Effect of X-Irradiation on Weight and Contents of Rat Stomach, Small and Large Intestine

1. The effect of 500 r whole body irradiation on organ weights and weights of the contents of the stomach, small intestine and large intestine of the rat was studied. All three components showed loss of weight during the first 3- to 4-day post-irradiation period which was greater than body weight loss. The stomach, small intestine and large intestine showed percentage weight losses of 15.7, 34.4 and 23.6, respectively. Organ weights, except for the stomach, returned nearly to normal on the 4th and 5th day. The significantly greater weight loss in the small intestine was believed to reflect greater sensitivity of this part to ionizing radiation. It was pointed out that these weight changes were not due to dehydration or edema of the tissues or to the lowered food intake alone, but were in a large pad due to specific effects of radiation. 2. The stomach showed the greatest variation in contents after irradiation, with a marked increase occurring during the first 72 hours which was believed to be associated with delayed emptying of the stomach. During this same period the small intestine and large intestine showed slightly reduced contents which became liquid and foul-smelling in character. From the 3rd to 4th days through the 7th day there was a marked increase in contents in all parts above the control range with a change to the normal semi-solid state. It was believed that this change was the reflection of compensatory increased food consumption associated with improved gastrointestinal function.