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  • Research Article
  • Open Access

Monitoring of membrane phospholipid scrambling in human erythrocytes and K562 cells with FM1-43 — a comparison with annexin V-FITC

  • 1,
  • 2,
  • 2 and
  • 2, 3Email author
Cellular & Molecular Biology LettersAn International Journal201419:195

  • Received: 25 September 2013
  • Accepted: 16 April 2014
  • Published:


The styryl dye FM1-43 becomes highly fluorescent upon binding to cell membranes. The breakdown of membrane phospholipid asymmetry in ionophore-stimulated T-lymphocytes further increases this fluorescence [Zweifach, 2000]. In this study, the capacity of FM1-43 to monitor membrane phospholipid scrambling was explored using flow cytometry in human erythrocytes and human erythrocyte progenitor K562 cells. The Ca2+-dependent phosphatidylserine-specific probe annexin V-FITC was used for comparison. The presented data show that the loss of phospholipid asymmetry that could be induced in human erythrocytes by elevated intracellular Ca2+ or by structurally different membrane intercalated amphiphilic compounds increases the FM1-43 fluorescence two- to fivefold. The profile of FM1-43 fluorescence for various treatments resembles that of phosphatidylserine exposure reported by annexin V-FITC. FM1-43 detected the onset of scrambling more efficiently than annexin V-FITC. The amphiphile-induced scrambling was shown to be a Ca2+-independent process. Monitoring of scrambling in K562 cells caused by NEM-induced Ca2+-release from intracellular stores and by Ca2+ and ionophore A23187 treatment showed that the increase in FM1-43 fluorescence correlated well with the number of annexin V-FITC-detected phosphatidylserine-positive cells. The results presented here show the usefulness of FM1-43 as a Ca2+-independent marker of dissipation in asymmetric membrane phospholipid distribution induced by various stimuli in both nucleated and non-nucleated cells.


  • FM1-43
  • Phospholipid scrambling
  • Annexin V-FITC
  • Phosphatidylserine exposure
  • Human erythrocytes
  • K562 cells
  • Ionophores
  • Amphiphiles