RETENTION OF 134CS AS AN INDEX TO METABOLISM IN COTTON RAT (SIGMODON HISPIDUS)

Biological half-lives (Tb) of 134Cs were compared with resting metabolism measurements of cotton rats maintained at 5, 15, and 25°C in an endeavor to develop a technique for determining respiration rates of animals in the field. Average Tb values of the experimental groups were 6.3 days at 5°, 6.9 days at 15°, and 8.1 days at 25°; oxygen consumption measurements (cc/hr/g) averaged 3.2, 2.3 and 1.5, respectively. Regression and correlation analysis performed on the data of the individual animals revealed a strong linear relationship between Tb of 134Cs and resting metabolism. Although 134Cs retention correlated well with oxygen consumption, it could not be shown to correlate with body weight. Further investigations of 24-hr oxygen consumption measurements made over a wider range of metabolic rates (i.e. both above and below thermoneutrality) and consideration of certain factors which promote elimination of cesium are necessary to validate the apparent relationship between 134Cs retention and general metabolism. © 1969 Health Physics Society.