Membrane damage caused by free radicals--radiation perspective.

Irradiation experiments were performed with Ehrlich ascites tumour cells grown in the peritoneal cavity of mice. A 20 MeV proton beam was used as the source of ionizing radiation. The generation of free radicals was investigated with EPR spectrometry. Lipid peroxidation products were determined by the thiobarbiturate reaction, UV-absorption, and fluorometric measurements. Membrane injuries were visualized by electron microscopy. Free radicals (like H and OH) were formed in the cells during the irradiation. Radical reactions were transferred to membrane lipids producing secondary radicals, diene conjugation, malondialdehyde formation and fluorescent end products. By using electron microscopy severe damage could be detected in cell membranes.