Fluoride absorption through the hamster cheek pouch: a pH-dependent event.

The fractional absorptions of fluoride, 3H2O, 125I and 14C-DMO from the hamster cheek pouch were determined as functions of solution pH. When the pH was less than 5, fluoride absorption rate was inversely related to pH. The absorption rates of the other substances were not influenced by pH. The fractional absorptions of fluoride and 3H2O were independent of fluoride concentrations over the range 1-53 mM. The data indicate that the absorption of fluoride through this keratinized epithelium occurs mainly by the diffusion of non-ionic HF.