Calcein accumulation as a fluorometric functional assay of the multidrug transporter

Biochim Biophys Acta. 1994 May 11;1191(2):384-8. doi: 10.1016/0005-2736(94)90190-2.

Abstract

Acetoxymethyl ester (AM) derivatives of various fluorescent indicators (fura-2, fluo-3, indo-1, BCECF, calcein) are actively extruded by the multidrug transporter (MDR1, P-glycoprotein-Homolya, L. et al. (1993) J. Biol. Chem. 268, 21493-21496). In the present paper we show that the measurement of the accumulation of a fluorescent cell viability marker, calcein, can be effectively used as a rapid and sensitive fluorometric and flow cytometric assay for studying P-glycoprotein function. The rate of calcein accumulation in human MDR1-expressing cells is significantly lower than in the control cells, while various drug-resistance reversing agents (verapamil, vinblastine, oligomycin, cyclosporin A and UIC2 monoclonal antibody) greatly increase calcein trapping only in the MDR1-expressing cells. Since calcein-AM is not fluorescent and free calcein is not a substrate of the multidrug transporter, the assay is readily applicable for rapid kinetic studies of the MDR1 function. Calcein has a high fluorescence intensity in the visible range, thus changes in calcein uptake can be easily visualised and MDR1-expressing and control cells separated by conventional flow cytometry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells / metabolism
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Animals
  • Carrier Proteins / analysis*
  • Carrier Proteins / antagonists & inhibitors
  • Carrier Proteins / genetics
  • Flow Cytometry
  • Fluoresceins* / chemistry
  • Fluorometry
  • Humans
  • Membrane Glycoproteins / analysis*
  • Membrane Glycoproteins / antagonists & inhibitors
  • Membrane Glycoproteins / genetics
  • Mice
  • Transfection

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Carrier Proteins
  • Fluoresceins
  • Membrane Glycoproteins
  • fluorexon