CARRIER-MEDIATED TRANSPORT OF MONOCARBOXYLIC ACIDS IN PRIMARY CULTURED EPITHELIAL-CELLS FROM RABBIT ORAL-MUCOSA

Purpose. Using primary cultured rabbit oral mucosal epithelial cells ( ROEpi), we investigated whether carrier-mediated drug absorption via t he oral mucosal route occurs. Methods. Oral mucosal epithelial cells w ere isolated from rabbit buccal mucosa and cultured on tissue culture plates. When the cells reached confluence, drug uptake experiments wer e performed. [C-14]Benzoic acid or [C-14]acetic acid was used as a mar ker for monocarboxylic acid carrier-mediated transport. Results. The u ptake of [C-14]benzoic acid by ROEpi occurred at a much lower rate at 4 degrees C than at 37 degrees C. The metabolic inhibitors, sodium azi de and 2,4-dinitrophenol, significantly inhibited the uptake of [C-14] benzoic acid by ROEpi. Various monocarboxylic acids inhibited the upt ake of [C-14]benzoic acid or [C-14]acetic acid by ROEpi, whereas dicar boxylic acids did not affect the uptake. Kinetic analysis using Linewe aver-Burk plots revealed that acetic acid competitively inhibited the uptake of [C-14]benzoic acid, and benzoic acid competitively inhibited the uptake of [C-14]acetic acid by ROEpi. Conclusions. There exists a carrier-mediated transport system for monocarboxylic acids in oral mu cosal epithelial cells.