Influence of Nutritional Factors on 239Np and 233Pa Retention in Weanling Rats

Abstract

The estimated intestinal absorption after a single administration of ²³⁹NR-nitrate to fasted weanling rats (about 2% of the oral dose) was ten times higher than that of ²³³Pa administered as the chloride. Rats drinking tomato juice, apple juice or tea instead of water had a similar retention to the control group. However, when a small amount of tea was administered immediately before ²³⁹Np, the absorption and retention values were six times lower. When animals received only milk or glucose, the whole body retention of ²³⁹Np and ²³³Pa increased about 20 and 200-300 times, respectively, due mainly to a very high retention in the large intestine. When rats were fed milk plus rat chow, the whole body and gut retention of ²³³Pa was only two and three times higher, respectively; in the other organs less ²³³Pa was found than in control animals. This indicates that the extremely high retention of radionuclides in the gut contents of young rats fed only milk is temporary and disappears when solid food is available.