6). Normalised mRNA data were used to calculate ‘fold differences’ to monitor batch to batch differences. The results showed no significant differences in mRNA expression levels of BCRP, occludin and claudin-5 between batches of PBEC cultures (based on 2-fold difference threshold; Fig. 7A) for all genes assayed. PI3K Inhibitor Library manufacturer Batch2/batch1 fold difference ratio was less than 2-fold, which confirms the stability of the expression levels of the genes between batches. Passage 1/primary fold difference ratio was calculated to assess differences in mRNA expression levels in PBECs in different batches. The results showed no significant differences

in mRNA expression levels between primary and P.1 PBEC cultures for either batch 1 or 2 (Fig. 7B) for all genes assayed. Selleck Bafetinib Mean P.1/primary fold difference ratio was less than 1.6, below the 2-fold difference of mRNA expression considered significant. The plot of Pappvs. calculated Log Poctanol ( Fig. 8) showed that compounds predicted to move by passive permeation either paracellularly or transcellularly (sucrose, naloxone, propranolol, diazepam) had Papp that was a linear function of calculated Log Poctanol, with R2=0.96. Leucine, taken up by LAT-1 (large neutral amino acid carrier), and caffeine (saturable carrier-mediated transport mechanism) ( McCall et al., 1982) are both

clear outliers above the line as predicted (permeation >predicted from Log P), while the four compounds that are known substrates for either ATP-dependent efflux transporters (digoxin, colchicine and vinblastine for P-gp) or basolateral Na-dependent secondary active transport (glutamate, substrate for excitatory amino acid Orotic acid transporter, EAAT) are clear outliers below the line as

predicted (permeation