Chemical damage in gamma-irradiated human erythrocyte membranes

In air saturated suspensions of erythrocyte ghost membranes γ-irradiation causes formation of lipid peroxides, measured as malonaldehyde, and a loss of membrane protein sulphydryl groups. Addition of N-(p-amino-benzoyl)-1-glutamate prevented peroxidation up to doses of 2 x 103 Gy, due to scavenging of hydroxyl radicals. Another hydroxyl scavenger sodium formate, also prevented peroxidation at low doses, but lost its protective effect at higher doses probably because of secondary reactions of the resulting superoxide radical anion. Two sulphur containing radioprotectants also were able to reduce the extent of lipid peroxidation. The enzymes catalase and superoxide dismutase were added to the irradiated suspensions in order to determine the contribution from hydrogen peroxide and superoxide to peroxidation. The extents of peroxidation are compared with structural modification of the membrane under the same conditions of irradiation. (U.K.)