Summary: Gut tissue (by region- e.g ileum & colon) will be opened along the mesenteric border and mounted in Ussing chambers (Physiologic Instruments, San Diego, CA, USA), exposing 0.3 cm\u00b2 of tissue surface area to 2.5ml of oxygenated Krebs-glucose (10mM) and Krebs-mannitol (10mM) at 37\u00b0C on the serosal and luminal sides, respectively. The paracellular pathway and transcellular pathway will be measured as the flux of FITC-Dextran 4000 (FD-4, Sigma \u2013Aldrich) and horseradish peroxidase (HRP Type VI, Sigma Aldrich), respectively. FD-4 (400\u00b5g\/ml) and HRP (200\u00b5g\/ml) will be added to the mucosal chamber and samples will be collected from the serosal chamber every 30 min for 2 hours. Concentration of FD-4 is measured via fluorescence at excitation 485 nm, emission 538 nm. O-dianisidine substrate is used to detect HRP at absorbance 450 nm.