Transepithelial transport of bepridil in the human intestinal cell line, Caco-2, using two media, DMEMc and HBSS

The purpose of this work was to study transepithelial transport of bepridil , an anticalcic agent, through monolayer cells Caco-2, using two experiment al media with different chemical components. For experimentation, the measu re of the transepithelial electrical resistance (TEER) allowed us to evalua te the state of cells; and the quantities of bepridil have been quantified using a gas chromatography/mass spectrometry system. First, when using the medium alone, without bepridil, Caco-2 cell integrity is, at least, maintai ned for 8 h using both media. However, for 24-h studies, only the DMEMc med ium, rich in essential nutriments, allowed cell integrity to be maintained. Then, with bepridil in HBSS medium, the TEER measurement showed a dose-dep endent toxic effect of bepridil, whereas in the DMEMc medium, the toxic eff ect was only found for the highest dose (12 mu g). This difference is proba bly related to the high binding of bepridil to proteins of the DMEMc medium , therefore minimising the concentration of the free compound. The kinetics of bepridil result from two phenomena: first, an immediate passage of a sl ight part of bepridil through the cell barrier and second, a high retention of most of the bepridil dose in the cell level. The transfer of bepridil f rom the apical to the basolateral compartment appears quantitatively and ki netically different using DMEMc or HBSS medium. The retention of the compou nd in the 'filter with Caco-2 cells' compartment is higher in DMEMc medium (60% at 3 mu g) than in HBSS medium (46% at 3 mu g), and bepridil entering the basolateral compartment is delayed in the DMEMc medium. This study exhi bits the importance of the selected medium on results and interpretation of data and the predominance of DMEMc to study the transport of lipophilic co mpounds highly retained in cells. (C) 1999 Elsevier Science B.V. All rights reserved.