Carrier-mediated transport of monocarboxylic acids in primary cultured epithelial cells from rabbit oral mucosa.
OBJECTIVE
Using primary cultured rabbit oral mucosal epithelial cells (ROEpi), we investigated whether carrier-mediated drug absorption via the oral mucosal route occurs.


METHODS
Oral mucosal epithelial cells were isolated from rabbit buccal mucosa and cultured on tissue culture plates. When the cells reached confluence, drug uptake experiments were performed. [14C]Benzoic acid or [14C]acetic acid was used as a marker for monocarboxylic acid carrier-mediated transport.


RESULTS
The uptake of [14C]benzoic acid by ROEpi occurred at a much lower rate at 4 degrees C than at 37 degrees C. The metabolic inhibitors, sodium azide and 2,4-dinitrophenol, significantly inhibited the uptake of [14C]benzoic acid by ROEpi. Various monocarboxylic acids inhibited the uptake of [14C]benzoic acid or [14C]acetic acid by ROEpi, whereas dicarboxylic acids did not affect the uptake. Kinetic analysis using Lineweaver-Burk plots revealed that acetic acid competitively inhibited the uptake of [14C]benzoic acid, and benzoic acid competitively inhibited the uptake of [14C]acetic acid by ROEpi.


CONCLUSIONS
There exists a carrier-mediated transport system for monocarboxylic acids in oral mucosal epithelial cells.
Utoguchi
N
N
Department of Pharmaceutics, Showa College of Pharmaceutical Sciences, Tokyo, Japan.
Watanabe
Y
Y
Suzuki
T
T
Maehara
J
J
Matsumoto
Y
Y
Matsumoto
M
M
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000042:Absorption; D019342:Acetic Acid / Q000378:metabolism; D000818:Animals; D001386:Azides / Q000494:pharmacology; D001565:Benzoates / Q000378:metabolism; D019817:Benzoic Acid; D001692:Biological Transport; D002250:Carbon Radioisotopes; D002264:Carboxylic Acids / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D003998:Dicarboxylic Acids / Q000494:pharmacology; D010450:Endopeptidases / Q000494:pharmacology; D004847:Epithelial Cells; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D009061:Mouth Mucosa / Q000166:cytology / Q000378:metabolism; D009994:Osmolar Concentration; D011817:Rabbits; D011849:Radioactive Tracers; D019810:Sodium Azide; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013696:Temperature
D001386:Azides; D001565:Benzoates; D002250:Carbon Radioisotopes; D002264:Carboxylic Acids; D003998:Dicarboxylic Acids; D011849:Radioactive Tracers; D013439:Sulfhydryl Reagents; D019817:Benzoic Acid; D019810:Sodium Azide; D010450:Endopeptidases; D019297:2,4-Dinitrophenol; D019342:Acetic Acid