FITC-Dextran 4-kD Detection

Intestinal barrier permeability was assessed using 4 kDa fluorescein isothiocyanate (FITC)-dextran (FD4, Sigma-Aldrich, St. Louis, MO, United States). In brief, a 200-mg/ml solution of FD4 was prepared with PBS and stored in a black Eppendorf tube. Then, the FD4 solution was orally administered to rats in each group at 200 mg/kg body weight, and rats were held in an upright position for 30 s to avoid regurgitation before the HS stage. Then, plasma samples were collected according to the study plan after the HS intervention and added to black 96-well microplates. Concentrations of FD4 were detected using a microplate spectrophotometer (excitation wavelength, 485 nm; emission wavelength, 530 nm). Concentrations of FD4 were calculated by preparing a standard curve with a serial dilution of FD4.