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      P2Y Receptors Present in the Native and Isolated Rat Glomerulus

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          Abstract

          Extracellular ATP can mobilize intracellular calcium in rat glomeruli by interacting with P2Y receptors. However, the identity of the receptor subtypes involved is not known. In the present study, we have used RT-PCR to identify mRNAs for specific P2Y receptor subtypes expressed in the rat glomerulus: mRNA for P2Y<sub>1</sub>, P2Y<sub>2</sub>, P2Y<sub>4</sub> and P2Y<sub>6</sub> receptors was detected. Functional expression of P2Y<sub>1</sub> and P2Y<sub>2</sub>/P2Y<sub>4</sub>, but not P2Y<sub>6</sub>, receptors in intact glomeruli was confirmed by measuring the relative stimulation of the inositol phosphate pathway induced by selective agonists of a particular receptor subtype. Finally, we have used available polyclonal antibodies to confirm the expression of P2Y<sub>1</sub> and P2Y<sub>2</sub> in the glomerulus, in mesangial cells and glomerular epithelial cells (podocytes), respectively; but we could not demonstrate P2Y<sub>4</sub> or P2Y<sub>6</sub> receptor expression by this means. In a separate series of experiments, we have examined the possibility that intra-renal sympathetic nerve terminals are a source of extracellular ATP and that this would be supported, though not excluded, by supersensitivity to ATP following denervation. Nucleotide-induced stimulation of the inositol phosphate pathway was measured in both control rats and rats that had been sympathectomized by intraperitoneal injection of 6-hydroxydopamine. The response to norepinephrine was measured as a positive control. In the sympathectomized rats, the effect of norepinephrine was significantly enhanced, whereas ATP-induced inositol phosphate production was unaffected, being similar in both groups of animals.

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          Most cited references 13

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          The Pattern of Distribution of Selected ATP-Sensitive P2 Receptor Subtypes in Normal Rat Kidney: An Immunohistological Study

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            ATP release in human kidney cortex and its mitogenic effects in visceral glomerular epithelial cells.

            In chronic renal failure the sympathetic nervous system is activated. Sympathetic cotransmitters released within the kidney may contribute to the progression of renal disease through receptor-mediated proliferative mechanisms. In human renal cortex electrical stimulation induced adenosine 5'-triphosphate (ATP; luciferin-luciferase-assay) and norepinephrine (HPLC) release was measured. ATP release also was induced by alpha1- and alpha2-adrenergic agonists. [3H]-thymidine uptake was tested in human visceral glomerular epithelial cells (vGEC) and mitogen-activated protein kinase (MAPK42/44) activation in vGEC and kidney cortex. The involved P2-receptors were characterized pharmacologically and by RT-PCR. Sympathetic nerve stimulation and alpha-adrenergic agonists induced release of ATP from human kidney cortex. Seventy-five percent of the ATP released originated from non-neuronal sources, mainly through activation of alpha2-adrenergic receptors. ATP (1 to 100 micromol/L) and related nucleotides (1 to 100 micromol/L) increased [3H]-thymidine uptake. The adenine nucleotides ATP, ATPgammaS, ADP and ADPbetaS were about equally potent. UTP, UDP and alpha,beta-methylene ATP had no effect. ATP, ADPbetaS but not alpha,beta-methylene ATP activated MAPK42/44. ATP induced MAPK42/44 activation, and [3H]-thymidine uptake was abolished in the presence of the MAPK inhibitor PD 98059 (100 micromol/L). mRNA for P2X4,5,6,7 and P2Y1,2,4,6,11 were detected in human vGEC by RT-PCR. In human renal cortex, adrenergic stimulation releases ATP from neuronal and non-neuronal sources. ATP has mitogenic effects in vGEC and therefore the potential to contribute to progression in chronic renal disease. The pattern of purinoceptor agonist effects on DNA synthesis together with the mRNA expression suggests a major contribution of a P2Y1-like receptor.
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              Ultrastructural localization of nitric oxide synthase immunoreactivity in guinea-pig enteric neurons.

              Electron microscopic immunocytochemistry was used to localize immunoreactivity for nitric oxide synthase (NOS) in whole-mount preparations of myenteric plexus and circular muscle from guinea-pig ileum. NOS immunoreactivity was patchily distributed in myenteric neurons and was not specifically associated with any subcellular organelle or with the plasma membrane. This localization leaves unanswered the question of how nitric oxide is stored and released. NOS immunoreactive fibres in the circular muscle were found closer than 100 nm to muscle cells. NOS immunoreactive nerve fibres made synaptic contacts with NOS immunoreactive and non-immunoreactive enteric neurons. These results indicate that nitric oxide may regulate the activity of both myenteric neurons and smooth muscle.
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                Author and article information

                Journal
                NEP
                Nephron Physiol
                10.1159/issn.1660-2137
                Nephron Physiology
                S. Karger AG
                1660-2137
                2004
                March 2004
                29 March 2004
                : 96
                : 3
                : p79-p90
                Affiliations
                aCentre for Nephrology and Departments of Medicine and Physiology, and bAutonomic Neuroscience Institute, Royal Free and University College Medical School, London, UK; cLaboratoire de Physiologie et Génomique des Cellules Rénales, UMR 7134 CNRS-Université Paris 6, Centre Biomédical des Cordeliers, Paris, dChaire de Médecine Expérimentale, Collège de France and U36 INSERM, and eLaboratoire de Physiologie et Pathologie Expérimentale Vasculaires, U367 INSERM, Paris, France
                Article
                76753 Nephron Physiol 2004;96:p79–p90
                10.1159/000076753
                15056981
                © 2004 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 5, References: 64, Pages: 1
                Product
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/76753
                Categories
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