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1,25-Dihydroxyvitamin D3 Stimulates Calcium and Phosphate Absorption by Different Mechanisms: Contrasting Requirements for Sodium

  • David B. N. Lee
  • Marlin W. Walling
  • Dalila B. Corry
  • Jack W. Coburn
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 178)

Abstract

Previous studies from our laboratory have demonstrated that 1,25-dihydroxyvitamin D3 (1,25D) stimulates separate calcium (Ca) and inorganic phosphate (P) absorptive mechanisms in rat intestine (1,2). The proportion of Ca to P “pumps” varies in different regions of the intestine. Thus, there is a preponderance of Ca pumps in the duodenum, a preponderance of P pumps in the jejunum and an equal distribution of Ca and P pumps in the ileum (3). Interestingly, the colon has only 1,25D-responsive Ca pumps (2). The active Ca absorptive mechanisms in duodenum, ileum and colon appear to share certain characteristics, all exhibiting a Km of approximately 1 mM (2,3). The expression of this 1,25D-induced Ca absorption in colon does not appear to require the presence of extracellular sodium ions (4). In the present study we examined the sodium (Na) requirement of 1,25D-stimulated P transport processes in rat jejunum.

Keywords

Brush Border Membrane Phosphate Transport Rabbit Small Intestine Absorptive Mechanism Unidirectional Influx 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

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Copyright information

© Plenum Press, New York 1984

Authors and Affiliations

  • David B. N. Lee
    • 1
  • Marlin W. Walling
    • 1
  • Dalila B. Corry
    • 1
  • Jack W. Coburn
    • 1
  1. 1.Research and Medical ServicesSepulveda and Wadsworth VA Medical Centers. UCLA School of MedicineLos AngelesUSA

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