The effect of microwave-induced whole-body hyperthermia on the mucosa of mouse small intestine.

Whole-body hyperthermia on small intestine Effect of microwave-induced whole-body hyperthermia (WBH) was examined using ddY/ SLC mice for the basic understandings of the critical organs. The treatment at 43.5°C for 20 min resulted in the mortality ratio of 30-40% within several hours, the peak of 3 hours. The other mice survived thereafter showed no specific critical disease. The examination of autopsy evinced, a considerable amount of the body fluid leaked into intestinal lumen due to the transitory denudation of the epithelial cells of the small intestinal villi within 3 hours, whereas epithelial cells of the crypts appeared intact until these cells of villi were completely denuded. After 6-9 hours, cryptal epithelial cells regenerated in some of the animals which probably could survive at least for more than the one day if they were not sacrificed. At 24 hours, the mucosa showed normal appearance with recovered long villi and normal cellularity in crypt. Thus, the histology of the mice died within the one day suggested, the complete denudation of the villus epithelial cells might be one of the initial events leading to death. These results suggest as follows: 1) One of the critical organs of the WBH is mucosa of the small intestine. 2) WBH affects the epithelial cells of intestinal villi whereas those of the crypts are not injured, in contrast radiation effect is mainly given on the proliferative epithelial cells, i.e., of the crypts.