Intestinal Transport of D-Xylose.

Csáaky, T. Z.; Ho, Patrick

doi:10.3181/00379727-120-30548

Cited by 21 publications

(10 citation statements)

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“…Only small amounts of the administered radioactivity (125I) were absorbed, in accordance with find ings in neonatal pigs [12] Xylose, when mixed with treated or un treated colostrum, was less absorbed than if dissolved in saline, possibly due to the compe tition of xylose with lactose/glucose present in colostrum of the jejunal carrier system [29], On the other hand, the absorption of 3H and/ or [-'Hjlysine was similar and independent of whether dissolved in saline or colostrum. Re covery' of xylose and of 3H and/or [3H]lysine in the clamped intestinal segment was mark edly less than for rhlGF-I, indicating much better absorption than of IGF-I, in accor dance with a relatively greater amount of these substances in mesenteric blood.…”

Section: Discussionmentioning

confidence: 68%

Insulin-Like Growth Factor I Absorption in the Jejunum of Neonatal Calves

Vacher¹,

Blum³

1995

Neonatology

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The absorption of recombinant human insulin-like growth factor I (rhIGF-I), [¹²⁵I]rhIGF-I, xylose and [³H]lysine, administered into a clamped jejunal segment in anesthetized neonatal calves, was studied by measuring their appearance in the mesenteric vein draining the gut segment. Only trace amounts of IGF-I and of [¹²⁵I]rhIGF-I and/or ¹²⁵I were absorbed following dissolution in saline, buffer or colostrum. The absorption rate of both [³H]lysine and/or 3H and of xylose was much greater than the absorption of rhIGF-I, [¹²⁵I]rhIGF-I and/or ¹²⁵I but was also transient. Biological effects of ingested IGF-I in neonatal calves should barely occur as a consequence of intestinal absorption even in 1-day-old calves, known to absorb various peptides and proteins.

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Section: Discussionmentioning

confidence: 68%

Insulin-Like Growth Factor I Absorption in the Jejunum of Neonatal Calves

Vacher¹,

Blum³

1995

Neonatology

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“…The 3 green points have P-glycloprotein mediated efflux (digoxin and β-methyl digoxon [40] and colchicine [41]) which should reduce their permeability. The blue point is lamivudine which is a substrate for the organic cation transporters [42] and the red point is xylose which has a carrier mediated transport (probably the glucose transport system) [43-45], both of which will increase the “permeability”. The black line is the least squares regression fit to the black (non-protein mediated) points.…”

Section: Discussionmentioning

confidence: 99%

Quantitation of small intestinal permeability during normal human drug absorption

Levitt

2013

BMC Pharmacol Toxicol

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BackgroundUnderstanding the quantitative relationship between a drug’s physical chemical properties and its rate of intestinal absorption (QSAR) is critical for selecting candidate drugs. Because of limited experimental human small intestinal permeability data, approximate surrogates such as the fraction absorbed or Caco-2 permeability are used, both of which have limitations.MethodsGiven the blood concentration following an oral and intravenous dose, the time course of intestinal absorption in humans was determined by deconvolution and related to the intestinal permeability by the use of a new 3 parameter model function (“Averaged Model” (AM)). The theoretical validity of this AM model was evaluated by comparing it to the standard diffusion-convection model (DC). This analysis was applied to 90 drugs using previously published data. Only drugs that were administered in oral solution form to fasting subjects were considered so that the rate of gastric emptying was approximately known. All the calculations are carried out using the freely available routine PKQuest Java (http://www.pkquest.com) which has an easy to use, simple interface.ResultsTheoretically, the AM permeability provides an accurate estimate of the intestinal DC permeability for solutes whose absorption ranges from 1% to 99%. The experimental human AM permeabilities determined by deconvolution are similar to those determined by direct human jejunal perfusion. The small intestinal pH varies with position and the results are interpreted in terms of the pH dependent octanol partition. The permeability versus partition relations are presented separately for the uncharged, basic, acidic and charged solutes. The small uncharged solutes caffeine, acetaminophen and antipyrine have very high permeabilities (about 20 x 10-4 cm/sec) corresponding to an unstirred layer of only 45 μm. The weak acid aspirin also has a large AM permeability despite its low octanol partition at pH 7.4, suggesting that it is nearly completely absorbed in the first part of the intestine where the pH is about 5.4.ConclusionsThe AM deconvolution method provides an accurate estimate of the human intestinal permeability. The results for these 90 drugs should provide a useful benchmark for evaluating QSAR models.

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“…This observation is not unexpected in view of the clinical observations which initiated this study (Duthie et al 1966). Furthermore, the general rule H. L. DUTHIE AND J. T. HINDMARSH suggested by Hindmarsh et al (1966c) that actively transported amino acids partially inhibit the intestinal transfer of actively transferred sugars has been obeyed in this case, as there is now abundant evidence that the absorption of D-xylose involves some active process (Crane, 1960;Salomon, Allums & Smith, 1961;Csaky & Lassen, 1964;Alvarado, 1964;Csaky & Ho, 1965;Alvarado, 1966a, b).…”

Section: Discussionmentioning

confidence: 92%

“…Inhibition may be due to competition for an identical binding site on the membrane carrier. This is unlikely because of the dissimilarity of the molecular structure of amino acids and D-xylose and because the accumulation of D-xylose by hamster small intestinal epithelial cells (Alvarado, 1964(Alvarado, , 1966a and the intestinal absorption of 198 AMINO ACIDS AND XYLOSE TRANSPORT D-xylose by rats in vivo (Csaky & Ho, 1965) are reduced by 104 M phlorrhizin, whereas the intestinal transport of actively transported amino acids is not affected by similar concentrations of phlorrhizin (Fridhandler & Quastel, 1955;Newey & Smyth, 1964).…”

Section: Discussionmentioning

confidence: 99%

The effect of amino acids on the intestinal transport of L‐ and D‐xylose in vitro

Duthie¹,

Hindmarsh²

1966

The Journal of Physiology

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SUMMARY1. The intestinal transport of D-xylose by sacs of everted small intestine of the hamster is partially inhibited by L-histidine in concentrations of 5, 10 and 20 mM but not of 2 mM.2. 20 mm concentrations of D-histidine and L-methionine also produce inhibition.3. The inhibition is not due to an alteration in water transport or to a change in pH of the incubating medium.4. The rate of the intestinal transport of L-xylose is about ; of the rate of D-xylose transport and is unaffected by a 20 mm concentration of L-histidine.

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Intestinal Transport of D-Xylose.

Cited by 21 publications

References 0 publications

Insulin-Like Growth Factor I Absorption in the Jejunum of Neonatal Calves

Insulin-Like Growth Factor I Absorption in the Jejunum of Neonatal Calves

Quantitation of small intestinal permeability during normal human drug absorption

The effect of amino acids on the intestinal transport of L‐ and D‐xylose in vitro

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