Mitochondrial modifications during rat thymocyte apoptosis: A study at the single cell level

Andrea Cossarizza, Galina Kalashnikova, Emanuela Grassilli, Francesco Chiappelli, Stefano Salvioli, Miriam Capri, Daniela Barbieri, Leonarda Troiano, Daniela Monti, Claudio Franceschi

Research output: Contribution to journalArticlepeer-review


Apoptosis is an active type of cell death, occurring under several physiological and pathological conditions. The role of cellular organelles such as mitochondria in this process is still an open question. We recently described a new method to measure mitochondrial membrane potential in intact cells using flow cytometry. Using this method we studied alterations of mitochondrial membrane potential in a classical model of apoptosis, i.e., dexamethasone-treated rat thymocytes. Moreover, apoptosis induced by heat shock was also studied in the same cells. Mitochondria are functionally intact during the early phases of apoptosis, when DNA fragmentation occurs, whereas early alteration in their potential and mass takes place after DNA damage. According to flow-cytometric analysis, the presence of a hypodiploid peak, an index of nuclear DNA loss, predates depolarization of mitochondrial membrane and decrease of mitochondrial mass. Loss of plasma membrane integrity, which indicates cell death and is revealed by the permeability to propidium iodide, eventually follows. All these phenomena are more evident in dexamethasone-treated cells than in heat-shocked cells. Thus, in these types of apoptosis the involvement of mitochondria is apparently not a primary event.

Original languageEnglish
Pages (from-to)323-330
Number of pages8
JournalExperimental Cell Research
Issue number1
Publication statusPublished - 1994

ASJC Scopus subject areas

  • Cell Biology


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