Determination of unidirectional uptake rates for lipids across the intestinal brush border

V. L. Sallee, F. A. Wilson, J. M. Dietschy

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

An in vitro method is presented which measures valid, unidirectional uptake rates for lipids across the intestinal brush border. This method combines analysis by a newly devised, double isotope counting system for solubilized tissue with the use of a nonabsorbable marker to correct gross uptake determinations for contamination by adherent mucosal fluid. Of seven markers, only [3H]inulin measured adherent mucosal fluid volumes as much as 20% greater than the other markers. Diffusion of the nonabsorbable marker, as well as of the compound being studied, into the unstirred layer made the time course of uptake critically important. The time lag for diffusion of marker invalidates the use of 1 min incubation periods; however, a linear time course of uptake that intercepts essentially at zero was found for taurocholate and octanoate for periods of from 2 to 5 min. Working within this critical time period with jejunum, it was shown that tissue dry weight was an appropriate measure of the amount of tissue and that uptake rates for taurocholic, octanoic, and lauric acids were linear with respect to concentration. Tissue binding of compounds was not significant. The results demonstrate that careful use of the described method yields accurate measurement of unidirectional uptake rates of lipids across the brush border that are of critical importance in defining the characteristics of membrane penetration and the rate limiting steps in fat and sterol absorption.

Original languageEnglish (US)
Pages (from-to)184-192
Number of pages9
JournalJournal of Lipid Research
Volume13
Issue number2
StatePublished - 1972

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Brushes
Microvilli
Tissue
Lipids
Lauric Acids
Caprylates
Taurocholic Acid
Fluids
Inulin
Sterols
Jejunum
Isotopes
Contamination
Fats
Membranes
Weights and Measures

ASJC Scopus subject areas

  • Endocrinology

Cite this

Determination of unidirectional uptake rates for lipids across the intestinal brush border. / Sallee, V. L.; Wilson, F. A.; Dietschy, J. M.

In: Journal of Lipid Research, Vol. 13, No. 2, 1972, p. 184-192.

Research output: Contribution to journalArticle

Sallee, VL, Wilson, FA & Dietschy, JM 1972, 'Determination of unidirectional uptake rates for lipids across the intestinal brush border', Journal of Lipid Research, vol. 13, no. 2, pp. 184-192.
Sallee, V. L. ; Wilson, F. A. ; Dietschy, J. M. / Determination of unidirectional uptake rates for lipids across the intestinal brush border. In: Journal of Lipid Research. 1972 ; Vol. 13, No. 2. pp. 184-192.
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