COMPARISON OF EFFECTS OF IRON AND CALCIUM CHELATORS ON THE RESPONSE OF L5178Y SUBLINES TO X-RAYS AND H2O2

The L5178Y murine lymphoma subline LY-R is twofold more resistant to k illing by ionizing radiation than the subline LY-S. In contrast, LY-R cells are more sensitive to killing by hydrogen peroxide: at 37 degree s C LY-R cells are 1.4 times more sensitive to the killing effect of H 2O2 than LY-S cells. Pretreatment with the iron chelator desferroxamin e followed by hydrogen peroxide treatment at 37 degrees C gives a cons iderable sparing effect, which is substantially greater for the LY-R s ubline than for the LY-S subline. This is reflected in the initial DNA damage (estimated by single cell gel electrophoresis), survival and m utation frequency in the HGPRT locus. Similar results have been obtain ed with calcium chelators, which, according to recent findings (Sandst rom and Granstrom 1993), also are efficient iron chelators. In contras t, the response to X-rays is not modified by the above chelators, with the exception of mutation frequencies: lower mutant numbers are found in desferroxamine pretreated LY-R cells.