Temperature dependence of anisotonic NaC1 effect on radiosensitization and ultrastructure of V79 Chinese hamster cells.

Isodose radiation survival of V79 Chinese hamster cells, pretreated with strongly hypertonic concentrations of NaC1 at 22 degrees C, or at 37 degrees C, has been determined and correlated with ultrastructural changes within the nucleus. After an exposure of less than 10 min to 1.5 M NaC1, at both temperatures, the cells are radioprotected, but after longer exposures, the cells treated at 37 degrees C are radiosensitive, whereas those treated at 22 degrees C still show protection. The cells are radiosensitized at both temperatures by pretreatment with 0.5 M and 0.05 M NaC1. The ultrastructure of the nucleus observed after the anisotonic treatments suggests that contraction or swelling of chromatin may be associated with the observed variation in radiation sensitivity.