[Compared study on Fura-2/AM assay and MTT assay for screening multidrug resistant modulators]

To explore the difference of screening results of reversing multidrug resistance (MDR) by modulators between Fura-2/AM assay and MTT assay, 25 compounds which have active structure were studied for MDR reversal activity with both methods. The fold of MDR reversal was shown to have remarkable relation with the amount of Fura-2 accumulation (Y = -3.66 + 17.5X, gamma = 0.86, P < 0.01). On the other hand, Fura-2/AM assay has several advantages as compared with MTT assay. Fura-2/AM assay needs shorter time (4 h) than MTT assay (96 h), and the MTT assay needs more steps than the Fura-2/AM assay. Furthermore, Fura-2/AM assay was more reliable than MTT assay for screening MDR modulators because MTT assay was dependent on the viable cells, while Fura-2/AM assay was dependent on the function of P-gp. The results suggest that Fura-2/AM assay may replace MTT assay in the screening of MDR modulators on a large scale.