title: Increased membrane permeability of apoptotic thymocytes: a flow cytometric study.
abstract: We have recently developed a method for the separation and quantification of viable apoptotic cells without the need for permeabilisation or fixation of the cells. The method is based on the observation that apoptotic rat thymocytes fluoresce more brightly than normal cells after a brief incubation with the DNA binding dye, Hoechst 33342. In order to understand these differences, we have investigated the uptake of Hoechst 33342 by normal and apoptotic thymocytes. By staining with fluorescein diacetate, we have shown that the efflux of fluorescein from apoptotic cells is more rapid than that from normal thymocytes. This result demonstrated an increase in the permeability of the plasma membrane of the apoptotic thymocytes and it is this change which probably results in the more rapid uptake of Hoechst 33342. The data also revealed two populations of apoptotic thymocytes.
authors.affiliation: MRC Toxicology Unit, Carshalton, Surrey, United Kingdom.
authors.forename: M G
authors.initials: MG
authors.lastname: Ormerod
authors.forename: X M
authors.initials: XM
authors.lastname: Sun
authors.forename: R T
authors.initials: RT
authors.lastname: Snowden
authors.forename: R
authors.initials: R
authors.lastname: Davies
authors.forename: H
authors.initials: H
authors.lastname: Fearnhead
authors.forename: G M
authors.initials: GM
authors.lastname: Cohen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001562:Benzimidazoles / Q000493:pharmacokinetics; D002463:Cell Membrane Permeability / Q000502:physiology*; D002467:Cell Nucleus / Q000737:chemistry / Q000648:ultrastructure; D002469:Cell Separation; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis / Q000737:chemistry; D005434:Flow Cytometry / Q000379:methods; D005452:Fluoresceins; D008297:Male; D011744:Pyrimidinones / Q000493:pharmacokinetics; D051381:Rats; D011916:Rats, Inbred F344; D013950:Thymus Gland / Q000737:chemistry / Q000166:cytology* / Q000502:physiology
chemical_list: D001562:Benzimidazoles; D005452:Fluoresceins; D011744:Pyrimidinones; C003954:merocyanine dye; D004247:DNA; C017807:bisbenzimide ethoxide trihydrochloride; C018506:diacetylfluorescein