S26 



ADVENTURES IN RADIOISOTOPE RESEARCH 



We found that the non-fasting irradiated mice exhale only some 80 

 per cent of the amount of carbon dioxide exhaled by control mice. This 

 result does not necessarily prove an impaired catabolism of body glucose. 

 Since only about one-half of the exhaled carbon dioxide originates from 

 catabolism of glucose(®\ the other half having its origin in catabolism 

 of fatty acids and other body constituents, it may be that the catabolism 



40 



30 



S 20 



a. 



^,0 





20 



30 



min. 



40 



50 



60 



Fig. 1. Effect of irradiation with 2000 r. on the production of 



exhaled carbon- 14 dioxide after injection of labelled glucose to 



non-fasting mice. O, control; X , irradiated. 



of the last-mentioned compounds and not that of glucose is responsible 

 for the reduced exhalation of carbon dioxide by the irradiated mouse. 

 The fact, however, that if labelled glucose is administered the irradiated 

 mice exhale a smaller amount of carbon- 14 labelled carbon dioxide 

 than the controls, proves unambiguously that irradiation depresses the 

 glucose catabolism of irradiated mice. The graph indicates that the depres- 

 sion is already apparent after the lapse of 12 min and may possibly be 

 still more pronounced at an earlier time. 



It is of interest to note that Lourau and Lartigue observed that 

 addition of glucose to the diet of the guinea pig increases its radiosensi- 

 tivity^^\ that irradiation with 500 r. produces hyperglycaemia in the 

 irradiated animal^^"^ and, quite recently, that 12—15 days after irra- 

 diation glycogen formation in the liver is reduced 1 — 2 hr after feeding 

 glucose^^^^ 



The reduced catabolism of glucose in the irradiated mouse is reflected 

 in an increase of forty to one hundred per cent in the carbon-14 content 

 of liver fats. 



