Weight, nitrogen and DNA content of small intestine mucosa of rats exposed to X-rays

¹ Biological and Medical Sciences Division, U. S. Naval Radiological Defense Laboratory, San Francisco, California

The quantitative relationships between the changes in small intestine weight, mucosa weight, mucosa DNA and nitrogen following exposure to x-rays were investigated. It was found that these relationships depend upon the magnitude of the dose, time of observation, nutritional state of the rat and number of doses administered. Thus, depending on the particular combination of these variables, different effects of x-irradiation on mucosa weight, intestine weight and mucosa DNA and nitrogen were observed. The following relationships were found: a) weight changes in the small intestine always reflected the changes in mucosa weight, b) changes in mucosa nitrogen after a single x-irradiation always paralleled the changes in mucosa weight, whereas the changes in mucosa DNA were not as closely related to the weight changes, c) changes in mucosa weight and nitrogen did not correlate well with the dose received, whereas DNA level approximated a linear relationship over the range 300 to 900 r, and d) there was a minimum level to which the mucosa weight, DNA and nitrogen decreased following x-irradiation.