Cytoplasmic effects of X-irradiation on cultured cells in a nondividing stage. 3. Alterations in plasma membrane motility.

Cultured, density-dependent growth inhibited human glia cells were exposed to X-radiation, generated by an 8-MeV linear accelerator, at a dose of 200 Gy. Phase contrast microscopy, time-lapse cinemicrography and scanning electron microscopy showed the irradiated cells to have increased ruffling activity of plasma membranes and enhanced macropinocytosis with a maximum approximately 24 hours after irradiation. "Atypical" central ruffles arising from the upper cell surface were demonstrated on some irradiated cells. The turnover of plasma membranes was supposed to be increased in the irradiated cells resulting in the formation of the observed branched, thread-like cells. The diminished cell surface area was believed to result from an unbalance between degradation and renewal of the plasma membranes in the irradiated cells.