Membrane ATPase assays of P-gp and BCRP activity.

<p>Drug efflux transporter ATPase activity was examined in P-gp (A and B) and BCRP (D and E) membrane preparations following various concentrations of FLZ exposure and specific drug efflux transport inhibitors. 200 µM Verapamil was used as a positive control in P-gp ATPase assays. Only the P-gp membranes produced a clear concentration dependent response to FLZ. Results are expressed as mean ± SD (n = 3). Inset in panel C shows the P-gp mediated ATPase activity examined in the presence of 10 µM FLZ and 5 µM zosuquidar (P-gp inhibitor) or/and 10 µM FTC (BCRP inhibitor). All data are expressed as the means ± SD (n = 3). *<i>P</i><<i>0.05</i>, **<i>P</i><<i>0.01</i>, significantly different from FLZ alone.