RESORPTION RATE OF INJECTED Na^HCOj 



831 



In the later part of the experiment the amount of ^^COg expired, de- 

 creases more and more with increasing time. After the lapse of 30 minutes 

 the amount exhaled in the course of 10 minutes made up only about 

 1% of the injected quantity. It is, therefore, difficult to judge whether 

 the 20 — 25% higher output of activity from irradiated mice some 30 

 minutes after the injection of the bicarbonate may be explained solely 

 by an initial lag very shortly after injection. As, however, irradiation 

 influences the incorporation of i*C into different body constituents and 

 as incorporation and release of ^^C are intimately connected, a preferential 

 release of '^C from the compounds of the irradiated mice may contribute 

 to the increased exhalation in the later part of the experiment. 



The slower exhalation of ^^COg by the exposed animals shortly after 

 injection of the labelled bicarbonate could be due to a depressed resorp- 

 tion and/or a circulation disturbance. To investigate the latter possibility 

 we injected labelled bicarbonate into the tail vein of both control and 

 irradiated mice and collected the exhalatory CO^ in 2-minute intervals 

 starting immediately after injection. No conspicuous differences could 

 be noticed in the amount of ^^COg exhaled as shown in Figure 2. The 

 depressed exhalation of ^^('O.^, hy the exposed mouse is probably caused 

 by a decreased resorption rate of the injected bicarbonate and not by 

 circulation disturbances. 



We investigated also the effect of irradiation on the exhalation of 

 i^COg following a subcutaneous injection. The results obtained in six 

 experiments varied much more than those observed after intraperitoneal 

 injection and do not permit definite conclusions on the effect of irra- 

 diation on the rate of resorption. The mean value of the aggregate amount 

 exhaled in the course of 10 minutes was 57.7% for the controls and 

 45.5% for the X-rayed animals compared with 65.8 and 65.3% after 

 intraperitoneal injection. The amount exhaled in the first 4 minutes 

 varied between 9.6 and 34.6%. 



Table 1. — Percentage of Activity 



Adminlstebed Exhaled in the 



Course of the first 10 Min. 



The irradiated and control mice had in each experiment within 5% identical weights, which, however,, 

 differed from experiment to experiment. 



