Perfusion cells for studying regional variation in oral mucosal permeability in humans. 2. A specialized transport mechanism in D-glucose absorption exists in dorsum of tongue

To clarify the site of D-glucose absorption in human oral cavity, newly designed perfusion cells were applied to five different sites in the human oral cavity, i.e., the dorsum of the tongue, the ventral surface of the tongue, the labial mucosa, the floor of the mouth, and the buccal mucosa. The solution of D-glucose was perfused for 1 h and the rate of absorption was calculated from the amount that disappeared from the perfusate. D-Glucose was absorbed rapidly from the dorsum of the tongue and the absorption was saturable. The saturable absorption was also observed in the ventral surface of the tongue, but not in the other three sites. The rate of D-glucose absorption in the dorsum and the ventral surface of the tongue was significantly larger than that of L-glucose, while in the other sites they were not significantly different. The presence of a specialized transport system for D-glucose absorption in the dorsum of human tongue was suggested.