2.7. Gut permeability in vivo

In vivo permeability measurement was modified from previously described methods based on gut permeability to 4‐kD FITC‐dextran. 29 Rats were fasted for 6 hours and gavaged with 4‐kD FITC‐dextran (360 mg/kg bodyweight, 10 mL/kg). After 1 hour, 200 μL blood was collected from the tip of the tail vein. Plasma was diluted in an equal volume of PBS (pH 7.4), and the FITC‐dextran concentration was determined with a Synergy 2 microplate reader (BioTek), with serial dilutions of FITC‐dextran used as a standard curve.