BIOKINETICS OF SYSTEMICALLY DISTRIBUTED CO-60 IN THE RAT: AN EXPERIMENTAL MODEL USEFUL IN EVALUATING MEDICAL COUNTERMEASURES FOR INTERNAL CONTAMINATION

摘要

LBERI, a member of the Medical Countermeasures to Radiologic Threats (MCART) consortium funded by NIAID, was tasked to develop biokinetic models for the distribution of radionuclide threats using the most likely routes of incorporation in both small and large animals. In the present paper, the biokinetics of systemically administered soluble cobalt-60 (⁶⁰Co) have been examined. Male and female jugular-vein-catheterized (JVC) F344 rats received intravenous (IV) doses of 11.2 kBq of ⁶⁰CoCl2. The distribution of the radiocobalt was followed for 28 d, with tissue sampling done at 1 and 4 h, and at 1, 2, 4, 8, 16, and 28 d. Urine and feces were collected daily. Tissues and excreta were analyzed by gamma pulse height analysis. Within 8d, 93% of the cobalt was eliminated from the body primarily though urine. The highest tissue burdens were found in liver, gastrointestinal (GI) tract, and muscle shortly after administration. These tissues cleared quickly so that by the conclusion of the 28-d study, less than 3% of the recovered dose remained in the body. The results are comparable to published literature values for tissue content of ⁶⁰Co and for excretion patterns up to 30 d after injection. These results will provide the data needed to construct a biokinetic model for the unperturbed biokinetics of ⁶⁰Co in rats, which will subsequently be used to evaluate the impact of administered decorporating agents on organ radiation doses. The animal model described in this paper is representative of that used for other routes of radionuclide administration such as inhalation, ingestion and wound contamination that have been studied at LBERI in support of the MCART and NIAID programs.