994 



ADVENTURES IN RADIOISOTOPE RESEARCH 



specific activity of the body acetate is necessarily reflected in the specific 

 activity of those products with which acetate carbon is incorporated. 

 As resorption, distribution, and conversion of acetate take some time, 

 the i*C content of a rapidly metabolizing fatty acid fraction found to be 

 present in the liver of the mouse after intraperitoneal injection of label- 

 led acetate increases during the first minutes; soon, however, a very 

 rapid decline in the activity figure of the fatty acids is observed^^^^ The 

 strongly active fatty acid'^molecules formed in the initial phase of the 



Liver 



^ 



^ 



intesr, 

 Mucosa 



I 



V 



I 



Infest 

 Mucosa 



^ 



Muscles 



D 



21 



Control Urerhone 

 Kidneys 



Brain 



Liver 





^ 



Control Urethone 



a 



Kidneys 



Muscles 



Fig. 16. — Effect of urethane on 



the incorporation of ^*C into total 



fat. Mice killed 110 mins. after 



injection of CH3 • COjNa. 



Fig. 17. — Effect of urethane on 

 the incorporation of i*C into tissue 

 proteins. Mice killed 110 mins. 

 after injection of CH3 • "COjNa. 



experiment are soon metabolized and replaced by molecules formed 

 from less active precursors; correspondingly, a rapid decrease in the 

 fatty acid activity takes place. 



Dinitro-compounds, e.g., dinitroc ?/cZopentylphenol, when given in proper 

 doses, are metabolic accelerators. Consequently, they enhance the 

 incorporation of acetate i^Q into liver fats of the mouse, as seen in Fig. 

 14.(55) Soon, however, the accelerated metabohsm leads to an accelerated 

 replacement of the labelled fatty acid molecules (in which most of the 

 14C of the total fats is to be found) formed in the early phase of the 

 experiment by molecules formed from less active precursors. The des- 

 cending part of the curve correspondingly takes a steeper course in the 

 case of the dinitroc?/cZopentylplienyl-treated animals than in that of the 



(55) Hevesy, Ruyssen and Beeckmans, Experientia (1^51), Beeckmans and 

 DE Elliott, Nature 167, 200 (1951). 



^56) Beeckman, Caiser and Hevesy, Arch. Int. Pharmacodyn. 86, 33 (1951). 



