In vitro evaluation of intestinal fluoride absorption using different cell models.

The main routes of fluoride (F) exposure are drinking water and certain foods; consequently, intestinal absorption is an important stage in the study of F exposure. In the present study, different cell models [Caco-2, HT29-MTX and various proportions of Caco-2/HT29-MTX)] were used to evaluate intestinal transport of F. The influence of cell type, pH, mucus layer, bile salts and food matrices on the apparent permeability coefficient (P(app)) was evaluated. The results show that a higher proportion of HT29-MTX in the monolayer produces an increase in F permeability, although the mucus layer secreted by HT29-MTX decreases F transport. The results also show that taurocholic acid, a component of bile salts, and acid pH increase F permeability, whereas the presence of a food matrix (rice) decreases intestinal transport of F. In all cases, alterations in F permeability were closely related with modulation of cell junctions.