Molecular characterisation of carbohydrate digestion and absorption in equine small intestine

Molecular characterisation of carbohydrate digestion and absorption in equine small intestine Summary Dietary carbohydrates, when digested and absorbed in the small intestine of the horse, provide a substantial fraction of metabolisable energy. However, if levels in diets exceed the capacity of the equine small intestine to digest and absorb them, they reach the hindgut, cause alterations in microbial populations and the metabolite products and predispose the horse to gastrointestinal diseases. We set out to determine, at the molecular level, the mechanisms, properties and the site of expression of carbohydrate digestive and absorptive functions of the equine small intestinal brush‐border membrane. We have demonstrated that the disaccharidases sucrase, lactase and maltase are expressed diversely along the length of the intestine and D‐glucose is transported across the equine intestinal brush‐border membrane by a high affinity, low capacity, Na+/glucose cotransporter type 1 isoform (SGLT1). The highest rate of transport is in duodenum > jejunum > ileum. We have cloned and sequenced the cDNA encoding equine SGLT1 and alignment with SGLT1 of other species indicates 85–89% homology at the nucleotide and 84–87% identity at the amino acid levels. We have shown that there is a good correlation between levels of functional SGLT1 protein and SGLT1 mRNA abundance along the length of the small intestine. This indicates that the major site of glucose absorption in horses maintained on conventional grass‐based diets is in the proximal intestine, and the expression of equine intestinal SGLT1 along the proximal to distal axis of the intestine is regulated at the level of mRNA abundance. The data presented in this paper are the first to provide information on the capacity of the equine intestine to digest and absorb soluble carbohydrates and has implications for a better feed management, pharmaceutical intervention and for dietary supplementation in horses following intestinal resection. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Equine Veterinary Journal Wiley

Molecular characterisation of carbohydrate digestion and absorption in equine small intestine

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Publisher
Wiley
Copyright
2002 EVJ Ltd
ISSN
0425-1644
eISSN
2042-3306
D.O.I.
10.2746/042516402776249209
Publisher site
See Article on Publisher Site

Abstract

Summary Dietary carbohydrates, when digested and absorbed in the small intestine of the horse, provide a substantial fraction of metabolisable energy. However, if levels in diets exceed the capacity of the equine small intestine to digest and absorb them, they reach the hindgut, cause alterations in microbial populations and the metabolite products and predispose the horse to gastrointestinal diseases. We set out to determine, at the molecular level, the mechanisms, properties and the site of expression of carbohydrate digestive and absorptive functions of the equine small intestinal brush‐border membrane. We have demonstrated that the disaccharidases sucrase, lactase and maltase are expressed diversely along the length of the intestine and D‐glucose is transported across the equine intestinal brush‐border membrane by a high affinity, low capacity, Na+/glucose cotransporter type 1 isoform (SGLT1). The highest rate of transport is in duodenum > jejunum > ileum. We have cloned and sequenced the cDNA encoding equine SGLT1 and alignment with SGLT1 of other species indicates 85–89% homology at the nucleotide and 84–87% identity at the amino acid levels. We have shown that there is a good correlation between levels of functional SGLT1 protein and SGLT1 mRNA abundance along the length of the small intestine. This indicates that the major site of glucose absorption in horses maintained on conventional grass‐based diets is in the proximal intestine, and the expression of equine intestinal SGLT1 along the proximal to distal axis of the intestine is regulated at the level of mRNA abundance. The data presented in this paper are the first to provide information on the capacity of the equine intestine to digest and absorb soluble carbohydrates and has implications for a better feed management, pharmaceutical intervention and for dietary supplementation in horses following intestinal resection.

Journal

Equine Veterinary JournalWiley

Published: Jul 1, 2002

References

  • Na + ‐to‐sugar stoichiometry of SGLT3
    Diez‐Sampedro, Diez‐Sampedro; Eskandari, Eskandari; Wright, Wright; Hirayama, Hirayama
  • Nutrient regulation of the intestinal Na + /glucose co‐transporter (SGLT1) gene expression
    Dyer, Dyer; Barker, Barker; Shirazi‐Beechey, Shirazi‐Beechey
  • Molecular physiology of sodium‐glucose cotransporters
    Hediger, Hediger; Rhoads, Rhoads
  • Kinetic and specificity differences between rat, human and rabbit Na + ‐glucose cotransporters (SGLT‐1)
    Hirayama, Hirayama; Lostao, Lostao; Panayotova‐Heiermann, Panayotova‐Heiermann; Loo, Loo; Turk, Turk; Wright, Wright
  • Postnatal development of lamb intestinal digestive enzymes is not regulated by diet
    Shirazi‐Beechey, Shirazi‐Beechey; Smith, Smith; Wang, Wang; James, James
  • Expression of the Na + /glucose co‐transporter (SGLT1) in the intestine of domestic and wild ruminants
    Wood, Wood; Dyer, Dyer; Hofmann, Hofmann; Shirazi‐Beechey, Shirazi‐Beechey

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