Efficiency of P-glycoprotein-mediated exclusion of rhodamine dyes from multidrug-resistant cells is determined by their passive transmembrane movement rate

Eur J Biochem. 1997 Aug 15;248(1):104-12. doi: 10.1111/j.1432-1033.1997.00104.x.


The aim of the present study was to examine the relationship between the rate of the passive transmembrane movement of multidrug resistance (MDR)-type substrates and the ability of P-glycoprotein to extrude them from MDR cells. For this purpose, seven rhodamine dyes were examined for their P-glycoprotein-mediated exclusion from MDR cells, their localization in wild-type drug-sensitive cells, their capacity to stimulate the ATPase activity of P-glycoprotein reconstituted in proteoliposomes, and their transmembrane movement rate in artificial liposomes. All these rhodamine dyes were accumulated in wild-type drug-sensitive cells and were localized mainly in the mitochondria. All the dyes tested were substrates of reconstituted P-glycoprotein and cellular P-glycoprotein and were excluded to a variable degree from MDR cells. The transmembrane movement rate proved the major factor determining the efficacy of the P-glycoprotein-mediated exclusion of rhodamine dyes from MDR cells. Thus, rhodamine B, the poorest cellular P-glycoprotein substrate, exhibited a high affinity toward reconstituted P-glycoprotein, but was the fastest membrane-traversing dye. In contrast, tetramethylrosamine, the best cellular MDR probe, exhibited high affinity toward reconstituted P-glycoprotein and slow transmembrane movement rate. Therefore, an anticancer drug with a fast transmembrane movement rate is expected to overcome the MDR phenomenon. Furthermore, the widely used MDR marker, rhodamine 123, was a poor cellular MDR substrate compared with other rhodamine dyes, especially tetramethylrosamine, which was a superior cellular MDR substrate for functional dye-exclusion studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Adenosine Triphosphatases / metabolism
  • Animals
  • Biological Transport
  • CHO Cells
  • Cell Membrane / metabolism
  • Cricetinae
  • Drug Resistance, Multiple / physiology*
  • Flow Cytometry
  • Fluorescent Dyes / chemistry
  • Fluorescent Dyes / pharmacokinetics*
  • Humans
  • Kinetics
  • Mitochondria / metabolism
  • Molecular Probes
  • Proteolipids
  • Rhodamine 123
  • Rhodamines / chemistry
  • Rhodamines / pharmacokinetics*
  • Spectrometry, Fluorescence
  • Tumor Cells, Cultured


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Fluorescent Dyes
  • Molecular Probes
  • Proteolipids
  • Rhodamines
  • proteoliposomes
  • Rhodamine 123
  • Adenosine Triphosphatases