Light-induced permeabilization and merocyanine 540 staining of mouse spleen cells

Gábor Szabo, Imre Rédai, Zsolt Bacso, Jozsef Hovessy, Sándor Damjanovich

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Merocyanine 540 (M540) is a potential-sensitive, hydrophobic dye that preferentially incorporates into the 'fluid' domains of cellular membranes, distinguishing between hemopoietic cells according to their differentiation state. A bright staining with M540 is usually achieved by UV illumination of the cells during staining. We show by flow cytometric analysis that: (1) staining is greatly enhanced by UV illumination of mouse spleen cells before addition of the dye; (2) UV treatment causes an increased permeability toward propidium iodide and intracellular fluorescein as well; (3) the increment in M540 fluorescence precedes permeabilization to propidium iodide, while the latter precedes leakage of fluorescein. We also describe an overshoot and accelerated recovery of M540 fluorescence after photobleaching by a 514 nm laser beam. It is suggested that penetration of M540 to the more fluid inner membrane structures explains the fluorescence increment in both experiments.

Original languageEnglish
Pages (from-to)365-370
Number of pages6
JournalBBA - Biomembranes
Issue number3
Publication statusPublished - Mar 13 1989



  • (Mouse spleen)
  • Cell permeabilization
  • FRAP
  • Flow cytometry
  • Merocyanine
  • Photobleaching
  • Ultraviolet irradiation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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