The oxygen effects of x-rays and neutrons on the membrane permeability of sheep erythrocytes

In order to clarify the sites in a cell which were susceptible to oxygen effect by radiation, its effect on the membrane permeability of sheep erythrocytes was investigated with 200 kVsub(p) x-rays and 6 MeV cyclotron neutron in the presence and absence of oxygen. Radiation damage to membranes, irradiated at room temperature and stored for 20 hours at 40 and 370C, was assessed from both the escape of K+ from the cells and the incorporation of Na+ into the cells. The values of OER (oxygen enhancement ratio) and RBE (relative biological effectiveness) for the damage by neutrons at 40C were 1.0 and 3.1, respectively. The same value of OER was obtained by x-rays. No oxygen effect was also observed even at 370C where the repair of damage to membranes existed. These results are incompatible with the model that membranes are sites of type '0' damage susceptible to oxygen effect. (auth.)