Kinetic transport analysis of daunorubicin by LoVo and LoVo/DX cells

We describe a fluorometric technique for the measurement of transport parameters of fluorescent drugs through cellular membranes. Unlike other procedures, this method gives an accurate measure of drug accumulated in the cells and measures the fraction of free and bound drug in the cell. The kinetic parameters of transport through cellular membranes are determined using a simple three-compartment model combined with fluorescence measurements performed on the extracellular medium and on Triton-permeabilized cells during daunorubicin incorporation. With this technique we found that LoVo cells have a greater daunorubicin uptake, a similar input rate constant and a lower output rate constant than the drug-resistant LoVo/DX cells.