Mg2+ transport in the kidney

Jun Ichi Satoh, Michael F. Romero

Research output: Contribution to journalReview article

19 Scopus citations

Abstract

Magnesium is abundant in biological systems and an important divalent cation in the human body. Mg2+ helps mediate cellular energy metabolism, ribosomal and membrane integrity. Additionally Mg2+ modulates the activity of several membrane transport and signal transduction systems. Despite its importance however, little is known about the molecular mechanisms of Mg2+ transport and homeostasis in mammals. In mammals the amount of Mg2+ absorption is about the same as the amount of M2+ excretion in urine. Additionally, when total M2+ intake is deficient, the kidney is capable of reabsorbing all filtered Mg2+. This balance between intake and excretion indicates that the kidney plays a principal role in maintenance of total body Mg2+ homeostasis. Within the kidney, Mg2+ filtered by the glomerulus is handled in different ways along the nephron. About 10-20% of Mg2+ is reabsorbed by the proximal tubule, the bulk of Mg2+ (about 50-70%) is reabsorbed by the cortical thick ascending limb of the loop of Henle. In this region, Mg2+ moves across the epithelium through the paracellular pathway, driven by the positive lumenal transepithelial voltage. A recently cloned human gene, paracellin-1 was shown to encode a protein localized to the tight junctions of the cortical thick ascending limb and is thought to mediate Mg2+ transport via the paracellular space of this epithelium. The distal convoluted tubule reabsorbs the remaining 5-10% of filtered Mg2+. This segment seems to play an important role in determining final urinary excretion, since there is no evidence for significant Mg2+ absorption beyond the distal tubule. Although many renal Mg2+ transport activities have been characterized, no Mg2+ transporter cDNAs have been cloned from mammalian tissues. Recent research has certainly expanded our knowledge of Mg2+ transport in kidney; but details of the transport processes and the mechanisms by which they control Mg2+ excretion must await cloning of renal Mg2+ transporters and/or channels. Such information would provide new concepts in our understanding of renal Mg2+ handling.

Original languageEnglish (US)
Pages (from-to)285-296
Number of pages12
JournalBioMetals
Volume15
Issue number3
DOIs
StatePublished - Jan 1 2002

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Keywords

  • Cortical thick ascending limb of the loop of Henle
  • Distal convoluted tubule
  • Homeostasis
  • Kidney
  • Magnesium (Mg)
  • Mg transport
  • Paracellin-1 (PCLN-1)
  • Proximal tubule

ASJC Scopus subject areas

  • Biomaterials
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Metals and Alloys

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