+1 Recommend
1 collections
      • Record: found
      • Abstract: found
      • Article: found

      Renal 31-Phosphorus-Magnetic Resonance Spectral Changes in Experimental Uremia

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          Altered renal cellular phosphate (P<sub>i</sub>) homeostasis may be involved in disturbed regulation of lα,25-dihydroxyvitamin D<sub>3</sub> [1,25(OH)<sub>2</sub>D<sub>3</sub>] production in chronic renal failure. To assess cytoplasmic concentrations of P<sub>i</sub> and other phosphate metabolites in uremia, phosphorus-magnetic resonance spectroscopy (<sup>31</sup>P-MRS) studies were carried out in vivo in rat remnant kidney. Five-sixths-nephrectomized animals (Nx, n = 8, serum creatinine 1.28 ± 0.18 mg/ dl) and sham-operated control animals (n = 8) were pair-fed a high-phosphate diet (1.6% phosphate, 1.0% calcium) for 19 days. In both remnant and intact kidneys, <sup>31</sup>P-magnetic resonance spectra displayed six major peaks: phospho-monoesters (PME), P<sub>i</sub>, phosphodiesters, and adenosine triphosphate (ATP)-γ -α, and -β. Phosphocreatine was absent. The relative intensity of the renal γATP signal was comparable between the remnant kidney in Nx and the sham-operated kidney in control animals and was, therefore, used as the internal standard to assess the P<sub>i</sub>/γATP ratio. The P<sub>i</sub>/γATP ratio was significantly (p < 0.05) increased in the remnant kidney as compared to the sham-operated control kidney (0.97 ± 0.24 in Nx vs. 0.75 ± 0.12 in sham-operated controls; means ± SE). Similarly, the PME/γATP ratio was significantly increased in Nx (p < 0.01), whereas the relative intensities of other phosphate metabolite signals were not altered in Nx. Mean serum 1,25(OH)<sub>2</sub>D<sub>3</sub> concentrations were 62 pg/ml for Nx and 93 for sham-operated controls (p < 0.05); mean serum phosphate levels were 4.35 mmol/l for Nx and 2.61 for sham-operated controls (p < 0.01). The pH in the remnant kidneys was 7.20 ± 0.06 (mean ± SE, n = 8), whereas the pH in intact kidneys was 7.29 ± 0.05 (n = 8, p < 0.05). To examine the contribution of blood cells to <sup>31</sup>P-magnetic resonance spectra, an exchange transfusion with a fluorocarbonated oxygen carrier (to a final hematocrit of 8%) was carried out, while animals (n = 5) were monitored by MRS. This did not significantly change the relative intensities of phosphate metabolite peaks, indicating that blood phosphorus did not measurably contribute to the renal P<sub>i</sub> signal. The data suggest that intrarenal P<sub>i</sub> concentration is elevated in renal failure. This could inhibit 25-hydroxyvitamin D<sub>3</sub>-1 α-hydroxylase activity and thus have some relevance for pathogenesis of renal hyperparathyroidism.

          Related collections

          Author and article information

          S. Karger AG
          19 December 2008
          : 73
          : 1
          : 27-33
          188994 Nephron 1996;73:27–33
          © 1996 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: 7
          Original Paper


          Comment on this article