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Updated: Feb 9, 2026

Assessment of Gut Barrier Integrity in Mice Using Fluorescein-Isothiocyanate-Labeled Dextran
Published on: November 18, 2022
Small Intestinal Permeability and Gut-Transit Time Determined with Low and High Molecular Weight Fluorescein
1Department of Gastrointestinal Microbiology, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany. anni.woting@dife.de.
Abstract:
Protocols for intestinal permeability measurements in mice using 4-kDa fluorescein isothiocyanate-conjugated (FITC) dextran differ considerably among laboratories on the blood-sampling time. To find the optimal point in time for blood sampling, we administered 4-kDa FITC dextran to C3H mice and monitored the marker in plasma over 8 h. We also determined gut-transit time using 70-kDa FITC dextran, which does not cross the intestinal epithelium. The 4-kDa FITC dextran concentration in plasma reached its maximum 45 min after administration. The 70-kDa FITC dextran reached the jejunum after 15 min and passed the entire small intestine within 1 h after its administration, demonstrating that 4-kDa FITC dextran measured in plasma 1 h after its oral application is a marker of small intestinal permeability.
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