Radiation Effects on Membranes: III. The Effect of X Irradiation on Survival of Mammalian Cells Substituted by Polyunsaturated Fatty Acids

Abstract

Murine fibroblast LM cells cultured in vitro were modified with respect to the content of polyunsaturated fatty acids in the acyl chains of the membrane phospholipids. The effect of these membrane alterations on cell survival after X irradiation was examined. The acyl chains of the phospholipids of the control cells were predominantly of a saturated and a monoenoic nature. Only 6.6% of the total fatty acid content in the phospholipids of the control cells consisted of polyunsaturated fatty acids (PUFA). In the modified cells less monoenoic fatty acyl chains were found and the precentage of PUFA was raised to 35.9. Irradiation of the cells took place at 0, 10, 22, and 37/sup 0/C. No significant differences in cell survival (D/sub q/ and D/sub O/) could be observed after irradiation at these temperatures. It is suggested that the gel-phase state of the membrane lipids starts below 0/sup 0/C for both cell lines and that the differences in physicodynamic properties of the membrane during the irradiation have no effect on cell survival. When the two cell lines were compared with respect to cell survival after irradiation at one particular temperature, the radiosensitivity for both lines was about the same with a D/submore » O/ of about 1 Gy. These results indicate that the presence of a higher concentration of the radiosensitive polyunsaturated fatty acyl chains in the membrane does not necessarily lead to a lower cell survival after irradiation.« less