Figure 5.

Comparison of MDR1 mRNA expression to digoxin transport. Confluent monolayers of T84 cells were treated for 72 h with 10 μM rifampin and 100 nM and 1 μM digoxin. (a) Fold changes in net [³H]digoxin flux were calculated in relation to control values. Significant increases in net flux were observed following both rifampin and digoxin treatments (P<0.05, n=6 replicates from individual experiments). (b) Fold changes in MDR1 (ABCB1) mRNA expression were determined by TaqMan analysis following amplification using gene-specific primers and probes (see Table 2). ^*Significantly different from control values; P<0.05. Data are expressed as±s.e.mean, n=4 replicate wells. ABCB1, ATP-binding cassette B1; MDR1, multidrug resistance 1.