Micro-organisation of the membrane after radiation-induced apoptosis: a flow cytometry study.
The aim of this study was to detect membrane fluidity modifications in blood lymphocytes that had been exposed to gamma-radiation, at a graded series of depths from the surface to the centre of the membrane bilayer and as a function of cell viability. A time course was performed to verify the contribution of the membrane to radiation-induced apoptosis. In comparison with spectrofluorimetry, flow cytometry proved to be a reliable method for measuring radiation-induced membrane alterations. Late apoptotic lymphocytes were characterised by a significant decrease of the 3-SA, 6-SA and 9-SA fluorescence anisotropy values, compared to viable lymphocytes. Moreover, a highly significant difference was observed in the early apoptotic lymphocyte subpopulation between the fluorescence anisotropy values measured 24 h (radiation-induced apoptosis) and those measured 1 h (spontaneous apoptosis) after irradiation. The simultaneous assessment of cellular viability and membrane fluidity using n-(9-anthroyloxy) fatty acid probes, may be relevant for the investigation of interactions which may exist between membrane modifications and the apoptotic process. Our observations support the specificity of radiation-induced apoptosis compared to spontaneous apoptosis in terms of biophysical modifications of membrane properties.
Vincent-Genod
L
L
Institut de Protection et de Sûrete Nucléaire, Département de Protection de la Santé de l'Homme et de Dosimétrie, Fontenay-aux-Roses, France.
Benderitter
M
M
Voisin
P
P
D016880:Anisotropy; D017209:Apoptosis / Q000528:radiation effects*; D002462:Cell Membrane / Q000378:metabolism / Q000528:radiation effects*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008214:Lymphocytes / Q000473:pathology; D013050:Spectrometry, Fluorescence; D013997:Time Factors