Table 1

Contribution of oatp1 to Na+-independent uptake of ligands into rat hepatocytes

CompoundCLuptake(Hepatocyte)RhepCLuptake(COS-7)RCOSContribution of oatp1
μl/min/mg protein μl/min/mg protein %
E217βG63.11.0019.01.00100
Taurocholate12.80.2032.330.12360
Cholate39.80.6316.240.32952
Estrone sulfate77.71.236.300.33227
E3040 sulfate29.10.4611.800.094721
E3040 glucuronide5.610.0889NDNDND
Ibuprofen24.50.388NDNDND
Pravastatin6.200.0983NDNDND
Ouabain2.800.0444NDNDND
DNP-SG1.300.0206NDNDND

Data shown in Figs. 2 and 4 were used to determine the clearance for the Na+-independent uptake by hepatocytes and that for oatp1-mediated uptake by transfected COS-7 cells. Based on these clearance values, Rhep and RCOSvalues were determined to calculate the contribution of oatp1.