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      Effect of Parathyroid-Hormone-Related Protein on Sodium-Dependent Phosphate Transport in Renal Brush Border Membrane Vesicles in Rats

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          Abstract

          Parathyroid-hormone-related protein (PTHrP) has significant homology with parathyroid hormone (PTH) in the amino-terminal region. We compared the effects of synthetic human PTHrP [hPTHrP(1-34)] on Na<sup>+</sup>-dependent phosphate transport with those of synthetic human PTH [hPTH(1-34)]. Intravenous administration of hPTHrP(1-34) in parathyroidectomized rats caused hypercalcemia, hypophosphatemia and phosphaturia to the same degree as hPTH(1-34). In kinetic studies using renal brush border membrane vesicles, the apparent K<sub>m</sub> and V<sub>max</sub> of phosphate transport were identical for the two peptides [hPTHrP(1-34): K<sub>m</sub> 27.6 + 0.8 μM, V<sub>max</sub> 3.78 ± 0.04 nmol/mg protein, hPTH(1-34): K<sub>m</sub> 29.6 ± 0.9 μM, V<sub>max</sub> 3.04 ± 0.90 nmol/mg protein]. Both hPTHrP(1-34) and hPTH(1-34) at a supramaximal dose were equipotent in eliciting a 12-fold increase in cyclic adenosine 3’,5’-monophosphate (cAMP) production in the kidney. These results indicate that, in addition to the similar effect of hPTHrP(1-34) and hPTH(1-34) on serum calcium levels and urinary phosphorus and nephrogenous cAMP excretion in vivo, these two peptides have similar effects on Na<sup>+</sup>-dependent phosphate transport in brush border membrane vesicles in vitro.

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          Author and article information

          Journal
          NEF
          Nephron
          10.1159/issn.1660-8151
          Nephron
          S. Karger AG
          1660-8151
          2235-3186
          1993
          1993
          12 December 2008
          : 64
          : 4
          : 600-604
          Affiliations
          Division of Nephrology, Department of Medicine, Juntendo University School of Medicine, Hongo, Tokyo, Japan
          Article
          187407 Nephron 1993;64:600–604
          10.1159/000187407
          8366986
          © 1993 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
          Pages: 5
          Categories
          Original Paper

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