Abstract
Fructose is an important dietary sugar, and its intake is increasing. However, the mechanism of its absorption is unknown. It is genrrally accepted that active transport does not occur and it is thought that transport is either passive or facilitaed. We studied fructose uptake by the small intestine using rat jejunal segments 1.5 cm long, fixed in Plexiglas chambers [1] and incubated in Krebs-Henseleit buffer containing C11 fructose. A double incubation technique was used [2]. A base tissue concentration is thus achieved during the first incubation, and subsequent absorption of the sugar from the second medium can then be studied. This method consistently showed accumulation of the sugar against a concentration gradient. This effect is more easily demonstrated and more marked in young rats, just after weaning. We have therefore shown active transport of furctose in the small intestine of the rat. This process is disrupted by lithium and so is sodium dependent: it is also depressed by dinitrophenol. Moderate inhibition occurs with galactose, lysine, and proline. These findings suggest that active transport of fuuctose occurs vis a sodium-dependent, energy-dependent mechanism which may be shared by other small, water-soluble molecules. These findings are relevant to clinical situations seen in childhood, particularly temporary monosaccharide malabsorption and glucose-galactose malabsorption.
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Gracey, M., Burke, V. & Oshin, A. 8. Studies of intestinal fructose absorption in the rat. Pediatr Res 5, 84 (1971). https://doi.org/10.1203/00006450-197102000-00013
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DOI: https://doi.org/10.1203/00006450-197102000-00013