Uptake of doxorubicin and phenytoin by astrocytes: effect of MDR1 blockade. Panel A shows 1 μM doxorubicin uptake in astrocytes from epileptic human brain (n = 3 patients) and controls. Note that uptake was decreased in "epileptic" astrocytes compared to normal astrocytes, and this difference was abolished when MDR1 inhibitors (1 μM XR9576 or 50 μM verapamil) were added. Micrographs depict red fluorescent doxorubicin uptake in the various experimental conditions as assessed by fluorescence microscopy. Panel B shows the time-course of intracellular accumulation of 14C-Phenytoin in "epileptic" astrocytes and controls. Note that 14C-Phenytoin uptake into epileptic astrocytes reached a plateau after 10 s incubation, while uptake in control astrocytes was greater at each time point and reached a plateau after 10 min incubation (p < 0.01 vs. control; n = 3). 14C-Phenytoin uptake in "epileptic" astrocytes returned to control level in the presence of 1 μM XR9576 (°p < 0.01 vs. control''; ^p < = 0.01 vs. "epileptic'' astrocytes+XR9576).