These findings suggest that specific enhancement of the pFlux for small organic solutes across the claudin-based TJs initiates colonic inflammation.

We previously showed that epilactose, a nondigestible disaccharide, increased calcium (Ca) absorption in the small intestines of rats. Here, we explored the mechanism(s) underlying the epilactose-mediated promotion of Ca absorption in a ligated intestinal segment of anesthetized rats. The addition of epilactose to the luminal solution increased Ca absorption and chromium (Cr)-EDTA permeability, a paracellular indicator, with a strong correlation (R = 0.93) between these changes. Epilactose induced the phosphorylation of myosin regulatory light chains (MLCs), which is known to activate the paracellular route, without any change in the association of tight junction proteins with the actin cytoskeleton. The epilactose-mediated promotion of the Ca absorption was suppressed by specific inhibitors of myosin light chain kinase (MLCK) and Rho-associated kinase (ROCK). These results indicate that epilactose increases paracellular Ca absorption in the small intestine of rats through the induction of MLC phosphorylation via MLCK- and ROCK-dependent mechanisms.