Influence of α-linked glucose on sodium-glucose cotransport activity along the small intestine in cattle

M. L. Bauer, D. L. Harmon, D. W. Bohnert, A. F. Branco, G. B. Huntington

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27 Scopus citations

Abstract

Thirteen steers (378 ± 23 kg) were used in a split-plot experimental design to evaluate the effect of small intestinal carbohydrate on sodium-glucose cotransport in brush border membrane vesicles prepared from five equidistant sites along the small intestine. The steers consumed 7.2 ± 0.4 kg/d ground fescue hay and soybean meal-based supplement and were infused ruminally or postruminally with a partial α-amylase starch hydrolysate (914.5 ± 8.3 g/d) for 7 d. On d 7, five equidistant 1-m small intestinal sections were harvested and frozen in liquid N for later preparation of brush-border membrane vesicles. Maltase activity of the homogenate and vesicle preparations changed (P < 0.001; lowest in the duodenum, highest in the jejunum) and alkaline phosphatase decreased (P < 0.001) along the small intestine. With respect to the original homogenates, the vesicle preparations were enriched 9.80 ± 0.83- and 7.64 ± 0.67-fold for alkaline phosphatase and maltase, respectively; enrichments were not different between treatments (P = 0.76 and 0.39, respectively). However, alkaline phosphatase and maltase enrichment changed (P < 0.001) along the small intestine. Recoveries of alkaline phosphatase and maltase activities (25.0 ± 0.2% and 19.5 ± 0.2%, respectively) in the vesicle preparation were not affected (P = 0.29 and 0.21, respectively) by treatment but changed (P < 0.001) along the intestine. Recovery of protein in the vesicle preparation was 2.60 ± 0.01% and was not affected by treatment or intestinal site. Sodium-glucose cotransport activity (220 ± 44 pmol·mg-1·s-1) was not affected (P = 0.34) by treatment but did change (P < 0.001; lowest in the ileum, highest in the proximal and mid-jejunum) along the small intestine. Apparent Km of the sodium-glucose cotransporter for glucose was 62.8 ± 5.8 μM. The specific activity of maltase was highest in the jejunum, and sodium-glucose cotransport was highest in the first two jejunal sites. However, duodenal maltase activity was lowest and ileal sodium-glucose cotransport activity was lowest. Sodium-glucose cotransport activity may limit small intestinal starch assimilation in the distal small intestine. It does not seem that glucose arising from carbohydrate hydrolysis regulates activity of sodium-dependent glucose transport in cattle.

Original languageEnglish
Pages (from-to)1917-1924
Number of pages8
JournalJournal of Animal Science
Volume79
Issue number7
DOIs
StatePublished - Jul 2001

Keywords

  • Absorption
  • Bovidae
  • Glucose
  • Small intestine
  • Starch

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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