Dietary calcium deficiency increases Ca2+ uptake and Ca 2+ extrusion mechanisms in chick enterocytes

Viviana A. Centeno, Gabriela E. Díaz De Barboza, Ana M. Marchionatti, Arturo E. Alisio, Maria E. Dallorso, Renée Nasif, Nori G. Tolosa De Talamoni

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53 Scopus citations

Abstract

Ca2+ uptake and Ca2+ extrusion mechanisms were studied in enterocytes with different degree of differentiation from chicks adapted to a low Ca2+ diet as compared to animals fed a normal diet. Chicks adapted to a low Ca2+ diet presented hypocalcemia, hypophosphatemia and increased serum 1,25(OH)2D3 and Ca2+ absorption. Low Ca2+ diet increased the alkaline phosphatase (AP) activity, independently of the cellular maturation, but it did not alter γ-glutamyl-transpeptidase activity. Ca2+ uptake, Ca2+-ATPase and Na+/Ca2+ exchanger activities and expressions were increased by the mineral-deficient diet either in mature or immature enterocytes. Western blots analysis showS that vitamin D receptor (VDR) expression was much higher in crypt cells than in mature cells. Low Ca2+ diet decreased the number of vitamin D receptor units in both kinds of cells. In conclusion, changes in Ca2+ uptake and Ca 2+ extrusion mechanisms in the enterocytes by a low Ca2+ diet appear to be a result of enhanced serum levels of 1,25(OH) 2D3, which would promote cellular differentiation producing cells more efficient to express vitamin D dependent genes required for Ca2+ absorption.

Original languageEnglish
Pages (from-to)133-141
Number of pages9
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume139
Issue number2
DOIs
StatePublished - Oct 2004

Keywords

  • Alkaline phosphatase
  • Calcitriol
  • Chick
  • Villus tip/crypt axis
  • Vitamin D receptor

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