830 



ADVENTURES IN RADIOISOTOPE RESEARCH 



after the injection of the bicarbonate, leaving these animals with an 

 increased pool of ^^C some 10 — 60 minutes afterwards. This conclusion 

 induced us to carry out corresponding experiments in which collection 

 of ^^COg M-as started immediately after the injection, making use of the 

 second arrangement described above. 



The results of these experiments are plotted in Figure 1 . In the first 

 4 minutes of the experiment during which a very appreciable percentage 



lOmin. 



Fig. 1. Exhalation of i^COg 

 of x-rayed (0) and control 

 (O) mice after intraperito- 

 neal injection of NaHi^COg. 

 Values for the determina- 

 tions of "COg in the interval 

 0—2 minutes are plotted at 

 1 minute, etc. 



lOmin. 



Fig. 2. Exhalation of "cOg 

 of x-rayed (^) and control 

 (O) niice after intravenous 

 injection of NaHi^COg. Less 

 activity than in the intra- 

 peritoneal experiments was 

 injected. 



of the injected ^^COg is exhaled, the controls gave off more ^^CO, (45%) 

 than the irradiated animals (29%), and more ^^COg was retained in the 

 exposed animals which gave off more ^^COg in the later stage of the expe- 

 riment. Between 4 and 10 minutes 46% was given off by the irradiated 

 animals against 34% by the controls. The aggregate amount of "COg 

 exhaled during the first 10 minutes by the two groups of mice is by 

 chance the same as seen in Table l.The results are remarkablj^ repro- 

 ducible. 



Evidently it would be expected that the activity expired by the irra- 

 diated mice during the first minute ^^ ould be decreased even more from 

 that of the control mice. In a few trials of this hypothesis the activity 

 expired during the 1st minute, including the 6 seconds taken for the 

 injection in these experiments, was found to be only 43% of that of 

 the controls. This indicates that the X-ray effect on the process of resorp- 

 tion of the bicarbonate and the intrusion of COg into the alveolar space 

 is very marked. 



