842 ADVENTURES IN RADIOISOTOPE RESEARCH 



EXPERIMENTAL 



Albino mice, weighing 14 — 16 gm, were placed each in one of six perforated 

 aluminium boxes which were fixed in a plexy glass box of 1.5 htre volume. COg- 

 free air passed through the box carrying the exhalatory COg which was absorbed 

 by a set of centrifuge tubes containing saturated Ba(0H)2. 3 bottles each contain- 

 ing 50 ml solution proved to be sufficient to absorb all COg. The centrifuged BaCOg 

 precipitate was washed with COg-free water and ethanol, dried first in a vacuum 

 exsiccator, then by heating to 105°. 



In one set of experiments, minute amounts (3jMgm) of methyl alcohol dissolved 

 in 0.050 ml saline were administered by intraperitoneal injection to each mouse 

 having an activity of 1.5 ^curie. In another set massive doses (8 mg) of methyl 

 -alcohol dissolved in 0.050 ml saUne were injected. The exhalatory ^^CO, of the 

 same group of mice was collected first, previous to irradiation and again after 

 the lapse of one day or more and also after exposure to a dose of 1500 r. In both 

 cases methanol was injected in each experiment shortly before the collection 

 of the exhaled COg had started. As one day after the administration of 3 //gm of 

 methanol the specific activity of the exhaled COg was less than 1 percent of that 

 observed in the early stage of the experiment, repeating the experiment the follow- 

 ing day the ^*C present in the exhalatory CO, originating from the first experiment 

 could be disregarded. Even after administration of a massive dose of methanol 

 the i*C content of the exhalatory CO2 declined in the course of 1 day to less than 

 one per cent of the value observed in the early part of the experiment. 



In contrast to the controls exposed mice could only be applied once. Before 

 starting the irradiation, food but not water was withdrawn from the mice and from 

 the controls at a corresponding time. In those experiments, in which the effect 

 of exposure was not studied immediately after irradiation, but first after the lapse 

 of 1 day, food was withdrawn 40 hr before starting the experiment, as the food 

 consumed and resorbed by the exposed rats differs from that of the controls; 

 -even by pair-feeding this source of error can not be completely eliminated. The 

 experiments were carried out in a thermostat room kept at a constant temperature 

 of 27.1°. The control mice were kept in the same wooden box in which irradiation 

 took place as were the exposed mice. As the amount of COg exhaled shows a diur- 

 nal variation, the experiments had to be carried out always at the same hour. 



The specific activity of the exhaled COg was determined by comparing the 

 activity of BaCOg samples of identical weight (100 mgm) with that of a known 

 aliquot of the methanol injected after converting it into BaCOg. 



RESULTS 



The result of a set of experiments in which after injecting a small 

 amount (3 /<gm) of methanol, the animals were kept previous to the collec- 

 tion of the exhalatory CO2 10 minutes in the apparatus, through which 

 COg-free air passed, is seen in Fig. 1. This figure shows also the results 

 of a second experiment on mice freshly injected the next day; it gives 

 furthermore, the data obtained the third day, when the same animal 

 was exposed to a dose of 1500 r previous to injection of methanol. 



The amount of exhaled CO2 by the same group of mice is mostly show- 

 ing quite appreciable variations, even if the exhalatory CO2 is collected 



