Radiopathology of normal tissues

Initial responses of normal organs to radiation may lead to further nonspecific harmful reactions, both local and abscopal. These reactions could in principle be prevented or alleviated by suitable treatment applied after radiation exposure, in addition to such established procedures as substitution of depleted cells (e.g., bone marrow transplatation), their products (e.g., hormones) or the use of antimicrobial chemotherapy for secondary infections. The choice of effective treatment depends on recognition of the involved pathomechanisms shared with conditions due to noxious agents other than radiation. These views are put forward and illustrated with findings in mice irradiated to their stomach or the lower mediastinum. The former animals develop within days a selective, long-lasting hypochlorhydria due to apparent malfunction of the regulatory (eneterochromaffin-like) cells and/or a breakdown of the gastric mucosal barrier leading to injurious back-diffusion of sectreted acid. Administration of H2 histamine receptor blockers or gastic H+-ATPase inhibitors might limit the secondary damage suffered by the stomach. Some of the mediastunum-irradiated mice develop an acute to chronic duodenal ulcer preventable by truncal vagotomy performed one day after exposure to radiation. (author)