Ionizing radiation-induced structural modification of human red blood cells.

The effect of gamma radiation on red blood cells have been examined using a spin labeling method. For this purpose two spin labels were used to monitor membrane fluidity: methyl 5-doxylpalmitate (Met 5-DP) and methyl 12-doxylstearate (Met 12-DS). The irradiation of red cells with the doses of 200 and 500 Gy caused decrease of microviscosity in certain regions of lipid bilayer (as indicated by Met 5-DP and Met 12-DS spectra) but did not affect lipid order parameter. The behavior of two other spin labels, maleimide(4-maleimido-2,2,6,6-tetramethylpiperidine-1-oxyl) and TEMPONE (4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl) indicated: 1) conformational changes of membrane proteins, 2) modification of cell internal peptides and proteins, 3) decreased internal viscosity of red blood cells.