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Science 11 December 1981:
Vol. 214. no. 4526, pp. 1241 - 1244
DOI: 10.1126/science.7302593
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Articles

Science, Vol 214, Issue 4526, 1241-1244
Copyright © 1981 by American Association for the Advancement of Science

articles

Intestinal diffusion barrier: unstirred water layer or membrane surface mucous coat?

KW Smithson, DB Millar, LR Jacobs, and GM Gray

The dimensions of the small intestinal diffusion barrier interposed between luminal nutrients and their membrane receptors were determined from kinetic analysis of substrate hydrolysis by integral surface membrane enzymes. The calculated equivalent thickness of the unstirred water layer was too large to be compatible with the known dimensions of rat intestine. The discrepancy could be reconciled by consideration of the mucous coat overlying the intestinal surface membrane. Integral surface membrane proteins could not be labeled by an iodine-125 probe unless the surface coat was first removed. The mucoprotein surface coat appears to constitute an important diffusion barrier for nutrients seeking their digestive and transport sites on the outer intestinal membrane.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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Increased Luminal Mucin Does Not Disturb Glucose or Ovalbumin Absorption in Rats Fed Insoluble Dietary Fiber.
T. Morita, H. Tanabe, H. Ito, S. Yuto, T. Matsubara, T. Matsuda, K. Sugiyama, and S. Kiriyama (2006)
J. Nutr. 136, 2486-2491
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Lack of the intestinal Muc1 mucin impairs cholesterol uptake and absorption but not fatty acid uptake in Muc1-/- mice.
H. H. Wang, N. H. Afdhal, S. J. Gendler, and D. Q.-H. Wang (2004)
Am J Physiol Gastrointest Liver Physiol 287, G547-G554
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Mucin Dynamics in the Chick Small Intestine Are Altered by Starvation.
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The Physicochemical Environment of the Neonatal Intestine.
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Effect of Micelle Fatty Acid Composition and 3,4,3',4'-Tetrachlorobiphenyl (TCB) Exposure on Intestinal [14C]-TCB Bioavailability and Biotransformation in Channel Catfish in Situ Preparations.
A. M. Doi, Z. Lou, E. Holmes, C.-L. J. Li, C. S. Venugopal, M. O. James, and K. M. Kleinow (2000)
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Adherent surface mucus gel restricts diffusion of macromolecules in rat duodenum in vivo.
G. Flemstrom, A. Hallgren, O. Nylander, L. Engstrand, E. Wilander, and A. Allen (1999)
Am J Physiol Gastrointest Liver Physiol 277, G375-G382
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The physicochemical environment of the neonatal intestine.
I. R Sanderson (1999)
Am. J. Clinical Nutrition 69 , 1028S-1034S
   Abstract »    Full Text »    PDF »
Diffusion barrier in the small intestine.
J. DeSimone (1983)
Science 220, 221-222
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Diffusion Barrier in the Small Intestine.
K. W. SMITHSON (1983)
Science 220, 222
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