In vivo spin trapping of free radicals generated in brain, spleen, and liver during gamma radiation of mice

Spin trapping techniques combined with electron spin resonance spectroscopy were used to capture and detect free radicals generated in vivo during exposure to ionizing radiation. Tissue extracts of mice given an intraperitoneal or intragastric dose of the spin trap, alpha-phenyl-t-butyl nitrone prior to exposure to gamma radiation (2 to 5 Gy), contained a radical adduct with hyperfine splitting constants characteristic of spin adducts of carbon-centered lipid radicals. Considerably more radicals were trapped in tissues when the trap was given 3 h before radiation as compared to 30 min before exposure. The radicals observed may either be secondary species resulting from an attack on cellular components by products of water radiolysis, or primary radicals resulting from direct interaction of the radiation with biological molecules. The results indicate that the spin trapping agent is able to penetrate well into animal tissues, and to capture radical species under conditions where the latter would be expected to occur.