enzymes and ion channels. Recent studies have revealed the importance of various isoforms of both alpha and betagamma subunits of G proteins in initiation of signaling as well as the role of the small monomeric G protein, Rho, in the activation of phospholipase D. Modulation of adenylyl cyclase activity by mAChRs appears more diverse as the interaction of various receptor subtypes with the many isoforms of the enzyme are studied. Read More

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April 2004
2 Reads

Structure/activity relationships of M2 muscarinic allosteric modulators.

Receptors Channels 2003 ;9(4):229-40

Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Bonn, Germany.

Allosteric modulation of G protein-coupled receptors has been intensively studied at muscarinic acetylcholine receptors. Findings made with archetypal allosteric agents such as gallamine, alcuronium, and bis(ammonio)alkane-type agents revealed that binding of orthosteric ligands that attach to the acetylcholine site can be allosterically decreased or increased or left unaltered in a subtype-selective fashion. Analyses of structure/activity relationships (SARs) help to elucidate the molecular events underlying the allosteric action and they may pilot the development of new allosteric agents with improved properties and therapeutic perspectives. Read More

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April 2004
4 Reads

Scanning mutagenesis studies of the M1 muscarinic acetylcholine receptor.

Receptors Channels 2003 ;9(4):215-28

Division of Physical Biochemistry, National Institute for Medical Research, London, UK.

Following the solution of the structure of bovine rhodopsin by X-ray crystallography, it has been possible to build an improved homology model of the M(1) muscarinic acetylcholine receptor. This has been used to interpret the outcome of an extensive series of scanning and point mutagenesis studies on the transmembrane domain of the receptor. Potential intramolecular interactions enhancing the stability of the protein fold have been identified. Read More

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April 2004
3 Reads

CYTOCENTERING: a novel technique enabling automated cell-by-cell patch clamping with the CYTOPATCH chip.

Receptors Channels 2003 ;9(1):59-66

NMI Natural and Medical Sciences Institute, Cytocentrics CCS GmbH, Reutlingen, Germany.

Automats for patch clamping suspended cells in whole-cell configuration must (1) bring isolated cells in contact with patch contacts, (2) form gigaseals, and (3) establish stable intracellular access that allows for high quality recording of ionic currents. Single openings in planar substrates seem to be intriguing simple solutions for these problems, but due to the low rate of formation of whole-cell configurations we discarded this approach. Single openings are not suited for both attracting cells to the opening by suction and forming gigaseals with subsequent membrane rupture. Read More

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July 2003
19 Reads

Upscaling and automation of electrophysiology: toward high throughput screening in ion channel drug discovery.

Receptors Channels 2003 ;9(1):49-58

Sophion Bioscience, Baltorpvej 154, DK-2750 Ballerup, Denmark.

Effective screening of large compound libraries in ion channel drug discovery requires the development of new electrophysiological techniques with substantially increased throughputs compared to the conventional patch clamp technique. Sophion Bioscience is aiming to meet this challenge by developing two lines of automated patch clamp products, a traditional pipette-based system called Apatchi-1, and a silicon chip-based system QPatch. The degree of automation spans from semi-automation (Apatchi-1) where a trained technician interacts with the system in a limited way, to a complete automation (QPatch 96) where the system works continuously and unattended until screening of a full compound library is completed. Read More

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July 2003
12 Reads

The roboocyte: automated cDNA/mRNA injection and subsequent TEVC recording on Xenopus oocytes in 96-well microtiter plates.

Receptors Channels 2003 ;9(1):41-8

Bayer Technology Services, Biophysics Group, Leverkusen, Germany.

Membrane-bound neurotransmitter receptors and ion channels are among the most numerous and important drug targets, and electrophysiological methods are the gold standard for the study of their functional properties and their response to drugs. However, electrophysiological measurements are usually performed one at a time by highly skilled individuals, and secondary functional screening is often hampered by this lack of throughput. Accordingly, the use of automated procedures to increase the efficiency of electrophysiological techniques is of great interest. Read More

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July 2003
9 Reads

Microstructured apertures in planar glass substrates for ion channel research.

Receptors Channels 2003 ;9(1):29-40

Nanion Technologies GmbH, München, Germany.

We have developed planar glass chip devices for patch clamp recording. Glass has several key advantages as a substrate for planar patch clamp devices. It is a good dielectric, is well-known to interact strongly with cell membranes and is also a relatively in-expensive material. Read More

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July 2003
4 Reads
4 Citations

High throughput electrophysiology using a fully automated, multiplexed recording system.

Receptors Channels 2003 ;9(1):19-28

Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Rd., Abbott Park, IL 60064, USA.

The drug discovery process centers around finding and optimizing novel compounds active at therapeutic targets. This process involves direct and indirect measures of how compounds affect the behavior of the target in question. The sheer number of compounds that must be tested poses problems for classes of ion channel targets for which direct functional measurements (e. Read More

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July 2003
11 Reads

Flip the tip: an automated, high quality, cost-effective patch clamp screen.

Receptors Channels 2003 ;9(1):13-7

Flyion GmbH, Tübingen, Waldhäuserstr. 64, D-72076, Tübingen, Germany.

The race for creating an automated patch clamp has begun. Here, we present a novel technology to produce true gigaseals and whole cell preparations at a high rate. Suspended cells are flushed toward the tip of glass micropipettes. Read More

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July 2003
22 Reads