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Increase of Intracellular pH in p53-Dependent Apoptosis of Thymocytes Induced by Gamma Radiation
H-Y. Dai, N. Tsao, W-C. Leung and H-Y. Lei
Vol. 150, No. 2 (Aug., 1998), pp. 183-189
Published by: Radiation Research Society
Stable URL: http://www.jstor.org/stable/3579853
Page Count: 7
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Irradiation with γ rays induces apoptosis of thymocytes by a p53-dependent pathway, but its mechanism is not clear. In this study, we report that γ-ray-induced apoptosis was associated with the intracellular alkalinization of the thymocytes. After exposure to γ rays, thymocytes underwent apoptosis when cultured in vitro, and the degree of apoptosis was dependent on the incubation period: The longer the incubation period, the greater the number of cells undergoing apoptosis. However, this apoptosis could be inhibited by the acidic condition of the culture. There was a positive correlation between the pH i of thymocytes and the degree of apoptosis. Treatment with γ radiation induced apoptosis as well as the elevation of the pH i in thymocytes. The intracellular pH was higher in pre-apoptotic thymocytes than in those that did not undergo apoptosis. Furthermore, apoptosis induced by γ radiation was inhibited by cycloheximide, actinomycin D or the intracellular Ca2+ chelator, TMB-8. The p53 protein is induced after γ irradiation. Thus it appears that intracellular pH is increased during the γ-ray-induced p53-dependent apoptosis of thymocytes.
Radiation Research © 1998 Radiation Research Society