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Pflügers Archiv

, Volume 439, Issue 6, pp 765–771 | Cite as

Cellular adaptation of the mouse cortical thick ascending limb of Henle's loop (CTAL) to dietary magnesium restriction: enhanced transepithelial Mg2+ and Ca2+ transport

  • M. Wittner
  • S. Jounier
  • G. Deschênes
  • C. de Rouffignac
  • A. Di Stefano
Original Article

Abstract

Mice aged 4 or 8 weeks were fed with a low-Mg2+ diet for 1, 2, 3 or 4 days. After 1 day of diet, the urinary excretion of Mg2+ and Ca2+ was strongly reduced in both animal groups (4 and 8 weeks), accompanied by a significant fall in plasma Mg2+ concentration and an increase in urinary volume. This profile persisted after 2, 3 or 4 days of dietary Mg2+ restriction. After 1 day of diet, transepithelial ion net fluxes of Na+, Cl, Ca2+ and Mg2+ (J Na, J Cl, J Ca, J Mg) measured in vitro from isolated perfused cortical thick ascending limbs (CTALs) of these animals remained unchanged. After 2 days of diet, measurements of J Ca and J Mg in isolated perfused CTALs showed that transepithelial Mg2+ and Ca2+ reabsorption were enhanced in CTALs from Mg2+-depleted, 8-week-old animals, whereas transepithelial Mg2+ and Ca2+ transport were not altered in 4-week-old mice. J Na and J Cl and the transepithelial potential (PDte) were not modified in CTALs from either animal group. Our results suggest that a low-Mg2+ diet leads to urinary retention of Mg2+ and Ca2+ which is most likely due to increased Mg2+ and Ca2+ transport in the CTAL. Furthermore, in response to dietary Mg2+ restriction, the reabsorption of divalent cations in the CTAL of adult, but not of young, mice undergoes cellular adaptation.

Cortical thick ascending limb Low-Mg2+ diet Mg2+ transport Microperfusion 

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Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • M. Wittner
    • 1
  • S. Jounier
    • 1
  • G. Deschênes
    • 2
  • C. de Rouffignac
    • 1
  • A. Di Stefano
    • 1
  1. 1.Département de Biologie Cellulaire et Moléculaire, CEA Saclay, URA CNRS 1859, F-91191 Gif-sur-YvetteFrance
  2. 2.Service de Néphrologie Pédiatrique, Hôpital d'Enfants Armand-Trousseau, 26, av. A. Netter, F-75012 ParisFrance

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