Cell volume alteration has been described as a necessary event in cell death, cell shrinkage during apoptosis and cell swelling during necrosis. In our experiments we have employed quail red blood cells (QRBC) as cellular model (Lou 2003) and H₂O₂ as apoptotic inducer by reactive oxygen species in order to produce synchronized cell death, letting us to study cell volume and ionic fluxes during this process. H₂O₂ was employed at different concentrations (62–500 mM) capable to induce apoptosis in different kind of cells. For measuring cell volume we have employed a Coulter Gen-S (COULTER Corp, Miami, USA). Cell death was confirmed by tripan blue dying and by electrophoretic determination of DNA fragmentation.

All assayed concentrations of H₂O₂ induced volume changes in QRBC, following the sequence "shrinkage–swelling–shrinkage". H₂O₂ 500 mM develop this volume change more quickly (3 min- 15 min- 75 min) and swelling was higher. Whereas consecutive smaller H₂O₂ concentrations induce volume changes slowly (7 min- 30 min- 120 min) and first shrinkage was more pronounced while swelling was smaller. Nor bumetanide or extracellular potassium changes provoke difference in this phenomenon. Calcium free medium induce a very soft difference. Cells start to be dyed by tripan blue at 120 min (0'5 %), and 24 hours later cells continued shrunk and DNA fragmentation was verified. Our results suggest the possibility that in this cell volume changes was not implicated ionic fluxes. If any intracellular contractile protein or cytoskeleton is implicated deserve further investigation.