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Passive permeability in experimental intestinal damage in rats.
Clinical Science (London, England : 1979)
|January 1, 1981
Summary
Intestinal absorption of polar molecules depends on molecular size and mucosal integrity. Smaller molecules like mannitol use cellular pores, while larger molecules like lactulose utilize extracellular pathways, with absorption varying based on intestinal damage.
Area of Science:
- Gastroenterology
- Pharmacokinetics
- Molecular Biology
Background:
- Intestinal absorption mechanisms for polar molecules are not fully elucidated.
- Understanding permeation routes is crucial for drug delivery and disease understanding.
Purpose of the Study:
- To investigate the absorption of polar probes of different molecular sizes in rats with induced intestinal mucosal lesions.
- To differentiate absorption pathways for small versus large polar molecules.
Main Methods:
- Simultaneous administration of mannitol and lactulose in closed intestinal loops in rats.
- Induction of mucosal lesions using methotrexate, nematode infection, or detergent.
- Quantification of probe absorption under varying conditions of mucosal damage.
Main Results:
- Methotrexate-induced villous atrophy decreased absorption of both mannitol and lactulose.
- Detergent-induced villous tip damage increased lactulose absorption.
- Absorption of mannitol correlated with mucosal surface area, while lactulose absorption was linked to mucosal damage.
Conclusions:
- Evidence supports at least two distinct permeation routes for polar molecules in the intestine.
- Small molecules (e.g., mannitol) likely traverse cellular pores, dependent on surface area.
- Larger molecules (e.g., lactulose) may use extracellular pathways, influenced by cell shedding and mucosal damage.