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Human jejunal unstirred layer: evidence for extremely efficient luminal stirring
M D Levitt1, A Strocchi, D G Levitt
1Research Service, Veterans Affairs Medical Center, Minneapolis, Minnesota.
The American Journal of Physiology
|March 1, 1992
Summary
The human jejunal unstirred layer is much thinner than previously thought, approximately 35 microns. This finding impacts our understanding of nutrient absorption in the small intestine.
Area of Science:
- Gastroenterology
- Physiology
- Biophysics
Background:
- Previous studies using the osmotic transient technique estimated a human jejunal unstirred layer thickness of ~600 microns.
- Recent estimations, assuming negligible epithelial resistance, suggested a maximum thickness of 48 microns.
Purpose of the Study:
- To accurately determine the unstirred layer thickness in the human jejunum.
- To re-evaluate the unstirred layer's role in nutrient absorption and transport.
Main Methods:
- Utilized published hydrolysis data for sucrose and maltose.
- Calculated unstirred layer thickness based on disaccharidase activity on the brush border, independent of epithelial transport.
Main Results:
- The calculated unstirred layer thickness in the normal human jejunum was approximately 35 microns.
- This value is significantly smaller (<1/15th) than the 600 microns previously reported using the osmotic transient technique.
Conclusions:
- The unstirred layer in the human jejunum is considerably thinner than previously estimated.
- A thinner unstirred layer suggests that epithelial function and luminal stirring play a more significant role in nutrient absorption rates.