[D2O inhibition of interphase thymocyte death]

Using the method of flow cytometry and biochemical analysis it was shown that D2O, an agent that stabilizes microtubules, prevented the internucleosome fragmentation of DNA in thymocytes exposed to gamma radiation and dexamethasone in vitro. It was also found that D2O is ineffective with respect to Ca2+/Mg2(+)-dependent nuclease. The transfer of irradiated cells from a medium containing 90% of D2O to a normal one caused rapid DNA degradation; the fragmentation process ceased with the irradiated cells being transferred from H2O to heavy water. The results obtained permit us to assume that the disturbance of microtubules is not a trigger mechanism of DNA degradation by apoptosis, but is some intermediate stage of cell death preceding the chromatin fragmentation proper.