Studies of Injected 237Pu(IV) Citrate in Beagles

Abstract

Three beagles aged 17 months were injected intravenously with about 0.03 μCi/kg of the photon emitter 237Pu(IV) as the citrate. Retention in liver and in non-liver tissue was measured serially in the living dogs by a combination of total- and partial-body counting. All excreta were collected throughout the experiment, and blood was sampled at intervals during the first 2 days. About 4 of the total excretion was in the feces. The concentration of 237Pu in blood plasma decreased from 0.2 % of the injected Pu/ml at 0.5 hr after injection to about 0.02%/ml at 48 hr, and was indistinguishable from corresponding values for dogs injected with about 0.016 μCi/kg of 239Pu(IV) citrate. After the first few days, total-body retention was between 80 and 90 %, similar to that of other beagles in our colony given 239Pu citrate. The dogs injected with 237Pu had 50–60 % of the injected Pu in the skeleton, while the corresponding values for dogs given 239Pu were between 40 and 50 %. Liver retention of 237Pu was 20–25 %, somewhat lower than the 30–35 % found for 239Pu. Although the retention of 237Pu in the skeleton was higher than that of 239Pu, the relative distribution of skeletal 237Pu in these three dogs which were sacrificed at 13, 20 and 27 days after the injection of about 25 pg Pu resembled that of five dogs given about 2.6 × 106 pg 239Pu and sacrificed less than 1 yr later. Similarities of injected 237Pu and 239Pu citrate in the beagle were more striking than the observed differences.