M. Wojewódzka1, M. Kruszewski1, I. Szumiel1, A. Wójcik1, C. Streffer2, A. Gasińska 3
1 Department of Radiobiology and Health Protection, Institute of Nuclear Chemistry and
Technology, 03-195 Warsaw, Poland,
2 Institut für Medizinische Strahlenbiologie, Universitaetsklinikum Essen, D-45122 Essen,
Germany,
3 Radiotherapy Clinic Oncology Center, 31-115 Cracow, Poland
Irradiation of human lymphocytes (1 cGy, 37°C) evoked a 30% decrease in the frequency of micronuclei
upon subsequent X-irradiation (1.5 Gy). The response was reflected both by a reduction in the
formation of micronuclei frequency and in an increase in the DNA repair rate measured by the comet
assay directly after the challenge dose. The calcium antagonist, TMB-8, and staurosporine, an
inhibitor of protein kinases, prevented the development of the adaptive response measured by the
appearance of micronuclei. Psi-tec-torigenin, an inhibitor of phosphatidyl/nositol turnover, did not
modify the adaptive response, The induction of adaptation was not accompanied by altered progression
through the cell cycle, or changes in chromatin condensation as determined by flow cytometry (DNA
content and 90° side scatter, respectively).