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Updated: Jul 31, 2026
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Ex Vivo Intestinal Sacs to Assess Mucosal Permeability in Models of Gastrointestinal Disease
Published on: February 9, 2016
Intestinal diffusion barrier: unstirred water layer or membrane surface mucous coat?
Science (New York, N.Y.)
|December 11, 1981
Summary
The small intestine
Area of Science:
- Gastroenterology
- Cell Biology
- Biophysics
Background:
- The small intestine facilitates nutrient absorption through membrane-bound enzymes.
- Understanding the diffusion barrier is crucial for nutrient uptake.
- Previous models underestimated the barrier's complexity.
Purpose of the Study:
- To determine the dimensions of the small intestinal diffusion barrier.
- To investigate the role of the mucous coat in nutrient diffusion.
- To reconcile discrepancies in diffusion barrier models.
Main Methods:
- Kinetic analysis of substrate hydrolysis by integral surface membrane enzymes.
- Measurement of diffusion barrier dimensions in rat intestine.
- Iodine-125 labeling of surface membrane proteins after mucoprotein coat removal.
Main Results:
- The unstirred water layer's calculated thickness was incompatible with rat intestine dimensions.
- The mucoprotein surface coat was identified as a significant diffusion barrier.
- Integral surface membrane proteins were inaccessible without removing the surface coat.
Conclusions:
- The mucoprotein surface coat is a critical diffusion barrier for nutrients.
- This barrier influences nutrient access to digestive and transport sites.
- Accurate models of intestinal absorption must account for the surface coat.
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