Cytoplasmic acidification is not an effector mechanism of VP16 or DEX-induced apoptosis in CEM T leukaemia cells

The role of intracellular acidification in the execution phase of apoptosis is not well understood. Here we examine the effect of Bcl-2 over-expressio n on intracellular acidification occurring during apoptosis. We found, that in CEM cells, neither DEX nor VP16-induced apoptosis lead to a significant change in intracellular pH (pH(i)). Furthermore, we found that shifting pH i away from physiological values was unable to induce chromatin condensatio n or poly(ADP-ribose) polymerase (PARP) cleavage in the presence of Bcl-2 o ver-expression. However, it was found that maximum chromatin condensation a nd PARP cleavage occurred at near physiological pHi values. Taken together these data suggest that intracellular acidification does not trigger the ef fector phase of CEM apoptosis.