Passive uptake in the small intestine and active uptake in the hindgut contribute to the highly efficient mineral metabolism of the common mole-rat. cryptomys hottentotus

Tammy Pitcher, Rochelle Buffenstein

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Cryptomys hottentotus has no access to dietary or endogenous sources of cholecalciferol (D3). Serum concentrations of calcifediol (25(OH)D3) were undetectable (5 ng/ml) and calcitriol (l,25(OH)2D3), although detectable in plasma, was at a low concentration (31.40 (sem 3.06 pg/ml). Despite their naturally impoverished vitamin D status, these animals exhibited highly efficient mineral absorption processes (Ca apparent fractional absorption efficiency, AFA (%) 9533 (sem 1.36); inorganic P (Pi) AFA (%) 93.49 (sem 0.81)). Furthermore, plasma mineral content was tightly regulated (Ca 2 57 (sem 0.08) mmol/1; Mg 1.23 (sem 0.05) mmol/1; Pi 2–12 (sem 0.15) mmol/1). Mode of uptake in C. hottentotus was unlike that in other D3-replete mammals. First, passive (rather than active) uptake occurred in the traditional site of active Ca absorption (with serosal:mucosal (S:M) ratios in the duodenum of 1.32 (sem 0.13)), and the only site of active Ca uptake was the hindgut (caecum S :M 3.35 (sem 0.46); proximal colon S: M 2.13(sem 0.30)). Despite the presence of active uptake in these hindgut regions, their overall contribution to the daily rate of mineral absorption was small (9.53 (sem 1.27) %). These underground inhabitants rely upon highly efficient, passive mineral uptake. This is adequate to meet their mineral requirements and maintain mineral homeostasis in the absence of vitamin D.

Original languageEnglish (US)
Pages (from-to)573-582
Number of pages10
JournalBritish Journal of Nutrition
Volume71
Issue number4
DOIs
StatePublished - Apr 1994

Keywords

  • Calcium: Mole-rat
  • Mineral metabolism

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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