Specificity of doxorubicin versus rhodamine-123 in assessing P-glycoprotein functionality in the LLC-PK1, LLC-PK1:MDR1 and Caco-2 cell lines

Eur J Pharm Sci. 2000 Sep;11(3):207-14. doi: 10.1016/s0928-0987(00)00097-x.


The LLC-PK1:MDR1, LLC-PK1 and Caco-2 cell lines were used to investigate whether rhodamine-123 or doxorubicin would be the preferred substrate to study P-glycoprotein (P-gp) functionality in vitro. Both rhodamine-123 and doxorubicin showed highly polarised transport in the Caco-2 cell line and the LLC-PK1:MDR1 cell line, indicating that P-gp is actively transporting these drugs. However, for rhodamine-123 polarised transport was also seen in the monolayers of the wild-type LLC-PK1 cell line, indicating the presence of another active transporter for this compound. Polarised transport of doxorubicin in the Caco-2 and the LLC-PK1:MDR1 cell lines could be inhibited by the P-gp inhibitors SDZ-PSC 833 (PSC 833), cyclosporin A (CsA), verapamil and quinine, but not by the inhibitors for the organic cation carrier systems cimetidine and tetraethylammonium (TEA). Polarised transport of rhodamine-123 in the Caco-2 cell line could only be inhibited by P-gp inhibitors. In the LLC-PK1:MDR1 and LLC-PK1 cell lines transport was also inhibited by inhibitors for the organic cation transport systems. In conclusion, rhodamine-123 is a substrate for both P-gp and the organic cation carrier systems in the kidney cell line. This indicates that rhodamine-123 is not selective enough to study P-gp functionality in cell systems were organic cation carrier systems are also present. Doxorubicin appears to be a more selective P-gp substrate and therefore more useful in studying P-gp functionality in vitro.

Publication types

  • Comparative Study

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Animals
  • Biological Transport / drug effects
  • Caco-2 Cells
  • Cell Line
  • Cell Polarity
  • Cimetidine / pharmacology
  • Cyclosporine / pharmacology
  • Doxorubicin / pharmacokinetics*
  • Drug Resistance, Multiple / physiology*
  • Epithelial Cells / cytology
  • Epithelial Cells / physiology
  • Humans
  • Kinetics
  • LLC-PK1 Cells
  • Rhodamine 123 / pharmacokinetics*
  • Swine
  • Tumor Cells, Cultured
  • Verapamil / pharmacology


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Rhodamine 123
  • Cimetidine
  • Doxorubicin
  • Cyclosporine
  • Verapamil