HEAVY-ION-INDUCED CHANGES IN SMALL-INTESTINAL PARAMETERS

The effects on 17 different structural parameters of mouse small intestine three days after treatment with three types of heavy ion (neon, iron and niobium) are compared, the first two being of particular relevance to space flight. The data for niobium are given in full, showing that changes after niobium ion treatment are not standard and are concentrated in the epithelial compartment, with few of the parameters having a response which is dose dependent. When comparisons are made for the three types of heavy ion, the damage is greatest after neon ion irradiation, implying that the additional non-epithelial damage produced as LET rises from X rays through neutrons to neon ions is not necessarily maintained as LET continues to rise. Further understanding is therefore needed of the balance between changes affecting the vascular and absorptive components of the organ. Variation from group to group is also important, as is variation of strain or gastrointestinal status. All such factors are important in the understanding of changes in multicellular organs after exposure to heavy ion radiation.